• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Measurements of RME ADI-2 DAC and Headphone Amp

Willem

Addicted to Fun and Learning
Joined
Jan 8, 2019
Messages
810
Likes
992
From the manual:
NOS (Non-Oversampling, SuperSlow) The DAC includes another filter which is called Super Slow in its data sheet. The impulse re-sponse looks perfect, but checking the output signal with an Oscilloscope reveals steps that are more typical for so called Non-OverSampling (NOS) devices, so we renamed it NOS within the DAC filter menu. Note that there is no audible distortion, the steps equal high frequency har-monics that are mostly higher than 20 kHz. Please also note that Slow and NOS filters cause much more aliasing into the audio band and out-of-band noise than Sharp filters.
 

yummy

Active Member
Joined
Oct 21, 2017
Messages
140
Likes
44
For the THD and Noise measurements we should note that the DAC's volume control is digital, complemented by two only selectable (or auto-set) output gains for phones output (as compared to four settings for the XLR and RCA outs). The 4Vrms (+14dBu) level Amir has used can only be established in hi-gain mode (max V_out = +22dBu) and the DAC chip fed with about -8dBr.

it's pro, some even higher
 

ShiZo

Active Member
Joined
Sep 7, 2018
Messages
126
Likes
65
I use sd sharp as a dac filter. Does anyone know the most linear one? I've read conflicting information.
 
Joined
Feb 13, 2018
Messages
18
Likes
52
I use sd sharp as a dac filter. Does anyone know the most linear one? I've read conflicting information.
From the manual itself:

DA Filter
Short Delay Sharp, Short Delay Slow, Sharp, Slow, NOS. The Digital to Analog Converter chip
offers several oversampling filters. Default is SD Sharp, offering the widest and most linear frequency
response and lowest latency. [...]
 

ripvw

Active Member
Patreon Donor
Joined
May 31, 2018
Messages
166
Likes
223
Location
California's Central Coast
BTW: Tidal has started having trouble switching to exclusive mode on my PC. Tidal tech support has been notified. It's not an RME issue because other music players on my PC switch to exclusive mode and set sampling rate automatically.
The same thing started happening to me, running the Tidal app on my Mac. I have had to check every day this week to confirm it is set to "Master" with Exclusive mode and forced volume - most of the time it has set itself back to "High". This is with the generic Khadas Tone Board...
 

Keis

New Member
Joined
Dec 28, 2018
Messages
4
Likes
2
From the manual itself:

DA Filter
Short Delay Sharp, Short Delay Slow, Sharp, Slow, NOS. The Digital to Analog Converter chip
offers several oversampling filters. Default is SD Sharp, offering the widest and most linear frequency
response and lowest latency. [...]
But the manual didn't tell you that all of them are having problem of out of phase, and Slow / SD Slow filter have high frequency roll off, except only the Sharp filter don't have any kind of odd problems.
 
Last edited:

Veri

Major Contributor
Patreon Donor
Joined
Feb 6, 2018
Messages
2,963
Likes
2,899
I use sd sharp as a dac filter. Does anyone know the most linear one? I've read conflicting information.
'Sharp' is 'the most linear' one. But differences in audibility should be none, except perhaps the roll-off with slow filters.
 

Keis

New Member
Joined
Dec 28, 2018
Messages
4
Likes
2

MC_RME

Technical Expert
Technical Expert
Manufacturer
Joined
May 15, 2019
Messages
115
Likes
486
My question was about phase only. The other point was no point at all as the manual clearly explains the loss of treble in both SD Slow and Slow filters (as well with the NOS), in two different places, plus gives the measurement that you yourself point to.

Regarding phase: The Sharp and Slow filters (non SD) are phase-linear. That expression means exactly that. And because the ADIs have DC coupled outputs the phase is stable at 0° even down to 0 Hz. There is nothing 'out of phase', which also seems to be the wrong expression used here as that would mean the phase is inverted at the output (a positive signal comes out as negative). This only happens if you intentionally use the ADI's Polarity option.

As much as you missed the explanations in the manual you seem to have missed the first measurement presented in that Stereophile article which shows how the Sharp and Slow filter work. There is no phase diagram because it's zero throughout.
 
Last edited:

daftcombo

Major Contributor
Patreon Donor
Joined
Feb 5, 2019
Messages
1,414
Likes
1,110
My question was about phase only. The other point was no point at all as the manual clearly explains the loss of treble in both SD Slow and Slow filters (as well with the NOS), in two different places, plus gives the measurement that you yourself point too.

Regarding phase: The Sharp and Slow filters (non SD) are phase-linear. That expression means exactly that. And because the ADIs have DC coupled outputs the phase is stable at 0° even down to 0 Hz. There is nothing 'out of phase', which also seems to be the wrong expression used here as that would mean the phase is inverted at the output (a positive signal comes out as negative). This only happens if you intentionally use the ADI's Polarity option.

As much as you missed the explanations in the manual you seem to have missed the first measurement presented in that Stereophile article which shows how the Sharp and Slow filter work. There is no phase diagram because it's zero throughout.
Thans but I still don't inderstand why there are so many filters.
I understand that a linear phase filter will give the best sound quality but implies latency which can be a problem for movies or other audio applications needing the least latency possible.
I understand that a minimal phase filter is not as good but doesn't have latency.
So why not only Sharp (linear) & SD Sharp (minimal)? What is the use of the others?
 

MC_RME

Technical Expert
Technical Expert
Manufacturer
Joined
May 15, 2019
Messages
115
Likes
486
You seem to have missed my reply (post 77) to your request (yes?).

As long as there are users that think they can hear a difference and prefer any of the provided filters, I see no reason to remove any of them. It wouldn't change the unit's price. Apart from that there are a lot of applications for such a unit, not only 'HiFi'. For example when measuring experimental stuff I often use the Slow filter to prevent excessive ringing in my screenshots...
 

daftcombo

Major Contributor
Patreon Donor
Joined
Feb 5, 2019
Messages
1,414
Likes
1,110
You seem to have missed my reply (post 77) to your request (yes?).

As long as there are users that think they can hear a difference and prefer any of the provided filters, I see no reason to remove any of them. It wouldn't change the unit's price. Apart from that there are a lot of applications for such a unit, not only 'HiFi'. For example when measuring experimental stuff I often use the Slow filter to prevent excessive ringing in my screenshots...
Thank you and yes, I miseed those posts. Will read them now!
 

Veri

Major Contributor
Patreon Donor
Joined
Feb 6, 2018
Messages
2,963
Likes
2,899
I understand that a linear phase filter will give the best sound quality but implies latency which can be a problem for movies
No, lip sync does not give problems until a much larger latency issue. The SD low latency filter is for pro use, recording, monitoring, ...
 

trl

Addicted to Fun and Learning
King of Mods
Joined
Feb 28, 2018
Messages
781
Likes
675
Location
Iasi, RO
I don't proof it, but it is clearly show in the graph of the manual page 56, Slow and SD Slow filter having roll off.
The out of phase is a thing not only RME but every single delta sigma DAC do this if they are not using Sharp filter, stereophile.com wrote it long time ago.
https://www.stereophile.com/content/ringing-false-digital-audios-ubiquitous-filter-page-2
This could be easily even with an 8-bit scope.
According to RME:
"NOS is the filter with the smallest steepness and therefore affecting treble more than the others, but offers the best impulse response".
 
Top Bottom