Soundcard Measurement Variation - Home Theater Forum and Systems -

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post #1 of 9 Old 05-15-14, 01:42 AM Thread Starter
Join Date: May 2012
Posts: 9
Exclamation Soundcard Measurement Variation


I hate writing on a forum and flashing myself in the nube, but, I'm at a loss of what I'm doing wrong here.

I'm trying to make a calibration file for my new setup using the updated V5 of REW. I'm using for my sound card an external USB interface by Native Instruments - Komplete Audio 6

I've got my Loop-Back set as follows: From my Phones Out, to a 3.5mm - 2.5mm TRS jack adapter into a 2.5mm TRS - Cable to Red and White RCA which each have RCA - 3.5mm TS jack adapters looped-back into my Inputs 1/2.

In the Preferences of REW:
- I've tried to use ASIO but the "Java VM Aborts" and REW closes (even after ensuring latest Java).
- So Driver set to Java.
- Sample Rate is 48kHz.
- Input Options are still default unchecked.

- The Output Device and Output is recognized and I've tried with both the default out and the available drop down "LINE_OUT" to make calibration.

- My Input Device and Input is recognized as Input 1/2 and the only available is Default Input.

- I've tried Buffer Settings of both 32k and 64k

Managed to achieve = to the output of -12.0dB FS in the Check Levels leading into the Soundcard Calibration. But between 20Hz and 20kHz the best I can muster is an 8dB variation and the warning to dismiss this as a calibration.

I've read all the tips and pointers before hassling the forum, checked my cables and software. Any help would be greatly appreciated.


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post #2 of 9 Old 05-15-14, 10:56 AM
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Location: GTA, Ontario
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Re: Soundcard Measurement Variation

( As best practice ) your soundcard calibration should be made from the outputs that you use to drive your system ( which is generally not the head-phone output such as you've used & which is giving you problems ) .

I'd suggest getting the correct cables ( a pair of mono RCA-1/4" cables ) & then calibrating again using the RCA outs on the back of your SC .

BTW, you can get these ( low level ) types of warnings if you've mistakenly engaged input monitoring ( to the outputs ). The resulting cancellations ( of adding input to output ) can trigger the warning that you encountered .

A soundcard calibration ( via loopback cabes ) should result in an almost flat line ( from 20 - 20K hz ) .
- What does yours look like ?

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post #3 of 9 Old 05-15-14, 11:26 AM Thread Starter
Join Date: May 2012
Posts: 9
Re: Soundcard Measurement Variation

Hi Earl,

Thanks for writing back!

The calibration plot I have been getting at the moment is a medium curve into around 250Hz and then a wiggle in the higher freqs at around 16kHz onward.

I'll knick down to the shops and get a dedicated cable for this today too and I'll let you know the results as soon as I give it a go.

Considering that I'm using the Right Channel for calibration is it just as important to have the Left input plugged in and leveled also? I've tried it both ways using the phones output, but I vaguely remember reading somewhere that you should have it unplugged.

Oh! I definitely had the monitor inputs turned off while performing Calibration. At least I can eliminate this....

Thanks again, I'll let you know how it goes!
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post #4 of 9 Old 05-15-14, 12:09 PM
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Peter Stoffregen
Join Date: Oct 2012
Location: Barrie, Ontario, Canad
Posts: 14
My System
Re: Soundcard Measurement Variation

Hi every one;
I'm also new to HTS. I have used REW on my Windows XP desk top with amazing results. I am perfecting a large line array system, driven by 3 Phase Linear 700 B's. (I like living on the edge!)
The computer died and I now use a Toshiba Lap top with Windows 8. The sound card is a "Conexant smartaudio HD"
Getting to the point; trying to calibrate this card reveals an apparently horrible freq response. Mic 'boost' was reduced to zero as per Youtube videos. Is there any way of using this card or is an external sound card a must for this lap top.
If I have to go external, Can any one suggest a good value model?
Thanks for any help, Peter S
PS; Hope i'm not Hi-Jacking the thread
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post #5 of 9 Old 05-15-14, 01:06 PM Thread Starter
Join Date: May 2012
Posts: 9
Re: Soundcard Measurement Variation

Hi Pete,

Not at all. I've been doing some reading around the forum the last couple of days and found this:

" Important notes:
You will require a soundcard with a line-in and a line-out jack.

