# Thick person about to cry



## blasted (May 14, 2008)

I have been messing around for a while now trying to get the sound card and meter calibrated. However I seem to be getting no where. 

First dumb question of probably many, 

How do I know if the computer is even seeing my meter? 

Im using a DFI lanparty board with the karajan module that came with it. I can get sound out to my amp, but plugging and unpluging the meter seems to have no effect. When i go to measure i dont get any trace either. Could it be that it doesnt support in and out at the same time? 

Any help on how to get going in the most basic of instructions would be greatly appreciated.


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## brucek (Apr 11, 2006)

> I have been messing around for a while now trying to get the sound card and meter calibrated


Calibrating the soundcard is the first hurdle (and doesn't use the SPL meter).

Have you successfully calibrated the soundcard and then saved and stored that calibration file in REW and then taken a measurement of the looped back cable from line-out to line-in (that you used to accomplish the calibration) and gotten a flat result?

brucek


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## Blaser (Aug 28, 2006)

blasted said:


> First dumb question of probably many,
> 
> How do I know if the computer is even seeing my meter?


You remind me of the first time I tried to use REW :bigsmile: I had similar questions. I can at least tell you how to check ifthe line out of the SPL meter is working. It's easy. Connect the SPL meter to an audio input on your receiver and talk. It should act like a mic, then you know it is working.


> Im using a DFI lanparty board with the karajan module that came with it. I can get sound out to my amp, but plugging and unpluging the meter seems to have no effect. When i go to measure i dont get any trace either. Could it be that it doesnt support in and out at the same time?


Again I had similar problems. If you're using RS meter, note that it has a mono input, and if your soundcard has a stereo input, it won't work until you connect a stereo jack to your computer and receive only mono to the RS meter (one of both inputs shoud be working). This is of course to be after soundcard calibration step. Iam also assuming you computer soundcard has line out and line in.


> Any help on how to get going in the most basic of instructions would be greatly appreciated.


Hope this helps a bit


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## Wayne A. Pflughaupt (Apr 13, 2006)

Welcome to the Forum, blasted!

Sorry, I don't know a thing about your soundcard, but you do need one that has line inputs as well as line outputs. Mic inputs won't work. Keep us posted!

Regards,
Wayne


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## blasted (May 14, 2008)

Thanks chaps, 

so the first step is to forget the spl meter and calibrate the sound card. :scratch:

I tried pluggining into the aux input on the amp. it does indeed work like a mic, if i fail to get the sub set up at least i can do some singing along to the music, that way we will both be out of tune.


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## brucek (Apr 11, 2006)

> so the first step is to forget the spl meter and calibrate the sound card


Yep.

I trust you've completely read the Cabling and Connection thread and also completely read the REW HELP FILES before you even considered doing anything else?

brucek


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## blasted (May 14, 2008)

I have been reading for a while, the more i read the more confused i get. In fact i am having trouble getting my head around connecting it all up. 

I have two cables each has a 3.5mm jack on one end and a pair of phono connectors on the other end (male, red and white)

The sound card has line in and a line out

I plug one of the cables into the line out using the 3.5mm jack. The other end of the cable, i plug the red bit into the red bit of the aux channel. I can now play a test tone from the computer through the amp and out of the speakers. I have a white plug spare. 

The second cable, the 3.5mm plug goes into the line in on the soundcard. At the other end of that cable the red and white ends, i plug the red bit into the spl meter. 

To create the loop that is required i took the white end of one cable and connected it to the white end of the other cable. This gives me horrendous feedback.

so starting again, 

What i have done in REW so far, with a single cable running from the line out to the amp, red connector into aux, white connector not hanging free. No spl connected

I open it up
I select settings, i dont change anything 
I press check levels
adjusting the volume on the amp does nothing, using the sweep i can up and down the reading on the screen, i set it to approx 75 on the screen spl meter. (sweep level 19)
click finish

at this point i go a bit pear shaped.


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## brucek (Apr 11, 2006)

> I plug one of the cables into the line out using the 3.5mm jack. The other end of the cable, i plug the red bit into the red bit of the aux channel. I can now play a test tone from the computer through the amp and out of the speakers. I have a white plug spare.
> 
> The second cable, the 3.5mm plug goes into the line in on the soundcard. At the other end of that cable the red and white ends, i plug the red bit into the spl meter.


