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

[morillon]

Thanks for sharing! I was trying to figure out if it was worth the money or not. Maybe when I get into recording/capturing content I can justify the price.

if not too much money to devote to it and needs to capture in usb ...
there are solutions at art project nad cambridge etc
;-)

 

[Rja4000]

15dB over 5mV means the front end is overloading at 28mV @1kHz.

Look at my table of measurements at 5mV.

As you'll see, you may choose to have up to 27.4dB of margin above 15mV (118mV) before digital clipping.

Do you think more than that is really needed ?

 

[Sonic-Wall]

All these measurements are fine but how does the ADI-2/4 sound compared to a phone Pre connected to the analog input?
Recording a vinyl and sharing the two files would be great.

 

[morillon]

All these measurements are fine but how does the ADI-2/4 sound compared to a phone Pre connected to the analog input?
Recording a vinyl and sharing the two files would be great.

will be a nice occasion indeed.. subjectively..(I know a bad word )
the subject of riaa correction via dsp is not discussed so much...
on a basis of this adi..face at schitt or art etc affordable mm solutions....?
;-)
(
maybe it would be nice to make specific external gain stages (variable? 30db --75db) with input impedance adjustment mm or mc..and only use the dsp of the adi for the riaa correction on the line input?
is that possible?
rme could also consider in the same genre a hdg microphone stage to "graft"
or ," just external 2 channel gain phono and microphone input stage" ? )

 

[Gregg Hermetech]

Got mine on Saturday, sounds great so far, will try and get the turntable hooked up to it this week, if I have time I could test direct in vs. with my phono pre.

 

[levimax]

will be a nice occasion indeed.. subjectively..(I know a bad word )
the subject of riaa correction via dsp is not discussed so much...
on a basis of this adi..face at schitt or art etc affordable mm solutions....?
;-)
(
maybe it would be nice to make specific external gain stages (variable? 30db --75db) with input impedance adjustment mm or mc..and only use the dsp of the adi for the riaa correction on the line input?
is that possible?
rme could also consider in the same genre a hdg microphone stage to "graft"
or ," just external 2 channel gain phono and microphone input stage" ? )

To me it's looks like ADI nailed it for a digital MM phono pre-amp. If you want to use a MC get a SUT (which is the best solution). While not common DSP works fine for RIAA, I have been doing it DIY for years and the Puffin is another example of a product that is proven to work well.

 

[morillon]

don't worry I know a little
;-)
the practice of riaa via dsp is in fact interesting because little practiced..
almost unnatural for followers of "vinyl-analog"...
digitization a/d... then processing riaa- then reconversion d/a
;-)


if I was not clear or too illegible
my point was just to ask me if it's not interesting to make an external analog gain stage, see mm-mc, so as not to overuse the adi ... and ask it to essentially manage the correction ...
;-)

 

[Mnyb]

I think it makes very much sense to use DSP to make the RIAA curve , thats whats DSP is good at . I'm no analog circuit designer , but reading these forums the experts here pionts on some issues and caveats using typical RIAA correction . And a big overload margin is very much a killer feature and very exact RIAA curve, nice

Hint hint for professionell user RME could create DSP presets for all the other curves that are not RIAA , organisations archiving old media would be pleased.
There have been a bunch of these curves around until we standardized on RIAA .

 

[Labjr]

I once suggested that Metric Halo make profiles for using DSP to EQ tape head amplifiers.

 

[Purité Audio]

I remember a very nice guy who wrote an RIAA profile for my Amarra rebadged Metric Halo.
Keith

 

[restorer-john]

Do you think more than that is really needed ?

Absolutely. 118mV @1Khz is really poor for MM overload.

But it's what you get when you use an audio interface for something it wasn't designed for, I guess.

Look at my table of measurements at 5mV.

View attachment 249421

As you'll see, you may choose to have up to 27.4dB of margin above 15mV (118mV) before digital clipping.

Do you think more than that is really needed ?

The phono stages built into standalone preamplifiers in the early 1980s offered better performance in all aspects except perhaps RIAA deviation, and even those were pretty darn good.

Example:

Incidentally, the MM phono overload on the preamp listed above (one of mine) overloaded at 340mV (above spec) for an overload margin of >34dB.

 

[levimax]

Absolutely. 118mV @1Khz is really poor for MM overload.

But it's what you get when you use an audio interface for something it wasn't designed for, I guess.




The phono stages built into standalone preamplifiers in the early 1980s offered better performance in all aspects except perhaps RIAA deviation, and even those were pretty darn good.

Example:
View attachment 249580

Incidentally, the MM phono overload on the preamp listed above (one of mine) overloaded at 340mV (above spec) for an overload margin of >34dB.

While I understand that you don't want the phono stage to "clip" or "hang up on the rails" when a loud clip or pop is encountered how exactly does 34dB of headroom help "overall" as a 340 mV "pop" would generate over 18 volts at the phono stage output which would clip the pre-amp stage, and even if it didn't some how it would certainly clip the power-amp output. Maybe I am missing something but it seems like a well behaved phono stage would recover gracefully from a "pop" / clipping without sending crazy voltage down the chain to disrupt everything down stream? Thanks for explaining.

 

[dlaloum]

All these measurements are fine but how does the ADI-2/4 sound compared to a phone Pre connected to the analog input?
Recording a vinyl and sharing the two files would be great.

That would depend rather a lot on the phono pre chosen...

Lots of phono pre's won't achieve the spec quoted here...

And then there is the issue where the combination of a specific cartridges output level, may suit eiter the phono pre or the RME interface better...

Yes that headroom is marginal for many configurations... and will work well for others.

My preferred digitisation method, is to use an analogue pre - "flat" (no RIAA) - and to try to optimise the gain in the analogue domain for maximum headroom before digitising - then apply RIAA digitally.

