How does RIAA pre-emphasis work on reducing record noise?


There is much confusion over what RIAA actually does in a vinyl playback system. For years we have fought for accurate RIAA, yet, when I ask, Professionals and engineers disagree many giving what I believe is the wrong answer.

Here are the details for the technical folks. Although IEC has thrown in another inflection point this does not affect the main RIAA which is a accomplished by an expansion of groove size starting at 500 Hz . This EQ is then reversed on playback ( accuratey we hope) with the benefit of lowering the noise starting at 500 HZ. Over this two octave span the EQ boosts the recording cutter's depth putting more signal on the disc. The 3 db rise is called at 500 Hz as one does in any filter. At 2,200 the curve flattens out again and we cut at constant amplitude just as we did below 500 Hz. Over the audio band the total rise is 12 dB. (6 dB x two octaves). Not an insignificant number.

I invite the math people and anyone knowledgble to join this discussion.
Fe8c8cab 4117 4c51 b1aa 6b134ad0dca6ramtubes
The **depth** of the cutter is not modified by the RIAA pre-emphasis. The **excursion** of the cutter is.

I suspect that readers of this will be confused by this statement:
Over the audio band the total rise is 12 dB. (6 dB x two octaves)
It appears that by 'the audio band' you mean 'these two octaves'.

If that is the case, the *actual* rise in this part of the audio band (500Hz to 2KHz, due to pre-emphasis) is slightly less than 6db. 


So- what is the answer you've been given, and what are you suggesting is the correct answer? Neither is depicted in your OP.
I’m not sure you know what an octave is. The audible range is approximately 10 octaves.
Over the audio band, the RIAA curve varies by a total about 40 dB.
https://en.wikipedia.org/wiki/RIAA_equalization#The_Enhanced_RIAA_curve

At 2,200 the curve flattens out again and we cut at constant amplitude just as we did below 500 Hz.

That is not my understanding. I have always understood that the RIAA curve corresponds to what is shown in Figure 1 of the reference Erik provided, and varies over the entire audible frequency range in the manner shown in the Figure.  Not just over the approximately two octaves between 500 Hz and 2200 Hz.   With 1 kHz being the only audible frequency that is neither boosted nor attenuated, and with a total variation of approximately 40 db occurring between 20 Hz and 20 kHz as Erik stated.

Regards,
-- Al

And finally, I don’t think the raison d’etre of RIAA has much to do with noise reduction.
It has to do with the pitch and heat limitations of the cutting head, the more pitch, the shorter the available time on a record side. Also, lower frequencies require more displacement of the cutter, which means more heat, and that can ruin a cutting head. The RIAA curve seeks to alleviate some of the physical limitations on the cutting process in order to maximize playing time and protect cutting heads from destructive damage. Helium is typically used as a coolant on the cutting head.
And finally, I don’t think the raison d’etre of RIAA has much to do with noise reduction.

It does. See the first paragraph in the wiki page. It is pretty accurate. It is not the only benefit however.

The noise issue has to do with the innate noise in the vinyl as well as the unamplified signal coming from the cartridge.

It is kind of a similar problem tape recorders and film had which Dolby tried to fix.

Had vinyl come after tape, it's quite likely they would have used a combination of EQ curve and Dolby to correct for it.

Best,
E

To quote from Wiki: "Equalization practice for electrical recordings dates to the beginning of the art. In 1926 Joseph P. Maxwell and Henry C. Harrison from Bell Telephone Laboratories disclosed that the recording pattern of the Western Electric "rubber line" magnetic disc cutter had a constant velocity characteristic. This meant that as frequency increased in the treble, recording amplitude decreased. Conversely, in the bass as frequency decreased, recording amplitude increased. Therefore, it was necessary to attenuate the bass frequencies below about 250 Hz, the bass turnover point, in the amplified microphone signal fed to the recording head. Otherwise, bass modulation became excessive and overcutting took place, with the cutter into the next record groove. When played back electrically with a magnetic pickup having a smooth response in the bass region, a complementary boost in amplitude at the bass turnover point was necessary."

