# Mic thoughts



## Phillips

Hi this is my first thread on the shack.
Can i use a Dayton Omnimic (USB) with a external sound card with REW?


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## JohnM

You should be able to use the Omnimic as the input and your PC's built-in soundcard as the output. You won't be able to make a loopback measurement, so check carefully to make sure the signal from the omnimic is not being fed back out to the audio output.


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## Phillips

Thanks John
How would i go about this, never done this type of thing.


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## JohnM

Not clear what you mean by "this". To make sure the signal picked up by the omnimic is not being fed back to the outputs, talk into or tap the mic and make sure nothing comes out of the speakers. If you were meaning how to go about making measurements, read through the REW help and the threads linked in the Information Index - Links - Guides sticky.


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## Phillips

Hi John 

Sorry i meant how to wire it up. By doing it this way is it going to be accurate, i hear that laptop soundcards are not good.

1. Hook up via USB
2. What connection do i use for the output for the laptop, e.g from the laptop to the stereo?

Is all this i need?
I have a calibration file, so do i just follow the instructions as normal for setting up the calibration?


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## JohnM

Laptop soundcards are fine, from the laptop use the 'Headphone' or 'Speakers' output. You can load your mic cal file from the REW Mic/Meter preferences.


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## Phillips

Hi John thank you.

As this doesn't appear to be normal setup where/when do i take on the instructions (help) setup after all the connections have breen made?


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## gnojham

JohnM said:


> Laptop soundcards are fine, from the laptop use the 'Headphone' or 'Speakers' output. You can load your mic cal file from the REW Mic/Meter preferences.


as a noob, im interested in this. i have been reading the help guide, and it says we will need "A soundcard (internal or external) with line inputs and outputs. Note that most PC and laptop mic inputs are NOT suitable and should not be used (they have too much gain and most suffer from high noise levels and limited bandwidth)."

are you saying we can hook our mic up to the laptop mic input and connect the laptop headphones output to the receiver? or am i not understanding something in your statement? 

im hoping we can actually use the laptop mic and headphone jacks, because that seems easier.


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## Phillips

gnojham said:


> as a noob, im interested in this. i have been reading the help guide, and it says we will need "A soundcard (internal or external) with line inputs and outputs. Note that most PC and laptop mic inputs are NOT suitable and should not be used (they have too much gain and most suffer from high noise levels and limited bandwidth)."
> 
> are you saying we can hook our mic up to the laptop mic input and connect the laptop headphones output to the receiver? or am i not understanding something in your statement?
> 
> im hoping we can actually use the laptop mic and headphone jacks, because that seems easier.


John will correct me if i am wrong, but the mic i have is USB, and has a calibration file. I cannot use a outboard soundcard/preamp with my mic. 
It is 8pm over here at present, John normally responds by the morning. 
What mic do you have?


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## gnojham

Phillips said:


> John will correct me if i am wrong, but the mic i have is USB, and has a calibration file. I cannot use a outboard soundcard/preamp with my mic.
> It is 8pm over here at present, John normally responds by the morning.
> What mic do you have?


i dont have a mic as of yet
i have no hardware yet
im just trying to get some type of understanding of most of this so i know what i need to buy. hopefully i can get everything at once from the same spot so i dont have to pay multiple shipping fees for no reason.


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## Phillips

gnojham said:


> i dont have a mic as of yet
> i have no hardware yet
> im just trying to get some type of understanding of most of this so i know what i need to buy. hopefully i can get everything at once from the same spot so i dont have to pay multiple shipping fees for no reason.


Personally i would go with a Dayton EMM-6 Electret Measurement Microphone, they are calibrated and you get a TXT file to import into the software. You can purchase this from Parts Express and then buy a Mic Preamp/soundcard. I am not sure which ones Parts Express stock. M-Audio Fast Track Pro USB 48V seems to be popular. 
They can also supply the cabling required.
Room EQ Wizard software is free, John is the designer of this software.


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## Zeitgeist

I would actually highly recommend buying a mic that's already calibrated from Cross Spectrum Labs.

The EMM-6 calibration that comes from Parts Express isn't great. It's plus or minus 2-3 db, and off by as much as 5db in some cases.

http://www.cross-spectrum.com/measurement/calibrated_dayton.html


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## gnojham

Phillips said:


> Personally i would go with a Dayton EMM-6 Electret Measurement Microphone, they are calibrated and you get a TXT file to import into the software. You can purchase this from Parts Express and then buy a Mic Preamp/soundcard. I am not sure which ones Parts Express stock. M-Audio Fast Track Pro USB 48V seems to be popular.
> They can also supply the cabling required.
> Room EQ Wizard software is free, John is the designer of this software.


yeah, parts express is where i get most of my parts


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## JohnM

Phillips said:


> As this doesn't appear to be normal setup where/when do i take on the instructions (help) setup after all the connections have been made?


Just skip the "Calibrating the soundcard" section of the help.


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## Phillips

JohnM said:


> Just skip the "Calibrating the soundcard" section of the help.


Thanks John

So the connection would be stereo 3.5? head phone jack to RCA?


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## Phillips

Zeitgeist said:


> I would actually highly recommend buying a mic that's already calibrated from Cross Spectrum Labs.
> 
> The EMM-6 calibration that comes from Parts Express isn't great. It's plus or minus 2-3 db, and off by as much as 5db in some cases.
> 
> http://www.cross-spectrum.com/measurement/calibrated_dayton.html


Thanks
I thought that as long as you had the INDIVIDUAL CALIBRATION TXT FILE the software would take care of the interfections?
Maybe John could chip in here?


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## JohnM

Phillips said:


> So the connection would be stereo 3.5? head phone jack to RCA?


Yup


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## JohnM

Phillips said:


> I thought that as long as you had the INDIVIDUAL CALIBRATION TXT FILE the software would take care of the interfections??


The concern is how good (or not) the PE calibration data is.


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## Phillips

JohnM said:


> The concern is how good (or not) the PE calibration data is.


Hi John
How do you know if the data is accurate?
How do you know any other calibration data is more accuate than another?
With your experience how accurate is the data file from PE?


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## Zeitgeist

Phillips said:


> Hi John
> How do you know if the data is accurate?
> How do you know any other calibration data is more accuate than another?
> With your experience how accurate is the data file from PE?


Here is a useful post by Herb of Cross Spectrum Labs:
http://www.htguide.com/forum/showpost.php4?p=472257&postcount=84

I'm not pushing his services - but my experiences with the Dayton calibration -- and what he provided were similar.

I trust that Cross Spectrum's calibrations are accurate, even if they are not NIST traceable. My measurements aren't THAT important!


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## Phillips

Hi 
I have a Acer 4315 Vista Home Basic laptop that i am trying to setup but there is no sound from the headphone jack, but when unplugged there is sound from the speakers when playing a CD. I have connected with a 3.5mm stereo adapter to twin RCA (RED & WHITE) but only using a single RCA cable (RED on the adapter) to the stereo end which has a Y Adapter. Do i need to run twin RCA from the adapter (Laptop end) to the receiver to make it work?

1. With the mic placement for setting up REW is this critrical?
2. Setup at the quietest time of the day?
3. My speakers go down to about 35hz is it best to leave them at full range when doing the setup or add the subs so it goes down to 10hz?
4. I have a calibration file that i have loaded into the mic/meter tab, do i tick the c weighting box, i have no c SPL Meter e.g. Radio Shack just a Omnimic microphone.

Also please suggest the settings below keeping in mind i have the Omnimic USB mic + using the laptop soundcard and using Vista
*Output Device and Output*
Default Device
Primary Sound Driver
Speakers (Realtek High Defination Audio
Java Sound Audio Engine

Default Output (this is the only option drop down box doesn’t work)

*Input Device and Input*
Default Device
Primary Sound Capture Driver
Microphone (2-Omnimic
Microphone (Realtek High Defination Audio

Default Input
MICROPHONE (Master Volume)


I would appreciate help
Thank you


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## Diskohouse

@Phillips
I would suggest doing more reading as the questions you are asking are basics and are already answered in this forum. I would also check out http://polaraudio.blogspot.com/2012/01/calibration.html and redspade-audio.blogspot.com/2011/05/quickstart-guide-to-bass-measurements.html 

Please take the time to read the manual...it's not fun, but it will answer many of your questions. I have spent hours upon hours reading about this stuff and there will always be something new to learn.


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## Phillips

Diskohouse said:


> @Phillips
> I would suggest doing more reading as the questions you are asking are basics and are already answered in this forum. I would also check out http://polaraudio.blogspot.com/2012/01/calibration.html and redspade-audio.blogspot.com/2011/05/quickstart-guide-to-bass-measurements.html
> 
> Please take the time to read the manual...it's not fun, but it will answer many of your questions. I have spent hours upon hours reading about this stuff and there will always be something new to learn.


Thanks for that. I can't seem to find help (unless i have been looking to long on the website and missed something in front of me) with the below. 
Just wondering because i am using a Omnimic mic (USB) and using the built in laptop soundcard.

I managed to get sound out of the headphone jack but no matter what i did (turn up the volume on both the receiver & computer) it didn't seem loud enough. 
Just wondering because i am only running a single RCA cable from the laptop to the receiver? The adapter is stereo 3.5mm to twin RCA then run a single RCA to the reciver which has a Y adaptor. 
Should i be using both RCA (running stereo from laptop to receiver)?


