# Problem of calibration at 96kHz sampling rate. Bug?



## AndreaT (Jan 17, 2012)

Hello Friends,
my measuring suite includes the MOTU 896 mk3 as A/DAC and mic preamply.
I am using the last REW ver 5 beta 9 via ASIO driver in a PC running Windows 7 32bit and Java 7 update 5.

So far, NO problems of calibration at 44.1, 48 and 88.2 kHz.

*Instead, I am HAVING PROBLEM at 96kHz.*

REW output is directly to MOTU Analog Output n. 8 and the loopback is to Analog Input n. 8.
In this case I HAVE the calibration problem (+/- 3dB ringing) you can see in this graph:









It looks to be a synchronization issue, however, I have no idea if it is due to a REW bug driving the ASIO driver at 96kHz or if due to the MOTU ASIO driver itself.

Anybody had a similar problem with other A/DAC or soundacards?

Kind regards,
Andrea.


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## JohnM (Apr 11, 2006)

If that was measured with a single sweep then it shows some feedback/monitoring engaged at the 96k setting, with a delay of 0.333ms (which is 32 samples at 96k). If it was multiple sweeps it could be a sync problem between sweeps, but that would be pretty unusual for ASIO. Looking at the scope trace may give some clues, also worth making sure the ASIO buffer is not too small (i.e. latency not set too low) - worth trying with max buffer/max latency.


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## EarlK (Jan 1, 2010)

I typically change sample rates from within the ASIO driver first / then match that rate in REW .

As JohnM mentioned , bigger buffers can help .

:sn:


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## AndreaT (Jan 17, 2012)

Dear John and Earl, I confirm it was a single sweep (done by the REW calibration process).
I also confirm that the ASIO buffer was set to the max allowed.

I tryed to run the calibration at least 3 or 4 times getting always the same response I provided.

Again I confirm that I never had such a kind of problem at 44.1, 48 and 88.2 kHz.

Could it be the new Jave 7 update 5 environment?

Many thanks and kind regards,
Andrea


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## JohnM (Apr 11, 2006)

Couldn't be Java as the ASIO interface does not use Java drivers. How does the scope graph look?


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## Chester (Feb 19, 2007)

I am pretty sure I had this issue when I tested 96khz also (it was a while ago), I ended up averaging two sweeps with the same but opposite problem, if I have time, if there are things I can do to help test let me know


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## AndreaT (Jan 17, 2012)

Hello Chester, thanks for your post. I also opened a ticket to MOTU to check if it could a problem of my ADAC, a MOTU 896 mk3.
Regards,
Andrea


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## Chester (Feb 19, 2007)

Well, I experienced it on an audigy 2 zs notebook (or it may have been on my desktop, which would have been audigy 2 platnium pro) - in any case, i experienced the issue, however it was not with a MOTU dac so it is likely not your dac.


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## JohnM (Apr 11, 2006)

Chester said:


> Well, I experienced it on an audigy 2 zs notebook (or it may have been on my desktop, which would have been audigy 2 platnium pro) - in any case, i experienced the issue, however it was not with a MOTU dac so it is likely not your dac.


I don't think that can be assumed, the implication is there is some problem with using 96kHz sampling but that is not the case, e.g. here is a cal measurement of a Tascam US-144MKII at 96 kHz:


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## Barleywater (Dec 11, 2011)

E-MU 0404 USB sound card has front panel control for selecting input monitoring and controlling its level.

Here I have done loopback measurements at 96kHz sample rate. Spdif loop is used as timing reference.

Three runs were made: No direct monitor; direct monitor with zero volume; and with enough direct monitor to emulate Andrea's situation:

 


Other runs were done with much lower levels of monitoring, with correspondingly less ringing.

Feedback shows up in IR at about 2.7ms.

Very similar results also obtained with Roland Octa-Capture at 96kHz sample rate. Mix is software controllable and input control needs to be set -1.7dB to get your observed level of ringing.


Andrew


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## Chester (Feb 19, 2007)

I have had some time today and was making some measurements at 96khz, I was using the 'auxilary box' for the audigy 2 zs platnium pro (the one that goes into a drive bay on the front of the computer tower) - I did not experience the ringing this time. It could have been on my laptop before though before, point being: it seems to be working for me now


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## Barleywater (Dec 11, 2011)

Still pondering this.

Have you tried 96kHz sample rate loopback measurement with WDM drivers?

Motu manual describes CueMix FX, and may have default settings for 96kHz sample rate that are possibly source of problem.

Also described p.69 is:



> Controlling CueMix FX from your audio
> software
> Some ASIO-compatible audio applications, such as
> Cubase and Nuendo, allow you to control
> ...


Is it possible that REW inadvertently sets input monitoring in ASIO?

Return assignment setting?

It's really quite a deluxe interface!  

Andrew


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## AndreaT (Jan 17, 2012)

Hello Andrew/Barleywater,
in my case, I am NOT using CueMix to set the MOTU 896 mk3, NOR I have it open/running while using REW.

I simply set, once at the beginning, the MOTU 896 sampling rate at 96 kHz (I can do that from the device control knobs or by the Audio Console (not CueMix)), than I let REW drive directly the output over the ASIO drivers, and the same for getting its input.

I never used another driver, so I cannot give you a feedback on your other question.

Now I am on vacation until the 4th of August. I will do some other testing after that date.
Kind regards,
Andrea


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