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Review and Measurements of RME ADI-2 DAC

Thomas savage

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Don't let @amirm know there are more of us in the area or he'll try to recruit us for a road trip in the same camper van that scares @Thomas savage so badly.

I don't even know the back story, but it sounds sinister....
He’s a expert anesthetist .
 

amirm

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I am in the Everett area and would be willing to offer my ADI-2 DAC for additional testing.
Thanks. Let me get my workload down and then we can go after this. Thanks for the offer.
 
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Don't let @amirm know there are more of us in the area or he'll try to recruit us for a road trip in the same camper van that scares @Thomas savage so badly.

I don't even know the back story, but it sounds sinister....
As long as the bus is headed to someplace warm and sunny, I'm in!
 

helloworld

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The ghetto way to turn your RME ADI-2 DAC into a Pro. Just add a TI PCM4222EVM.
Hi, could you give more details about your configuration? I am thinking of buying an ADC to pair with the DAC to make an audio interface. Which software and microphone amplifier do you use to do the recording? I am more interested with the AKM 5578 but could not find the Evaluation Module.
 

maverickronin

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I'm not actually recording anything with it so I don't have any recommendations on that front. I'm basically using it as an aux input so I can run analog only sources through the ADI-2's DSP engine for EQ and crossfeed. It's working well for that so far. I haven't built a preamp or anything for it yet but as is the whole system is quiet enough I can crank it to compensate for weak sources without hearing the noise floor.

It needs two power supplies, +5V and +/-15V. I built mine mostly from spare parts, tearing apart old wall warts. I've seen this PSU recommended if you don't keep mountains of spare parts laying around of have my curious habit of stocking up on old wal warts from Goodwill.

Here's a couple of links with basic descriptions of setting it up.

https://www.proaudiodesignforum.com/forum/php/viewtopic.php?t=886
http://www.dimdim.gr/2015/04/the-texas-instruments-pcm4222-evaluation-board/

The manual in the link to TI's page above plus those links should cover the set up pretty well. The only hiccup I ran into was that the digital output chips need to be manually set to the same rates of the ADC chip which may be a problem if you don't want to copy the settings in either of those links exactly.
 

Ngd3

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Just ordered an ADI-2 DAC as my first desktop setup - just going to be hooked up to my laptop dock. This might not be the right thread to ask, but is there much benefit to getting a higher quality USB cable than the one provided?

Feel free to redirect me elsewhere to discuss
 

RayDunzl

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Anyone have one of these and wiling to take the cover off to take pics of the "guts" and post?

Also: any other NOS (non-oversampling) DAC lovers out there, who also own this ADI-2 DAC? I'm curious if the combination of parametric EQ and user selectable filters allows this DAC to approximate the NOS "sound"?
 
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Anyone have one of these and wiling to take the cover off to take pics of the "guts" and post?
Not my own pic, but found this:
RME-ADI-2-DAC-offen-1649x1099.jpg

Also: any other NOS (non-oversampling) DAC lovers out there, who also own this ADI-2 DAC? I'm curious if the combination of parametric EQ and user selectable filters allows this DAC to approximate the NOS "sound"?
"NOS filter" has, in theory, the "worst" frequency response of all filters.
I would say: go for the SD Sharp (stock filter) and from that, tweak your own EQ.
 
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I asked RME team about reclocking of TOSLINK input, using internal, high precision clock.

Normally clock is being retrieved from spdif and can be very noisy. I don't want to use any galvanic connection to be sure there are no ground loops, HF noise being injected from PC USB etc (I know I could use coaxial input which is transformer coupled but still - if there is no reclocking inside, I would have to buy another state of the art USB to COAXIAL (SPDIF) converter to be sure that the output jitter is ultra low and will not degrade state of the art RME DAC performance).

That's why I would like to be purist here and only use TOSLINK + integrated headphone amp to not degrade unit's performance at all (connecting with external headamps may also affect the overall performance if the design is bad). But if there is no such mechanism like for example in AUNE S16 with FPGA FIFO buffering and reclocking all possible inputs before they go to the DAC, I would rather focus on benchmark dac which does that.

So there it is - really interesting article regarding jitter suppression in RME products and this is called STEADY CLOCK (not just "FS" in new releases which stands for femtosecond and in general high precision, internal clock):

http://www.rme-audio.de/en/support/techinfo/steadyclock.php

So it mainly depends on what is the audio frequency + incoming amount of jitter on specific input interface (it also takes care of TOSLINK if I got this right).

Have fun checking this out. Extra comments on presented measurements are welcome !
 
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amirm

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Extra comments on presented measurements are welcome !
All DACs have internal PLLs that attempt to extract the clock and leave behind jitter/noise. The problem is that some only filter out what is above audio band which leaves jitter where we don't want it. Good implementations will filter down pretty low. My jitter tests show issues here readily (much better than the time domain ones they show in their link).



My tests are also better because they operate backward, analyzing the analog output of the DAC. There are many other sources of jitter beyond the incoming one and my measurements show them (clock ones like they are showing will not).
 
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All DACs have internal PLLs that attempt to extract the clock and leave behind jitter/noise. The problem is that some only filter out what is above audio band which leaves jitter where we don't want it. Good implementations will filter down pretty low. My jitter tests show issues here readily (much better than the time domain ones they show in their link).
Thank you for the comment amirm. Really appreciate it.

But how you can tell or set certain level of jitter in your test using for example TOSLINK digital input with your own test signal ? Any ideas what can be ballpark figure of incoming jitter these days on high-end motherboard (TOSLINK) ? More like 1ns, 10ns or 100ns ? Can you somehow measure it once you have a chance in the future ? Because only then I could calculate final jitter after suppression before it goes to the DAC (something they showed there about reducing jitter to 1ns is not so great regarding femtosecond clock inside or at least should go below 100ps jitter which was always good result or maybe I am not interpreting it right).

Why not use something like in AUNE S16 ? Is it so expensive or hard to implement ? The sound was out of this world between USB input but also IDENTICAL from any TOSLINK source with tons of jitter. But they used FPGA FIFO buffer with total reclocking, so completely asynchronous for all kind of inputs. Only this can remove jitter completely if I am right (regardless of audio frequency and amount of incoming jitter, yeah unless it is still in range of locking window, and there are no data drops). All samples clocked again after buffering, using internal, ultra high precision clock. Some kind of "on the fly" jitter reduction or maybe patented ESS "time domain jitter reduction" can only achieve some level of suppression but can't remove it completely - am I right here ? And situation get worse when there is more input jitter.

Yeah you won't find this solution in modern aune dacs - for instance in the new one S6 that is waiting for your tests ;]. They cut it out in S6 to cut cost of the unit. It is far inferior to S16 soundwise. Maybe I will find S16 somewhere and forget about this issue. The only problem is that integrated headphone amp is bad (very high output, high output impedance, maybe fine for very high impedance headphones or planars where damping factor is not the case, sounded weird, somehow restrained and a bit distorted but after connecting to external amp it was out of this world). Dac itself is amongst the best I have heard.

You should measure this unit if you have chance (S16). It sounds marvelously. Breathtaking, real life experience. They designed this thing under full supervisor and support from Asahi Kasei (crystek ultra low phase noise oscillators, PGA digital volume regulators, FIFO FPGA, USB uses ADUM isolators and PCB looks like 1 mln $ project and YES, it was a few years ago :>). They claimed with their measurements to go beyond capabilities of the DAC itself - AK4495S. Doesn't cost too much either (sorry for a bit of offtop but this is really interesting how it works).

1543385175379.png


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