RME ADI-2/4 Pro SE - RIAA mode measurements

[Rja4000]

Can even click remove whilst listening, with something like REAPER and iZotope or Acon plugs.

What do you mean ?

 

[MC_RME]

Removing vinyl clicks in real-time...

 

[Gregg Hermetech]

What do you mean ?

Yes, as MC from RME said. You're never listening to the analogue signal with this box, only the analogue signal after it's been through the ADC and DAC loop (the RIAA curve is done digitally), so with a DAW you can route the signal through click/pop/rumble/noise removal plugins if needed, either for recording your vinyl, or just listening in real time. Then there are all the cool options the box itself offers (different AD/DA reconstruction filters, EQ, auto loudness, headphone adjustment with crossfeed etc.) The ADC/DAC quality is exceptional, IMO, better than the Crookwood mastering console converters I had for a decade previously. About to take my 2/4 with a laptop and cans to Japan for three weeks so I can keep working (I'm a mastering engineer) while on holiday, if needed.

 

[jwmitchell]

Hi

here are some measurement of the new RME ADI-2/4 Pro SE in RIAA (phono) mode

The RME ADI-24 Pro SE is RME's last addition to their ADI-2 converters range.

RME explains that SE means "Special Edition", and they advertise it as a Special, Limited edition, on top of the existing ADI-2 serie.

Externally, the family relation with the ADI-2 range can't be denied.

View attachment 249033

Here-above, from top to bottom,
RME ADI-2 Pro fs BE
RME ADI-2 Pro fs R BE
RME ADI-2/4 Pro SE

The most obvious difference with the ADI-2 Pro fs (R) is the presence of an additional 4.4mm Pentacon connector, to allow direct connection of balanced phones.
On the rear, there is also a Trigger output, to remotely switch on a power amplifier, as an example.

The new ADI-2/4 is also deeper than the ADI-2 pro (160mm vs 130mm) and it includes those large "HiFi look" silver feets instead of the small rubber feet of the Pro,
In fact, it shares more of the look of the Audiophile-targeted ADI-2 DAC fs.
For functionalities, it is of course closer to the Pro, with its 2 stereo DACs and the inclusion of a stereo ADC.


Another difference is the new Power Supply, which, while still an external 12V DC PS with a lockable connector, is now more powerfull and grounded.


Internally, we read that the DAC is using ESS chips, similar to the one used in the ADI-2 DAC
and a new ESS ADC (the previous Pro were all using AKM ADC) with improved performance.

Also, the selectable DAC and ADC ranges are modified:
The previous "Pro" allowed a selection between +4dBu / +13dBu / +19dBu /+24dBu ranges,
The new ADI-2/4 has now +1dBU / +7dBu / +13dBu / +19dBu / +24dBu
That's one more range.

On top of this, the ADI-2/4 has a new RIAA mode "for directly digitizing vinyl discs"

This is not really a Phono Preamp.
But given the low noise level of the ADC, RME seems to think that the performance of the RIAA mode could compete with some very good phono preamp.

Let's find out if this is true.

Measurements below were performed using the RME ADI-2/4 Pro SE as a generator, Behringer Monitor1 and Shure A15AS to attenuate the level, and Virtins Multi-Instrument 3.9.7 software.


RME ADI-2/4 Pro SE - RIAA Mode

The RIAA mode can be selected from the Analog Input Menu.
It then allows selecting an additional "Gain" and, of course, will activate RIAA equalization / correction.

Here are the specs, copied from the manual

View attachment 249028

To compare with other measurements here, I chose 5mV / +26dB
Here is what the SINAD / Noise Dashboard looks like at that level

RIAA Mode SINAD / Noise Dashboard 5mV

View attachment 249030

80.8dB SNR
(and we get the same figure for SINAD: distortion is way below, as it measures 23dB below the noise at that level)

This is a pretty respectable figure.
We have 15dB headroom above 5mV, which is probably more than enough.

