# How to setup?



## JapanDave (Mar 29, 2010)

I have an art dual mic preamp with an onkyo sound card and I am lost as to how I should be setting this up? 



















Do I need to run an RCA cable from the "RCA IN" on the sound card to a 1/4" mono TS adapter into the preamp? Should I plug the cable into the Left input or right input? or should the cables go into the monitor output? If so left or right? Then do I run RCA cables from the sound card to the proccessor? Or should I be using the mic and headphones input out put? 

Also what gain should I be setting the dials on?

Sorry for the noob questions, but I am stumped.


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## JohnM (Apr 11, 2006)

The USB Dual Pre is a soundcard itself, so you would not need the Onkyo with it. Turn the monitor mix knob all the way to the right, to "computer", that way the monitor outputs will have the signal generated by REW on them. REW generates the same signal on left and right, so you can use either monitor output or one channel of the headphone output, they all carry the same signal. If you have a line level source (such as an SPL meter) you would need the gain of the USB Pre input turned around to 0dB (which is unity gain), if you have a mic of some sort the gain will need adjusting according to the mic.

If you are using an SPL meter as the source you could also use the Onkyo on its own, with the SPL meter connecetd to the R channel on the line in and the line out R channel connected to an input on the receiver.


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## JapanDave (Mar 29, 2010)

JohnM said:


> The USB Dual Pre is a soundcard itself, so you would not need the Onkyo with it. Turn the monitor mix knob all the way to the right, to "computer", that way the monitor outputs will have the signal generated by REW on them. REW generates the same signal on left and right, so you can use either monitor output or one channel of the headphone output, they all carry the same signal. If you have a line level source (such as an SPL meter) you would need the gain of the USB Pre input turned around to 0dB (which is unity gain), if you have a mic of some sort the gain will need adjusting according to the mic.
> 
> If you are using an SPL meter as the source you could also use the Onkyo on its own, with the SPL meter connecetd to the R channel on the line in and the line out R channel connected to an input on the receiver.


I am using a Calibrated Behringer ECM8000 "premium plus" microphone, but I also have an SPL meter comming soon. 

Just to clarify, I would connect the USB dual pre with a 3.5mm Stereo Male To RCA Male Cable to the processor from either the headphone or either monitor outputs (in the monitor outputs use a 1/4" TS to RCA cable). 

Could you tell me if the circled part in the pic below is the USB pre input or is that the monitor mix knob ? 










How do I know what level the mic needs to be at? 

Which input do I connect the mic to with the XLR cable? Would it be the right input?

And this is probably a dumb question , but will all the data taken by the mic be transferred through the USB bus to the PC? (I am guessing that it does)

Sorry for all the questions.


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## JohnM (Apr 11, 2006)

JapanDave said:


> Just to clarify, I would connect the USB dual pre with a 3.5mm Stereo Male To RCA Male Cable to the processor from either the headphone or either monitor outputs (in the monitor outputs use a 1/4" TS to RCA cable).


Correct



JapanDave said:


> Could you tell me if the circled part in the pic below is the USB pre input or is that the monitor mix knob ?


That is the monitor mix knob



JapanDave said:


> How do I know what level the mic needs to be at?


You would adjust the mic gain during the REW level setting, with a signal playing through your speakers or sub, per the REW instructions.



JapanDave said:


> Which input do I connect the mic to with the XLR cable? Would it be the right input?


Yes, use the right input



JapanDave said:


> And this is probably a dumb question , but will all the data taken by the mic be transferred through the USB bus to the PC? (I am guessing that it does)


Yes it will



JapanDave said:


> Sorry for all the questions.


No apology required, if there were no questions there wouldn't be a forum


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## JapanDave (Mar 29, 2010)

Thanks so much for the help. I may have everything connected now.


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## JapanDave (Mar 29, 2010)

Ok, it looks like I have got this setup. However I am trying to calibrate the sound card and this is the graph I am getting. Does this look right?











Also , I can only get the sound card calibrated when I connect the loopback cable to the left input and left output. Would this then mean I would have to connect the mic to the left input?


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## laser188139 (Sep 19, 2009)

JapanDave said:


> Ok, it looks like I have got this setup. However I am trying to calibrate the sound card and this is the graph I am getting. Does this look right? ...