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## Phillips

Hi i have a question about the check levels. If the "out" meter is measureing -12db FS and the "left" & "right" meters are reading 18db FS is this ok?
If i adjust the level in the "microphone properties" in the computer settings (Vista) what will this do? 

Thank you


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## JohnM

Phillips said:


> Hi i have a question about the check levels. If the "out" meter is measureing -12db FS and the "left" & "right" meters are reading 18db FS is this ok?


Yes



> If i adjust the level in the "microphone properties" in the computer settings (Vista) what will this do?


Quickest would be to make the adjustments and look at the effect directly, but it should alter the input levels (those shown on the left and right meters) if that is the input you are using for REW.


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## Phillips

JohnM said:


> Yes
> 
> Quickest would be to make the adjustments and look at the effect directly, but it should alter the input levels (those shown on the left and right meters) if that is the input you are using for REW.




Thanks John. Please can you help for the following. By the way great software. 

I have done some more measurements and all of a sudden 

1. The "level is low", i hadnt adjusted anything yet. I adjusted the mic input in the computer and it made a slight difference, i went from volume = 33 to 70. I have noticed that the "left" & "right" meters are at a different level when checking the level. The "left" meter is higher than the "right" meter, before the "left" & "right" meters where even.
2. When doing measurements the headroom colour (red, green, blue) changes, how do i read into this?
3. I have calibrated the SPL with the same mic against the Omnimic SPL software using the REw test signal, would this have anything to do with the changes?
4. The settings i have done on the "soundcard" tab is *OUTPUT DEVICE AND OUTPUT* Speakers (Realtek High Definition Audio) & Default Output + *INPUT DEVICE AND INPUT* Omnimic & Default Input, but i have noticed that there is Master Mic Volume as well for the Input

Look forward to your reply.


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## JohnM

Phillips said:


> all of a sudden


Do you mean all was working OK but then stopped working without any change being made?



> 1. The "level is low", i hadnt adjusted anything yet. I adjusted the mic input in the computer and it made a slight difference, i went from volume = 33 to 70. I have noticed that the "left" & "right" meters are at a different level when checking the level. The "left" meter is higher than the "right" meter, before the "left" & "right" meters where even.


Which input have you told REW to use on the Soundcard tab? Does the Omnimic produce a stereo signal or a mono signal?


> 2. When doing measurements the headroom colour (red, green, blue) changes, how do i read into this?


The colour reflects the level at the time (high/OK/low), it is the final figure that matters.


> 3. I have calibrated the SPL with the same mic against the Omnimic SPL software using the REw test signal, would this have anything to do with the changes?


No


> 4. The settings i have done on the "soundcard" tab is *OUTPUT DEVICE AND OUTPUT* Speakers (Realtek High Definition Audio) & Default Output + *INPUT DEVICE AND INPUT* Omnimic & Default Input, but i have noticed that there is Master Mic Volume as well for the Input


If there is another option for input may as well try it to see what happens.


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## Phillips

JohnM said:


> Do you mean all was working OK but then stopped working without any change being made?
> 
> 
> 
> Hi John basically yes, i was getting measurements with very little effort, with the levels being in the red knowing the levels for full range (-10) & subs only (-3) and thought to have both meters producing equal level. But now the levels are in the blue and had to adjust the mic input in the computer (Vista) from 33 to 89 to just in the green. When doing a check levels before measuring it was ok but now to low.
> 
> 
> 
> Which input have you told REW to use on the Soundcard tab? Does the Omnimic produce a stereo signal or a mono signal?
> 
> 
> 
> The Omnimic for the top and default for the next one down.
> Checked with Omnimic and they said the test tracks (CD) are stereo but the mic is mono.
> 
> The colour reflects the level at the time (high/OK/low), it is the final figure that matters.
> 
> 
> 
> If there is another option for input may as well try it to see what happens.


 I will try again


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## JohnM

Note that by "which input" I meant "which input channel", i.e. left or right.


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## Phillips

JohnM said:


> Note that by "which input" I meant "which input channel", i.e. left or right.




Hi John, the right.

Would a preamp/soundcard work better with the USB mic? I was thinking going from the Omnimic mic (USB) to the laptop (USB) then from the laptop (USB) to the preamp/soundcard (USB) then from the preamp/soundcard to the receiver.The only problem is that there wouldn't be a loopback, or could that be done?


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## JohnM

No, you can't have a loopback connection with the Omnimic as the input device. If the mic can be separated from the USB interface then the mic could probably be used with a preamp and a soundcard, or a combined soundcard/pre.


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## Phillips

JohnM said:


> No, you can't have a loopback connection with the Omnimic as the input device. If the mic can be separated from the USB interface then the mic could probably be used with a preamp and a soundcard, or a combined soundcard/pre.





Hi John thank you. 
1. I can get my hands on a Steinberg CI 1 preamp/soundcard very easily.

2. When using a external pre/soundcard do you have to do a loopback.

3. _*I was thinking going from the Omnimic mic (USB) to the laptop (USB) then from the laptop (USB) to the preamp/soundcard (USB) then from the preamp/soundcard to the receiver.*_ Wouldn't this work?

4. Is using the right channel ok (as per earlier post)?


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## SAC

You have to use the loopback if you want the time of flight time arrival from source to receiving mic display to be accurate.*

And a time based measurement looses quite a bit of its usefulness if the time scale is not referenced to a true point of origin. (Which should also give you a pretty good estimate of how 'useful' is the ETC in OmniMic that is sourced from a sweep in a CD player that is not synced in any way to the time of origin.)

(I will condition this statement as I am not going to get into a few possible techniques that are beyond the capability of even more of the common hardware configurations and tools...as it will do little more than further confuse things)


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## JohnM

Phillips said:


> 2. When using a external pre/soundcard do you have to do a loopback.


There are two uses of a loopback connection. 

1. When setting up the system, a loopback connection between the output and input that will be used to measure is put in place to calibrate the signal chain so that roll-offs in the chain can be removed from the measurement - this is the "soundcard calibration" process. It also has the benefit of highlighting any inadvertent monitoring settings that cause feedback loops which would render measurements invalid. If your input is a USB microphone you will not be able to do this, so you will not be able to compensate for roll-offs (not a major issue) and you need another method to ensure there are no feedback loops - with the REW output connected to your system, talk into the mic and make sure that when you do that you do not hear your voice through the speakers.

2. When making measurements, a loopback connection between the output and input that are _not_ being used for measurement can provide REW with a timing reference. This is not required for typical home theater system measurement and tuning.



> 3. _*I was thinking going from the Omnimic mic (USB) to the laptop (USB) then from the laptop (USB) to the preamp/soundcard (USB) then from the preamp/soundcard to the receiver.*_ Wouldn't this work?


Sure, but you would not be making any use of a preamp as the soundcard would only be used for the REW output.



> 4. Is using the right channel ok (as per earlier post)?


If the Omnimic puts its signal on the right channel, yes - if you talk into the mic does the input level meter on the right channel change? If it does then OK to use that input channel.


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## Phillips

JohnM said:


> Sure, but you would not be making any use of a preamp as the soundcard would only be used for the REW output.
> 
> 
> Thanks John, would this be better than usin the computers soundcard?
> 
> 
> If the Omnimic puts its signal on the right channel, yes - if you talk into the mic does the input level meter on the right channel change? If it does then OK to use that input channel.



I did some more measurements last night, and ended up changing the channel to left, and it worked. The final result was 9db (green) headroom, this ok? The other meter moves as well, not much though, is this normal?

I have calibrated the SPL meter on REW using the SPL meter on Omnimic software as the reference, but when measuring on the REW frequency graph the SPL shows a fall of 8-9db below the 75db calibration, in other words showing 65db, does this matter?


I have noticed that there is a 22db null @ 490hz and 17db null @ 979hz then a 6.8db peak @ 1.97khz and 5db peak @ 3.90khz.
This does not show on the Omnimic software at all.


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## Doctor X

> I have noticed that there is a 22db null @ 490hz and 17db null @ 979hz then a 6.8db peak @ 1.97khz and 5db peak @ 3.90khz.
> This does not show on the Omnimic software at all.


Does this mean that the Omnimic (mic or software) is inaccurate?


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## Phillips

Vaughan100 said:


> Does this mean that the Omnimic (mic or software) is inaccurate?




I don't think so, i have had other measuring equipment in this room before and didn't have this problem.

It seems to be similar at the low end.

Hopefully John will have an answer.


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## JimP

Interesting thread.

I've been looking at the omnimic as well as I'm pretty burned out dealing with the external sound card, sound mixer, etc. Sure would be nice if all I had was a mic plugged into the usb port and an audio out cable coming from my laptop's audio out.

I suspect what I'll do is get the omnimic and do a comparison of it versus my current setup and if necessary, come up with some corrections.


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## JohnM

Phillips said:


> I have noticed that there is a 22db null @ 490hz and 17db null @ 979hz then a 6.8db peak @ 1.97khz and 5db peak @ 3.90khz.


Perhaps some smoothing is applied to the Omnimic measurement. I think it is possible to export measurements from Omnimic and then import them into REW, you could then see better how they compare.