Measuring the other "Gain" settings for their respective specificied sensitivity, I got this

View attachment 249027

This pretty well matches the Specifications.

We see the SNR decreasing with the test signal.
(This most probably is partly due to the noise in the test signal, as the level is lowered)


If I measure all settings at 5mV, I get this:

View attachment 249026
The SNR remains the same for +20dB up to +38dB.
That just means that the difference in "gain" is purely done in the digital domain.

But for +14dB, you see a lower figure.

There is a distinct relay-switching sound when you go from +14dB to +20dB mode (and none above)
This means that some analog level stage is modified between those 2 levels.
This is not just digital compensation.
And we see this in the measurements.

RIAA Mono Bass
RME includes a setting called "RIAA Mono Bass"
The idea is that, on a vinyl, bass is mono anyway.
Therefore, noise may be decreased without loss by just averaging both channels for low frequencies.

Indeed, we can even measure some benefit on the ADC side.
(NB: a much more dramatic benefit can be expected on the Vinyl noise itself)

View attachment 249029


RIAA Mode - Frequency response after RIAA correction

One of the most critical measurements is the RIAA correction accuracy.

To perform this one, I went back to the original RIAA correction formula

View attachment 249037
(Where t1=3180µs, t2=318µs, t3=75µs)
I then computed a compensation curve, including a point for each of the FFT bins, for Virtins Multi-Instrument.


I usually perform Frequency response measurements with REW generated Periodic noise at 192kHz tuned for 128k FFT.
I use the same +/-5dB scale that Amir is using.

View attachment 249023

This looks like text-book perfect to me.

But RIAA compensation the way it's done here may have a different accuracy for different Sampling rates.
So I compared the correction for each sampling rate (44.1kHz, 48kHz, 96kHz, 192kHz) and compared with the flat Frequency Response of the ADI-2/4 DAC+ADC with no RIAA correction at 192kHz - In black in the plot.

View attachment 249025

Now we see a very (VERY) small amount of difference around 50Hz between the sampling rates.

Let's zoom in a bit:
(Warning: This is a +/- 1dB scale - a microscope look)

View attachment 249024

We see that the 192kHz sampling is slightly more accurate.

OK, that was fun, but let's be serious: there is absolutely NO audible difference between those correction curves.


RIAA Mode - Distortion vs Frequency at 5mV (90kHz BW)

I added the input level (dashed blue), so you may understand why the distortion is higher in lower frequencies: that's because the level is.
NB: This is measured at a -relatively- high level of 5mV.

View attachment 249040


RIAA mode - Conclusion

When I first read about the addition of the RIAA correction, I thought it was kind of a marketing gadget.
Now after measurements, I have to say this is quite serious.

If you try to rank this with Amir's ranking, here is where it would be located versus the very top of the chart.
Black arrow is where the "standard RIAA" mode +26dB result of 80.8dB would land,
The red arrow shows the "RIAA Mono Bass" mode ranking.

View attachment 249022


On top of the very serious performances we see here, we also have the powerfull parametric EQ at hand to fine tune any cartridge-specific FR difficulties.
And the benefits of the "Mono bass" mode are probably much more dramatic on the reading noise of an actual vinyl.

So no, it's definitely NOT a gadget.

Well done !

Many thanks! The application of DSP to RIAA is well justified and welcome. Easy enough to use with MC cartridge using head amp. I use Marshall Leach design From late 1970s.

 

[Matias]

New video.

 

[MC_RME]

Thanks Matias. Was about to post this link as well. We had a 15 minute video and it was just too long. Now it's about 10 minutes of detailed explanations on how the digital RIAA mode works, with much more info than I could ever pour into a manual. And in a way filming it was fun too

Kudos also to @amirm for allowing us to use his measurements to show how our solution compares to purely analog solutions.

 

[Rja4000]

Thanks Matias. Was about to post this link as well. We had a 15 minute video and it was just too long. Now it's about 10 minutes of detailed explanations on how the digital RIAA mode works, with much more info than I could ever pour into a manual. And in a way filming it was fun too

Kudos also to @amirm for allowing us to use his measurements to show how our solution compares to purely analog solutions.

