help setting up MOTU 4Pre

[tony359]

Hi all,

I was wondering if anybody could help me setting up REW with a MOTU 4Pre external card.
I have multiple issues. Basically if I use the ASIO driver, only ONE output works, so I cannot use the reference for timing. NO matter what combination I use, only one channel of the main output works.
If I use the JAVA driver, I can use the timing reference but all my measurements are completely off. Below is what the sound card reads when try to calibrate.


Below in purple and red the measurements taken in ASIO and using an external USB microphone. They are consistent. In Green, the measurement taken using the Java driver. Wiring was unchanged.


So I ended up using the ASIO driver but with no timing reference. All worked ok.
Below my ASIO configuration


Can someone please shed some light on this?

Thank you!

 

[John Mulcahy]

The ASIO output naming looks odd - ASIO channels are mono, but "Main out 1-2" sounds like a stereo designation.

The Java plot looks as if there is a buffer delay somewhere causing the input capture to miss the early part of the sweep. Could try a measurement with the option to wait for timing reference ticked to see if that helps.

 

[tony359]

Hi John - thank you for your input.

I tried using an "acoustical timing reference". I can hear the loud chirp and the measurement starts but it produces the same results.

As a side note, this time I could not have any sound at all from the MOTU when in Java mode. I played with sample rate in the control panel and suddenly I now have sound! Still, the sound card calibration produces the same result. I have noticed the card does not follow the sample rate shown on REW (when REW says 48Khz, the sound card still says 44.1Khz)

Regarding the ASIO naming, I see what you mean. Indeed the Main Out is a stereo output. But "Main Out 1-2" is mentioned twice in the list so I assumed the first instance was Left and the second was Right.
I have done an additional test with interesting results: whatever I select under "output" will follow the channel mapping (1=Left, 2=Right). Whatever I select under "Timing Reference Output" does not matter.



EDIT: I think it works now. It was just a matter of matching the card sample rate with what the software says. Everything is on 44.1Khz and it seems to work now. Both sound card calibration and ambient measurement. Next step would be to find out how to change it to 48Khz!

Still, I wouldn't mind using the ASIO drivers, if anybody has any input I'd appreciate that!

 

[John Mulcahy]

REW can't dictate the sample rate for Windows, so if it is different to the rate configured for the card under the Windows audio properties Windows will resample the data. To change the rate in Windows usually need to go to the properties for the device (right click on volume control, select playback devices, select the device and then Properties, then go to the Advanced tab to change the default format).

 

[tony359]

Thanks John - that's indeed what I did. It's now working at 48Khz, happy days.
What about the ASIO driver, is it something worth reporting to MOTU or do you think it something within REW?

 

[John Mulcahy]

REW uses JAsioHost to interface with ASIO drivers. The channel names are provided by the device driver, I've not seen another driver use the same name for the left and right channels. It shouldn't really matter though, the channels are accessed by their index, not their name, so should all be accessible. From your later description it sounded like they were accessible as the output? When you say the timing reference selection doesn't work, what is happening and what are you expecting?

 

[tony359]

Thanks for the details.
When I am in ASIO mode, I can see two drop-down lists: OUTPUT and TIMING REFERENCE OUTPUT.

The OUTPUT field works. I can choose 1:Main Out 1-2 or 2:Main Out 1-2 and I have output on Left or Right respectively.
The TIMING REFERENCE OUTPUT field simply does not work. I can put whatever I want in that field but I won't have sound out of that channel. Please note that in the "timing reference output" dropdown I can see the same channels available that are listed in the "OUTPUT" field.

I am expecting to be able to tell the MOTU where to output a 'copy' of the main output sound to be looped back (LOOPBACK INPUT) into the card itself.

I hope this makes sense. Thanks again for your help.

 

[John Mulcahy]

You will only get a copy of the main output on the timing reference output if 'Use loopback as timing reference' is selected on the Measure dialog (or in the Analysis preferences). If 'Use acoustic timing reference' is selected that output carries a short high frequency sweep before the main sweep starts on the measurement channel. Which timing reference mode was selected?

 

[tony359]

Hi John,
I went back to double check and I have now output on both OUTPUT and TIME REFERENCE OUTPUT when in ASIO mode. I have no idea what happened that changed that, I am 100% sure it was not working before, I tried everything.
I guess this solves the problem! Thank you for your kind support on this matter!
Tony