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## Phillips

JohnM said:


> Perhaps some smoothing is applied to the Omnimic measurement. I think it is possible to export measurements from Omnimic and then import them into REW, you could then see better how they compare.



Thanks John i have tried that and they are very DIFFERENT.
Very simliar in the low region 400hz down.

Any suggestions, maybe its the soundcard in the laptop or maybe the mic? If the mic is ok with the Omni software then it must be ok in theory.

I noticed that using the Left input channel setting and also plugging in the USB mic before i start the laptop it recognizes the settings in the mic input level (control panel) and the other settings, input and output. 

The only problem is this difference in the graphs/measurements from 400hz up.

I am so close.

Please help.


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## Phillips

JimP said:


> Interesting thread.
> 
> I've been looking at the omnimic as well as I'm pretty burned out dealing with the external sound card, sound mixer, etc. Sure would be nice if all I had was a mic plugged into the usb port and an audio out cable coming from my laptop's audio out.
> 
> I suspect what I'll do is get the omnimic and do a comparison of it versus my current setup and if necessary, come up with some corrections.




Jim keep an eye on this thread, hopefully all will be sorted.

John is very knowledgeable.


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## Doctor X

Phillip, I'm also watching your thread with interest. I am very keen on this software/mic combo but before I pull the trigger I need to know that it's accurate enough for measuring. 

There are plenty of features on REW that I probably would never need. I just need to measure frequency response, LF decay and see waterfalls.  Those are the features I would making use of most. All the other stuff is icing on the cake. 

I'm not sure if any in-depth comparions have been made between REW and Omnimic, at least in terms of measuring resolution/accuracy. I also heard of some mic issues on AVSforums, but I believe these issues are being rectified.


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## Phillips

Vaughan100 said:


> Phillip, I'm also watching your thread with interest. I am very keen on this software/mic combo but before I pull the trigger I need to know that it's accurate enough for measuring.
> 
> There are plenty of features on REW that I probably would never need. I just need to measure frequency response, LF decay and see waterfalls.  Those are the features I would making use of most. All the other stuff is icing on the cake.
> 
> I'm not sure if any in-depth comparions have been made between REW and Omnimic, at least in terms of measuring resolution/accuracy. I also heard of some mic issues on AVSforums, but I believe these issues are being rectified.




I don't think there is any problem with accuracy with either, i am hoping it is something i have set or simple. 

Hopefully John will have a resolution.


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## JohnM

Phillips said:


> Thanks John i have tried that and they are very DIFFERENT.
> Very simliar in the low region 400hz down.


Probably smoothing, try adjusting the smoothing on the REW trace and see if the traces start to match better. Would also be handy if you post an image of the graphs, a picture is worth a thousand words and all that


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## Phillips

JohnM said:


> Probably smoothing, try adjusting the smoothing on the REW trace and see if the traces start to match better. Would also be handy if you post an image of the graphs, a picture is worth a thousand words and all that




Hi John thank you for the reply. I will try to upload the graphs, looks like there is a difference in smoothing but the nulls still look severe.

Tried variant smoothing on REW to match the Omni but still not right, the severe nulls still remain.

I tried it without the TXT mic/meter calibration file but made very little difference to the overall graph. I have included the mic measuremnt in the REW file.

I can only load the REW graph so far.


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## Phillips

JohnM said:


> Probably smoothing, try adjusting the smoothing on the REW trace and see if the traces start to match better. Would also be handy if you post an image of the graphs, a picture is worth a thousand words and all that




Hi John here is the Omni graph imported into REW, this was also 1/6 smoothing and the same mic + position.

Please don't take any notice from about 160hz down i had the subs on a different setting.


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## JohnM

Could you post the .mdat file of the REW measurement?


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## Phillips

View attachment Full Range Set 5 12_15.mdat


JohnM said:


> Could you post the .mdat file of the REW measurement?




Hi John thank you, attached is the .mdata file.

I have been playing around with the find resonances feature and find it useful.


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## JohnM

Thanks, I was a little concerned at what looked like a regular pattern of peaks at high frequencies in your measurement. Looking closely at the impulse response, there are 4 peaks of pretty much equal amplitude, and I see the measurement used 4 sweeps. That indicates a problem with the synchronisation of the sweeps, which can occur if (for example) the soundcard is operating at a different sample rate than REW is set to and the results are being resampled by the operating system. You might find that changing REW to 44.1kHz resolves that, but it would be safest to make measurements with single sweeps rather than multiple sweeps. You should disregard the measurements made with multiple sweeps.


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## Phillips

JohnM said:


> Thanks, I was a little concerned at what looked like a regular pattern of peaks at high frequencies in your measurement. Looking closely at the impulse response, there are 4 peaks of pretty much equal amplitude, and I see the measurement used 4 sweeps. That indicates a problem with the synchronisation of the sweeps, which can occur if (for example) the soundcard is operating at a different sample rate than REW is set to and the results are being resampled by the operating system. You might find that changing REW to 44.1kHz resolves that, but it would be safest to make measurements with single sweeps rather than multiple sweeps. You should disregard the measurements made with multiple sweeps.





Hi John i changed from 4 to 1 sweep it seem to work.

With the 44.1k REW setting, the sweeps have a noise at the end of the measurement, when i change it to 48k the noise goes away.


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## Phillips

JohnM said:


> Thanks, I was a little concerned at what looked like a regular pattern of peaks at high frequencies in your measurement. Looking closely at the impulse response, there are 4 peaks of pretty much equal amplitude, and I see the measurement used 4 sweeps. That indicates a problem with the synchronisation of the sweeps, which can occur if (for example) the soundcard is operating at a different sample rate than REW is set to and the results are being resampled by the operating system. You might find that changing REW to 44.1kHz resolves that, but it would be safest to make measurements with single sweeps rather than multiple sweeps. You should disregard the measurements made with multiple sweeps.



View attachment Test Measurements.mdat



Hi John attached is the new measurements to back my previous post.

I have labelled noise and quiet.With the noisy sweeps the very high end is effected, don't know if that helps.

Also there is on the spectrogram sharp lines on 50hz, 100hz etc please can you check that out, i am not sure which set of measurements. If there isn't any please let me know and i will post more. This doesn't happen 100% of the time.


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## JohnM

Best stick with 48k and single sweep. The line at 50Hz is probably mains hum pick-up, it can be identified as an external signal rather than part of the measurement as it does not decay and is also present before the measured response starts. Hum can also appear at harmonics of 50Hz, it can be picked up in cabling or be caused by ground loops in equipment wiring.


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## Phillips

JohnM said:


> Best stick with 48k and single sweep. The line at 50Hz is probably mains hum pick-up, it can be identified as an external signal rather than part of the measurement as it does not decay and is also present before the measured response starts. Hum can also appear at harmonics of 50Hz, it can be picked up in cabling or be caused by ground loops in equipment wiring.




Hi John thank you.

Is there anyway i can avoid/get rid of this hum, i am not using the mains to power the laptop?

At what level should i use to Find Resonances, are the measurements i posted at the right level?

How do I use the Find Resonances for measurements?

I have set the EQ window to SMS-1 for the sub.

I have Velodyne Digital Drive sub (with PEQ the same as the SMS-1) and the Receiver is a Yamaha Z9 which has a manual graphic equalizer , not sure how to describe it but it has 63, 125, 250, 500, 1000, 2000, 4000, 8000, 16000hz.


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## JohnM

Don't bother with find resonances for SMS-1, just select the correct target response shape for your sub in the Target Settings panel, use *Set Target Level* to set the level of the target response and *Match Response to Target* in the Filter Tasks panel to generate filter settings for the SMS-1.


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## Phillips

JohnM said:


> Don't bother with find resonances for SMS-1, just select the correct target response shape for your sub in the Target Settings panel, use *Set Target Level* to set the level of the target response and *Match Response to Target* in the Filter Tasks panel to generate filter settings for the SMS-1.




Thanks John

Can i get rid of that hum, i don't use the mains on the laptop?

Have you any suggestions on the how to use REW for the Z9s Graphic EQ?

Does REW find room modes in the bass region that is why looked at the Room Resonances?


----------



## JimP

phillips,

Regarding hum, I use to have that problem when I was using a power adapter to run my laptop. Disconnected the power adapter and ran only on laptop battery and the hum went away.


----------



## Phillips

JimP said:


> phillips,
> 
> Regarding hum, I use to have that problem when I was using a power adapter to run my laptop. Disconnected the power adapter and ran only on laptop battery and the hum went away.



Hi Jimp

Yeah i thought this might be the problem but i have always used the laptops battery. 

Any other suggestions?

Maybe measuring at night or different time of the day?


----------



## Wayne A. Pflughaupt

Phillips said:


> Have you any suggestions on the how to use REW for the Z9s Graphic EQ?


Hey Phillips,

Your best bet there is to use REW’s RTA feature. It will let you instantly see changes the Z9 equalizer makes to response. You just have to keep in mind that the graphic EQ isn’t going to be terribly precise and respect its limitations – i.e. it can’t address a problem you might have at 700 Hz, for instance. Of course, you need to be set up for full-range measurements, specifically a mic with custom calibration. You don’t want to do any equalizing to the main channels based on a generic calibration file.

BTW, I have a Z9 – nice unit!

