# Help calibrating soundcard



## ironglen (Mar 4, 2009)

Please tell me what to do :sad:

Besides a headache, this is what I get when I connect my desktop computer's Montego DDL front out jack (via stereo 1/8") to the line in jack. Been through the help area, but most problems relate to laptop computers/soundcard connections...and I didn't see any feedback loop control in the Montego menus, looked like a similar problem in the help area.


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

Are you sure the line in jack is actually line in and not *mic* in?

Regards,
Wayne


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## ironglen (Mar 4, 2009)

Absolutely sure: using a 1/8" stereo cable to connect.




Wayne A. Pflughaupt said:


> Are you sure the line in jack is actually line in and not *mic* in?
> 
> Regards,
> Wayne


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

That might be part of the problem. Typically we recommend calibrating only one channel of the sound card. So if your sound card has only 1/8” stereo connections, you’ll need a couple of splitters to separate the left and right channels, and then an RCA cable to loop the in and out together.










Regards,
Wayne


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

Scratch that, John tells me it’s fine to do a stereo loopback.

What level did you do the calibration at? It wouldn’t “take” with my soundcard unless I pushed the level higher than what the REW instructions recommended.

Regards,
Wayne


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## ///Matt/// (Oct 21, 2010)

Is it ok to use a usb DAC that outputs analog L/R RCA to calibrate the soundcard? I am going to try it this weekend but I thought i'd ask as well. 

the DAC is a HOTAUDIO DAC WOW.

Thanks,

This is a really great forum and the REW looks really interesting. Am trying to get it all sorted so i can find the best crossover and location for the Servo-15 V.1 with the Anti-mode 8033! Hope to post some graphs in the anti-mode thread once I'm sure i'm measuring properly. 

:T


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

///Matt/// said:


> Is it ok to use a usb DAC that outputs analog L/R RCA to calibrate the soundcard?
> the DAC is a HOTAUDIO DAC WOW.


No, a sound card that has both audio inputs _and_ outputs is needed. If the sound card or USB device only has one or the other you, can’t calibrate the sound card. 

The HOT DAC is especially problematic as it has only RCA _outputs_. You can’t get a signal from a measurement mic _into_ the computer using a device that only has _outputs._ Make sense?

Regards,
Wayne


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## ///Matt/// (Oct 21, 2010)

Yes - Thanks Wayne. I especially appreciate your patient response to my thick question because I realize now I failed to mention I would be using the R RCA output to the _3.5mm line in_ on the laptop! 
:doh:
I plan on using the RS SPL meter as I don't have a microphone (except for those supplied with the Anti-mode and AVR, which I doubt are suitable for use?)

Cheers


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

Nope, those mics aren't suitible. 

Regards,
Wayne


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## ///Matt/// (Oct 21, 2010)

So it _should_ work then right?


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

If by “it” you mean the HOT DAC – no it won't work. See Post #7. Also review the REW Help Files and REW Connection and Cabling Basics. They are listed in the REW Information Index. 

Regards,
Wayne


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## ///Matt/// (Oct 21, 2010)

Thanks Wayne, 

I have reviewed the Help file and gone over the cabling basics. 

Why is the USB conversion to RCA not a suitable line level output to use? Then, the right RCA connected to the line input on my laptop should work to calibrate the internal soundcard? 

It's clear i'm no expert on the subject, so please forgive me if this idea is totally :thumbsdown:

I know the headphone out to line in won't work, so if the above isn't an option either, I guess i'll be tracking down a suitable soundcard.

Thanks again


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

So you’re just trying to calibrate your computer’s internal sound card, not use this HOT _as_ your sound card? Somehow that didn’t come across in your previous posts.

The bottom line is, you can’t perform a sound card calibration with a USB to RCA loop. I can’t explain why, you’ll have to ask John. If your computer can’t switch the mic input to a line input, you’ll need an external sound card.

Regards,
Wayne


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## ///Matt/// (Oct 21, 2010)

Wayne A. Pflughaupt said:


> So you’re just trying to calibrate your computer’s internal sound card, not use this HOT _as_ your sound card? Somehow that didn’t come across in your previous posts.
> 
> The bottom line is, you can’t perform a sound card calibration with a USB to RCA loop. I can’t explain why, you’ll have to ask John. If your computer can’t switch the mic input to a line input, you’ll need an external sound card.
> 
> ...


Sorry I wasn't clearer in my description. My laptop has a dedicated line in, so I just figured that the RCA from the DAC would work as a line level output.

In any case, i'll give it a try this weekend for kicks.


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## JohnM (Apr 11, 2006)

///Matt/// said:


> I know the headphone out to line in won't work


Why not?


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## ///Matt/// (Oct 21, 2010)

Hi John, 

I was under the impression that the gain of the headphone out would not work properly. Though I have re-read (again) the cabling basics and it does not make any mention of this. Here is the calibration using a
3.5mm headphone out to 3.5mm line input on my laptop.


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## ///Matt/// (Oct 21, 2010)

And the levels check... Does this look right to you? Why is the corrected level +120db? Thought the soundcard cal looks good.


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## laser188139 (Sep 19, 2009)

///Matt/// said:


> And the levels check... Does this look right to you? Why is the corrected level +120db? Thought the soundcard cal looks good.
> ...


When you test the soundcard calibration by doing a measurement to see if the overall result is flat, it displays whatever SPL level is calibrated for that electrical level. If you did not do the SPL calibration step to define the level as 75dB before running the measurement, your result could be significantly higher or lower than 75 depending on what REW remembered from the last time you did the SPL calibration. The important result is that the measurement verification appears flat, as yours does. You can ignore the absolute level, as you will be doing the SPL calibration again before any room measurement. 

Bill


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## ///Matt/// (Oct 21, 2010)

laser188139 said:


> When you test the soundcard calibration by doing a measurement to see if the overall result is flat, it displays whatever SPL level is calibrated for that electrical level. If you did not do the SPL calibration step to define the level as 75dB before running the measurement, your result could be significantly higher or lower than 75 depending on what REW remembered from the last time you did the SPL calibration. The important result is that the measurement verification appears flat, as yours does. You can ignore the absolute level, as you will be doing the SPL calibration again before any room measurement.
> 
> Bill


Ahhhh that makes sense. And because my systems soundcard is setting the levels I really have to watch the volume controls to make sure they are always calibrated for 75dbs I guess.

Thanks Bill :T


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## ///Matt/// (Oct 21, 2010)

Ok so I got some time to mess around with this thing and it seems the USB DAc will provide a suitable line level output for this purpose. I was able to calibrate and get it up and running. Below are my measurements with and w/o anti-mode - will post them there as well just posting here for the purpose of the connection discussion. 

without anti-mode;


With Anti-mode:


Nice! But could be better with proper placement. :clap:


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

Yup - looks good! :T

Regards,
Wayne


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