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Beta Test: Multitone Loopback Analyzer software

Grooved

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Hey @pkane,

Since few days, Multitone stopped working, whatever the version I use (10.0.11 or 10.0.10).
View attachment 174201
This message occurs with either ASIO, WASAPI, DirectSound, whatever for input or output (E1DA Cosmos).

Just tested 1.0.12. Still the same. I've either this with ASIO (Matrix or Topping):

View attachment 174202

Or this with WASAPI:

View attachment 174203

Any thoughts?
Got the same thing yesterday, but I don't remember if it was coming from the "shared mode" or if it was another software opened and having exclusive mode on the same device.
I also got the ASIO devices only, no WASAPI devices appearing, which was fixed after rebooting the computer, so maybe it was from installing the last version without uninstalling first the previous one (which I did every time before this last one)
Sorry to not remember the problem but it was working after that and I didn't get it anymore
 
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pkane

pkane

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Got the same thing yesterday, but I don't remember if it was coming from the "shared mode" or if was another software opened and having exclusive mode on the same device.
Sorry to not remember the problem but it was working after that and I didn't get it anymore

That error is indicating that there are no audio channels available through this driver (channel range is from 0 to 0 :)), while Multitone is asking for a 2 channel input device. The reason, most likely, is that an output device was selected for input, or vice versa (@VintageFlanker -- please check)

index.php
 
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VintageFlanker

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For ASIO, did you set the output sample rate in settings? It needs to be selected for the rate that's supported by the driver.

For WASAPI, try switching between shared and not shared modes to see if it makes a difference.


-Paul
It was WASAPI shared mode that caused trouble. Fixed ! Many thanks, @pkane !:)
 
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pkane

pkane

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Quick update to v1.0.13 based on the feedback from @IVX.

Please note that with this version, you'll need to set the system volume control to the desired level (usually 100%) for measurements. Multitone will no longer do this automatically to accommodate devices such as Cosmos ADC that use the volume setting for a different purpose.

Changes in 1.0.13

  • Change: Multitone will no longer automatically set the system volume control to 100%. The user will need to make that change manually, if desired.
 
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jan.didden

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Paul, I may have missed it in all the previous pages, but I have a Q. How does the ADC-DAC combo impact the measured results? Are they the limiting factor or are you somehow measuring/compensating for their distortion?

Jan
 
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pkane

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Paul, I may have missed it in all the previous pages, but I have a Q. How does the ADC-DAC combo impact the measured results? Are they the limiting factor or are you somehow measuring/compensating for their distortion?

Jan
Hi Jan,

Ideally, the DAC/ADC is significantly lower distortion than the DUT you're trying to measure. That said, current released version doesn't have this feature yet, but I’ve been playing with a distortion pre-compensation feature. It works (sometimes) to reduce THD. This might help remove some of the harmonic distortions if calibrated with DAC / ADC loop, before inserting the DUT.
 

KSTR

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Paul, yes, I was wondering about that pre-distortion or cancellation. There's a thread over at diyaudio by Pavel Hoffman who has been working on that and has shown interesting results. It's not for the faint at hearth though.
I wondered if you know about that project. I can search for it.

Edit: found it: https://www.diyaudio.com/community/...tion-applications.347854/page-65#post-6796435

Jan
The point is that in many cases any pre-distortion works only for a given level and frequency as the distortion mechanisms are often not a simple static transfer function nonlinearity.
 
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KSTR

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This might help remove some of the harmonic distortions if calibrated with DAC / ADC loop, before inserting the DUT.
IME calibrating the DAC-->ADC (un-embedding the distortion) before inserting the DUT only works reliably to a high degree when
- the level is the same
- the frequency response is the same (mag and phase, and absolute polarity)
- the impedances (DAC load and ADC source) are the same, and the hookup (like mixing balanced and unbalanced)
- there are no warm-up drifts etc

It often may give an improvement but you cannot easily know to what extent the normalization still holds with the DUT in place.
 
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pkane

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Paul, yes, I was wondering about that pre-distortion or cancellation. There's a thread over at diyaudio by Pavel Hoffman who has been working on that and has shown interesting results. It's not for the faint at hearth though.
I wondered if you know about that project. I can search for it.

Edit: found it: https://www.diyaudio.com/community/...tion-applications.347854/page-65#post-6796435

Jan

I've done something similar, although I just read the first few posts on the DIY thread so far. As @KSTR pointed out, this kind of THD compensation works primarily with static/memory-less nonlinearities. Once frequency and level dependencies start to impact it, you'll need to make sure that the conditions used for testing at both, DAC and ADC are very similar to those that were used to create the compensation. Otherwise, you may just be adding more distortion into the mix instead of reducing it.
 
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pkane

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IME calibrating the DAC-->ADC (un-embedding the distortion) before inserting the DUT only works reliably to a high degree when
- the level is the same
- the frequency response is the same (mag and phase, and absolute polarity)
- the impedances (DAC load and ADC source) are the same, and the hookup (like mixing balanced and unbalanced)
- there are no warm-up drifts etc

It often may give an improvement but you cannot easily know to what extent the normalization still holds with the DUT in place.

Correct on all counts, Klaus! In my testing, this works best in a reasonably small frequency and level range around where the compensation was created. It is possible to find compensation that's similar or common to different frequency ranges. For example, I've created compensation at 100Hz, 1kHz and 10kHz, and then tried to find compensation that would reduce THD at all of those frequencies. It's not a simple or easy process, and there's no guarantee that such a compensation exists for every device. But it is somewhat fun to play with - almost like a game :)
 
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