Regards,
Wayne


----------



## Phillips

Wayne A. Pflughaupt said:


> Hey Phillips,
> 
> Your best bet there is to use REW’s RTA feature. It will let you instantly see changes the Z9 equalizer makes to response. You just have to keep in mind that the graphic EQ isn’t going to be terribly precise and respect its limitations – i.e. it can’t address a problem you might have at 700 Hz, for instance. Of course, you need to be set up for full-range measurements, specifically a mic with custom calibration. You don’t want to do any equalizing to the main channels based on a generic calibration file.
> 
> BTW, I have a Z9 – nice unit!
> 
> Regards,
> Wayne



Thanks Wayne
View attachment Main Speakers Full Range EQ Defeat.mdat


I have attached a m.data as reference.

Hi Wayne thanks. I always measure full range, with both with speakers or subs. 

Did you use the Auto EQ on the Z9; I agree it is fantastic amp especially for music, which it got high marks in reviews. I listen to mainly 2 channel (90%), multichannel music (5%) and movies (5%).

I have noticed that using smaller speakers have made a difference, I was using Energy Veritas 2.3i (floorstanders), now using Paradigm S2 Signature. I have tried the Proac Tablettes Signature Ref sounded improved without having to use the graphic eq. I thought it might have been the equipment but have tried different speakers and amps with similar results. As subs i have two, Velodyne DD12 + DD15. 

The sound without EQ has a drone, honky, murky, cloudy, no clarity between vocal and music sound. Its like the treble has been turned right down and a couple of frequencies have been increased significantly. I reduced the 63 & 125 & 250hz down to -6 and especially the 125hz made a difference in the bass region. The high end i increased as well to bring clarity to voices etc. 

I have attached measurements labelled which only has the EQ defeat measurements for the combined mains (left & right) + individual. Please can you look at these?

The Omnimic has its own specific calibration file.

What graphs/frequencies should be used for what? 

Find resonances look interesting if you have the right eq system? How is this used in the right way?

Do you have a PEQ attached to your Z9? I hear that you can setup this way. One thing that worries me if it would changes the characteristics of the Z9.


----------



## Wayne A. Pflughaupt

Hey Phillips, 



Phillips said:


> I have attached measurements labelled which only has the EQ defeat measurements for the combined mains (left & right) + individual. Please can you look at these?


I just installed a new operating system on my computer and haven’t yet re-installed REW – it’s on my “to do” list. Perhaps you could just post some .jpg’s of your response graphs.




> Did you use the Auto EQ on the Z9;


I haven’t used the Z9’s auto EQ function – I only got it a few months ago and had managed to misplace the mic. I used the one from the RX-V2500 in my bedroom system. That shouldn’t have mattered for the auto level and distance setting procedures, but I didn’t want to do an auto EQ without the proper mic. I’ve since re-located the correct mic; running the auto EQ is – you guessed it – on my “to do” list. 




> Do you have a PEQ attached to your Z9? I hear that you can setup this way.


Yes I have a PEQ across my front three channels. It’s easily accomplished with the Z9, as it has both pre-outputs and amp inputs for the front three channels. Just connect the Yamaha’s “pre out” jacks to the equalizer inputs, and the equalizer outputs to the Yamaha’s “amp in” connections. Yamaha had these connections on their flagship models for many years, but has discontinued the practice. As far as I can tell, the Z9 was the last flagship receiver with the front amp inputs.




> One thing that worries me if it would changes the characteristics of the Z9.


Only if the equalizer is an inferior model. Doesn’t pay to “cheap out” when using an outboard equalizer.

Regards,
Wayne


----------



## Phillips

Wayne A. Pflughaupt said:


> Hey Phillips,
> 
> I just installed a new operating system on my computer and haven’t yet re-installed REW – it’s on my “to do” list. Perhaps you could just post some .jpg’s of your response graphs.
> 
> *I think it would pay to look at the whole picture, if thats ok, that would be really appreciated. It takes a real long time to send attachments for some reason. Sometimes it doesn't send, i have to try several times.*
> 
> I haven’t used the Z9’s auto EQ function – I only got it a few months ago and had managed to misplace the mic. I used the one from the RX-V2500 in my bedroom system. That shouldn’t have mattered for the auto level and distance setting procedures, but I didn’t want to do an auto EQ without the proper mic. I’ve since re-located the correct mic; running the auto EQ is – you guessed it – on my “to do” list.
> 
> *Please could you post back when you have experienced the Auto PEQ?*
> 
> Yes I have a PEQ across my front three channels. It’s easily accomplished with the Z9, as it has both pre-outputs and amp inputs for the front three channels. Just connect the Yamaha’s “pre out” jacks to the equalizer inputs, and the equalizer outputs to the Yamaha’s “amp in” connections. Yamaha had these connections on their flagship models for many years, but has discontinued the practice. As far as I can tell, the Z9 was the last flagship receiver with the front amp inputs.
> 
> 
> Only if the equalizer is an inferior model. Doesn’t pay to “cheap out” when using an outboard equalizer.
> 
> *Which PEQ have you connected to your Z9 and if you have any suggestions going of my last posted measurements. *
> 
> Regards,
> Wayne


*Just to add to the SOUND on my last post was very dry/drony. I wonder if they are out of phase?*
*When eqing the front speakers does it pay to eq them seperately first, to find the problem side/speaker then combined?*

Thanks Wayne appreciate your help.[/B]


----------



## Phillips

Hi have managed to send the attached graphs of my mains running full range. They are Paradigm S2 Reference stand mounts.

Could someone please comment on these graphs, combined they sound drony, honky, murky, cloudy, dry, no clarity between vocal and music sound. 

When eqing the front speakers does it pay to eq them seperately first, to find the problem side/speaker then combined?

Thank you

Read more: Mic thoughts - Page 6 - Home Theater Forum and Systems - HomeTheaterShack.com


----------



## Wayne A. Pflughaupt

Phillips said:


> [Just to add to the SOUND on my last post was very dry/drony. I wonder if they are out of phase?


Easy way to tell, flop the positive and negative on one of the speakers and see if the bass increases or decreases. If the latter, then one speaker has the polarity reversed. That said, I would think the Z9’s auto calibration would detect reversed polarity...




Phillips said:


> Could someone please comment on these graphs, combined they sound drony, honky, murky, cloudy, dry, no clarity between vocal and music sound.


The individual graphs look really good. I can’t readily see any obvious problem that would account for the “honky” sound quality you’re hearing. Except that perhaps response may be a little _too_ flat. I’d suggest using the basic tone control to increase the overall bass level. If that doesn’t work, then perhaps the S2’s just aren’t the speakers for you.

Have you run the Z9’s auto EQ function?




> When eqing the front speakers does it pay to eq them seperately first, to find the problem side/speaker then combined?


Ordinaily I’d say EQ them combined above 400 Hz (i.e. matching filters for both channels), and independently below 400 Hz, if the measurements indicate that is needed. However, you really don’t need any equalization for the upper frequencies. 

You do appear to have a problem in one speaker that reaches above 400 Hz that could be addressed. Which gets us to the only problem I see that’s probably audible, a broad trough between 250 and 600 Hz that appears when both speakers are operating.

This could be addressed by separately EQing each speaker: 

The left, by bringing up the notch at 300 Hz, then a second filter for the broader area between 250 - 550 Hz. (Note: if the 300 Hz filter doesn’t respond to equalization, then eliminate it).

The right speaker, decrease the peak at 250 Hz a bit, and raise the broad area centered at450 Hz.

These steps should adequately fill up the combined 250 Hz – 600 Hz trough.

It’s possible that the auto EQ function could recognize and address these problems.

Regards,
Wayne


----------



## Phillips

Wayne A. Pflughaupt said:


> Easy way to tell, flop the positive and negative on one of the speakers and see if the bass increases or decreases. If the latter, then one speaker has the polarity reversed. That said, I would think the Z9’s auto calibration would detect reversed polarity...
> 
> 
> The individual graphs look really good. I can’t readily see any obvious problem that would account for the “honky” sound quality you’re hearing. Except that perhaps response may be a little _too_ flat. I’d suggest using the basic tone control to increase the overall bass level. If that doesn’t work, then perhaps the S2’s just aren’t the speakers for you.
> 
> Have you run the Z9’s auto EQ function?
> 
> 
> Ordinaily I’d say EQ them combined above 400 Hz (i.e. matching filters for both channels), and independently below 400 Hz, if the measurements indicate that is needed. However, you really don’t need any equalization for the upper frequencies.
> 
> You do appear to have a problem in one speaker that reaches above 400 Hz that could be addressed. Which gets us to the only problem I see that’s probably audible, a broad trough between 250 and 600 Hz that appears when both speakers are operating.
> 
> This could be addressed by separately EQing each speaker:
> 
> The left, by bringing up the notch at 300 Hz, then a second filter for the broader area between 250 - 550 Hz. (Note: if the 300 Hz filter doesn’t respond to equalization, then eliminate it).
> 
> The right speaker, decrease the peak at 250 Hz a bit, and raise the broad area centered at450 Hz.
> 
> These steps should adequately fill up the combined 250 Hz – 600 Hz trough.
> 
> It’s possible that the auto EQ function could recognize and address these problems.
> 
> Regards,
> Wayne




Thanks Wayne

Acutually i was thinking of the Auto Eq the other day.

Which Auto Eq would you recommend e.g Check Flat, Front, Low, Mid, High?

