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Measurements of RME ADI-2 DAC and Headphone Amp

Willem

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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

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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

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I use sd sharp as a dac filter. Does anyone know the most linear one? I've read conflicting information.
 

tusing

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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

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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

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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.
 
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Veri

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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

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MC_RME

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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.
 
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daftcombo

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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

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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

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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

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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, ...
 

ShiZo

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So if you are just listening to music for enjoyment use non sd sharp in your opinion?
 

trl

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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".
 
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