Mainly, that's the reason for RIAA and similar filters in vinyl reproduction.  If attenuation of high frequency noise occurs in the process, that is a byproduct, not the main goal.
Lew, I'd have to agree with Erik that reduction of high frequency noise and reduction of groove excursion at low frequencies are **both** primary goals of RIAA equalization.

Here is an excerpt from this writeup by a prominent mastering engineer:

If you were to cut an ordinary audio source (without the RIAA EQ) into a lacquer at a reasonably hot level you would notice two things: First, the bass frequencies, with their long wavelengths, are so big and loud that they cause the groove to make really large squiggles. So large, in fact, that it would be hard for a cartridge to playback the squiggles. These very large cut grooves would take up a huge amount of space on the disk and limit your playing time to only a few minutes on a 12″ LP side.


The second thing you would notice is that records are noisy. Yeah I know, you already know that. But I mean a vinyl record is REALLY noisy. That audio source played back without the EQ would be mostly scratchy noise and clicks like you’ve heard from an Edison Cylinder. The only way the LP works to make pleasing realistic music is for the audio to be pre-EQ’d so that the bass is reduced dramatically—by 20dB—and the treble is increased dramatically, also by 20dB. The original music returns when the opposite EQ is applied by the phono preamp.



(BTW, the links to the two music clips near the end of the article appear to be interchanged).

Best regards,
-- Al
@lewm
First allow me to re-quote myself:

It is not the only benefit however.

Then allow me to quote from your quote

When played back electrically with a magnetic pickup having a smooth response in the bass region, a complementary boost in amplitude at the bass turnover point was necessary."

So, in summary, the entire quote you used explains only the bass EQ, not the treble. :-)
It is clear that, as I alluded to, there are different challenges in LP production on both ends of the spectrum. Noise in the treble, and excursion in the bass.

Best,
E
Al, I think the difference in our views is semantic, when you put it as you have just put it. Enough said.
Dear @ramtubes: What are you looking for, can you post a wider explanation?

The ones like me that own LP's are interested in the MM/MI/LOMC cartridges that tracks the LP groove modulations and that are " velocity " transducer items against other kind of cartridges that are " displacement " items and that understand what the RIAA means for those velocity transducers.

What's your " history " because I think you know the answers.

Btw, why the RIAA did not took in count from the began the Neumann pole. It's not " official " ? when exist a real problem in the cutting heads ( burn-in. ) when approaching 40khz-50khz and in DMM at around 60khz-70khz.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.




What’s your " history " because I think you know the answers.
@rauliruegas: ramtubes is Roger Modjeski of Music Reference. If you are curious about his history you can read about it here:

http://www.ramlabs-musicreference.com/bio.html

In my opinion there are only two people who have posted so far (one being the OP} who have the credentials and experience to address this topic. Let’s see if a few more will join the conversation. I could certainly benefit from it.
IEC has thrown in another inflection point this does not affect the main RIAA which is a accomplished by an expansion of groove size starting at 500 Hz . This EQ is then reversed on playback ( accuratey we hope) with the benefit of lowering the noise starting at 500 HZ.
IEC thrown in another enhanced RIAA?
@clio09
A lot of what has been stated here is correct. The most erroneous statements are actually found in the OP.

Take this one from Al:
That is not my understanding. I have always understood that the RIAA curve corresponds to what is shown in Figure 1 of the reference Erik provided, and varies over the entire audible frequency range in the manner shown in the Figure. Not just over the approximately two octaves between 500 Hz and 2200 Hz. With 1 kHz being the only audible frequency that is neither boosted nor attenuated, and with a total variation of approximately 40 db occurring between 20 Hz and 20 kHz as Erik stated.
This statement is completely accurate. I can see that there might be some confusion about what Roger was trying to say, as I pointed out in my initial post. But compare that to:
Here are the details for the technical folks. Although IEC has thrown in another inflection point this does not affect the main RIAA which is a accomplished by an expansion of groove size starting at 500 Hz . This EQ is then reversed on playback ( accuratey we hope) with the benefit of lowering the noise starting at 500 HZ. Over this two octave span the EQ boosts the recording cutter’s depth putting more signal on the disc. The 3 db rise is called at 500 Hz as one does in any filter. At 2,200 the curve flattens out again and we cut at constant amplitude just as we did below 500 Hz. Over the audio band the total rise is 12 dB. (6 dB x two octaves). Not an insignificant number.
In this statement taken from the OP, there are a coupling of problems.

