SH Spotlight Vinyl collectors: What is the RIAA curve and why do you need it? See SH Post #7*

Discussion in 'Music Corner' started by Chooke, Dec 20, 2016.

  1. Chooke

    Chooke Forum Resident Thread Starter

    Location:
    Perth, Australia
    I stopped by vintage audio collector's house the other day and there was this old valve pre-amp that intrigued me. It had a control knob on it for various record labels, eg Decca, Columbia, RCA etc. The guy at the place explained that it applies the correct RIAA curve for each of the labels as standardisation did not commence until the late 50s and was still being rolled out into the 60s.

    Having a few old 50s and early 60s records that got me thinking. Does this mean to get the optimum sound from these records I should somehow implement a variable RIAA curve specific to each label? Has this already been done or am I missing something?
     
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  2. Sid Hartha

    Sid Hartha Forum Resident

    Location:
    The Midwest
  3. Chooke

    Chooke Forum Resident Thread Starter

    Location:
    Perth, Australia
    Yes of course, the RIAA curve is the standardised curve. I should have phrased that question to just curve rather than RIAA curve, but the point remains the same doesn't it?
     
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  4. Strat-Mangler

    Strat-Mangler Forum Resident

    Location:
    Toronto
    This is supposedly still the stuff of urban legend as Michael Fremer had this to say about it when I read his review on ifi's iPhono 2 ;

    "I was fortunate enough to speak with one of the last surviving original UK Decca mastering engineers George Bettyes. Mr. Bettyes insisted that Decca implemented the RIAA curve as soon as the company began issuing stereo records. He also insisted that UK Decca and American London records were identical other than the labels used. That is why, he insisted, all older American stereo London records say on them “use the RIAA curve”. So when you read in the instructions here about using the Columbia curve on ‘70s era stereo records, do yourself a favor and ignore them! Ditto what’s suggested about Decca records and the Decca FFRR curve!!!!!!!!

    If these records sound “better” with those curves, you are using them as a tone control and not for strictly accurate playback."


    The Even More Amazing ifi Micro iPhono 2 MM/MC Phono Preamplifier »
     
  5. Fedot L

    Fedot L Member

    «Does this mean to get the optimum sound from these records I should somehow implement a variable … curve specific to each label?» - right.
    Please see
    Reproducing Old Records - HiFi System Components »
    «Old LPs and singles».
     
    Chooke likes this.
  6. Sid Hartha

    Sid Hartha Forum Resident

    Location:
    The Midwest
    In theory, yes. In practice, not so much for anything pressed after 1955. And even then, it's debatable (excluding pre-'40s shellac.)

    I once built a custom phono stage with several different EQ standards. That's when I realized it wasn't much of an issue. If you listen to 78s a lot, you'll find you may need to occasionally adjust bass and treble to taste. RIAA is fine for everything else.
     
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  7. Steve Hoffman

    Steve Hoffman Your Host Your Host

    There is no such thing as a variable RIAA curve, there is only one RIAA curve. Your machine has pre-RIAA EQ curves on it, for playing records cut before the RIAA style curve became standard. People had large record collections in the early 1950s, mainly 78s and they needed to be played back on different curves. Why? I'll tell you!

    First, the RIAA curve has been applied during the cutting of a record since only 1955 or so. This just means that the treble is boosted really a lot and the bass is reduced really a lot so the music can fit on the record. The curve is then applied in reverse at home by your phono preamplifier when you play back the record. The bass is restored and the treble is brought way down and with it, the surface noise (in theory).

    Before the RIAA curve it was every company for itself. Each record label had a "secret" EQ curve that was applied to cuttings going back to 1925. Each did the same thing, basically. Reducing bass and boosting treble. But not in the same areas of the sonic spectrum. Sometimes each STUDIO that a label used had their own curve (Decca Records had three studios: LA, Chicago, NYC and each had a different curve in the 1930s and 40s, quite silly).

    The idea was, each label thought their curve was the best compromise for good sound with the least amount of "scratch" as they called it, but for this industry wide system to work, the Columbia recordings had to be played back on a COLUMBIA phonograph, HMV or RCA-Victor recordings on a HMV or Victor machine, US Decca on a Decca machine, and so on. These machines had the same curve applied in reverse to the electronics and were the best at getting the most out of the (usually) lo fi gear sound of the time.

    This of course went all to hell in the early 1950s when McIntosh and other companies with Hi Fidelity systems started to be sold, so these preamplifier designers of the era GUESSED at a curve for each of the labels and put the switching on the machines. A switch for Columbia records, for Decca, for RCA-Victor and on and on. Chaos. The Columbia Curve on a McIntosh didn't really match the Columbia curve on a different brand of preamplifier in the early 1950s. They were just guessing! This prompted the recording curve to be standardized and the RIAA curve was born, all labels agreed to use it for the good of the industry.

    But the older records (even the records cut in 1954 and pressed into the 1960s) were not cut with the proper RIAA curve. So, what to do? Use an old preamp with alternative curves on it?