Thank you


----------



## Wayne A. Pflughaupt

Can’t say since I’ve never used the auto EQ function. You might try each and see what they get you in the 250-600 Hz region.

Regards, 
Wayne


----------



## Phillips

Z9s Graphic EQ settings:
Left Speaker 
63hz + 3.0 
125hz + 1.5 
250hz - 0.5 
500hz + 0.5
1000hz + 2.0
2000hz + 0.5
4000hz + 4.0
8000hz + 4.0
16000hz 0

Right Speaker 
63hz + 1.5
125hz 0 
250hz - 3.0 
500hz + 0.5
1000hz + 2.0
2000hz + 0.5
4000hz + 4.0
8000hz + 4.0
16000hz 0









Z9 Graphic EQ settings

Both speakers exactly the same settings

63hz 0
125hz 0
250hz - 2.0
500hz + 0.5
1000hz + 2.0
2000hz + 0.5
4000hz + 4.0
8000HZ + 4.0
16000HZ 0


I have changed to 1/3 smoothing instead of 1/6.
With + 4.0 on 2000 & 4000 has taken the veil away and is clearer. The sound without these boosts sounds like the treble has been turned right down.
I have used the Auto YPAO Check Front and this didn't make a very good job, i will post the graph tomorrow.
I have a Velodyne DD12 & 15, what crossover going of the graphs above would you recommend?


----------



## Wayne A. Pflughaupt

The 250-600 Hz range does look better, but it’s hard to say for sure since you switched to 1/3-octave smoothing. Makes it hard to compare “before and after.”

As far as the crossover frequency, no reason not to go with the usual 80 or 90 Hz.

Regards, 
Wayne


----------



## Phillips

Wayne A. Pflughaupt said:


> The 250-600 Hz range does look better, but it’s hard to say for sure since you switched to 1/3-octave smoothing. Makes it hard to compare “before and after.”
> 
> As far as the crossover frequency, no reason not to go with the usual 80 or 90 Hz.
> 
> Regards,
> Wayne



Thanks Wayne.

I have attached the 1/6th smoothing of the two graphs, sorry about that. 

What is the best smoothing for adjusting EQs?

I have also attached the YPAO Check Front option on the Yamaha.

What is REW graphs best used for and what frequencies e.g. the waterfall best used for bass frequencies only 15-300hz?

























Thanks again


----------



## Wayne A. Pflughaupt

Phillips said:


> What is the best smoothing for adjusting EQs?


For equalizing the main channels I prefer 1/3-octave smoothing. It shows you the general trend of response, which is what you want to equalize anyway (if it’s needed). Finer smoothing gets a more “ragged” graph that tempts people to over-equalize. (I only asked for the 1/6-octave graphs because that’s what we were already working with here, for the sake of comparison.)




> I have also attached the YPAO Check Front option on the Yamaha.


I have no idea what that does, but it doesn’t look like it would sound as good as the other two graphs. The Bass Boost graph does appear to have made a slight difference in the 50 Hz area. Any noticeable difference in the sound?

BTW, are these are full-range graphs for your Signature S2 speakers (no sub)?




> What is REW graphs best used for and what frequencies e.g. the waterfall best used for bass frequencies only 15-300hz?


Yes, waterfalls are best for low frequencies below ~300 Hz. They show low frequency decay times (aka “ringing”). Not a bad FYI display, but mainly useful for comparing “before and after” installing low frequency absorbers like bass traps.

Regards, 
Wayne


----------



## Phillips

Wayne A. Pflughaupt said:


> I have no idea what that does, but it doesn’t look like it would sound as good as the other two graphs. The Bass Boost graph does appear to have made a slight difference in the 50 Hz area. Any noticeable difference in the sound?
> 
> BTW, are these are full-range graphs for your Signature S2 speakers (no sub)?
> 
> *The sound has stronger bass, but sounds more compressed, closed in. The EQ flat sounds best so far, there is a big room mode at 36hz.
> Yes what graphs i have posted are all full range with the S2s, receiver set to large.*
> 
> 
> *I have just done some more measurements and there is a big roll off at 10,000HZ, where on the ones above (EQ flat and Bass Boost) it is resonably flat from 2,000-20,000hz. I put the mic in the same place, i shifted the mic a couple of inches and it didn't make any difference. Is there something wrong?*
> 
> *Thanks Wayne*


----------



## Phillips

Phillips said:


> Wayne A. Pflughaupt said:
> 
> 
> 
> 
> I have no idea what that does, but it doesn’t look like it would sound as good as the other two graphs. The Bass Boost graph does appear to have made a slight difference in the 50 Hz area. Any noticeable difference in the sound?
> 
> BTW, are these are full-range graphs for your Signature S2 speakers (no sub)?
> 
> *The sound has stronger bass, but sounds more compressed, closed in. The EQ flat sounds best so far, there is a big room mode at 36hz.
> Yes what graphs i have posted are all full range with the S2s, receiver set to large.*
> 
> 
> *I have just done some more measurements and there is a big roll off at 10,000HZ, where on the ones above (EQ flat and Bass Boost) it is resonably flat from 2,000-20,000hz. I put the mic in the same place, i shifted the mic a couple of inches and it didn't make any difference. Is there something wrong?*
> 
> *Thanks Wayne*
> 
> 
> 
> 
> 
> 
> 
> 
> Just to add to above
> 
> I did some more measurements again and the roll off at 10,000hz is not there any more, back to normal.
> 
> What could this be?
> 
> Thank you
Click to expand...


----------



## JohnM

Are the sweeps smooth with no gaps or glitches? If there are any problems during the sweep that would lead to corrupted measurements. Some PCs/soundcards also seem to struggle with synchronisation across multiple sweeps so it is best to use single sweeps.


----------



## Phillips

JohnM said:


> Are the sweeps smooth with no gaps or glitches? If there are any problems during the sweep that would lead to corrupted measurements. Some PCs/soundcards also seem to struggle with synchronisation across multiple sweeps so it is best to use single sweeps.



Thanks John

The sweeps don't seem to have any gaps or glitches.

After the last problem (earlier post) with the big nulls etc i have set the input channel to left and single sweeps. I seem to get 6-10db (green) headroom.

Is there anything i can do to fix this?

When i go to reuse the program i have to reset the input device (Ominmic), i thought the program remembered the settings? 

Thank you


----------



## JohnM

Not sure what could be causing the behaviour above 10kHz then. 

Is the Omnimic always plugged in? REW does remember its settings, but for a USB mic (or USB soundcard) you need to make sure it is plugged in before REW starts and until REW is closed, it can not select a device which is not present.


----------



## Phillips

JohnM said:


> Not sure what could be causing the behaviour above 10kHz then.
> 
> Is the Omnimic always plugged in? REW does remember its settings, but for a USB mic (or USB soundcard) you need to make sure it is plugged in before REW starts and until REW is closed, it can not select a device which is not present.



Thanks John

The behaviour above 10,000hz is only happen once, but thru me out a bit. The behaviour was too much to be mic position dependent.


I plug the mic in before i start the computer, then keep it plugged in while shutdown. Sometimes i run cleaners (registry, history etc).


----------



## Phillips

Hi please make sure that my connections are correct.
My mic is the OmniMic (USB).

My connections from my laptop are:
Stereo 3.5mm adapter out (headphones)
*Single RCA* 
Y adapter in to receiver

My question is should i be running Left & Right (instead of single) RCA to my receiver and leaving out the Y adapter on the receiver?

Also when measuring, the Left bar rises to the correct level, but the Right doesn't move much at all. 
Should both of them be moving to the same level?

Thank you


----------



## JohnM

Phillips said:


> My question is should i be running Left & Right (instead of single) RCA to my receiver and leaving out the Y adapter on the receiver?


You can run left and right to the receiver as REW puts its test signal on both channels when using the Java soundcard drivers. You would not necessarily want both connected, however, as you should use either one receiver input or the other when making full range measurements to avoid having both speakers running - if they are both running your measurement will show severe comb filtering unless the distance from the mic to each speaker is identical, full range measurements are best made one speaker at a time.



> Also when measuring, the Left bar rises to the correct level, but the Right doesn't move much at all.
> Should both of them be moving to the same level?


The Omnimic is mono, so it may only put its signal on one input - from your description sounds like that is the left input, so make sure REW is set up (on the soundcard preferences) to use the left input for measurement.


----------



## Phillips

JohnM said:


> You can run left and right to the receiver as REW puts its test signal on both channels when using the Java soundcard drivers. You would not necessarily want both connected, however, as you should use either one receiver input or the other when making full range measurements to avoid having both speakers running - if they are both running your measurement will show severe comb filtering unless the distance from the mic to each speaker is identical, full range measurements are best made one speaker at a time.
> 
> The Omnimic is mono, so it may only put its signal on one input - from your description sounds like that is the left input, so make sure REW is set up (on the soundcard preferences) to use the left input for measurement.




Thanks John

Is the Java Sound Audio Engine (Java Soundcard?) better than the Speakers (Realtek High Definition Audio)? I have that option in the Output Device.

Is the Java Audio Engine the same as Java Soundcard?

For measuring/EQing main front speakers what is the best way to do this? 

