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In Reply to: Best inductors for RIAA? posted by chaslieb on October 27, 2001 at 21:10:26:
Air core inductors, such as the ones you mention will work best I think. One question: what are the equalization equations for an inductive RIAA? I have a copy of the Lipschitz paper around here somewhere, all I can remember is a CR model.Dan
Follow Ups:
Come on guys, dig out some theory and do your homeworks ;))t
Check out the RIAA curve link at : http://www.infomaniak.ch/~bonavolt/audioel.htmThis equation varies based on what year the RIAA put it out. I would really like to find the RIAA curve used by Columbia in the 50's and 60's because their recordings are always the best to my ears and the have the artists I like best.
I think I saw on another post that you have a 27 based preamp. Have any advice on operating this tube and any ideas where to get the 5pin sockets?
Thanks,
Charles
I've done a lot of modeling of my RIAA design in spice, and have read and pondered the original Lipschitz paper. The thing I don't understand, is how to go from the RC model Lipschitz uses (for passive equalization) to an RL model. I couldn't find anything on that site explaining that.> I think I saw on another post that you
> have a 27 based preamp. Have any advice
> on operating this tube and any ideas
> where to get the 5pin sockets?The sockets are everywhere. China makes a nice Johnson replacement, and Angela (www.angela.com) has the cheapest prices I've found. I have a big collection of 27 tubes, and prefer the mesh plates, but only loaded by a C4S (see Doc B's site). I think I run 4 mA through them.
The globes are microphonic and prone to hum. I use massive filtering on the filaments, with a high current LM317 (IIRC) feeding the filaments.
Dan
This equation varies based on what year the RIAA put it out. I would really like to find the RIAA curve used by Columbia in the 50's and 60's because their recordings are always the best to my ears and the have the artists I like best.
not to be a smartass here, but if these recordings always sound so good, could it be because they are being played back through an improper (post 60's) filter??? and if you recreated their proper filter, suddenly all the 50-60's stuff would then suck, but everything else would sound like those awesome 50-60's recordings????its at least something to think about... maybe we should look more into the differences of the filter through the years and see if there is a correalation, and see if we can learn something.
dave
dya want 20 preamps, each for the right vintage recording!??! :) I've got an old, what is it, MC30 McIntosh preamp. It has 4 or 5 equalization schemes built in, for those pre-RIAA recordings. I'll check and see if it has a Columbia setting :)Dan
I think that you might be referring to the Mac C-8. It has multiple frequency eq switches on the front panel to select different settings as required by different record manufacturers back in the pre-stereo days. As it had no power supply of its own, the C-8 was frequently partnered with the MC-30 amp, from which power was drawn via an octal-socketed umbilical.
I would suspect that Roger Russell's McIntosh history website would have the definitive story, but I don't have the URL to pass along right now.
Mark
Actually it has its own power supply. I think it might be a C10 or C20, C10 probably. I've got it sitting in a box at home - too much other audio stuff to mess with at the moment :)Dan
its just this kind of history that can actually teach us something... multiple riaa schemes in a single phono pre??? never heard of that one... what i find interesting is that if indeed the cutterhead riaa of the most cherished recordings may be substantially different from the playback riaa of the folks who made them so cherished... talk about irony....dave
Columbia did once have their own eq curve which, as I recall, boosted the highs and lows relative to the mids compared to RIAA.
My folks had a Harmon-Kardon mono tube receiver that had a built-in phono section with at least three different equalization curves, switchable from the front panel. If memory serves, these equalization choices were RIAA, Columbia, and LP. (I am the least certain of the last one; there may have been another or 4th curve, beginning with the letter "E".) I own the "Ella and Louis" recordings on Verve, original cuts, English pressings. The tonal balance is all wrong, and I've wondered whether its because they were not made to the RIAA standard. There is at least one current production pre-amp, made in Switzerland but I cannot remember the company, that offers multiple equalization curves in phono, for about $20,000.
/
Although I haven't tried it; Diego Nardi gifted us with a pretty cool mono phono stage with multiple eq settings.
"multiple riaa schemes in a single phono pre??? never heard of that one... "RIAA standardized the equalization for phono. Before that every major recording company did its own equalization and sold the phonographs with their equalization scheme built in. All of these were mono records, mostly 78's. Later some preamps built "universal equalization", a switch to the one you needed. kind of like "universal digital players" today. RIAA stepped in and created the standard we live with today. There were no "multiple RIAA schemes." Early records will often be labelled with the RIAA logo on it to tell you it's equalization was for the new standard.
Kurt
i dunno??? i was going by the post above... is this accurate???http://www.AudioAsylum.com/forums/tubediy/messages/465.html
dave
When the LP was developed, there were still multiple standards but they were soon consolidated into RIAA and a European standard which was the same as RIAA but with a subsonic filter. Short-lived LP EQ curves included the Decca standard, RIAA, and I think maybe two or three more. There were different, non-standard playback EQ settings in the 78 era. More info can be found in one of the reprints from Wireless World published by Old Colony Sound Lab, which contains a full-function preamp designed during the transition era with built-in switchable EQ settings. The reprint is:ITEM #BKAA27 $16.95 Mullard Tube Circuits For Audio Amplifiers
There is also more info in Morgan Jones, Valve Amplifiers.
I have a friend who transfers 78s for reissue projects and he has several variables to consider: playback speed (78s were not all cut at the nominal 78 RPM); stylus shape; stylus material; playback EQ. He has a table of EQ settings and speeds that MOSTLY work for each label but there are always exceptions.
In contrast, us LP-heads have it easy!
-j
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