The 12 db comment is incorrect (take a look at the RIAA curves posted by Erik and see for yourself)- its slightly less than 6 db over those two octaves. He also incorrectly states that the depth is increased- but groove depth is adjustable by the engineer and is governed more by that setting than the excursion of the cutter. For example, we have an older cutter- the Westerex 3D, which cut a lot of the stereo projects in the Golden Era of hifi and was used by RCA and Mercury. To set groove depth, the cutter has two aspects- the cutting weight, which is similar to playback tracking weight (but a lot more) and the groove depth itself, which is set by something call the ’lead ball’ or ’track ball’ which is a tiny semi-spherical gadget that rides the lacquer surface a couple of groove widths before the actual cutter stylus. The tracking pressure is carried by the track ball, and a little adjustment screw determines how deep the groove is from there.

Newer setups have variable groove depth which can be handy. But overall, the groove depth is a thing you set up as part of the recording project- how much modulation will be in the groove (deeper grooves can handle more but less time will be available on the disk).

I’m not sure what the point is here- the opening paragraph suggests at *something* but what that something is does not seem to be illuminated by the statements that follow. The responses to the OP are mostly that of correction, and they seem spot on.






IEC thrown in another enhanced RIAA?
Not really. Its playback only and since the LP is mastered on the RIAA curve, to avoid phase shift in the bass (which results in a loss of impact) the IEC curve really shouldn’t be used. It was withdrawn in 2009.
Dear @atmasphere : Agree and this is one of very few times that we are in agreement of " something ".

Did you know whom used that IEC curve, well nothing less than Vitus that set you back: over 60K++ price. 

The first Vitus reviewed was measured by J.Atkinson who told the great Phono Stage the Vitus was ( was named Class A in the ST recomended  products. ) and in this same forum I ask him for the " terrible " problem in the Vitus bass impact and he never posted here again. Yes, you know me and I made my critic to him about in  unit that along the needs for a line stage ( Vitus ) makes the combo price gone to more KKKK dollrs. Go figure !

R.
Post removed 
Dear @clio09 : Thank’s to know he was @ramtubes. Even that my questions to him are still with out answers.


R.
Dear @almarg @erik_squires : I think that @lewm is rigth about the main subjects that made to appeared the RIAA standarization. 

Before 1954 the LP system playback was a nightmare for to many eq. curves in the recording industry where almost no one were similar to the other.

In wikipedia we can read this:

"""  from 1940, each record company applied its own equalization; there were over 100 combinations of turnover and rolloff frequencies in use, the main ones being Columbia-78, Decca-U.S., European (various), Victor-78 (various), Associated, BBC, NAB, Orthacoustic, World, Columbia LP, FFRR-78 and microgroove, and AES. The obvious consequence was that different reproduction results were obtained if the recording and playback filtering were not matched. """

I think that that and what lewm posted were the very first targets for the RIAA eq. .

It has other benefits/necessities?, of course you already named.

I think the Association main target was because that " noise ", this is a " side line " benefit of the RIAA eq..

The only gentlemans that know exactly the main targets were the ones that participated for that eq. curve been the standard one for all recording industry that belongs to the RIAA.


Al, that gentleman in your link was one active member of the ones that participated to achieve the RIAA standard been the OFFICIAL and only eq. curve for the recordings starting around 1954?


R.
Al, that gentleman in your link was one active member of the ones that participated to achieve the RIAA standard been the OFFICIAL and only eq. curve for the recordings starting around 1954?

Hi Raul,

No, as indicated at the Masterdisk website, the mastering engineer I quoted didn’t begin his career until 1983. And information I found elsewhere indicates that he was about 22 years old at that time.

Regards,
-- Al


@atmasphere  It appears that by 'the audio band' you mean 'these two octaves'.