1. Measure both together
2. Measure Left then Right
3. Measure Left then Right, then together

Thank you


----------



## JohnM

Phillips said:


> Is the Java Sound Audio Engine (Java Soundcard?) better than the Speakers (Realtek High Definition Audio)? I have that option in the Output Device.
> 
> Is the Java Audio Engine the same as Java Soundcard?


No, by "Java soundcard drivers" I mean the selection box in REW that lets you choose Java or ASIO as the drivers, leave your output device as Speakers.



> For measuring/EQing main front speakers what is the best way to do this?


If you are looking at EQ above the bass range, only use separate speaker measurements. For the bass range it is best to measure with both speakers as most bass content is mixed mono, so both speakers would be reproducing it together. The room reacts differently at low frequencies when two sources are driving it rather than one.


----------



## Phillips

JohnM said:


> No, by "Java soundcard drivers" I mean the selection box in REW that lets you choose Java or ASIO as the drivers, leave your output device as Speakers.
> 
> If you are looking at EQ above the bass range, only use separate speaker measurements. For the bass range it is best to measure with both speakers as most bass content is mixed mono, so both speakers would be reproducing it together. The room reacts differently at low frequencies when two sources are driving it rather than one.



Thanks John

What would you recomend for the frequency cut off for the bass range for EQ?


----------



## Phillips

Hi John

I have attached two graphs.

Both graphs were taken with the same mic and same position exactly. 

I used the Omnimic CD system, then imported the FRD file into REW.

I realize that the Omnimic measurement will be different to a certain degree.

The two are pretty close except from about 600hz down, REW graph has a roll off from about 600hz down vs the Omnimic doesn't. 

What is making this happen?

Thank you


----------



## JimP

Phillips

With Omnimic, you have to be sure that your volume level is high enough to get consistant results.

A good way to confirm this is to save the file, reopen it while continuing to play the test tone(s). As you decrease and increase the volume, you'll see where the graph becomes less/more consistant.


----------



## JohnM

Phillips said:


> The two are pretty close except from about 600hz down, REW graph has a roll off from about 600hz down vs the Omnimic doesn't.
> 
> What is making this happen?


The Omnimic system applies a calibration data correction for the mic response.


----------



## Phillips

JimP said:


> Phillips
> 
> With Omnimic, you have to be sure that your volume level is high enough to get consistant results.
> 
> A good way to confirm this is to save the file, reopen it while continuing to play the test tone(s). As you decrease and increase the volume, you'll see where the graph becomes less/more consistant.



Thanks Jim

I always make sure the results are consistent with the appropiate volume.


----------



## Phillips

JohnM said:


> The Omnimic system applies a calibration data correction for the mic response.



Thanks John.

I have had other software in this room with similiar results to the Omnimic measurements. 

How can i overcome this using REW with the Omnimic microphone?

I have the Omnimic mic calibration file imported in to he Mic/Meter calibration, is this ok?


----------



## JohnM

Phillips said:


> I have the Omnimic mic calibration file imported in to he Mic/Meter calibration, is this ok?


It should be, but check the box to show the cal trace on the graphs to make sure it looks sensible.


----------



## Phillips

JohnM said:


> It should be, but check the box to show the cal trace on the graphs to make sure it looks sensible.



Hi John i have posted the graph with the Omnimic calibration file trace.

You say there is a correction for Omnimic system, was the mic calibration file the only correction?

Is there anything i can do to fix this problem, if it isn't going to give me accurate results?

Thank you


----------



## JohnM

Phillips said:


> You say there is a correction for Omnimic system, was the mic calibration file the only correction?


I presume so, but I don't know much about the Omnimic. If you are convinced there is a systematic difference between the measurement systems you are using you could adjust the calibration file to account for it, either modifying the mic cal file or creating a pseudo soundcard cal file with the required corrections. A way to do that (or at least to make a starting point) could be to make a measurement in REW, import a measurement from Omnimic (without allowing the mic to move between measurements), adjust the offset of the REW trace so that the two measurements have their levels aligned as closely as possible in the regions they seem the same, then use the trace arithmetic feature on the "All SPL" tab to create a difference measurement which could then be exported as text and loaded as a soundcard cal file.

However, be very careful to compare like with like in your measurements. Measurement platforms vary in their smoothing implementations, so 1/3 octave smoothing on one is typically not the same as 1/3 octave smoothing on another, and also vary in their measurement resolution, which can make comparisons tricky.


----------



## Phillips

JohnM said:


> I presume so, but I don't know much about the Omnimic. If you are convinced there is a systematic difference between the measurement systems you are using you could adjust the calibration file to account for it, either modifying the mic cal file or creating a pseudo soundcard cal file with the required corrections. A way to do that (or at least to make a starting point) could be to make a measurement in REW, import a measurement from Omnimic (without allowing the mic to move between measurements), adjust the offset of the REW trace so that the two measurements have their levels aligned as closely as possible in the regions they seem the same, then use the trace arithmetic feature on the "All SPL" tab to create a difference measurement which could then be exported as text and loaded as a soundcard cal file.
> 
> However, be very careful to compare like with like in your measurements. Measurement platforms vary in their smoothing implementations, so 1/3 octave smoothing on one is typically not the same as 1/3 octave smoothing on another, and also vary in their measurement resolution, which can make comparisons tricky.



View attachment REW Omnimic Measurement Comparison.mdat



Hi John i have attached the Mdata file that consists exactly what is required, the mic was not shifted at all + imported the FRD file in to REW + mic calibration file is included.

What do you think?

Do I set the Speaker Properties in the control panel of the laptop to 16 bit 48,000hz DVD Quality & Microphone Properties 2 channel 16 bit 48,000hz DVD Quality?

The measurements look pretty close except for the 600hz down.

What method would you reccomend for correcting this. Please can you explain the creating a pseudo soundcard cal file method more.

Thank you


----------



## JohnM

Copy these values into a text file called (for example) omnifix.txt:


Code:


* Pseudo soundcard cal file for Omnimic measurement
37.5 -4.5
635 0
3000 0
10000 -2

Load that file into REW as the soundcard cal file, that will apply that correction for new measurements. For existing measurements you can load the file using the Change Cal button on the measurement tab.

That should make the measurements correspond more closely, but whether the measurements are then more correct or not I can't tell - there's no way to know the actual response of your omnimic without getting it independently calibrated or making comparison measurements against a calibrated mic.


----------



## Phillips

JohnM said:


> Copy these values into a text file called (for example) omnifix.txt:
> 
> 
> Code:
> 
> 
> * Pseudo soundcard cal file for Omnimic measurement
> 37.5 -4.5
> 635 0
> 3000 0
> 10000 -2
> 
> Load that file into REW as the soundcard cal file, that will apply that correction for new measurements. For existing measurements you can load the file using the Change Cal button on the measurement tab.
> 
> That should make the measurements correspond more closely, but whether the measurements are then more correct or not I can't tell - there's no way to know the actual response of your omnimic without getting it independently calibrated or making comparison measurements against a calibrated mic.




Hi John do i enter * Pseudo soundcard cal file for Omnimic measurement as well, or leave it out and enter the numbers only?

Thank you very much, i will keep you posted.

Just a matter of interest what is a Pseudo soundcard cal file exactly?

Thanks again


----------



## JimP

John,

I just made a post on the mic calibration thread about that guy performing a calibration on an omnimic and generating a calibration file that I would intend to use on REW.

Do you see any reason why this wouldn't work?

Since I would be taking my mixer and other mic out of the loop is there another type of correction that I would have to run? Would sound card correction file then be left blank? Would I still need to run the external sound card for the audio out or is the internal audio in a laptop accurate enough for the signal out?


----------



## JohnM

Phillips said:


> Hi John do i enter * Pseudo soundcard cal file for Omnimic measurement as well, or leave it out and enter the numbers only?


It is a comment line, REW will ignore it or you can omit it.



> Just a matter of interest what is a Pseudo soundcard cal file exactly?


Pseudo as in not real, in this case hijacking the soundcard cal file to add a bit more mic correction. An alternative would be to change the mic cal file, but would require a lot more effort as many more values would have to be changed.


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## JohnM

JimP said:


> I just made a post on the mic calibration thread about that guy performing a calibration on an omnimic and generating a calibration file that I would intend to use on REW.
> 
> Do you see any reason why this wouldn't work?


Should work fine.



> Since I would be taking my mixer and other mic out of the loop is there another type of correction that I would have to run?


Nope.



> Would sound card correction file then be left blank?


Yes



> Would I still need to run the external sound card for the audio out or is the internal audio in a laptop accurate enough for the signal out?


Yes, internal audio is plenty accurate enough. You should still make sure none of the USB mic input is being fed to the output though.


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## Phillips

Hi John thank you

Do I set the Speaker Properties in the control panel of the laptop to 16 bit 48,000hz DVD Quality & Microphone Properties 2 channel 16 bit 48,000hz DVD Quality?

Currently the settings are
Speaker Properties = 16 bit 48,000hz (DVD Quality)
Microphone Properties 2 channel 24 bit 48,000hz (Studio Quality)


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## Phillips

JohnM said:


> If you are looking at EQ above the bass range, only use separate speaker measurements. For the bass range it is best to measure with both speakers as most bass content is mixed mono, so both speakers would be reproducing it together. The room reacts differently at low frequencies when two sources are driving it rather than one.



Hi John when you say above the bass range what would be your cut off bass range?