    Here is the kicker. None of these alternate curves really sound good. The reason is that once off of the 1955 standard RIAA curve, everything sounds worse because the surface noise is usually increased. a 1935 speaker won't catch it but your modern speakers will.

    So, what I do is leave it on RIAA, even for 1955 and older recordings, even 78s. If I want to alter the sound a bit I'll add some parametric EQ, usually a db or 2 around 35oo cycles with a Sontec slope of 6 to match the older curves. But once off of RIAA, forget it. So don't do it, don't even worry about it.

    PLEASE NOTE:

    The RIAA curve is NOT on the master tapes, it is just applied to the cutting of the lacquer. YOUR home phono preamp reverses the curve and the music sounds normal to you (hopefully). How WELL your home phono stage reproduces the RIAA curve (how exact) is CRUCIAL to good vinyl playback. Don't skimp on your phono stage, folks!
     
  8. BradOlson

    BradOlson Country/Christian Music Maven

    You are right, Steve. This is why good equipment is important.
     
  9. McLover

    McLover Forum Resident

    Location:
    East TN
    Also, a note. RIAA= RCA New Orthophonic curve. As that curve was standardized on.
     
  10. Steve Hoffman

    Steve Hoffman Your Host Your Host

    You're right but let's not confuse the people! That's a radio transcription curve.
     
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  11. Michael McGuire

    Michael McGuire Active Member

    Location:
    Texas
    What's a sontec slope of 6? 3500hz, 2db boost is from 0 to 3500 hz right?
     
  12. Chooke

    Chooke Forum Resident Thread Starter

    Location:
    Perth, Australia
    Thanks for all your replies. I've certainly learnt a lot since joining this forum.

    Just one last question, getting back to that vintage pre-amp, so is it safe to assume that the selector for different curves was a novelty curiosity and probably did not change the sound too much from a RIAA implementation?
     
    Last edited: Dec 20, 2016
  13. Steve Hoffman

    Steve Hoffman Your Host Your Host

    Try it and see. It changed the sound a lot. All bad. Leave it on RIAA.
     
  14. Steve Hoffman

    Steve Hoffman Your Host Your Host

    A wide slope. A "1" on a GML Parametric is a "6" on a Sontec Parametric. I'm saying add a db or two around 3,500 cycles with a nice width around it. If you have a graphic, make a nice little mountain peak. Don't overdo it or everything will have a midrange horn clang. Just a hint of it.
     
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  15. Chooke

    Chooke Forum Resident Thread Starter

    Location:
    Perth, Australia
    Cheers
     
  16. RiCat

    RiCat Forum Resident

    Location:
    CT, USA
    A question Steve if you please? As you pointed out the RIAA curve is applied when the master is made. How accurate is this process? Is it so standard that different production facilities with different cutters and electronics feeding them produce the same signal alteration across the board? HiFi gear usually lists very tight adherence specs to the RIAA standard. Since its' inception have the production facilities been able to produce masters that are as tight to the ideal specs?
     
  17. Bruce Mulle'

    Bruce Mulle' Forum Resident

    Location:
    Down South
    You got that everyone ?
    Test is tomorrow morning 10:30.
     
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  18. Krzysztof Maj

    Krzysztof Maj Active Member

    Location:
    Poland
    Fantastic thread!
     
  19. Didn't know any of this as to why the curve was established, etc. interesting stuff.
     
  20. Smartin62

    Smartin62 Forum Resident

    Location:
    Cleburne, Tx USA
  21. Sax-son

    Sax-son Forum Resident

    Location:
    Three Rivers, CA
    That is a great write up on this piece of history. It's laid out very well. Thank you for that. Fortunately, my collection is mostly post 1955 and up to the RIAA standard. For those interested in vintage hi-fi, this is valuable historical information.
     
  22. Steve Hoffman

    Steve Hoffman Your Host Your Host

    Glad you got something out of it.
     
  23. Steve Hoffman

    Steve Hoffman Your Host Your Host

    Neumann electronics or back in the day, Westrex. The curve is usually right on during cutting. It's the reversing it at home that is the tricky part. Sometimes, the old Japan receivers from the 1970s (Pioneer, Marantz, Sony, etc.) had the most accurate reproduction translation of all, better than many 1950s and 60s phono preamps.

    However, the trick is to translate the curve correctly and then make it sound like real music. That is the job of the best phono stages. It's up to your ears to find one that works for you within your price range. Once your home system strays too far off of RIAA, you have a "sound" that is built in to every record you play no matter who mastered it. That is to be avoided at all costs!
     
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  24. Michael P

    Michael P Forum Resident

    Location:
    Parma, Ohio
    Prior to RCA developing the "New Orthophonic" curve in '52, was there any pre-emphasis used on the earliest RCA 45's? I have 3 RCA Victor "Red Seal" 45's on red vinyl. I presume they were recorded prior to 1952.
     
  25. Steve Hoffman

    Steve Hoffman Your Host Your Host

    Of course. On every electric record going back to the 1920s. Don't call it pre-emphasis. That's too confusing.
     
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