Yes, the dotted line looks right. Be sure to save the soundcard calibration when you are done. 



JapanDave said:


> ... Also , I can only get the sound card calibrated when I connect the loopback cable to the left input and left output. Would this then mean I would have to connect the mic to the left input?


What happens when you connect the right output to the right input? Is there just no signal coming in? Or is something else happening? 

Yes, you can use the left channel out to the receiver/system under test. And the left channel input to REW. Just be sure to check the Left radio button under the Input Channel in the Settings. 

Bill


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## JapanDave (Mar 29, 2010)

laser188139 said:


> Yes, the dotted line looks right. Be sure to save the soundcard calibration when you are done.


　What is the other line? It does not look like the ones in the help stickies. 





laser188139 said:


> What happens when you connect the right output to the right input? Is there just no signal coming in? Or is something else happening?
> 
> Yes, you can use the left channel out to the receiver/system under test. And the left channel input to REW. Just be sure to check the Left radio button under the Input Channel in the Settings.
> 
> Bill


The preamp/soundcard is detecting a signal, but the REW software is not detecting any signal. I tried upping the DB on the preamp but nothing registers.


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## JapanDave (Mar 29, 2010)

Ok, so I am trying to check levels and the mic is not putting out any signal, or should I say the REW software is not reading any kind of decibles at all. I have the mic connected to the left input and have the left input box checked. I am getting a sound comming from the subs, so any idea what I am doing wrong here? Does the Behringer ECM8000 mic measure SPL? or do I need a seperate SPL meter?


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## laser188139 (Sep 19, 2009)

You only need a separate SPL meter to calibrate the absolute levels being read. Without an SPL meter, when it comes to the step of calibrating the levels, you can just enter 75dB as if that is the actual value. 

Are you seeing sound input on either of the Left or Right channels when you perform the Check Levels step? Perhaps something in the system is confusing left and right, and the left input to the preamp is appearing as the right input in the computer. 

If you are seeing no input on either side, and you are using an ECM8000 mic (or similar), these microphones require phantom power. Did you press in the Phantom Power button on the front of the preamp? 

Bill

P.S. The solid line in your graph is the filter target you have chosen. On the filter graph, the target is what you set to compare your actual to what it should be in an ideal world, and calculate equalization filters. The default is a subwoofer filter with an 80Hz crossover, which is what I see looking at your graph.


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## JapanDave (Mar 29, 2010)

laser188139 said:


> You only need a separate SPL meter to calibrate the absolute levels being read. Without an SPL meter, when it comes to the step of calibrating the levels, you can just enter 75dB as if that is the actual value.


 That is good to know, thanks. 



laser188139 said:


> Are you seeing sound input on either of the Left or Right channels when you perform the Check Levels step? Perhaps something in the system is confusing left and right, and the left input to the preamp is appearing as the right input in the computer.
> 
> If you are seeing no input on either side, and you are using an ECM8000 mic (or similar), these microphones require phantom power. Did you press in the Phantom Power button on the front of the preamp?
> 
> Bill


 At the present time I am not seeing anything. I did just try to calibrate the SPL on the main page and I finnaly got the mic to receive a signal, however it is 2 o'clock in the morning here and I can't complete the calibration for fear of waking the wife. So I will have to continue this tomorow.



laser188139 said:


> P.S. The solid line in your graph is the filter target you have chosen. On the filter graph, the target is what you set to compare your actual to what it should be in an ideal world, and calculate equalization filters. The default is a subwoofer filter with an 80Hz crossover, which is what I see looking at your graph.


I am going to have to do some more reading I think. Thanks for your help and everybody elses. 

I knew I would be a pain.:hissyfit:


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## JapanDave (Mar 29, 2010)

Ok, I have been checking everything and I have been able to get a signal by turning the Db dial on the USB dual pro soundcard/preamp. The only thing is that it is at max and still has a few Db's for the right and left to be exactly level with the the out column on the REW software.

The software is telling that their is no problem and to continue, so am I ok so far?


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## laser188139 (Sep 19, 2009)

You are fine. You don't need to have the input even with the output level: more important is that it is not too loud (greater than -12dB) where clipping could become an issue during the sweep, and hopefully so low (less than -24dB) that signal-to-noise ratio becomes an issue.


