How important is +- 0.1 db from RIAA curve?


For example here is an excerpt from an interview with Conrad Mas of Avid.

Conversations with Conrad Mas of Avid HiFi:
7. Could you talk about the RIAA curve you chose and how designing a RIAA section is not such a trivial matter?

... When we looked into this matter further, however, we realized that most recording studios whilst sticking very closely to the standard curve, used treble emphasis limitation in recording for decades (there is a quasi-standard defined by the leading record-cutting-machine manufacturer Neumann). Applying a correction according to Neumann standard makes a small but very audible difference. Whilst it's important to follow the RIAA curve, not doing so only alters the tonal balance of the sound; there are actually other items and components within a phono-stage that alter or make a bigger sonic difference than slight deviations off the correct curve. For instance if you played a record that was not cut with a perfect RIAA setting, say 1 dB difference between 1 K and 5 K, you'd be hard pressed to even notice. If we, however, changed the type of capacitors used in the phono stage, there would be a much bigger and totally noticeable difference.

Note: Avid phono stages are Neuman HF corrected, it is stated in their specifications.
captain_winters
There is a very good article in Stereophile discussing the merits of an additional HF correction like Neumann.  The author makes an interesting argument on page 3, suggesting that the HF role off of Neumann SAL 74/74B at 20K HZ is 0.1 db instead of the computed -.64db of the Neumann correction.  Although he does acknowledge lower phase distortion with the Neumann correction.  

http://www.stereophile.com/features/cut_and_thrust_riaa_lp_equalization/index.html
Dear Captain_winters: IMHO as better accuracy you have in each link of your audio system as more faithfull you have on what is in the recording ( everything the same. ), you are nearest to the recording.

From that point of view accuracy on the RIAA is a must to have for not change the tonal balance on the recording. Remember that the RIAA proccess in a phono stage is an inverse RIAA eq. to permit return/come back during playback to flat response that was altered during the recording overall proccess.

Now, the Neuman correction is always welcomed because during the cutting proccess the cutting head normally can't goes over 50khz with out burning so they stop here. During playback with out the Neuman correction the HF goes/follow falling to infinite according to the RIAA curve. So, you can here a difference when you hear a phono stage that comes with the Neuman correction that if we " see " on the whole subject is the way how the recording comes!.

There are some phono stages where you can switch between that Neuman correction and with out it and the owner decide what he like it.

Problem with the Neuman correction implementation is that has some troubles on the frequency domain as on phase shifts and other issues so you have to have the right knowledge level to make the design with out those " problems ".

All in all is a good characteristic for any phono stage. Today more and more manufacturers are implementd it.

Regards and enjoy the music,
R.
I am a pro violinist, and my instrument with the same strings, bow, rosin, etc. sounds different in every concert hall I have ever played in. I therefore wonder how important a minor electronic deviation is.
Stringreen, That's an excellent point and one that supports what a good friend involved with the Vienna Opera told me: He said "there is no absolute sound" precisely because of your observation. And then there is position in the audience, humidity, is the hall crowded etc. It never sounds the same. All we can hope for is get closer and closer to what is on the recording. Even that seems fruitless on some level.

However, to Raul's point, there is an argument for trying to maintain a standard in the playback equipment in order to decrease the variables which take us away from what is encoded in the recording.
Dear Stringreen: I don't know which is your main target you have with your home audio system when you started to build your system and when you make some changes of audio items trying to improve its quality performance level.

Mine is to enjoy the Music that comes in the LP recordings adding the less and losing the less of the recording signal. One factors/parameter/characteristic that always helps to achieve my main home system target is: accuracy at each single audio link in the audio chain.

+++++ " I therefore wonder how important a minor electronic deviation is. " +++++

maybe if that was the only system deviation could not matters at all but audio life is not so easy: we have a lot of different kind of deviations/distortions at each single system audio link. Got it?

Tha's all. Of course for what you posted your main target is different and nothing wrong with that. The audio worls can be boring if all of us thinked the same.

Regards and enjoy the music,
R.
Well if it is agreed that Neumann HF correction is a good thing, and that is debatable, then the +-0.1 db standard on RIAA cannot be achieved, since Neumann correction deviates from RIAA by -0.64 db, (referencing the work done in the Stereophile article).
Dear Captain_winters: You are right. You can't have everything, trade-offs is the name of the game on audio alternatives.

regards and enjoy the music,
R.
I currently own the Avid Pulsus which is Neumann HF corrected.  I selected it after comparing it with some other less expensive units, which I believe were not Neumann HF corrected.  However, I don't think my selection had anything to do with the Neumann HF correction, since I am not naive enough to believe my hearing is anywhere near that good in those upper frequencies.  The spec on the Avid Pulsus is 5Hz to 70K Hz +- 0.5db Neumann HF corrected.  Their spec goes way beyond the traditional 20hz to 20K Hz specification, which we typically see as the standard.  
Dear Captain_winters: That 20hz to 20khz specification is the Standard by the RIAA, it is not " the traditional " as you posted: no, it's no0t, it's what the RIAA " commanded " it's a rule not something that any one else could change, NO.

The unit I use for some years now measured/measures ( is not an spec but real measure, including cables. ) about the inverse RIAA eq. as next:

https://picasaweb.google.com/104284617601331669309/1606201109?authkey=Gv1sRgCNrBhveq5uzC-AE#slideshow/5618984106525365922

well, to the RIAA only " cares " 20hz to 20khz. Maybe whom cares beyond the RIAA rules are us audiophiles. That chart shows too that the deviation from the RIAA eq. curve in both channels is lower than: 0.015 db.

My unit ( Phonolinepream. ) came with a switched Neuman correction so you can choose in between and decide.

Regards and enjoy the msuic,
R.
Impressively flat, very nice. It would be interesting to know what it looks like with Neumann HF correction, if it down -0.64db at 20,000 hz.
Dear Captain_winters: Maybe that could be only academic. The first target any phono stage has to acomplish is the RIAA eq. curve. I don't know if you already have your Avid chart with the measures ( not specs but measures. ).

Here you can see what other very well regarded ( and expensive ) units measures on the same RIAA subject ( examples. ):

https://picasaweb.google.com/104284617601331669309/1606201107?authkey=Gv1sRgCI3hj-juiKXOGA#slideshow/5618983008834878562

IMHO Stereophile makes a very good job with the measures on audio items they review. The information could be relevant. In the archives of Stereophile you can find out some other units and of course other kind of items as amplifiers or speakers, interesting to read it and a learning information.

Of course that " numbers " can't say all but is part of any audio item.

Regards and enjoy the music,
R.