# REW with M-Audio Fast Track and OSX - Levels :(



## dastrix (Oct 21, 2011)

Hi All,

My first post! 

Im using Lion, REW 5.0 and M Audio mixer. I'm having issues with getting the levels set, it keeps complaining that my levels are too low.

When I connect my MAudio mixer, the windows volume controls are greyed out.

I can adjust the levels with 'Mic Gain' on the mixer, 'Output' on the mixer or my volume. Even setting the volume quite high and the various knobs on the mixer just before it starts to 'clip' my level is still around -40db

Can anyone please assist so I can start to take some measurements? Im using a ECM8000 mix with a generic calibration file for it.

My mixer doesnt allow me to calibrate the soundcard as it has no input, only a set of RCA outputs

Thanks
Kris


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## SAC (Dec 3, 2009)

dastrix said:


> My mixer doesnt allow me to calibrate the soundcard as *it has no input*, only a set of RCA outputs


First I might suggest that you need to review the REW tutorial configuration links on the forum.
Also, you need to note any applicable Mac I/O issues.

And then you are going to need to address the issue that your 'mixer' has "no input, only a set of RCA outputs".

What, pray tell, is is 'mixing', if "it has no input(s)"????

Also, you might provide an indication of exactly which wiring diagram you are following in the REW tutorials.

I am hoping that this is a perceptual or semantic issue and not in fact accurate...:scratch:


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## dastrix (Oct 21, 2011)

SAC said:


> First I might suggest that you need to review the REW tutorial configuration links on the forum.
> Also, you need to note any applicable Mac I/O issues.
> 
> And then you are going to need to address the issue that your 'mixer' has "no input, only a set of RCA outputs".
> ...


Hi, it has a USB input sorry, from the PC. Im assuming thats not enough to calibrate my PC soundcard?

I read the tutorial but had issues following it as I couldnt get the levels right.

My wiring is:

MAC ---USB--> Mixer ---RCA Output--> Preamplifer/Amplifer 

Microphone is connected with a XLR to the M-Audio Fast Tracks MIC IN

Hope this clarifies, my apologies.


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## SAC (Dec 3, 2009)

dastrix said:


> Hi, it has a USB input sorry, from the PC. Im assuming thats not enough to calibrate my PC soundcard?
> 
> I read the tutorial but had issues following it as I couldnt get the levels right.
> 
> ...


Where is the output of the soundcard connected to the recvr/amplifier?

Refer to the REW interconnection guide, figure 2 and wire it per the diagram. 

Additionally the left output of the preamp/soundcard will be connected to the left input for the hardware loopback and the Preferences -> Analysis will be set to use the Loopback as hardware reference, and make sure the set T=0 to IR peak is NOT chosen. (In the diagram the left output and input are left 'open' and unconfigured...)


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## dastrix (Oct 21, 2011)

The sound card has no output , it outputs it sound via the USB interface to the mixer


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## SAC (Dec 3, 2009)

Then I would assume that you treat the inputs and outputs of the mixer as it if was the PC soundcard in illustration 1 of the Interconnect diagram.


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## dastrix (Oct 21, 2011)

Do you know any USB soundcards with Mixers built in? that way I can use one device

ill return this Mixer and get one that has a proper sound card in it, along with RCA outputs. Ill also try Windows XP


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## SAC (Dec 3, 2009)

Not sure exactly what you mean by a "mixer", as almost any reputable 2 channel pre-amp has gain controls.
(The Behringer Xenix 502 has several more channels of input and is mre 'mixer-like', but for ~$49, its had to figure what quality of pre-amp is incorporated. But not having ever actually seen or used it, well.... Caveat emptor!)

Below ~$400, I am not aware of any unit that significantly outperforms another in terms of phase or magnitude linearity.

For that reason, if you are comfortable with those limitations in the extreme reaches of the passband, the ART USB Dual Pre, is still available for about $69 if you do a few searches. Its hard to justify spending more and not really getting appreciably more; unless you are prepared to go to the next level of performance - which will involve a more significant investment in both pre-amp and mic.

The Dual Pre, and most other similar units, has individual gain controls as well.


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## dastrix (Oct 21, 2011)

This unit (pre amp, mixer, i dont know what you call it) has no rca inputs, so i cant plug a SPL meter in. Ill also change to Windows. The Pre you mention isnt around locally in Australia


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## SAC (Dec 3, 2009)

You use an adapter. FEW (if any, will have RCA inputs!

Also, be aware of the very real limits of a large capsule SPL meter as input! You will essentially be limited to LF measurements.
I would Seriously suggest you invest in at least a Behringer ECM8000 or the Dayton EMM6 omni directional mics - noting also that you want a pre-amp that supplies phantom power!!!!!!

I would shop online. 
And I have NO idea what is available there locally.


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## dastrix (Oct 21, 2011)

SAC said:


> You use an adapter. FEW (if any, will have RCA inputs!
> 
> I would shop online.
> And I have NO idea what is available there locally.


Adapter, to connect to what? Like I said, the M Audio Fast track has rca outputs to my Linn preamplifier

It has no other connections but a MIC in. Sorry you're really not helping me understand this.


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## SAC (Dec 3, 2009)

dastrix said:


> The sound card has no output , it outputs it sound via the USB interface to the mixer





dastrix said:


> This unit (pre amp, mixer, i dont know what you call it) has no rca inputs, so i cant plug a SPL meter in. Ill also change to Windows. The Pre you mention isnt around locally in Australia





dastrix said:


> Adapter, to connect to what? Like I said, the M Audio Fast track has rca outputs to my Linn preamplifier
> It has no other connections but a MIC in. Sorry you're really not helping me understand this.