Both the Radio Shack and Galaxy CM-140 output a mono line-level signal. (note, we recommend the Galaxy meter for full range measurements. The Radio Shack meter is not suitable for full range, although it can be used up to ~3000Hz with no problems for testing subwoofers. Here's a fairly good article on the Radio Shack meters).

A microphone input (mic-in) on a soundcard is not suitable (many laptops only have mic-in). "

Found the link on this page here.

Hope that helps.

If you're still looking for a soundcard, there are plenty available to choose from, I guess it just depends what you really want to use it for and how much you want to spend? I have 3 at home at the moment.

Propellerhead - Balance ($250 AU) it's really nice and I bought it particularly for use with Reason but it can only be ran by my DAW and nothing else. So for when I need to share a soundcard for an intensive production session, I use Native Instruments - Komplete Audio 6 ($180 AU on special) the one I'm trying to calibrate now. Finally I have a Steinberg C11 ($100 AU) which was my entry level audio interface that got me going as a beginner but couldn't handle the latency that I get now using many software instruments.

Have a look at the images of the cards too and then you'll know better if it's got the right ins and outs for you.
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post #6 of 9 Old 05-15-14, 10:53 PM Thread Starter
Join Date: May 2012
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Re: Soundcard Measurement Variation

Hi Pete.

I've had a go now using my Main Outs rather than my Phones. I decided since I was using Main Outs I wouldn't need a new cable after all seeing I have two short 1/4" TS Line Leads perfect for the job. Again 8dB was the best result. I noticed I had to set the levels on my soundcard pretty high too, the right channel input pre is maxed out the left isn't far off it and then Main Out Volume is around 2/3rds of the way up.

Anyway, I'm not entirely sure that there's too much wrong with the graph though. Would you mind taking a look at it for me?

I'm certainly no expert but how flat does the response need to be?
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post #7 of 9 Old 05-16-14, 09:32 AM
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Peter Stoffregen
Join Date: Oct 2012
Location: Barrie, Ontario, Canad
Posts: 14
My System
Re: Soundcard Measurement Variation

Hi Ben;
I am new to digital audio, but my past career of 20 years was theatre sound installation (analogue). Your sound card curve seems perfect to me. (mirror flat and 3 db down at 18 kHz, no problem at all for my purposes.)
I have checked out the 'Komplete Audio 6' and the 'Steinberg CI 1'. These units seem to be more than what I require, recording and production, etc. My uses at this point are sound system alignment with REW and possibly 2 channel audio playback using my lap top as a source.
Do you have any opinions on the Sound-Blaster-X-Fi-HD external sound card?
Thanks, Peter
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post #8 of 9 Old 05-19-14, 08:40 PM Thread Starter
Join Date: May 2012
Posts: 9
Re: Soundcard Measurement Variation

Hi Pete,

Sorry about the late reply.

Thanks for taking a look at my Soundcard Cal file. If my file is so neat though, why wouldn't REW recommend me using it as a calibration file, and what's with the 8dB variance?

I checked out the Sound-Blaster Soundcard and found this review here

It had some good and some not so good things to say about it, but all in all seems like it would cover most of your needs. I think as a playback card it seems likely to be worth it's weight in coins.

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post #9 of 9 Old 05-20-14, 03:01 PM
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Location: UK
Posts: 6,298
Re: Soundcard Measurement Variation

REW warns about the response because it rolls off earlier than expected at the high end, -3 dB at 18 kHz and -7.7 dB at 20 kHz. The spec of the card is much flatter than that, so it might be some odd resampling artefact, e.g. the card operating at 44.1 k and REW at 48 k and Windows doing a low quality resample. Try changing REW's sample rate to 44.1 k or setting the card to operate at 48 k to see if that cleans up the response. The response is flat enough that you can use it without a cal file, though, assuming you are not worried about the very top of the audio band.
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calibration , komplete audio 6 , measurement , souncard , soundcard , variation

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