RIAA, Questions only please

Great article imhififan.

Contains an excellent glossary, and what appears to be a complete definition of terms.
For my own benefit as a form of reference, I challenge those in the know, to tell us of any inaccuracies, incorrect data, misleading information, in that article.

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For additional information.
A web page that I was familiar with in the past, from the IASA, these definitions relate to earlier 78’s, and the link contains an interesting table at the bottom. The table shows how varied the EQ’s were between companies, and just how limited in frequency the 78’s were.

A clear case of too many cooks in the kitchen ?

8^0

The control knobs on the preamps that allowed for setup of the different EQ’s must have been interesting.

https://www.iasa-web.org/tc04/mechanical-carriers-replay-equalisation

Yes, Imhififan has provided us with an outstanding reference on the subject. (Just as he had done, btw, in an unrelated thread not too long ago in which I and Roger had also been participating, which helped bring all parties to agreement). Thanks!

For one thing, the article appears to support statements Roger has made indicating that between approximately 50 Hz and 500 Hz, and above approximately 2122 Hz, records are cut at constant amplitude. ("Approximately" because as I think we all agree the transitions between constant velocity and constant amplitude are gradual, and those frequencies represent "3 db points" as Roger and the article have stated).

What the article leaves me uncertain about, however, given that in modern times a cutting head is to at least a loose approximation a velocity-based transducer (meaning that it converts signal amplitude to groove velocity), is **how** the cutter is caused to cut at constant amplitude at those frequencies.

If I recall correctly Roger had stated toward the end of the deleted thread that that is accomplished by means of an EQ applied to the signal prior to its application to the cutter, the EQ extending over a 60 db range (in addition to the "pre-emphasis"), between 20 Hz and 20 kHz. That would seem to be appropriate if behavior of the cutter corresponds to an idealized model of a velocity-based transducer. However, Ralph responded that cutter characteristics deviate considerably from the theoretical ideal, and with his cutter the required EQ is only about 15 db, and also is not linear over the frequency range. And I had pointed out, among other things, that neither EQ appears to be consistent with application of the approximately 40 db curve that I think we all agree is applied in playback.

Finally, and related to that, although the reference provided by Imhififan refers to the need to reduce groove excursion at low frequencies when a velocity-based cutter is used (specifically between approximately 50 Hz and 500 Hz), how that is accomplished is not made clear as far as I could tell.

So while the article is certainly helpful, and appears to me to be likely to bring us closer to settling these matters, there are still some basic questions that need to be answered before agreement can be reached.

Best regards,
-- Al

Dear @uberwaltz: Good that you found out the link P.Ledermann speaks on those threads 10 years ago. As a fact on those threads he made reference to 2-3 of the Galo diagrams. All is in what I posted here and in the other deleted thread.

We only have a shortage on the PL straing gauge italian magazyne review of that first SS model. As a fact before that old hot discussion the link was in his site and after the discussion the decided to deleted.

Anyway, Galo witres the whole " picture " rigth from the begening.

But, as I said before: P.Ledermann was " the man " behind all our posts in these 2 ramtubes threads. I understand that in the past PL made some kind of work at RM. He said it in what I posted here.

Good for him and thak's for your " excersice "/effort/time to found out the Galo papers.

Through those papers I confirm my believes.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.

@imhififan  Thank you very much
About the most complete article I have read so far that at least makes majority of sense and is somewhat easier to understand for the layman imho.

Still living and learning.

Im still learning too. That's the most reasonable article I have read to date. He states things factually, doesn't get into voodo about it. I can imagine the cutter takes some fine tuning and is fussy. I would think the tweeks are not to the RIAA but to other parts of the cutting amplifers.

In a studio tape machine there are 3 adjustments that are made for each reel of tape to get flat response from that reel. Those tones stay on the tape so the next guy in the process has something to reference. While he is adjusting the 10Khz level he is not changing the EQ shape, merely the level and only a few dB.

Dear @ramtubes: That's one of the reasons of digital alternative superiority to LPs other that today 32/768 DACs or 4XDSD.

The signal that recording microphones pick up, through that very long " road " on analog/LP, till that LP signal arrives to the system amps is  a real truly TORTURE at each link in the analog system chain.

That means heavy heavy degradations of every kind: distortions, added noise levels everywhere, etc, etc: but we are accustom to the whole LP overall distortions. Such is audio life.

Digital is really simple, even we human beens listen through an ADC at our inner ears.

So, nothing wrong with digital as almost we analog lovers could think.

R.

Raul,Roger ,Ralph, Al and all the other fine contributors to this thread and it's previous incarnation.

My compliments to imhififans post and link was not meant to slight any of your fine contributions and I hope that was not your takeaway from it.
I have been intrigued, enthralled and immersed in both threads since inception.
However even if you overlook the differences of opinions and the contradictions of some posts I still found myself struggling to grasp some of the technicalities of said posts at times.

What I meant in my earlier post here was that linked article was just a lot easier to comprehend and digest as a near one stop shop take on the subject.

Nothing more and hope that is understood.

Wow! thank you guys, I was just simply provide a link that Roger ( ramtubes) looking for.We should thanks Roger for spending his precious time to open this discussion to unlock the mystery of vinyl disc recording-equalization, answering questions, sharing his expertise and knowledge to us.BTW, Raul (rauliruegas) is the first poster mention the article by Gary A. Galo.

What the article leaves me uncertain about, however, given that in modern times a cutting head is to at least a loose approximation a velocity-based transducer (meaning that it converts signal amplitude to groove velocity), is **how** the cutter is caused to cut at constant amplitude at those frequencies.

I think I can answer that. Since the cutter isn't by any means a true constant velocity device, it gets equalized so it is. The CV equalizer is a pretty complex set of time constants; I'd hate to have to work them all out, since the actual cutter response is more like a loudspeaker with some odd peaks in it (complete with a 'nose' in the high frequencies, just like any raw driver response) than anything else. 

Now the slick way to set up the whole thing would be to combine the qualities of both the RIAA curve into the CV equalizer curve so that the output was both at the same time but I suspect in order to preserve hair follicles this wasn't done and probably won't ever :)

@Ramtubes,
Thanks Roger for the tip, ;yes I usually watch ebay for used test gear from those mfgrs.

best regrds.