Great, and that's exactly how you _will_ hook it up when you actually start to do measurements. But that only comes after you've calibrated the soundcard - which you haven't done yet.

So, disconnect all that and do the soundcard calibration first.

This involves connecting the 3.5mm plugs to the line-in and line-out. Then you will have the red and white ends dangling there. Connect the red ends together, so that now you have a loop on the right channel from line-out to line-in. You will never use the white ends. Leave it dangle forever.

Press the Measure button on the Settings page under the soundcard tab and follow the bouncing ball until that's done and save the file in REW with an appropriate name. Do not have the Use Left Channel calibrate as reference checked. Leave it unchecked forever. Do not have any meter calibration file loaded yet.

You should get a graph that looks like this if it's a crummy card: The better the card, the better it will look..










Report back when you get that far. (I want to see your graph). There's a little floppy icon in the lower left corner of the graph for saving.

brucek


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## blasted (May 14, 2008)

Thanks for that, 

I have done what you said and managed to get a graph. I find a lot of the technical aspects a bit over my head and the help files are so detailed i can get a little lost. If i stick to, red plug to red socket we will get there. 

adjusting the volume, as i cant hear anything i adjusted the sweep level until the spl figure on the screen was 75, then i adjusted the input level until the bar was at 18, this brought the spl figure on the screen up to about 78, however the input lervel is very low, if i drop it any more it will be doing nothing. Thescreen shot shows what is there 



the graph i managed to make:jump:


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## brucek (Apr 11, 2006)

> I have done what you said and managed to get a graph.


Yep, and you're almost there, but I need to point out some problems you have. 

It would be best to select your card type in the Settings Input and Output Device pull downs, and also select the line-out (speakers) and line-in pull downs. 
You'll see what I mean in the third picture below called (Windows Playback and Record Mixers interaction with REW).
See where I have the RealTek Audio card selected? Try and select that instead of default.

Your volume control Playback mixer is not correct. You want to Mute Line-in in Playback and enable it in Record. To select the Record mixer, pull down Options (on the Volume Playback Mixer you have shown in your pics) and select Properties and Recording Mixer.
My pics show what should and should not be muted. 
Basically in playback you want Volume and Wave only, and in Record you want line-in enabled. 
If line-in is enabled in playback, you get feedback.
I also show the interaction of the volume sliders and the controls in REW as a reference for you.

OK, when performing the soundcard cal you don't use the REW SPL meter as you have indicated. You don't use it at all in the routine. How would REW have any idea of an SPL level. It can't until its calibrated to the real world (later). That's what the VU meters are for. 
Set a -12dB sweep level for the output with the Wave and Output about where I show them to be and then adjust the input level until the VU meter is around -12dB on the input.

So, clear your file from the REW window and give it another try...



*Playback Mixer*










*Record Mixer*










*Windows Playback and Record Mixers interaction with REW*










*REW controls interaction with VU meters*








Hopefully this makes sense............


brucek


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## hot grits (May 9, 2008)

sorry to hijack this thread. I have related question. On my volume controle window< I dont have an option for line in. Only volume, wave, sw synth, cd player and imput monitor. Should I just assume it is muted. Also on your recording options window you posted. You have the line in muted, but then you have an arrow pointing towards the input volume. Should line in on recording control be muted or not?
Thanks


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## brucek (Apr 11, 2006)

> On my volume controle window< I dont have an option for line in.


You have an option to select what shows on the mixers..



> Also on your recording options window you posted. You have the line in muted


No, look again, it's _selected_, not muted.



> sorry to hijack this thread


Yeah, best to leave this thread to "blasted". Start a new thread for questions...

brucek


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## blasted (May 14, 2008)

Excellent pictures, thanks, I didnt even know about the recording parts. 

however i have found that i am unable to tick the box for line in on the recoding window and the advanced features seem locked. I have checked with the realtek site and it may be that i need a different driver. Im downloading it to see if it opens up the line in part. All other widnows will replicate the settings you have shown. I will update as i go on.

Thanks

Blasted


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## blasted (May 14, 2008)

Hello again, 

I have just handed in the last of my course work and the exams are all done, so i have had chance to re vist where i left off. 

