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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
ramtubes's avatar
ramtubes OP
451 posts
 
Here is something to consider. What if we didnt use RIAA or any EQ in making a record. If we recorded a constant voltage sweep from 20 to 20Khz and looked at it under a microscope what might we see? When we played the final product what would a voltmeter connected to the speaker (or elsewhere) indicate from 20 to 20 KHz.

Choose your cutter wisely and state if it is amplitude or Velocity. Even better do both.
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uberwaltz
4,946 posts
 
Clio
That is somewhat pretentious don't you think?
Who gave you the right to decide there were only 2 or 3 "experts" whose opinions are all that is valid here?
Your opinion maybe but still as has been stated many times this is a free forum and ALL opinions are welcome as long as they remain within the posting guidelines of this forum.
Whether you like them or not or agree with them is completely irrelevant.
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@ct0517 The thread was closed by the author. 
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rauliruegas
9,123 posts
 
Dear @ramtubes : I did not avoid  digital/vinyl but the other way around because first than all I’m a MUSIC LOVER, it’s with I’m " married " not with source media technology or system hardware.

R.
clio09
2,978 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.
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