Why would you think the audio band is 2 octaves when it is well known to be 10?

I am not talking about what happens in those 2 octaves, those are the corners. I am asking how it plays out over all 10. A single pole filter is 6 db per octave times 2 octaves... eventually. Its not a brick wall.

I am also not talking about the familiar curve which INCLUDES the compensation for a velocity cartridge.


@rauliruegas 

Before 1954 the LP system playback was a nightmare for to many eq. curves in the recording industry where almost no one were similar to the other.

In wikipedia we can read this:

""" from 1940, each record company applied its own equalization; there were over 100 combinations of turnover and rolloff frequencies in use, the main ones being Columbia-78, Decca-U.S., European (various), Victor-78 (various), Associated, BBC, NAB, Orthacoustic, World, Columbia LP, FFRR-78 and microgroove, and AES. The obvious consequence was that different reproduction results were obtained if the recording and playback filtering were not matched. """

I think that that and what lewm posted were the very first targets for the RIAA eq. .

It has other benefits/necessities?, of course you already named.

I think the Association main target was because that " noise ", this is a " side line " benefit of the RIAA eq..

The only gentlemans that know exactly the main targets were the ones that participated for that eq. curve been the standard one for all recording industry that belongs to the RIAA.



Al, that gentleman in your link was one active member of the ones that participated to achieve the RIAA standard been the OFFICIAL and only eq. curve for the recordings starting around 1954?


Thank your for your well considered answer. Sorry not to respond earlier. Saturday we had a phono preamp listening session at the San Francisco Audio Society, over 50 attendees.

I was in charge of matching levels and checking RIAA on 8 preamps. Most were spot on, John Curl's Vendetta being the best. Even the PS audio had accurate EQ. Which is not hard to achieve with 1% resistors and 2% capacitors in the network. Of course they have to be the right vaIues to start with. I use in Inverse RIAA which has been confirmed by Stereophile testing and my tests of over 100 preamps. One preamp was 20 dB down at 20 Hz.. Broken? it was a prototype with cables all over the place.  Another very expensive one down 7 dB at 8 Khz, not broken. We had the $31,000 CH which was also spot on. The owner was nervous as a cat on a hot tin roof. 

Yes I do know the answer to this question. It is a test for a person who writes here frequently. His preamp is the one that is 7 dB down and I just cant imagine why.

In production we all use an inverse RIAA network. One cannot do it by dB, its too hard to see a few tenths over 40 dB range. Thats the velocity cartridge you mentioned. If one is to EQ for a displacement cartridge the the EQ is only 12 db.

Now 12 dB is a lot of EQ and it was most assuredly done to reduce noise above 2 KHZ by 12 dB. Why else bother?

You are also correct that before the RIAA standard there was no standard hense those 4 position turn-over and roll off switches found on virtually all mono preamps.




And finally, I don’t think the raison d’etre of RIAA has much to do with noise reduction.


It has everything to do with noise reduction. Is there something else?
Over the audio band, the RIAA curve varies by a total about 40 dB.


That is the curve of RIAA plus a velocity (magnetic) cartridge. For a displacement cartridge the EQ is 12 dB. That is what is cut into the record.
If you're the "real" Roger Modjeski, I ain't gonna argue the point, because I am not qualified.  As a "lay person", my take home lesson on RIAA is that it is a filter algorithm that makes it possible to squeeze the audio frequencies (20Hz to 20kHz) into the confines of an LP "microgroove" such that playback can approximate high fidelity with acceptable S/N.  I do realize that modern phono cartridges are voltage-producing devices and that the magnitude of the voltage is proportional to stylus velocity.  During encoding, bass frequencies are attenuated, in my understanding, so as to permit very low frequencies to "fit" in the microgroove, then correspondingly boosted during playback in a phono stage.  Conversely, treble frequencies are boosted during encoding to assure an extended frequency response and then attenuated in the phono stage.  I guess this latter aspect of the process also reduces groove noise.  I just never thought of noise reduction as the major reason for using filter algorithms like RIAA and the others. I don't pretend to know more about this process than you or Almarg or any other real professional in this field.

