RIAA, Questions only please
Not wanting to leave the party without a clear and accurate statement I will say the following:
The answer to the question concerning noise reduction is that the simple filter that RIAA decided upon was to raise the high frequencies gradually by about 12 dB starting below 500 Hz, being up 3 dB at the 500 Hz pole. The circuit then cancells the pole with a zero at 2,200 Hz and there is then 3 dB of boosting left as one goes to 20 Khz. It is all done very gently with just two resistors and two capacitors.
By reversing this process on playback we get to enjoy 12 dB less noise above 500 Hz.
The RIAA part of things is the same for all cartridges. However we are accustomed to seeing RIAA combined with the 6 dB/octave compensation for a velocity cartridge. That takes off 12 dB, and along with two things that happen at the very ends of the response, brings the total EQ for a velocity cartridge to 40 dB. Next time you look at an RIAA curve ask yourself why there is that flat bench between 500 and 2,200 Hz.
An amplitude cartridge needs only the RIAA EQ of 12 dB. Which also speaks to the fact that the majority of the spectrum of a record is cut at constant amplitude. When you put a sewing needle in a paper cup and play the record you are getting amplitude playback not velocity.
I study these things because they interest me. Anyone can look up the parts values to make an RIAA filter or inverse RIAA. What interests me is that some manufacturers still get it wrong.
Tammy, here is a link to the deleted thread that has been referred to above by ct0517 and others: https://forum.audiogon.com/discussions/how-does-riaa-pre-emphasis-work-on-reducing-record-noise Best regards, -- Al |
Dear @ct0517 : Everybody knows the SS strain gauge must be connected with its dedicated preamp and I have the threads where PL explainded ( first version. ) why does not needs eq., even in that thread Ralph ask about and concluded that use no eq.. The idea to connect to an aux in a line stage came in the deleted thread only " thinking in high voice " and only to " see " what happens. At least I would like to try it because PL measured a really low inverse RIAA eq. deviation: plus,minus 1db. Yes is really high against the normal 0.1db achieved for today best phono stages but as I said in the other thread it has two big big advantages to put in the scales against that 1db devuiation that are: no inverse RIAA eq. heavy degradation to the carrtridge signal and no need of additional gain stages that adds more signal degradation ! ! ! For me both advantages makes a paramount differences. PL is rigth when he said that our ears are way more sensitive to time errors ( as the ones in any filter and the RIAA eq. are filters. ) than amplitude ones . @ramtubes thinks that he discovered the " black thread " with those 12 dbs and said that manufacturers not understand it. Well, in this forum PL talks about 10 years ago that’s where I took my conclusion on the whole subject and not because ramtubes as he could think. In the other side and this is for you @ramtubes and as @almarg posted but I will say in my own words: you are not the owner of your thread or OP and if you posted then any one including @atmasphere has the rigth to post what ever he wants in the same way that you have the rigth to post anything or say anything even if is contradictory to your own posts in between like happened in the other thread. Like me and any one in this forum you are onlyy a single one/other gentleman and nothing more than that. You are not better than almost all here as you think and exist a fact that proves you are not and that fact is that you design tube electronics when tubes ( no matter what. ) can’t honor MUSIC but you don't know yet. """ our local club is about 50% vinyl, "", so what, digital is way superior to LP but things are that that 50% of your club that includes you are just wrong but you don’t know yet all of you are wrong and I can prove it. Maybe in other thread because is off the topic here. Btw, I'm an analog lover and MUSIC lover. R. |
@ramtubes, let the other thread stay dead and if this one keeps going the way it is kill it too. @ramtubes thinks that he discovered the " black thread " with those 12 dbs and said that manufacturers not understand it. @rauliruegas: I don’t think Roger ever said he discovered the black thread as you say, and it was pretty obvious in the last thread that many disagreed with his theory anyway. However it does appear that perhaps Roger and Peter Ledermann agree, so there’s that at least. It would be nice if Peter Ledermann joined the conversation as it would be interesting to hear his thoughts and add another expert to the conversation bringing the total to 3 in my opinion. It’s really hard sifting through some of this stuff (as it was in the last thread) to get to the posts of two (or three) people whose posts you want to read. I wish Audiogon would let me filter out the "noise" so I can just read what I need. |
