• Registered: 2022-05-05
  • Posts: 3

Topic: Bit Test 32-bit passes for 24 Bit?

I'm on Mac OS and my tests have passed with the exception of the 32 bit.  It  says test passed **24 bit**.


Any reason why this might be the case?

2 Reply by Curt962 (edited by Curt962 2022-05-05 22:32:51)

  • Registered: 2019-01-07
  • Posts: 1,463

Re: Bit Test 32-bit passes for 24 Bit?

Mloiterman,

May I assume you're connecting the DAC via USB?   In that case, 32bit should pass...except when..

*Player Sftwr Volume is not set to 100%
*Player Sftwr "enhancements" (eq, etc) are active.
*Spdif (Coax, Optical) are used.  These connections are limited to 24bit.

That's my Generic List of likely Culprits, but know that things like Player Vol/EQ would most likely cause ALL the Tests to fail. 

With all that said:

Not all player software is created equally*, and it would appear that some popular Stfwr places Convenience, far above Audio Performance.

Assuming your other Tests PASS, the 32 bit test failing alone really isn't the end of the world, and should be of only Academic Concern. 32 Bit passing as a 24bit suggests the data was truncated in some way.   Even 1bit would cause this indication.

In the end?  The RME Bit-Test is brutally honest, and quickly separates the Men from the Boys in the Digital Data Transmission world.

Don't fret.  Nothing is broken.  Bit Test has simply alerted you that something in your Digital Data Path is not being honest with you.

Curt

*Take a look at this recent discussion.   

https://forum.rme-audio.de/viewtopic.php?id=35209

The Take-Away is that Corporate Computer Giants should not be trusted to hold Fidelity high amongst their Corporate Mission Objectives.   They couldn't care less. wink

Vintage 2018 ADI-2 DAC. "Classic AKM4490 Edition"
Cables:  Red, and White Ones.
Speakers:  Yes

3 Reply by ning (edited by ning 2022-05-06 03:58:55)

  • ning
  • DAW Mastermind
  • Offline
  • Registered: 2019-06-08
  • Posts: 579

Re: Bit Test 32-bit passes for 24 Bit?

> I'm on Mac OS and my tests have passed with the exception of the 32 bit.  It  says test passed **24 bit**.

The manual said that pretty clearly. Just read the section. it's expected.

Under the hood, Mac OS's audio pipeline uses 32bit float to process audio signals. ADI-2 accepts 32bit int. there's no 1:1 mapping between 32bit float and 32bit int.
So you'll not be able to maintain full 32bit transparency. you can, however maintain 24 bit transparency this way, as 32 bit float has 24 bits fractions+sign.
There is way to bypass Mac OS audio pipeline and have direct hardware access. Some players are able to write 32bit int directly to hardware. They call it "integer mode". With those players, you're able to achieve full 32bit transparency.
The code takes some effort to implement, and it does not bring any improvement, as the ADC/DAC does not have 24 bit transparency anyway. the DAC and  ADC have 120db SNR. that's just 20bit transparency. for 24bit it needs to reach 24*6 = 144dB.  So there's no need to pursue 32 bit transparency.

see my answer to previous similar questions: https://forum.rme-audio.de/viewtopic.ph … 89#p156289

  • Registered: 2022-05-05
  • Posts: 3

Re: Bit Test 32-bit passes for 24 Bit?

Thanks for the clarification.  Yes, I'm connecting to the DAC via USB and definetly experienced issues with volume causing it to fail.  Anyway, everything makes more sense now, but  just as an FYI, even Roon which has an "integer mode" wasn't able to pass the 32bit file.

Looks like it doesn't really matter, but thought that was interesting.

5 Reply by Curt962 (edited by Curt962 2022-05-06 17:58:00)

  • Registered: 2019-01-07
  • Posts: 1,463

Re: Bit Test 32-bit passes for 24 Bit?

Mloiterman,

smile  I didn't REALLY want to do this, but...

https://i.ibb.co/bNMycVD/20210702-153244.jpg

This is an extraordinarily inexpensive device, with "Donation-Ware" software that passes ALL Bit-Tests, and makes my Audio "World" quite nice!  Pairs with the RME wonderfully!

Repeat after me... "Raspberry Pi"   big_smile

When I'm convinced?  I'm Sold!   This is great!   Allow me to suggest such an option to you.

Curt

Vintage 2018 ADI-2 DAC. "Classic AKM4490 Edition"
Cables:  Red, and White Ones.
Speakers:  Yes
  • Registered: 2022-05-05
  • Posts: 3

Re: Bit Test 32-bit passes for 24 Bit?

I have several RaspberryPis.  What I really need is a second ADI-2 Pro FS R.