I think you built the Beveridge direct-drive amplifiers in my 2SWs.  (Someone signed inside the chassis with initials, RM.) Thanks for that; I love the system.
@ lewm

Glad you are still enjoying your 2SWs. Yes I am that RM and I did sign amplifiers after testing. I also designed the RM-1 and did the research to get the RIAA right 30 years ago. RIAA accuracy was a hot topic at the time. Remember Peter Moncrieff and IAR? He wanted 0.1 dB accuracy. Even today some are not even close. What do you say about a preamp that is 7 dB off?

Lets not call it an algorithm, its a very simple and clever solution to noise and not  bass groove size.

Below 500 Hz cutting is done at constant amplitude. The rise in the magnetic curve is take care of the low velocity of low frequencies. ie the cartridge doesn't put out much at 20 Hz so it needs help. Again an amplitude cartridge does not need any boost there. 

I wish i could draw here but take some paper draw a flat line from 20 to 500 hz. Then go down at 6 dB per octave for two octaves (12 db) then flatten out again. That is RIAA playback without the magnetic (velocity) compensation. For recording just go up 12 dB instead of down.

RIAA is just 12 dB. RIAA plus magnetic is 40 dB... Big difference.

During recording (encoding is not a good term, there is no code) the bass frequencies are not modified at all. Above 2200 Hz they are  again not modified. Between 500 HZ and 2200 HZ the highs are boosted 12 db so they can be cut on playback. There is no squeezing. 

Did you know that tape EQ is very similar and for the same reason... noise reduction.

Was I correct about the confusion?
@almarg That is not my understanding. I have always understood that the RIAA curve corresponds to what is shown in Figure 1 of the reference Erik provided, and varies over the entire audible frequency range in the manner shown in the Figure. Not just over the approximately two octaves between 500 Hz and 2200 Hz.   With 1 kHz being the only audible frequency that is neither boosted nor attenuated, and with a total variation of approximately 40 db occurring between 20 Hz and 20 kHz as Erik stated.


figure 1 is for a velocity cutter and velocity cartridge. It is not what is on the record.

@erik_squires  I’m not sure you know what an octave is. The audible range is approximately 10 octaves
Not sure if this is meant for me but I am assuming it is.

I play piano and read music. I am well aquainted what an octave is. 

The EQ corners are 2 octaves apart but those are just the corners which Ralph keeps quoting. Over 10 octaves the total EQ is 12 db.  

Would you care to comment on how many parts it takes to make a RIAA EQ and what their acccuracy needs to be?

In this case I managed to keep my thoughts to myself and not stick my nose into other’s business, but seeing an audiophile question whether or not RM knows what is an octave, and needed to be told "the audible range is approximately ten octaves" absolutely dumbfounded me. That person obviously has no idea to whom he is talking.
I m glad I kept quiet here too but I think I am learning a lot.

Keeping a close watch on this thread for sure, some very well respected members posting here.
In this case I managed to keep my thoughts to myself and not stick my nose into other’s business, but seeing an audiophile question whether or not RM knows what is an octave, and needed to be told "the audible range is approximately ten octaves" absolutely dumbfounded me. That person obviously has no idea to whom he is talking.

@bdp24: I’ve seen him do this on another occasion with another well respected designer, but ultimately what it boils down to is he’s a legend in his own mind. I’m interested to see what his response is, that is if he provides any, to Roger’s question.

I m glad I kept quiet here too but I think I am learning a lot.

I’m learning a lot too and I think it’s only going to get better.

Keeping a close watch on this thread for sure, some very well respected members posting here.

