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Old 13th May 2011, 04:01 AM   #21
dimitri is offline dimitri  United States
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This is a good source:
http://www.esotericsound.com/Electronics/REQ2MAN.pdf
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Old 13th May 2011, 04:15 AM   #22
Previously: Kuei Yang Wang
 
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John,

Quote:
Originally Posted by john curl View Post
Let me explain myself more carefully. The RIAA is a standard that is known and can be reproduced by any serious engineer.
Sure.

Quote:
Originally Posted by john curl View Post
It has been the standard for about 50 years.
The standard of the RECORDING INDUSTRY ASSOCIATION of AMERICA standard, which several RIAA Members of significant commercial impact in the market simply ignored for much of the 50 Years. So it is a standard only in the mind of those who like to have an easy way out.

In the actual reality it is not a standard at all.

Quote:
Originally Posted by john curl View Post
The correction curves are built into the electronics of recording lathes. This has nothing to do with record companies, per se, they have to buy the electronics from Ortofon or Neumann. Someone, somewhere, might make a 'special' but I don't have any examples.
Actually, standards other than RIAA existed worldwide (especially CCIR in Europe). EQ Cards certainly for Neumann Lathes where available.

East Germany had several DMM Lathes (and subcontracted a lot of cutting for west german companies in the 1980's) which had EQ cassettes that where interchanged between RIAA and CCIR in the 80's depending which market the issue was intended for (unless someone forgot to switch the cards when they should have, so some west german pressings have CCIR instead of RIAA and some east german pressings have RIAA instead of CCIR as a result).

Decca in the UK had a long tradition of either scratch buidling their gear or substantially modifying commercial stuff. Many US "Audiophile" Labels replaced the electronics of the Lathe's wholesale, I know some commercial labels other than Decca also did varying levels of modifications.

Quote:
Originally Posted by john curl View Post
Now what about deviation from the RIAA? It is OK, so long as you are able to, and know how to reset to the RIAA. Thorsten's design did not appear to offer that. However, if it is possible to do that, then everything is OK.
The PH-77 specifies and meets it's spec of less than +/- 0.5dB deviation from the RIAA EQ 20Hz to 20KHz and less than +/-0.25dB 100Hz-10KHz. This curve can be readily switched to without problems.

Do you have any problems with a RIAA Response that is +/-0.5dB? I don't.

If you check how many Phono Stages reviewed in Stereophile have more deviation than that you may understand why I feel that this spec is sufficient.

Phono Preamp Reviews | Stereophile.com

What you seem to object to is that I deliberately designed the shape of the deviation to be something I wanted, to give certain overall result when implemented in a Phono Stage. So instead of aiming for absolutely flat with the less than +/-0.1dB guaranteed deviation that I COULD have implemented in the design, using the same components, I choose to introduce a deliberate "trend" (still a very minimal one).

Yet your Vendetta as measured by Stereophile also does not offer a truely flat response but a similar tilt (no, I am not copying you), the tilt is less pronounced than the one in the PH-77 but both "trend the same way".

Maybe you also object to the fact that I deliberately adjusted the distortion spectrum of the Phono for a certain ratio between even and odd harmonics instead of simply going for the lowest THD?

In the end you design your gear according a set of goals you have, I design according to mine.

Mine included a specification that had a RIAA EQ (and other EQ) deviation of less than +/-0.5dB.

You may opine that this is not flat enough, I may opine that it is more than flat enough, there is no simple conclusion to that.

The customer will decide if he prefers to buy a Phono Stage specified as +/- 0.1dB RIAA EQ Error or +/- 0.5dB or if he perfers to listen to it and decide what he likes the sound of better or even if he likes a different manufacturers Phono that has more 3dB deviation from a flat RIAA response (trust me, there are plenty).

Quote:
Originally Posted by john curl View Post
If not, then you have added a deliberate frequency aberration to the playback response.
So did you, right?

Quote:
Originally Posted by john curl View Post
This is hi fi?
No, I have no interrest in "HiFi". HiFi does not sound like music, it sounds like HiFi.

To me all is "fair game" as long as the results justify it.

Quote:
Originally Posted by john curl View Post
If it sounds 'better' then why? Speaker, room? This is the pitfall. When we make electronics for playback, it is supposed to be compatible with the vast majority of listeners, not a specific room.
John, let us be clear again, we are talking about a frequency response deviation of less than +/-0.5dB.

That is 0.7dB more deviation than the sample of the Vendetta Stereophile measured.

But it is also 0.5dB less than one other manufacturers phono, 1dB less than two other manufacturers phonos, 2dB less than a fourth manufacturers phono and 3dB less than a fifth manufacturers phono (all measured by Stereophile).