This interface would work well, and would make things a lot easier but would benefit from a flat phono pre stage (for OCD prefectionists)

 

[Rja4000]

While I understand that you don't want the phono stage to "clip" or "hang up on the rails" when a loud clip or pop is encountered how exactly does 34dB of headroom help "overall" as a 340 mV "pop" would generate over 18 volts at the phono stage output which would clip the pre-amp stage, and even if it didn't some how it would certainly clip the power-amp output. Maybe I am missing something but it seems like a well behaved phono stage would recover gracefully from a "pop" / clipping without sending crazy voltage down the chain to disrupt everything down stream? Thanks for explaining.

I have the same doubts.
34dB headroom doesn't make sense for me.

On top of what you list:
How would you perform a recording with keeping 34dB headroom ?
You want to keep a reasonable dynamic for music, which means a reasonable difference between the average 1kHz level and the peaks. For classical music, 13dB, 14dB, maybe 16dB... (AES recommends to keep 20dB headroom for studio recording. EBU says 18dB). But 34dB ?

The level would be way too low for a normal listening.

It seems the only justification here is about the crackles and statics. Not about music.

But, first, why should we care about them saturating ?
They are high frequencies already, so harmonics would most likely be inaudible.

And, second, how high in level are they anyway ?

Did anyone actually measure that ?
It seems RME did at least evaluate it, using their integrated high speed digital meter at 192kHz, and the level remains within the music dynamic range. So no need for such a waste of dynamic. (For recording or listening, this would be nothing else than a waste).

Here is an extract of RME manual about this

(I was confused at first by the last statement. But as the gain is applied digitally, after ADC, the headroom limitation is purely in the digital domain, indeed. On the analog side, the range is still up to +1dBu [or -2.5dBu for "gains" of +20dB or higher], with vanishing low distortion up to that level. Hard to match by any analog preamp.)

I don't have the final word about this, but this seems like a pragmatic, scientific, approach to me.
Hypothesis, measurement, conclusion.

 

[morillon]

My preferred digitisation method, is to use an analogue pre - "flat" (no RIAA) - and to try to optimise the gain in the analogue domain for maximum headroom before digitising - then apply RIAA digitally.

This interface would work well, and would make things a lot easier but would benefit from a flat phono pre stage (for OCD prefectionists)

what I clumsily suggest...
;-)
what type of analog preamplifier do you use....microphone type?

note that the cosmos has been carrying out this same approach to riaa since the rme..
do we have any feedback for this?
gain...impedance input...?

 

[dlaloum]

what I clumsily suggest...
;-)
what type of analog preamplifier do you use....microphone type?

note that the cosmos has been carrying out this same approach to riaa since the rme..
do we have any feedback for this?
gain...impedance input...?

About 12 or so years ago, I had a chat to a phono stage manufacturer, and asked whether he could make a version with switchable RIAA circuit... (as well as external loading via plugs... so I could tune the loading for MM cartridges) - he agreed... (JLTI Phono Stage)

 

[morillon]

it must be able to study in diy on well-born prephono to bypass the correction but keep the gain stages and the impedance and capacitance settings...
to then attack a correction dsp ...

will remain a sacrilege for those who prefer analog...
the approach of an all in one as on the rme is nice .. attacked by a sut can be a snub ...

but hey, if we consider just the riaa correction aspect, in analog is not really complex or expensive and very well mastered etc.

amplification is complicated.. not the correction, it seems to me...since many 10 years
(on the background..
it seems to me that the power of the dsp mainly has its interest in its adaptability as in acoustic correction ..
but there for a well-known fixed thing requiring only a few components?

but why not too..
hehe)
;-)
I will still have to question the respect of the standard upstream... at the time of pressing... or in cartdridge...

was it as sharp as what animates the "asr" observers?
;-)))

 

[LTig]

but hey, if we consider just the riaa correction aspect, in analog is not really complex or expensive and very well mastered etc.

Yet still we see lots of phono preamps with more than 0.1 dB deviation from flat FR. You need to use capacitors with high precision, and a 2- stage RIAA circuit is easier to design but needs 2 stages of amplification. So as always the budget is the limiting factor ...

amplification is complicated.. not the correction, it seems to me...since many 10 years
(on the background..
it seems to me that the power of the dsp mainly has its interest in its adaptability as in acoustic correction ..
but there for a well-known fixed thing requiring only a few components?

but why not too..
hehe)
;-)
I will still have to question the respect of the standard upstream... at the time of pressing... or in cartdridge...

was it as sharp as what animates the "asr" observers?
;-)))

You speak in riddles but amplification is not complicated at all if you use proper opamps.

 

[morillon]

see the end of my post..
and then good I would like to see the response curve in your system ... if it is better than 0.1db ..
(is the vinyl source so rigorous to justify this focus on this kind of thing?)

the subject is passionate about the amplification of very low levels of mc cartdrige in particular... at like some time 0.15mv etc or less..impedance very low etc
in any case you will observe that despite the simplicity that you seemed to describe .. the measurements of the phono amplifier here are not
stratospheric...right?
like here..just in mm with... 5mv.. sinad etc
etc
;-)

 

[sarumbear]

The phono stages built into standalone preamplifiers in the early 1980s offered better performance in all aspects except perhaps RIAA deviation, and even those were pretty darn good.

Example:
View attachment 249580

Incidentally, the MM phono overload on the preamp listed above (one of mine) overloaded at 340mV (above spec) for an overload margin of >34dB.

Those were the days when there were engineers in charge of product development who also know their environment. These days a) engineers are not component, b) they are working against a budget, c) the buyers are not knowledgeable, hence the manufacturers are not challenged.