I did exactly as you said but I dont seem to be able to raise the input volume any where near your levels. I had reinstalled the driver and it allowed to select the line in channel on the recorder, which is a start. 

what shall i do?



thanks.


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## brucek (Apr 11, 2006)

> what shall i do?


Turn up the output volume to 1.000

If still not enough, turn up the receiver SPL, so the listening level is at 80dB instead of 75dB.

brucek


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## blasted (May 14, 2008)

hi brucek, 

i upped the output volume to 1.000. It had no effect on the right channel, which stayed low. 



To me, that doesnt look like what i think it should look like.


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## brucek (Apr 11, 2006)

Yeah, you're not measuring anything.

All the software looks setup correct.

I can't imagine what you're doing wrong except that one of your 3.5mm splitter adapters or the cable looping back between them has some problem.

I take it you're still attempting to get a soundcard cal file - correct?

brucek


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## blasted (May 14, 2008)

Im still stuck at stage one yes, 

I cant help but feel that the sound module that i am using on the board is not helping my cause. I used to have a sound card but not long back there was a thunder storm and i suspect lightening hit one of the phone lines which caused my pci modem to go bang, i actually saw it flash. From that point on i dont think any of the pci slots have worked, my grapics pci express do work though. Im tempted to get an external usb soundcard.


EDIT just found that by wiggling the jack in the back of the computer i can affect one of the readings for the loop back, i shall have to check further.


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## Blaser (Aug 28, 2006)

Blasted,

I don't know if this might help but I'll say again to make sure you're not using a mono jack into a stereo output...


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## blasted (May 14, 2008)

Im pretty sure they are both stereo, but I shall check none the less.

Thanks people and please bear with me, i can be a home theatre shack sucess story:nerd:


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## Blaser (Aug 28, 2006)

OK, the Stereo input to the soundcard should split into 2 RCA ends, only one of them will work when connected to the SPL meter. Be sure to switch between them and try.

I am also sure you are already a Shack success story :bigsmile:


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## blasted (May 14, 2008)

Right oh chaps, 

I bit the bullet and went and bought a soundblaster live 24, usb soundcard. I did what i did before and checked the settings against the soundblaster sticky at the top of the page and produced the following. 

I would appreciate it if someone gave me the nod before i proceed with getting the rest of it wrong.


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## Blaser (Aug 28, 2006)

Blasted,

I think you really need to take the time to carefully read the help files again. This will save you a lot of time.

After that you need to check the thread few posts above where Brucek made detailed explanation. Then if you have a problem, let us know.

PS: The response of the soundcard looks good to me


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## brucek (Apr 11, 2006)

> I would appreciate it if someone gave me the nod before i proceed


Proceed............ :T

brucek


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## blasted (May 14, 2008)

I think i am getting somwhere, slowely, but getting there none the less. 

I switched to the soundblaster live 24 external usb card, set it up as per what the on line notes say and followed through till i made a measurment. 

the first measurment was set to finish at 200



the second one i set the upper limit at 24,000, this did not finish as it said clipping was detected, and advised me to lower the volume on my amp, which i did. I got the following



im not quite sure whats going off but it looks odd at the end. 

Am i on the right path or am I making a massive mistake?


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## brucek (Apr 11, 2006)

They're both quite good except for graph scaling.

For the subwoofer graph change the axis to the standard vertical 45dB-105db and the horizontal to 15Hz-200Hz. Always return to this standard after each measure with a simple push of the Graph Limits button at the top right hand corner of REW.

For the full range graph keep the standard vertical 45dB-105dB, but change the horizontal to 15Hz-20000Hz. Also with full range graphs, click the Smoothing to 1/3 octave to remove the comb filtering.

I also don't see that you have loaded a meter calibration file? This is required. They are obtained from our download page for the Radio Shack and Galaxy and ECM8000 types.

If you are using an ECM8000 then you may continue to measure to 20000Hz. If you are using a Radio Shack meter, then limit the upper range to about 3000Hz. They're not reliable after that.

brucek


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## blasted (May 14, 2008)

Thanks for that, i have re done it and got a better looking graph



this is with the radio shack cal applied and 1/3 octave smoothing. 