Now Speakers & Room produce response deviations of > 20dB for a "flat". Speaker response. Now "flat" Speakers do not exist, even ones that do 50Hz-10KHz +/-3dB in room with a lot of averaging are rare. So even the worst "offenders" WRT to RIAA Response will see their effect mostly swamped by speakers and room.

Please retain some sense of perspective.

Ciao T
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Old 13th May 2011, 04:24 AM   #23
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Go for it, Thorsten. My only quibbles are the extended high frequency and reduced low frequency extremes, but if it works for you, why not?
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Old 13th May 2011, 04:27 AM   #24
Salas is offline Salas  Greece
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The man who deserves the curves.
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Old 13th May 2011, 04:36 AM   #25
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John,

Quote:
Originally Posted by john curl View Post
Go for it, Thorsten. My only quibbles are the extended high frequency and reduced low frequency extremes, but if it works for you, why not?
Low frequency is "flat" at 20Hz, only the region around 40Hz is boosted gently, so no loss of LF. Yes, 10Hz is 3dB down, arm resonances are usually around 8Hz, ideally I should have had a steeper filter there, but that does not sound good.

If you know how records are cut you know than anything at real low end is filtered with a steep filter (you actually cannot cut it, mechanically) plus, it's Mono anyway.

Perhaps my fault is that I know how records are and where cut and within reason adjust my designs to complement this, even it that means they vary somewhat from any given theoretical ideal or standard.

Ciao T
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Old 13th May 2011, 04:42 AM   #26
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Hi,

Quote:
Originally Posted by dimitri View Post
The information derives largely from exactly the same inaccurate article (in 1955 Audio IIRC) and is hence at least in part wrong. For a more accurate view:

Manual of analogue audio restoration techniques by Peter Copeland

Ciao T
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Old 13th May 2011, 04:53 AM   #27
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A sad story- long ago I somehow acquired a Fisher preamp, model lost to history. It had a beautiful gold colored front panel. The only thing I really remember is that it had a knob for various different phono equalization settings, riaa and others. One quick wipe with some alcohol on a cloth, and all the markings were completely gone. It made me so sick to look at it, I either cannibalized it or tossed it. A lesson in restoration learned the hard way.
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Old 13th May 2011, 07:14 AM   #28
gpapag is offline gpapag  Greece
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Quote:
The Baxandall Tone Control:
Passive Baxandall

Other approaces are to switch between the different EQ Networks and to calculate your EQ here:
http://www.kabusa.com/riaa.htm
Thank you ThorstenL for the links. Helpful as always.


Quote:
Sy is not a critic or skepticÖ.
No ThorstenL.
Sy is in principle against opinions presented as facts (luck of sufficiently supporting data).
And when he senses that the other person has the potential, he is purposely persuading to get this extra juice out for the benefit of all.

Otherwise he is an ordinary DWYL person

YouTube - Blind Faith Do What You Like



I donít think that I am way off if I say that both of you do feel an ease with the lyrics of this song (different paths may be)

YouTube - Porgy & Bess - It Ain't Necessarily So


Regards
George
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Old 13th May 2011, 07:26 AM   #29
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Hi,

Quote:
Originally Posted by gpapag View Post
Thank you ThorstenL for the links. Helpful as always.
No worries, glad to help.

Quote:
Originally Posted by gpapag View Post
No ThorstenL.
Sy is in principle against opinions presented as facts (luck of sufficiently supporting data).
And when he senses that the other person has the potential, he is purposely persuading to get this extra juice out for the benefit of all.
This is not the impression I am getting, so perchance we part company here on Sy.

Quote:
Originally Posted by gpapag View Post
I donít think that I am way off if I say that both of you do feel an ease with the lyrics of this song (different paths may be)

YouTube - Porgy & Bess - It Ain't Necessarily So
I do tend to quote this song myself. Here a recent example:

State of the Union - Asynchronous USB DAC - Caveat Emptor - Thorsten - DIY HiFi Forum

Some other songs in that as well...

Ciao T
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Old 13th May 2011, 08:36 AM   #30
MiiB is offline MiiB  Denmark
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when looking into this there seems to be so many different curves with different time constants...one vital information I am missing when reading the papers on this, is just how common they are...

In my time of playing vinyl and my collection of vinyl is manly Rock-pop from Beatles and onwards is clearly, but with a steady growing number of classical recordings...also older..I would like the option of hearing the records as intended...

In practical terms I was considering to make 3 to 4 different curves..that then could be switched in and out.. Question is where to start and where to end.. what is the most commonly used of the alternative curves...(apart from the Riaa)..
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