Topic: is the ADI-2 Pro really 32-bit through the entire signal path?

I have read that many 32-bit DACs actually truncate to 24 bit within the DAC chip before reaching the Converter itself.
is this also the case with the ADI-2 Pro fs?

2 (edited by KaiS 2022-07-26 13:11:18)

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

No, ADI-2 internally it‘s 42 bit, 3 bits of which are used for 24 dB internal level headroom.

Read ADI-2‘s manual page 66 (DAC) 93 (Pro), last line:

RME's digital volume control in 42 bit TotalMix technology avoids all the disadvantages of analog level control via pots, is easy to use, offers reproducible settings, and the highest sound quality.

A 24 bit truncation in the DAC chip would not allow the clean performance shown in the measurements on the same page - no distortions at -93.8 dB volume.

At -93.8 dB attenuation a 24 bit signal would show ca. 0.5% or -46 dB distortion relative to signal level, or -150 dB absolute.
The chart reaches down to -190 dB.

3

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

hasan.ay386 wrote:

I have read that many 32-bit DACs actually truncate to 24 bit within the DAC chip before reaching the Converter itself.
is this also the case with the ADI-2 Pro fs?

Tales from the past....

Regards
Matthias Carstens
RME

4 (edited by hasan.ay386 2022-07-27 08:48:43)

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

KaiS wrote:

A 24 bit truncation in the DAC chip would not allow the clean performance shown in the measurements on the same page - no distortions at -93.8 dB volume.

Wow! Thanks

so the signal path would be like this?
24bit file → 42 bit internal volume control → 32 bit DAC

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

whatever file -> 32 bit USB interface / 24 bit digital interface -> (optional 32 bit SRC) -> 42 bit DSP -> 32bit DAC.

6

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

Small correction - the SRC is 24 bit, and gets fed only 24 bit (via SPDIDF/AES/ADAT).

Regards
Matthias Carstens
RME

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

MC is always correct. I searched AK4127VF's datasheet from digikey (https://www.digikey.com/en/products/det … VF/2538694), whose download button gives what is actually 4137's datasheet.  -_-

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

Thanks!

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

ning wrote:

whatever file -> 32 bit USB interface / 24 bit digital interface -> (optional 32 bit SRC) -> 42 bit DSP -> 32bit DAC.

Can I avoid the conversion to 42 bit if I set the gain control to 0dB and set all settings to default e.g. disable subsonic filter etc. or will it still be converted to 42 bit because of other internal processes?

This question is purely technical and theoretical. I know I will not be able to hear a difference

10 (edited by KaiS 2023-04-04 08:37:56)

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

hasan.ay386 wrote:
ning wrote:

whatever file -> 32 bit USB interface / 24 bit digital interface -> (optional 32 bit SRC) -> 42 bit DSP -> 32bit DAC.

Can I avoid the conversion to 42 bit if I set the gain control to 0dB and set all settings to default e.g. disable subsonic filter etc. or will it still be converted to 42 bit because of other internal processes?

This question is purely technical and theoretical. I know I will not be able to hear a difference

No, you won’t, because there isn’t any.

The 42 bit is not a conversion, but an extension of the internal dynamic / processing range.

3 bits added above, 32 bit original signal, 7 bits below.
This extends the dynamic range and resolution for extra 24 dB of headroom and 40 dB “footroom” to preserve signal integrity with DSP processing.

Without processing and volume at 0 dB ADI-2 works bit-perfect, doesn’t change the signal in any way.


Don’t confuse bit-depth and sample rate.
Conversion to a different sample rate always changes the signal, extension of bit depth doesn’t.

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

Is Loopback 32bit?

12 (edited by KaiS 2023-04-04 14:26:17)

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

takt wrote:

Is Loopback 32bit?

Through USB, I think yes.

Check with RME Bit Test.
Re-record the 32 bit file and send it to ADI-2 again, then report back here smile

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

MC wrote:

Small correction - the SRC is 24 bit, and gets fed only 24 bit (via SPDIDF/AES/ADAT).

After the sample rate conversion with 24 bit, is the signal then dithered? Because I read that the AK4127VF also has a dithering circuit, but dithering is not mentioned in the RME manual.

14

Re: is the ADI-2 Pro really 32-bit through the entire signal path?

Dither is done by RME.

Regards
Matthias Carstens
RME