So from here is it case of moving it around and twidlling the dials, retaking measurments until i get a flat responce? To be honest im not sure what i should even be aiming for.


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## blasted (May 14, 2008)

i have been randomly fiddling with the dials and managed to do this, the roll of seems smoother and the dips less pronounced around 80hz, assuming i am reading it right though


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## blasted (May 14, 2008)

i turned the gain up to 2 o clock and shifted it to the other side of the room, now facing the sitting position and got this


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## brucek (Apr 11, 2006)

> i have re done it and got a better looking graph


I won't let you off the hook yet.

You must always use LOG (logarithmic) graphs and not LIN (linear) graphs as you've done. Push the Freq Axis button to accomplish that. The look will change quite a bit when you do that.

Also note that all the graphs you show (besides the LOG / LIN problem) are not 45dB-105dB vertical and 15Hz-200Hz horizontal.



> To be honest im not sure what i should even be aiming for.


OK, well now that you are an expert in measuring, I'll tell you what you're looking for.

You should first measure the sub by itself without the mains. You accomplish this by simply disconnecting the mains (with the power off) and running the sub as you normally would through your receiver using the standard crossover point. Always measure in stereo mode BTW.

You set the target line on REW at the crossover point that you normally use (i.e. 80Hz) and your goal is to try and get as close to that target as possible. You can do this with placement, treatment or EQ or a combination of all three.

Next, you add the mains to the sub and continue to measure the same way up to 200 Hz. Now you try and get the sub and mains level matched and the transition at the crossover as smooth as possible (usually with the phase control on the sub).

The end result should be a smooth flat line. Some like to boost the bottom end somewhat to get a more natural sounding bass (they call it a house curve).

See the pic below. It shows the desired target for a 80Hz crossed sub combined with a desired target for 80Hz crossed mains. The additive resultant is the red line at the crossover......

*Desired Subwoofer and Mains response targets*








brucek


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## blasted (May 14, 2008)

Thanks BruceK, you must have the patience of a saint. 

guess what my weekend is going to consist of:mooooh:


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## penngray (Feb 21, 2007)

> Thanks BruceK, you must have the patience of a saint.


He definitely does, you and me alone probably had him shaking his head several times !!!


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## blasted (May 14, 2008)

heads up on my new level of stupidity

for a while i had the sub cable plugged in the out not the in, that may expalin a few of the dodgy readings. I dont know how long its been like that.


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## blasted (May 14, 2008)

so far so good, at least i think 

0 - 200 sub only, 



0-200 sub and mains



now i tweaked the phase through to about 2 o'clock 



Is this looking like what it is supposed to look like? if it is, whats next?


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## Blaser (Aug 28, 2006)

Assign filters, adjust peek/gain to reduce the peek at 42 Hz maybe with a BFD? I'm glad you succeded at last


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## blasted (May 14, 2008)

Its good to know im pointing in the right direction. 

As its an SVS SB12+ it has the peq on the back. I have read the svs instructions and its gradually going.

Thanks again for the help so far.


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## blasted (May 14, 2008)

with a bit of tweaking i got this



how far do you go with the tweaking?


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## brucek (Apr 11, 2006)

> how far do you go with the tweaking?


That would be about it. Looks fine. Myself, I'd rather a bit more level on the sub (by slightly increasing the subs amp volume or receiver sub trim), but that's just me.

brucek


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## blasted (May 14, 2008)

Thanks for your help brucek, 

i just sat in my seating position and listened to golden brown by the stranglers and went from dissapointed at wasting money to really rather chuffed. :yay:

By level do you mean bring the gain up?


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## Blaser (Aug 28, 2006)

YEP! By the way your curve look great to me :T


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## blasted (May 14, 2008)

Thanks Blaser

I still cant swipe the grin from my face, from a **** sounding sub, to endless pink noise to leftfield in full glory, im certainly a happy bunny and shall preach the gospel that is REW, hallelujah

It only a shame i dont have any neighbours to annoy:neener:


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## acoustat6 (Mar 7, 2008)

Hi Blasted, Its looking good. Can you show us a graph 20 to 1000hz with no smoothing and another with 1/1 (one octave) smoothing?
Thanks,
Bob


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