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## JapanDave (Mar 29, 2010)

laser188139 said:


> You are fine. You don't need to have the input even with the output level: more important is that it is not too loud (greater than -12dB) where clipping could become an issue during the sweep, and hopefully so low (less than -24dB) that signal-to-noise ratio becomes an issue.


Thanks. It is pretty even so those things should not be an issue I think. The signal is not clipping which is good.


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## JapanDave (Mar 29, 2010)

Am I correct in assuming that I should be using the "Behringer ECM8000 Correction Values due to my system using Behringer ECM8000 mic?


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## laser188139 (Sep 19, 2009)

Yes. 

If you bought an individually calibrated mic, such as offered by Cross-Spectrum Labs, it would come with its own calibration file on disk. But, as you are in Japan, I imagine you bought a mic from a retailer, and the best available file is the generic one that you have already found. 

Bill


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## JapanDave (Mar 29, 2010)

laser188139 said:


> Yes.
> 
> If you bought an individually calibrated mic, such as offered by Cross-Spectrum Labs, it would come with its own calibration file on disk. But, as you are in Japan, I imagine you bought a mic from a retailer, and the best available file is the generic one that you have already found.
> 
> Bill


Actually, I bought it from Cross spectrum labs with the "premium + calibration" package. I was wondering what that disk was for, now I know!:whistling:

I had a friend of mine give me advise on what stuff to get , I just did not know what to do with it. LOL 

Here is my first graph.


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## JapanDave (Mar 29, 2010)

I can't get the waterfall graph to work? How do you get that going?


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## Nuance (Nov 2, 2008)

JapanDave said:


> I can't get the waterfall graph to work? How do you get that going?


Take a measurement of the subwoofer or speakers (one at a time), then under the waterfall tab click "Generate Waterfall." Then set the graph limits to the frequencies you want to look at. Click on the little picture of the floppy disk in the bottom left hand corner of the graph (right by the two arrows) to save it as a jpeg. That way you won't have to take a screenshot of your desktop.

The output below 10Hz is probably a measurement anomaly, for what its worth. I wouldn't bother measuring from below 15Hz or so. Can you take a measurement from 15-200Hz?

Is that measurement just the subwoofer(s), or the speakers crossed over to the subs? If the latter, what is your crossover frequency? I ask because trying a different crossover or messing with phase might get rid of the null at 55Hz. Otherwise try re-positioning the subwoofer in the room.


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## JapanDave (Mar 29, 2010)

Nuance said:


> Take a measurement of the subwoofer or speakers (one at a time), then under the waterfall tab click "Generate Waterfall." Then set the graph limits to the frequencies you want to look at. Click on the little picture of the floppy disk in the bottom left hand corner of the graph (right by the two arrows) to save it as a jpeg. That way you won't have to take a screenshot of your desktop.


　Ok, I will give that a try. Thanks.



Nuance said:


> The output below 10Hz is probably a measurement anomaly, for what its worth. I wouldn't bother measuring from below 15Hz or so. Can you take a measurement from 15-200Hz?


I don't know if it is an anomaly, b/c I was curious as to that myself. The subs are Seaton Sounds Submersives which are know to have flat in room response down to 7-8 hz in some rooms and I can say that the windows in the room ,glasswear plates and and anything else shakes violently without any audible noise, which I can only guess is sub 20hz content. The windows visibly shake violently for the first 5 or so seconds at the start of the the 1M sweep and I don't start hearing sound until about the 9 second mark of the 21 sec sweep, so much so I am a little afraid to try anything at higher Db's . 




Nuance said:


> Is that measurement just the subwoofer(s), or the speakers crossed over to the subs? If the latter, what is your crossover frequency? I ask because trying a different crossover or messing with phase might get rid of the null at 55Hz. Otherwise try re-positioning the subwoofer in the room.


 It is just my subs at the moment. How do I mess with the phase, sorry this is all just so new to me.:sweat:


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## JapanDave (Mar 29, 2010)

Nuance said:


> The output below 10Hz is probably a measurement anomaly, for what its worth. I wouldn't bother measuring from below 15Hz or so. Can you take a measurement from 15-200Hz?


Here is a graph taken from the speaker designer himself, so I guess it could be possible that they do go that low.