I stated previously that there are only two people who posted here with the credentials and experience to address the topic. I’ll amend that to add there is one other person who posted who I think has a good grasp of the discussion to add value to it. We could certainly use a few more for those of us like me looking for education here.
I used the term “encoding” out of habit, because I am a molecular biologist and accustomed to thinking about RNAs that “encode” protein. The analogy to an LP groove and its relationship to music is not very far fetched.
That is the curve of RIAA plus a velocity (magnetic) cartridge. For a displacement cartridge the EQ is 12 dB. That is what is cut into the record.
This statement is false. The RIAA pre-emphasis covers about a 40 dB range.
Why would you think the audio band is 2 octaves when it is well known to be 10?
I don't. That was the only way to interpret this comment from your OP:
Over this two octave span the EQ boosts the recording cutter's depth putting more signal on the disc. The 3 db rise is called at 500 Hz as one does in any filter. At 2,200 the curve flattens out again and we cut at constant amplitude just as we did below 500 Hz. Over the audio band the total rise is 12 dB. (6 dB x two octaves). 
That was because you put the '6 dB x two octaves' in parenthesis as if to make it clear that you really meant just those two octaves as the audio band to which you referred.

But now you are clarifying that you meant the entire audio band:

figure 1 is for a velocity cutter and velocity cartridge. It is not what is on the record.
'Figure 1' is for the RIAA pre-emphasis and has nothing to do with the cartridge used. That's just what's on the record.
RIAA is just 12 dB. RIAA plus magnetic is 40 dB... Big difference.

During recording (encoding is not a good term, there is no code) the bass frequencies are not modified at all. Above 2200 Hz they are again not modified. Between 500 HZ and 2200 HZ the highs are boosted 12 db so they can be cut on playback.
The proper term is 'pre-emphasis'. It seems to me that you are laboring under a misconception; this entire quote is false. Bass frequencies are EQed to help prevent over-cutting the groove (and also helps with the power needed to drive the cutter head). So the resulting curve covers a nearly 40 db range from 20Hz to 20KHz, as has been pointed out several times in this thread. What gives??



I play piano and read music. I am well aquainted what an octave is.

Sorry, I was confused by your wording. It doesn't add up.


The EQ corners are 2 octaves apart but those are just the corners which Ralph keeps quoting. Over 10 octaves the total EQ is 12 db.  

Um, no, 40 dB. +- 20 dB, as shown in the graph. Which is part of why I remain confused at your wording.

Would you care to comment on how many parts it takes to make a RIAA EQ and what their acccuracy needs to be? 

Would you like it with discrete solid state, op amps, or tubes? TBH, I'd be cribbing from my course notes from Georgia Tech. I learned about the RIAA curve from Dr. Marshall Leach Jr. ages ago.

To answer the last part, "not very." Dr. Leach mentioned a presentation at the AES where a presenter reviewed several phonograph preamps for accuracy and he felt the work done was silly. I'd be much more concerned with proper loading and noise, and let your ears determine which is "best."

Best,
Erik


P.S. I reviewed my class materials and could find little about the "whys." The notes I have focus on the "what" and "hows" of the RIAA curve. I don't mean to imply Dr. Leach's course taught me that. :)

After doing a little research I found the following article, which seems very apropos:

http://pspatialaudio.com/displacement.htm

While at first glance the article appears to fully support what Roger has been saying, after reading it several times I’m thinking that all of us may be partially correct, but that none of us (including him) may be seeing the full picture.

Note this statement:

... the physical "wiggles" inscribed in the disc do not match the frequency characteristic of either the pre-equalised signal, or the post-equalised signal. They exist in a little-appreciated nether-world.
That "little-appreciated nether-world" appears to refer to what is depicted in the frequency response curve shown in the writeup, which is consistent with what Roger has been saying. However, what the paper is addressing is how the "integration" performed by the cutter (which as stated in the paper is a voltage-to-velocity transducer) is compensated for by the "differentiation" performed by the cartridge. (As some will realize, the terms "integration" and "differentiation" are being used here based on their meanings in calculus).

But what I’m thinking is that the delta between the 12 db figure that has been cited (over the full frequency range of 20 Hz to 20 kHz) and the 40 db figure that has been cited (again over the full frequency range) results from equalization that is separate and in addition to what Roger and the article are addressing, the latter being compensation for the "integration" performed by the cutter.  With that additional equalization being done for the purposes of reducing groove excursion at low frequencies and reducing noise at high frequencies, as has been said.

