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RIAA, Questions only please

I have closed the previous thread on RIAA and concluded that very few indeed understand the curves or the purpose. Here is my closing statement from that thread. For those who want to understand and have valid well stated questions I am happy to answer. 

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.

128x128ramtubes

Showing 4 responses by clio09

clio09
3,343 posts
 
@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.
clio09
3,343 posts
 
@uberwaltz: I said there were 3 experts, but I never said I agreed with any of them or that their opinions were the only valid ones. I just happen to feel these 3 people have the most to offer to the discussion and they are people whose knowledge I respect, perhaps more will join in.

Furthermore, as you noted that was my opinion, if it’s a free forum as you say then my opinion is as good as anyone else’s, and as you further state, as long as it complies with forum guidelines, which I believe I have.

Now back to the discussion:

@solypsa mentioned cartridge design. I would like to learn more about the design of a strain gauge cartridge as it seems to me eliminating the EQ is a good thing.
clio09
3,343 posts
 
@ramtubes : What is the purpose or your target on both OP's threads?
I think he makes it very clear. Now whether I understand or agree with all the technical aspects is another matter.

I don't get yet in which way your threads can help any one of us to listen LPs. ! ! ? ? ? ? ? ? ?

So reduction in noise won't enhance your listening experience with LPs. That was certainly one of the points of the other thread Roger started (how does RIAA reduce noise...), and coming from someone who wants to enjoy the music and not distortion I would think that is important.

Now whether you understood or agree with his points is another matter.

clio09
3,343 posts
 
Your last post makes no sense and is useless and does not makes any real contribution to this thread.

Perhaps not from your point of view, but you did ask what the purpose of the OP’s thread was (both of them) and I posted what I recall to be one of the purposes of the now deleted thread.

Sorry it all got lost on you and your feathers were ruffled.

BTW - care to translate this:

I don’t get yet in which way your threads can help any one of us to listen LPs. ! ! ? ? ? ? ? ? ?

I may have misinterpreted what the purpose or the target was when I previously responded, and yes I read your entire post. You are one of the few people on here whose posts I always read.
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