# Sound card calibration on MAC: delay problem



## juanalexei (Jul 15, 2011)

The graphs shows what happens when I try to calibrate the sound card with a loop back cable.

They show a delay of around 700ms between output and input. This result in a phase characteristic of the delay and an incoherent frequency response.

















The setup for this capture:
REW5, MacOS 10.6.7, JAVA SE 6 version 1.6.0_26-b03-384, MacBook pro internal sound card

I tried also with the MOTU, in windows XP under VirtualBox, with Jack and had always similar results.

Did I miss something?:scratch:

This software looks great and I look forward to use it with success! 

Thanks,

Juan Alexei


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## EarlK (Jan 1, 2010)

Juan said:


> _*Did I miss something? *_*
> 
> - That may be a "feedback loop" .
> 
> - Check (both) of the Macs' sound control panels to make sure that you are not sending input to output .*





> *This software looks great and I look forward to use it with success!
> 
> It is truly great software , by far ( unfortunately ) the most straightforward way (to enjoy it) is to use it on a PC .
> *




<> EarlK


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## juanalexei (Jul 15, 2011)

Thanks for your answer.

You can't send the input to the output without an external program on mac. None of them was running. So I don't think it can be a feedback problem unless java or REW are creating one. Seeing the scope it does look more like a delay (buffer problem? : it looks like the delay depends on the buffer I choose in the preferences)

Unfortunately I don't have a PC and can't reboot in windows without reinstalling everything because of a stupid partition ordering problem.


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## EarlK (Jan 1, 2010)

Juan said:


> ,,,,,,,,snip ,,,,,You can't send the input to the output without an external program on mac.,,,,,snip,,,,,,


Maybe that's true / I don't really know . 

I do know that I can't check the veracity of that statement ( since I don't have an up-to-date Mac here ) .

I still believe it's worth your while to look at your Mac Audio Midi Utility to make sure that the *"Thru"* box isn't selected .

- ( Here's a example of what one sees when using an "M-Audio Mobile Pre USB" soundcard ) . 











<> EarlK


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## juanalexei (Jul 15, 2011)

Definitively worth a look!

Of course yes I forgot that thru box. It's really unchecked. (and disabled anyway).

So I checked with an external input to be 100% sure. No trace of input signal in the output.


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## EarlK (Jan 1, 2010)

Juan,

JohnM ( the author of REW ) will need to add his expertise to this .

I'm out of ideas .

<> EarlK


P|S : I do know ( from posts made here on this Forum ) that REW will run properly with some Macs internal soundcards , but not with others . I don't know the reason for this disparity .
FWIW, ( for some work related reasons ), I successfully ran REW on a Mac Mini ( OSX, 10.6.4 ) when using either, the internal card or an AVID MBox Mini .


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## JohnM (Apr 11, 2006)

Try the Mandolane M3DMixer if you are not already using that and set the playback and record buffers to their minimum values.


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## juanalexei (Jul 15, 2011)

Ah Good advice! I don't know why it works because the scope still looks the same.

It's not good with the internal mac sound card because I guess, the input and the output have a separated clock source.

I managed to use the MOTU traveller MKIII firewire by rerouting the input to the optical output and then the optical output to the mac optical in.
Otherwise java doesn't seem to like more than 2 channels of input.

I'm please to know that the preamps of the card seem very flat.

Thanks a lot!

I can now start the measures!


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## TIPIC MC (Jan 23, 2011)

I EARIK i ave a problem with rew to calibrate my motu trav mk3 in mac osx version 

when i want to shake in/out loop bake for frequency response sorry for my bad English I'm French people

can you help me please ?


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## TIPIC MC (Jan 23, 2011)

EarlK please can you help ?


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## JohnM (Apr 11, 2006)

Unfortunately Apple's Java runtime has a bug that prevents Java applications accessing the inputs of firewire-connected soundcards. They show no signs of planning to fix it, a fix may come when Oracle start providing a Java runtime for OS X.

You could try the tip juanalexei posted above:


> I managed to use the MOTU traveller MKIII firewire by rerouting the input to the optical output and then the optical output to the mac optical in.


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## TIPIC MC (Jan 23, 2011)

ok thank you for information

how i do make to contouning this difilculty please ?

can you say me one solution ?

thanks


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## EarlK (Jan 1, 2010)

TIPIC MC said:


> EarlK please can you help ?


> Sorry , I can't help you because I had nothing to do with the solution ( that "juanalexei" created on his own ) . :scratch:

> ( Using Google Translate on the above to aid my grade-school french ) ; :bigsmile:

*> Regrette, je ne peux pas aider parce que je n'avais rien à voir avec la solution ( que "juanalexei" créé pour lui-même ).* :doh:

:sn:


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