LOL! I'm not helping YOU to understand this... ...So you have a sound card with no external I/O.... To be honest, I am not sure what connector you use for That topology!

As you said the SPL meter had RCA outputs and the soundcard had "no RCA inputs" (as opposed to “no external inputs"), I suggested an adapter to convert from RCA to whatever input it had. Then you tell us it has NO inputs! That requires a magical input, and they cost extra and are very difficult to find...

_
We are suggesting you GET a pre-amp that DOES have physical inputs AND outputs, supplies phantom power suitable for driving an omnidirectional measurement microphone, and connects to your computer via USB or Firewire (as appropriate to your platform)!_

We suggested one inexpensive model. But no, I don't know what is available there locally - wherever "locally" is! You are going to have to do a BIT of the legwork here, be it locally or online!


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

Hey drastix,

First, welcome to the Forum!



dastrix said:


> This unit (pre amp, mixer, i dont know what you call it) has no rca inputs, so i cant plug a SPL meter in.


Since you have a ECM8000, you don’t need to plug the SPL meter into your mixer. That would only be necessary if you were using the SPL Meter’s mic for taking measurements.

Here’s the wiring diagram you need. It’s the third one on the REW Connnections page.










Since your M-Audio doesn’t appear to have a line input, you won’t be able to generate a soundcard calibration file. However, that shouldn’t be a big problem; most of these units have virtually flat response anyway. I’m using a similar device, a Tascam US122, and it’s only 1/4 dB down at 20 Hz.

Of course, this doesn’t do anything for your level issue, but it’s a step in the right direction. Hopefully someone else can help you with that.

Regards,
Wayne


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## dastrix (Oct 21, 2011)

Hi Wayne, SAC thanks for the help so far

I took the M Audio back and got the Yamaha Audiogram 3. Im running Windows XP now and its working better

I connected the LEFT output to the LEFT input and did a soundcard calibration, I had to adjust the level of the Input all the way up JUST before it clips to match the output. 

As a result, it generated this file. Hows it look?

 

I am still getting low levels, when I set the levels, it is showing -40db (LOW) as seen here. My preamplifier volume is quite high, my output gain is about 25% and the mic gain is about 60%




Ideas?

Thanks


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

> I connected the LEFT output to the LEFT input and did a soundcard calibration, I had to adjust the level of the Input all the way up JUST before it clips to match the output.
> 
> As a result, it generated this file. Hows it look?


Looks like a legitimate calibration file. I forget what causes the ripples at the lower end that you’re seeing. My main concern, however – I’d suggest that it’s a rather poor sound card that drops like a brick above 5 kHz. Not a big problem is your primary interest is only getting readings and/or EQing a subwoofer, but if you’re interested in full range readings, I’d go with something different.

As far as your levels, I haven’t used REW in a long time so I don’t know what the problem there is. If John doesn’t check in in the next day or so, start a new thread dedicated to that topic.

Regards,
Wayne


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## dastrix (Oct 21, 2011)

Wayne A. Pflughaupt said:


> Looks like a legitimate calibration file. I forget what causes the ripples at the lower end that you’re seeing. My main concern, however – I’d suggest that it’s a rather poor sound card that drops like a brick above 5 kHz. Not a big problem is your primary interest is only getting readings and/or EQing a subwoofer, but if you’re interested in full range readings, I’d go with something different.
> 
> As far as your levels, I haven’t used REW in a long time so I don’t know what the problem there is. If John doesn’t check in in the next day or so, start a new thread dedicated to that topic.
> 
> ...


Gday Wayne,

Its a $170 AUD sound card, so about $150 US, its the Yamaha Audiogram 3. Is it that bad? Definitely Im trying to improve things in the 50-1khz range, but if its not up to scratch I can return it for something better

Thanks


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## JohnM (Apr 11, 2006)

dastrix said:


> I am still getting low levels, when I set the levels, it is showing -40db (LOW) as seen here. My preamplifier volume is quite high, my output gain is about 25% and the mic gain is about 60%


Both channels are showing the same level, which is about the noise floor of unconnected mic inputs. Were you able to hear the test signal while reading those levels? 

The Audiogram 3 does not appear to have phantom power, in which case you would not be able to use it with an ECM8000 or similar.


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## dastrix (Oct 21, 2011)

JohnM said:


> Both channels are showing the same level, which is about the noise floor of unconnected mic inputs. Were you able to hear the test signal while reading those levels?
> 
> The Audiogram 3 does not appear to have phantom power, in which case you would not be able to use it with an ECM8000 or similar.


The Audiogram 3 does indeed have phantom


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## trebejo (Oct 26, 2011)

Interesting, I seem to be walking the very same footsteps! I am trying to get an audiogram 3 to work with OSX and REW. I got the Dayton EMM6 and rather than get the whole sound measurement setup at Parts Express I figured I'd get a mixer and do something else in addition to measuring room response. So far I have not been able to make REW and the audiogram play together (although Garageband can use it to make voice recordings).

I'll be following this thread with interest, but in general, should one have to boot into a Windows OS or does REW work well with OSX? Does it help to use Parallels and, say, Windows XP inside there instead?


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## dastrix (Oct 21, 2011)

I got rid of the Audiogram and also OSX.

I'm now using Windows Xp with a MAudio Mobile Pre. Windows likes it much better - as soon as my 1/4 to RCA adapters arrive ill do some sound card calibrations and room calibrations

My suggest, off OSX. Thats the majority of the issue here


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