During my 40 years as an audiophile I have seen countless references to RIAA equalization corresponding in the mastering process to a 20 db cut at 20 Hz and a 20 db boost at 20 kHz. With a complementary equalization being applied in playback. Just one example of that being the writeup I referenced earlier by the mastering engineer who owns Masterdisk, who can certainly be expected to know about these things. And I have never before encountered a statement corresponding to what Roger and the paper are saying. What I said in the paragraph just above this one appears to me to be the only way in which these conflicting viewpoints can be reconciled.

Regards,
-- Al

The manual for the Westerex 1700 cutting system is pretty cut and dried. I keep one copy in my office, another at the studio where the mastering lathe resides.

It lays out how the three main modules of the cutting system work (including theory of operation, schematics, parts list and calibration procedures): the input module, the feedback module, and the cutter amps themselves.

The equalization curve is applied by the input module. No bones about it- its a curve that ranges about 40 db from 20Hz to 20KHz. The actual curve is published in the appendices and is the same curve as linked on the Wiki page (by Erik) prior in this thread.

The signal is then amplified by the cutter amps and applied to the cutter head. Since the head has a mechanical resonance, a feedback winding is provided as an output from the head. This is sent to the feedback module, where it is used for monitoring the cut. The feedback signal is also amplified by the feedback module and then applied to the input module both to kill the resonance in the cutter head as well as to improve channel separation, since the cutter head employs a spring suspension.

At no point in the manual is any mention made of the importance of the kind of cartridge used during playback. Its not relevant. Thus the RIAA curve is defined as I laid out in my initial post. This requires a nearly 40 db range over the audio band. Anything else simply isn’t the RIAA curve.




Dear @ramtubes : Just a few seconds I " really " read the title of your thread. I read it before but was not " aware " of it, I gone directly to read the thread with out any care in the title.

I always posted and say that in our room/audio system we have to put all kind of distortions ( everywhere. ) at minimum and you are totally rigth when you said:

"""  It has everything to do with noise reduction. Is there something else? ""
 Noise/distorion reduction means more music information.

R.   


What I want to know is what phono stage is 7dB down! RM, is that at 20kHZ, or 20Hz?
Eric (bdp24), I noticed that comment.  Note that what he said was:

Another very expensive one down 7 dB at 8 Khz, not broken....

... Yes I do know the answer to this question. It is a test for a person who writes here frequently. His preamp is the one that is 7 dB down and I just cant imagine why.

Not sure how he would have concluded that it wasn't broken.

Best regards,
-- Al 

Thanks Al, I didn't recall the 8 kHz being in there. I jumped to the conclusion that RM was referring to an Atma-Sphere phono stage (as Ralph "writes here frequently"), but didn't want to say so, as things are already contentious enough!

I'm with you; 7 dB down at 8 kHz is not bad design, it's broken.

Our preamp's EQ was measured by Stereophile (the MP-1) and it was not off by anything like that. The MP-3 uses the same circuit as that original MP-1. The EQ components are precision matched to well within 1% of Stanley Lipshitz' RIAA article presented to the AES (https://www.pearl-hifi.com/06_Lit_Archive/14_Books_Tech_Papers/Lipschitz_Stanley/Lipshitz_on_RIAA_JA....).

An online calculator based on this math:https://www.kabusa.com/riaa.htm
But that wasn't around when the MP-1 phono section was designed.

Some of our preamps are optioned with tape head EQ and depending on the curve used it could easily be off by that much if the wrong input were used.
Dear @atmasphere  @almarg : """  What I said in the paragraph just above this one appears to me to be the only way in which these conflicting viewpoints can be reconciled. """

seems to me that you " not die " for your statement or you are not absolutely sure with and @ramtubes did not yet makes an additional comment on your post.

In the other side and  as you stated there and @atmasphere posted:

""  is any mention made of the importance of the kind of cartridge used during playback. Its not relevant. Thus the RIAA curve is defined as I laid out in my initial post. This requires a nearly 40 db range over the audio band. Anything else simply isn’t the RIAA curve. "

I'm with him but I was not a RIAA association member when they decided about.

I posted to @ramtubes this:  " seems to me you already know all answers "   and he said: " yes ".
So I would like to know from him if the link you/Al  posted is true. At this time for me is the more critical subject in the whole thread.

