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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
captain_winters OP
120 posts
 
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
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rauliruegas
9,123 posts
 
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.
stringreen's avatar
stringreen
5,112 posts
 
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.
peterayer
1,373 posts
 
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.
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