Thank you


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## Phillips

JimP said:


> John,
> 
> I just made a post on the mic calibration thread about that guy performing a calibration on an omnimic and generating a calibration file that I would intend to use on REW.
> 
> Do you see any reason why this wouldn't work?
> 
> Since I would be taking my mixer and other mic out of the loop is there another type of correction that I would have to run? Would sound card correction file then be left blank? Would I still need to run the external sound card for the audio out or is the internal audio in a laptop accurate enough for the signal out?



Where did you post on the mic calibration thread, i can't find it?

Also keep me posted on your results and ideas, graphs etc.


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## JimP

Phillips,

Here's the thread where I posted. http://www.hometheatershack.com/for...um-microphone-calibration-service-usa-17.html

Sounds like he wants a current version Omnimic to test.


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## JohnM

Phillips said:


> Do I set the Speaker Properties in the control panel of the laptop to 16 bit 48,000hz DVD Quality & Microphone Properties 2 channel 16 bit 48,000hz DVD Quality?
> 
> Currently the settings are
> Speaker Properties = 16 bit 48,000hz (DVD Quality)
> Microphone Properties 2 channel 24 bit 48,000hz (Studio Quality)


Either is OK.


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## JohnM

Phillips said:


> Hi John when you say above the bass range what would be your cut off bass range?


Around 100 - 150Hz.


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## Phillips

JohnM said:


> Either is OK.



Thanks John
Would it be better to keep both settings the same e.g. both DVD quality?


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## Phillips

JimP said:


> Phillips,
> 
> Here's the thread where I posted. http://www.hometheatershack.com/for...um-microphone-calibration-service-usa-17.html
> 
> Sounds like he wants a current version Omnimic to test.



Yeah it looks like it.

Do you have Version 1 or 2?

Did you get a calibration file with the Omnimic?

In the REW preferences Omnimic is noticed in the input selection drop down box.

Herb is saying something about USB audio device, i don't know if this should be showing in the input selcetion drop down box as this?


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## JimP

JohnM said:


> Around 100 - 150Hz.





Phillips said:


> Yeah it looks like it.
> 
> Do you have Version 1 or 2?
> 
> Did you get a calibration file with the Omnimic?
> 
> In the REW preferences Omnimic is noticed in the input selection drop down box.
> 
> Herb is saying something about USB audio device, i don't know if this should be showing in the input selcetion drop down box as this?



I've got version 2.

The calibration file we all get with Omnimic is the one that we install to activate the mic from Omnimic. Unfortunately, it's not in a format that REW would recognize. I'm thinking about sending off my Omnimic to have a calibration file created by the guy in the other thread.

REW does have a place where it recognizes REW as I've already done that. I just don't know how accurate it is. What I've thought about doing is run REW with Omnimic and then run it with my other mic setup (soundcard, mixer, and mic) with the correction file that I have for it and compare the difference. That'll tell me how close omnimic is. There's probably a way to juryrig a correction file for the omnimic doing that but I'd rather do it right and send it off if there is a difference....which I would expect.

Answering your other question about the frequency response to run REW, I'd strongly recommend going up to 150hz as LFE goes up to 150hz and its usually routed to the subwoofer. I've read where different preamps/receivers handle this differently, but generally the crossover redirects bass according to how you set it and LFE ignores it and still goes up to 150....however, rules get broken and its done a few different ways. At least with equalization up to 150hz, you're covered in all situations. 

I'm a bit lazy and haven't read your earlier post, but you do know that, the easier approach would be to use the omnimic software to capture the information, save it, then open it in REW. Easy peezy. My motive for using the omnimic mic on REW has to do with I much prefer running a controlled single sweep and having all the results easily post on the screen instead of having to pause, save and reopen each one I want to compare with the omnimic software. I still haven't figured out the labeling with omnimic and pretty soon forget which line represents what.


----------



## Phillips

JimP said:


> I've got version 2.
> 
> The calibration file we all get with Omnimic is the one that we install to activate the mic from Omnimic. Unfortunately, it's not in a format that REW would recognize. I'm thinking about sending off my Omnimic to have a calibration file created by the guy in the other thread.
> 
> REW does have a place where it recognizes REW as I've already done that. I just don't know how accurate it is. What I've thought about doing is run REW with Omnimic and then run it with my other mic setup (soundcard, mixer, and mic) with the correction file that I have for it and compare the difference. That'll tell me how close omnimic is. There's probably a way to juryrig a correction file for the omnimic doing that but I'd rather do it right and send it off if there is a difference....which I would expect.
> 
> Answering your other question about the frequency response to run REW, I'd strongly recommend going up to 150hz as LFE goes up to 150hz and its usually routed to the subwoofer. I've read where different preamps/receivers handle this differently, but generally the crossover redirects bass according to how you set it and LFE ignores it and still goes up to 150....however, rules get broken and its done a few different ways. At least with equalization up to 150hz, you're covered in all situations.
> 
> I'm a bit lazy and haven't read your earlier post, but you do know that, the easier approach would be to use the omnimic software to capture the information, save it, then open it in REW. Easy peezy. My motive for using the omnimic mic on REW has to do with I much prefer running a controlled single sweep and having all the results easily post on the screen instead of having to pause, save and reopen each one I want to compare with the omnimic software. I still haven't figured out the labeling with omnimic and pretty soon forget which line represents what.




REW recognizes the calibration file, copy and paste over to a text file and then import into REW, worked for me. Please keep me posted with the calibration by the other guy.

Pleasec keep me posted on the comparison with your other gear.

If you want you can read from about page 8 to current about the diifference in graphs REW vs Omnimic without moving the mic, same everything. I have imported the Omni graph into REW to compare. The graphs are pretty close except for about 600hz down, which John corrected with the soundcard calibration file.

Omnimic is more targeted at speaker design i feel. 

I saved the FRD file and imported into REW quite awhile ago, but couldn't use REW waterfall, spectrogram etc graphs. It is great to be able to measure, save, and then have everything, different graphs recalled at a finger tip.

Please keep me posted.


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## Phillips

Phillips said:


> View attachment 35987
> 
> 
> 
> Hi John i have attached the Mdata file that consists exactly what is required, the mic was not shifted at all + imported the FRD file in to REW + mic calibration file is included.
> 
> What do you think?
> 
> Do I set the Speaker Properties in the control panel of the laptop to 16 bit 48,000hz DVD Quality & Microphone Properties 2 channel 16 bit 48,000hz DVD Quality?
> 
> The measurements look pretty close except for the 600hz down.
> 
> What method would you reccomend for correcting this. Please can you explain the creating a pseudo soundcard cal file method more.
> 
> Thank you



Hi John does my mic calibration file look reasonable?

Does the file have the right information?

Thank you


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## JohnM

Phillips said:


> Hi John does my mic calibration file look reasonable?


Yes, the mic cal trace looks reasonable.


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## Phillips

Just a matter of interest, would a XTZ microphone and soundcard work with REW?


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## Phillips

With my setup, for Beta 9 do i use the Java or Asio in the preferences?


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## JohnM

Leave it on Java.


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## Phillips

Thanks John

I have two subs, Velodyne DD12 + DD15, how would you setup/measure them.

I measure them by themselves, no speakers.

Currently i measure the DD12 (full range), use the SMS-1 on REW, enter the filters suggested, then the same with the DD15 then measure them combined to find any more filters. Is this the right way?

Thank you


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## JohnM

Do you drive them from a single LFE output? If they are being fed the same signal better measuring with both running and use one set of filters. No point equalising them individually if they will never drive the room that way, the only use for individual measurements would be to get their levels balanced.

What do you mean when you say you measure "full range"? For sub measurements there is no point in using a sweep that goes beyond a few hundred Hz.


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## Phillips

JohnM said:


> Do you drive them from a single LFE output? If they are being fed the same signal better measuring with both running and use one set of filters. No point equalising them individually if they will never drive the room that way, the only use for individual measurements would be to get their levels balanced.
> 
> What do you mean when you say you measure "full range"? For sub measurements there is no point in using a sweep that goes beyond a few hundred Hz.



Thanks John

They are run as mono setting on the reciever (Yamaha Z9) and on the SVS ASEQ-1 they are set to one in two out. They are still hooked up to thre ASEQ-1 although i am using the Velodyne PEQ filters. The ASEQ-1 EQ is turned off (not the power). I am trying the Velodyne EQ system again.

Which sub should be fed the filters?

"Full range" sorry i meant crossover turned off on trhe sub.

I had thought of running the front speakers full range and under pinning them with the DD15 then using the DD12 as the LFE as i play 95% 2 channel music/3% multi channel music/2% movies?


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## JohnM

Phillips said:


> Which sub should be fed the filters?


Both if they are getting the same LFE signal, treat them as 1 sub, split the signal to the two subs after EQ.


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## Phillips

JohnM said:


> Both if they are getting the same LFE signal, treat them as 1 sub, split the signal to the two subs after EQ.



Thanks John

So i enter the same filters into each sub, with the same gain & Q?

When two subs (only) are playing does phase matter, or is it only when main speakers are playing?

Is there any way i can setup two different size woofers (DD12 & DD15) as stereo, is there any advantage?

Sorry i don't understand the "split the signal to the two subs after EQ"

I have attached three graphs.