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## laser188139 (Sep 19, 2009)

JapanDave said:


> Actually, I bought it from Cross spectrum labs with the "premium + calibration" package. I was wondering what that disk was for, now I know! ...


That's great that you have the individual calibration files. Since late last year, when I bought mine, Herb has been producing calibration files down to 5Hz for all the microphones, so you can trust the measurements down to a very low frequency. 

With the premium+ you will have received two calibration files, one for use with the microphone placed horizontally and another for use with the microphone oriented vertically. Do choose the correct one for how you are setting up the microphone, although I don't expect you will notice a difference when measuring the sub.

Bill


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## Nuance (Nov 2, 2008)

Seaton's Submersive is probably the best sealed subwoofer you can buy, so you're a lucky man. 

There should be a polarity or phase switch/knob on the back of the Submersive. Adjust it, then listen and measure to see if the null goes away. If it doesn't, room interaction is most likely causing it, in which case you should try placing it in different locations, measuring each time.

The crossover frequency is set on your receiver/preamp. What is it set to?


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## JapanDave (Mar 29, 2010)

laser188139 said:


> That's great that you have the individual calibration files. Since late last year, when I bought mine, Herb has been producing calibration files down to 5Hz for all the microphones, so you can trust the measurements down to a very low frequency.
> 
> With the premium+ you will have received two calibration files, one for use with the microphone placed horizontally and another for use with the microphone oriented vertically. Do choose the correct one for how you are setting up the microphone, although I don't expect you will notice a difference when measuring the sub.
> 
> Bill


That is very reassuring to know, thanks. Which ever way the mic is setup, the files should be downloaded into the Mic calibration part of the settings correct? (Just want to make sure)



Nuance said:


> Seaton's Submersive is probably the best sealed subwoofer you can buy, so you're a lucky man.
> 
> There should be a polarity or phase switch/knob on the back of the Submersive. Adjust it, then listen and measure to see if the null goes away. If it doesn't, room interaction is most likely causing it, in which case you should try placing it in different locations, measuring each time.
> 
> The crossover frequency is set on your receiver/preamp. What is it set to?


Thanks Nuance, they are some powerful subs for sure!

I can't remember what dials are on the sub, so I will check when I get home tonight. 

I have the crossover set to 80hz at the present time on the pre/pro.

Cheers.


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## laser188139 (Sep 19, 2009)

JapanDave said:


> That is very reassuring to know, thanks. Which ever way the mic is setup, the files should be downloaded into the Mic calibration part of the settings correct? (Just want to make sure) ...


Yes. Since Herb gives them different names, it is easy to copy them both to your local directory, then select the appropriate one in the Settings -> Mic for how you are going to take your measurements.


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## glaufman (Nov 25, 2007)

JapanDave said:


> I can't get the waterfall graph to work? How do you get that going?


When you do one, make sure to have the frequency axis in LOG mode.


JapanDave said:


> Seaton Sounds Submersives which are know to have flat in room response down to 7-8 hz in some rooms


"In some rooms" is the key here. In-room response down that low depends heavily on the room/boundary gain, and will vary significantly from room to room.


laser188139 said:


> Herb has been producing calibration files down to 5Hz for all the microphones, so you can trust the measurements down to a very low frequency.


Be careful here. There's more to "how low you can trust the measurements" than "how low the mic calibration can be trusted." The full story is that after a point the combined affects of both the mic cal and the soundcard cal elevate the noise floor (which is characteristic of the mic, the soundcard, the preamp, the room, the ambient noise, your heartbeat...) to a range where it looks like usable sound when it really isn't. Not much to really be concerned about, I just wanted to make the point.


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## laser188139 (Sep 19, 2009)

Dave, Greg makes a good point about the noise floor. (Thanks, Greg.)



glaufman said:


> ... There's more to "how low you can trust the measurements" than "how low the mic calibration can be trusted." The full story is that after a point the combined affects of both the mic cal and the soundcard cal elevate the noise floor (which is characteristic of the mic, the soundcard, the preamp, the room, the ambient noise, your heartbeat...) to a range where it looks like usable sound when it really isn't. Not much to really be concerned about, I just wanted to make the point.


If you look back at your graph from the manufacturer, you will see that it drops off at about 10Hz. In the first graph you posted, you have a dip around 9Hz. The lump in the level below that is more likely noise than response from the speaker. 