Al, your link is really " slim "/not wide enough to explain the overall subject to understand clearly that cartridge " role ". I would like too to have at least a direct RIAA association member or cartridge designer/manufacturer that can confirm your link information. 

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
Ok so call me stupid if you will,not that it matters as been called much worse in my time but......

What exactly does 7db down at 8khz mean?

And what would the audible effect of this present itself as?
I wonder if the main question is covered by now....

@Uberwaltz, 7 db down at 8 kHz means that there is a considerable dip in frequency response in the mid treble to upper treble region. It would manifest itself as some combination of dullness and sluggish transients, in a manner and to a degree that would depend on how wide a frequency range the dip extends over, and if it continued to get worse (i.e., to roll off) above 8 kHz.

Best regards,
-- Al
Dear @ramtubes : Very good experiences you had in that San Francisco audio meeting.

J.Curl is a legend since his Levinson JC2 and his Vendetta still today is a reference for any phonolinepreamp, no doubt about.

That the humble Parasound was accurated too in the RIAA deviation is no surprise becauzse de design comes from J.Curl.

The CH for that price must be accurated, its new integrated unit works in the digital domain: must be extremely accurated: I don’t know for sure.

Overall accuracy in audio means lower noise/distortions levels and in the RIAA inverse eq. is a must to have but not only accuracy but that both channels be accurated, that each one be a mirror of the other.

Specs by phono stage manufacturers not always even live measurements as the ones made it by Stereophile or other sources. Even through the time the owners of phono stages in reality don’t know if after say 2 years their phonolinepreamps are still " spot on " in both channels and not easy for us owners of those items to be aware about.

This is the one I own:

https://photos.google.com/share/AF1QipPJLuDhIxhHGsjv2ZABr3TIpxMewVor1Pz33vhLoiISsURJmmnxUQB9cuwNnpog...

that stays at lower than 0.012db. Fully analog design, non-feedback with passive eq.

Btw, I remember to well the reviews with measurements that that magazyne did it. Mf. " falls in love " with the Dartzeel that showed not only the interchannel hig db asymetry but showed +1.8db at 20hz and + 2.5db at 20khz go figure ! and MF was in love with.
The Halcro DM10 was other example with -1.4db at 20hz. and many more big and expensive names units. Vitus between them. and almost all tube designs as Lamm.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
 Al, I am trying to figure out how you could get a notch type defect at 7 kHz, or whatever it is, out of a otherwise well-designed RIAA filter. Or even out of a bad design. Because it seems unlikely that you would have a notch at that frequency, don’t you think it’s likely that the mystery phono stage simply rolls off at frequencies above 7 kHz? Everyone else seems to know what phono stage RAM is talking about, but I certainly do not.
don’t you think it’s likely that the mystery phono stage simply rolls off at frequencies above 7 kHz?


why not a bad vinyl setup ?

the only way the RIAA EQ values that are recorded/generated by the cutter into the record can be duplicated by the phono stage preamp's  inverse RIAA EQ - is if the record was played back in the same way it was cut.  This is impossible for many reasons. 

Anyone care to disagree ? 

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Analog Jack.... is running a customized vinyl setup .

1) He has a tonearm and a low level MC cartridge that has an incorrect anti skate setup.

2) he is running 8 feet (in total) of phono wiring comprised of shielded and unshielded. It has 3 breaks before it gets to the phono stage inputs. The wiring is going at one point through the back of his racks and running parallel to some equipment power cords.  

Does everyone agree that the RIAA EQ signal values generated by Analog Jack's setup will be skewed and contaminated due to the noise being picked up, and incorrect setup of the tonearm / cartridge ?

The phono stage RIAA inverse EQ in the mean time - will continue to do its inverse RIAA based on ......the skewed RIAA EQ values of input.

Garbage in ......

Anyone disagree ?

*********************

FWIW and IMO - RIAA EQ has two objectives.

1) Noise reduction.

2) uniform, small grooves allowing for 20 mins a side.

NO ONE is buying records without (1 AND 2).

this thread has primarily dealt with noise reduction and only hinted (Atmasphere) at the second objective.