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## Phillips

Phillips said:


> Thanks John
> 
> So i enter the same filters into each sub, with the same gain & Q?
> 
> When two subs (only) are playing does phase matter, or is it only when main speakers are playing?
> 
> Is there any way i can setup two different size woofers (DD12 & DD15) as stereo, is there any advantage?
> 
> Sorry i don't understand the "split the signal to the two subs after EQ"
> 
> I have attached three graphs.
> 
> 
> View attachment 36070
> 
> 
> View attachment 36071
> 
> 
> View attachment 36072




The graphs are the two subs seperate then combined


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## Wayne A. Pflughaupt

Hey Phillips,


> So i enter the same filters into each sub, with the same gain & Q?


Yes.



> When two subs (only) are playing does phase matter, or is it only when main speakers are playing?


Yes, because both subs should be time-aligned for the primary listening position.




> Is there any way i can setup two different size woofers (DD12 & DD15) as stereo, is there any advantage?


I believe you can do stereo subs with the RX-Z9, but there is no real advantage, unless you have lots of program material in your collection that has stereo bass. Typically with program material, the same bass signal is sent to both the left and right channels.




> Sorry i don't understand the "split the signal to the two subs after EQ"


The EQ’s output is sent to both subs, utilizing a “y” cable.


Regards, 
Wayne


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## Phillips

Wayne A. Pflughaupt said:


> Hey Phillips,
> Yes.
> 
> Yes, because both subs should be time-aligned for the primary listening position.
> 
> 
> I believe you can do stereo subs with the RX-Z9, but there is no real advantage, unless you have lots of program material in your collection that has stereo bass. Typically with program material, the same bass signal is sent to both the left and right channels.
> 
> 
> The EQ’s output is sent to both subs, utilizing a “y” cable.
> 
> 
> Regards,
> Wayne




Thanks Wayne

Currently I have the SVS ASEQ-1 hooked up. I use this when I want a change, by turning it off and on as required. It is hooked up as One in Two out, even when I use the Velodyne software. When I try the Velodyne software again I will try as above later and post some graphs.
Personally have you had any experience with the ASEQ-1 and what you thought, I know it depends on individuals, two different ways of Eq?

How is the phase best tested?
Is phase the same as distance in the receivers, Z9 has both for subs?
With distance do i test (Z9) with seperate subs or combined as i am running the ASEQ-1 as One in Two out?

Wouldn’t stereo subs be difficult when the subs have different size drivers?
How do I measure the subs with the mains, separately or combined?
Is it best to EQ with the mains playing first or last?

_*The EQ’s output is sent to both subs, utilizing a “y” cable.*_

How is this done, I run One in Two out on the ASEQ-1 even though sometimes I turn it off (still hooked up to the ASEQ-1).
If I was going straight from the Z9 to the subs how would I hook them up? 
Is this what is meant?


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## Pinchgrip

I've always used AKG 451s for a ref mic.


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## Phillips

Pinchgrip said:


> I've always used AKG 451s for a ref mic.


Do they come with a individual calibration file?


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## Phillips

Phillips said:


> Thanks Wayne
> 
> Currently I have the SVS ASEQ-1 hooked up. I use this when I want a change, by turning it off and on as required. It is hooked up as One in Two out, even when I use the Velodyne software. When I try the Velodyne software again I will try as above later and post some graphs.
> Personally have you had any experience with the ASEQ-1 and what you thought, I know it depends on individuals, two different ways of Eq?
> 
> How is the phase best tested?
> Is phase the same as distance in the receivers, Z9 has both for subs?
> With distance do i test (Z9) with seperate subs or combined as i am running the ASEQ-1 as One in Two out?
> 
> Wouldn’t stereo subs be difficult when the subs have different size drivers?
> How do I measure the subs with the mains, separately or combined?
> Is it best to EQ with the mains playing first or last?
> 
> _*The EQ’s output is sent to both subs, utilizing a “y” cable.*_
> 
> How is this done, I run One in Two out on the ASEQ-1 even though sometimes I turn it off (still hooked up to the ASEQ-1).
> If I was going straight from the Z9 to the subs how would I hook them up?
> Is this what is meant?


Please help


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## Phillips

How accurate is my soundcard in my laptop Acer 4315?

Has anyone got the Omnimic recalibrated and got different results?


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## JohnM

Phillips said:


> How accurate is my soundcard in my laptop Acer 4315?


Make a loopback connection and measure it.


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## Phillips

JohnM said:


> Make a loopback connection and measure it.


Thanks John.

How do i do this, i thought it couldn't be done with a internal laptop soundcard?

Any extra cables i will need?

Thank you


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## Phillips

View attachment Soundcard1.mdat


Hi John attached is my measuring soundcard.

Doesn't look right.

There is only one connection on the laptop for speakers and input. I connected these two and did the measurement. There was a message saying that the diiference was to high 136db.

Please can you help


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## JohnM

That looks like a mic input measurement, and one that the laptop only samples at 16kHz, which is why there is nothing above 8kHz. You need a line input.


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## Phillips

JohnM said:


> That looks like a mic input measurement, and one that the laptop only samples at 16kHz, which is why there is nothing above 8kHz. You need a line input.


Hi John there dosen't appear to be an line input, just mic jack & headphone/speaker jack, both 3.5mm.

Does this seem unusual?

Is there any other way i can do the measurement?

Thank you


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## JohnM

There were a few years when many laptops only had mic inputs, before the switchable (or auto switching) mic/line inputs became common. Those mic inputs are not suitable for use with REW.


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## Phillips

JohnM said:


> There were a few years when many laptops only had mic inputs, before the switchable (or auto switching) mic/line inputs became common. Those mic inputs are not suitable for use with REW.


Hi John thank you

Is it important to do a soundcard calibration?

The mic has it's txt file loaded.


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## JohnM

Phillips said:


> Is it important to do a soundcard calibration?


I think we are now back where we were in March, see post #34.


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## Phillips

JohnM said:


> I think we are now back where we were in March, see post #34.


Hi John thanks

Yeah you are right

What i am hearing in the bass region doesn't equate to the graph. 

I wonder if Jim has got his Omnimic recailbrated

I am trying to work out how to compare to get a good accurate measurement. I realize there is a certain of difference.

I tried measuring with Omnimic software then importing the file into REW then measuring with REW (with the mic unchanged), then John very nicely made up a txt correction file to compensate.

I wonder if the inaccuracy is in the Omnimic txt file?


----------



## Phillips

JohnM said:


> Copy these values into a text file called (for example) omnifix.txt:
> 
> 
> Code:
> 
> 
> * Pseudo soundcard cal file for Omnimic measurement
> 37.5 -4.5
> 635 0
> 3000 0
> 10000 -2
> 
> Load that file into REW as the soundcard cal file, that will apply that correction for new measurements. For existing measurements you can load the file using the Change Cal button on the measurement tab.
> 
> That should make the measurements correspond more closely, but whether the measurements are then more correct or not *I can't tell - there's no way to know the actual response of your omnimic without getting it independently calibrated or making comparison measurements against a calibrated mic*.


Hi John as highlighted, if i could get a calibrated mic how would i make comparison measurements against my mic?

Thank you


----------



## Skylinestar

I'm planning to order a calibrated mic from Cross Spectrum and have it shipped all the way to Asia.
Is the mic still accurate after going through all the bumps, drops and rough handling of the courier service?


----------



## Phillips

Skylinestar said:


> I'm planning to order a calibrated mic from Cross Spectrum and have it shipped all the way to Asia.
> Is the mic still accurate after going through all the bumps, drops and rough handling of the courier service?


My mic came from Parts Express. 

It was really well packed. The problem i am having is that i don't think it is the mic, possibly the laptop internal sound card. The Omnimic is already powered by USB and comes with its own txt calibration file.


----------



## JimP

Phillips,

Given the Mic is USB, I'd think that the sound card is built into the Mic. 

Wonder if there can be some compatability problems with the laptop's sound card. You might want to go into device manager and temporarily deactivate the internal sound card while using Omnimic to see if makes any difference.


----------



## Wayne A. Pflughaupt

Skylinestar said:


> I'm planning to order a calibrated mic from Cross Spectrum and have it shipped all the way to Asia.
> Is the mic still accurate after going through all the bumps, drops and rough handling of the courier service?


The calibration process involves no physical adjustments to the mic itself. It merely generates a calibration file that can be loaded into a program like REW. So yes, the mic will be fine once you get it.

Regards, 
Wayne


----------



## Phillips

JimP said:


> Phillips,
> 
> Given the Mic is USB, I'd think that the sound card is built into the Mic.
> 
> Wonder if there can be some compatability problems with the laptop's sound card. You might want to go into device manager and temporarily deactivate the internal sound card while using Omnimic to see if makes any difference.


H Jim

I think because it has a CD it doesn't (Omni software) require a soundcard, might be wrong.

Where abouts is the soundcard for Vista, i have the Device Manager, but can't find the soundcard?

Did you get your Omnimic re-calibrated?

Thank you


----------



## Phillips

JimP said:


> John,
> 
> I just made a post on the mic calibration thread about that guy performing a calibration on an omnimic and generating a calibration file that I would intend to use on REW.
> 
> 
> 
> Hi Jimp did you get your Omnimic re-calibrated?
> 
> Which version do you own?


----------