You can check this later by taking a spectrum measure of the room, with no signal to the receiver. It may also be obvious if you look at the waterfall chart. Or you can just decide to start your measurements at 10Hz all the time and not worry about it.

Speaking of graphs, your first image with the screen shot is helpful when tracking down what options have been selected. But generally the graph alone is sufficient, and REW has a button and a menu selection to save the graph as a .jpg. See the guide. In your case, you can be flexible with the lower x-axis limit down to 10Hz or so with the calibrated mic, once you have found where the noise floor is. But your graph will be easier for everyone to recognize if you keep the 45-105 dB y-axis.


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## glaufman (Nov 25, 2007)

Hey, I gotta say something usable once in a while... :T


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## JapanDave (Mar 29, 2010)

glaufman said:


> When you do one, make sure to have the frequency axis in LOG mode.
> 
> "In some rooms" is the key here. In-room response down that low depends heavily on the room/boundary gain, and will vary significantly from room to room.
> 
> Be careful here. There's more to "how low you can trust the measurements" than "how low the mic calibration can be trusted." The full story is that after a point the combined affects of both the mic cal and the soundcard cal elevate the noise floor (which is characteristic of the mic, the soundcard, the preamp, the room, the ambient noise, your heartbeat...) to a range where it looks like usable sound when it really isn't. Not much to really be concerned about, I just wanted to make the point.


Good to know about floor noise. So that obviously means that you have to have everything as quite as possible when doing measurements? 

What is LOG mode? I had a look and I can't find it.:doh:

BTW, on rooms with room/boundary gain, my temporary (This room I am measuring) rooms walls, celling and floor is all solid 10" concrete with 4 quite large windows but is sealed by a wooden door. Will this have an effect on room/boundary gain? It is about 8000cf btw.

Why I ask is b/c the dedicated HT I am having built has all walls and celling made with 10-12" solid concrete and the floor is 2' solid concrete and has no windows. The door with be a solid soundproof door with rubber seals and a locking mechanism that will allow no air to escape. I will have one vent that will circulate air in and out of the room, so essentially you can't get a room that is more sealed then this. Now I have a HT designer doing the room treatments as I know that solid concrete can cause problems with sound, I just don't know what. Anyway, will this type of room be "likely" to produce excessive room/boundary gain



laser188139 said:


> Dave, Greg makes a good point about the noise floor. (Thanks, Greg.)
> 
> 
> 
> ...


I want to try all measurements, so I will give some of the ones you suggested a try. Unfortunately during the week is impossible due to work, but it gives me time to research a little more. 

How do I know where the noise floor will be? 

Gotcha with the 45-105 Db y axsis.


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## glaufman (Nov 25, 2007)

JapanDave said:


> Good to know about floor noise. So that obviously means that you have to have everything as quite as possible when doing measurements?
> 
> What is LOG mode? I had a look and I can't find it.:doh:


Sorry... in the upper right you'll see a button called "Freq Axis" which will toggle it between LOG and LIN mode.


> BTW, on rooms with room/boundary gain, my temporary (This room I am measuring) rooms walls, celling and floor is all solid 10" concrete with 4 quite large windows but is sealed by a wooden door. Will this have an effect on room/boundary gain? It is about 8000cf btw.


Yes and no. Sealed rooms will give more room gain, but I believe there's a theoretical limit. Room gain isn't a bad thing anyway, except a lack of it deprive modes of their energy.


> Why I ask is b/c the dedicated HT I am having built has all walls and celling made with 10-12" solid concrete and the floor is 2' solid concrete and has no windows. The door with be a solid soundproof door with rubber seals and a locking mechanism that will allow no air to escape. I will have one vent that will circulate air in and out of the room, so essentially you can't get a room that is more sealed then this. Now I have a HT designer doing the room treatments as I know that solid concrete can cause problems with sound, I just don't know what. Anyway, will this type of room be "likely" to produce excessive room/boundary gain


Except for modes, I'm not sure there's such a thing as excessive room gain, as long as treatments are being used to limit reverb times. Boundary gain depends more on placement, but again has a theoretical limit...


> How do I know where the noise floor will be?


Run a measurement sweep to make sure everything is connected and at appropriate levels/gains... go to the spectrum tab and take a measurement in RTA mode without any signal playing. That's your noise floor.


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