Very interesting.

And it's great to keep it short.
Of course, it requires more work.

 

[Rja4000]

New video.

Thanks.
I added a link at the bottom of the review.

 

[Snoopy]

After seeing the video I really want one.
Sounds very good and well thought through

 

[badboygolf16v]

I currently use a moving coil cartridge with a single ended SUT. It sounds great but I do get a small amount of hum picked up. I've seen an SUT that has single ended inputs and balanced outputs. Hopefully that would eliminate the hum.

I wanted to confirm the balanced cables I would need. Am I right to say I would need to solder a 100k resistor across pins 2 and 3 of the XLR male connector that plugs into the ADI-2/4?

The SUT has a grounding post so I can connect the grounding wire from the turntable to that and then another grounding wire from there to the D-SUB connector. That should be sufficient for grounding purposes?

Thanks

 

[MC_RME]

I am not sure how a SUT can have an unbalanced output. This is nothing more than a transformer which naturally has a balanced output. Does it have RCA outs? And GND of these connected to metal housing? Maybe some modding is in order then...

Cabling and soldering both correct.

 

[badboygolf16v]

The inputs of the SUT I'm considering buying are RCA and the outputs are XLR. (I guess I have made the balanced vs differential error.)

 

[Chester]

As a total amateur, who just connects equipment and listens, could someone show me a picture of this 100k resistor soldering on the XLR please? I think I understand but want to make sure I’m not misunderstanding.

 

[JDSS]

@MC_RME @DrCWO @Rja4000 Hi today I tried to hook up 2/4 to a new turntable (Technics 1210GR). When I hooked the new RCA cables to the RCA to TS connector, there was loud hum coming form the speakers. I tried changing cables, but still got loud hum noise (can see this on the display of 2/4 as there are some spikes in lower frequencies). The interesting thing is: only when I hook it up with my old Rega RP-6, which non-detachable RCA cables does the noise go away. Even when I unplug the RCA to TS connectors completely form 2/4 still there is hum. Weird...Is it interference issue? Or is there sth wrong with my RCA to TS connectors? I'm completely lost here. Many thanks in advance for any input!

 

[JDSS]

I just took some pic:

This is with the connectors hooked to the combo jack in the back.

This is with the connectors completely removed.

This is when I hooked my RP6 table to 2/4 via the stock RCA cables. In this case, the hum is the lowest.

 

[Chester]

I assume you’re connecting the earth from the GR as well?

 

[Ricwa]

@MC_RME @DrCWO @Rja4000 Hi today I tried to hook up 2/4 to a new turntable (Technics 1210GR). When I hooked the new RCA cables to the RCA to TS connector, there was loud hum coming form the speakers. I tried changing cables, but still got loud hum noise (can see this on the display of 2/4 as there are some spikes in lower frequencies). The interesting thing is: only when I hook it up with my old Rega RP-6, which non-detachable RCA cables does the noise go away. Even when I unplug the RCA to TS connectors completely form 2/4 still there is hum. Weird...Is it interference issue? Or is there sth wrong with my RCA to TS connectors? I'm completely lost here. Many thanks in advance for any input!

As mentioned in the user guide, Make sure your rca to xlr adapters have pin 3 connected to ground.

 

[JDSS]

I assume you’re connecting the earth from the GR as well?

Yeah I found out it was ground issue. Fixed now, thanks!

 

[JDSS]

As mentioned in the user guide, Make sure your rca to xlr adapters have pin 3 connected to ground.

Hi thanks for your kind reply. It was ground issue since Technics needs to conect ground wire to the pre amp whereas Rega has an integrated gound wire with its signal cable. Thanks!

 

[fifeeliz]

Hi I think i have the same issue - Turntable/original cable have ground connector new cable does not. Where on the ADI-2/4 Pro does the ground connect or am i missing something - thanks