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.
128x128ramtubes

Showing 12 responses by clio09

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.
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.
@lewm and any others interested the following is the link to the write up for the phono shootout referenced by the OP (you can even see a picture of him in the write up):

https://sanfranciscoaudiophilesociety.com/event-write-ups/phono-stage-shoot-out-january-26-2019/

The write up includes the list of phono preamps that were part of the shootout. Don’t rack your brains trying to figure out which one was 7 dB down at 8k Hz, it’s not on the list.

You know, I just thought of something, and I say this with ZERO sarcasm: Why don’t you build yourself a phono preamp?

He has built one. Ironically there is an ad for one on here right now:

https://www.audiogon.com/listings/lis9a8gd-jose-raul-audio-essential-3160-balanced-phono-line-preamp...

It was probably in 2006 or thereabouts when I met Raul in San Diego when he was touring the country with the first iteration of the Essential and I had the opportunity to hear it in two different systems. Best solid state phono line preamp I have heard.


How do you explain that? are you just a troller or your OP was started in " good shape " where you want to share valuable information to this forum?

@rauliruegas: I think you are smart enough to know he is not a troller. He has designed and built many well known components (some reviewed and measured in Stereophile) and has his opinions on various topics in audio including this one. I don't think he personally cares if he is in the minority or if people feel he is completely wrong on this topic. If his silence baffles you then so be it. Deal with it.

As I said earlier there are two people on this thread that have the chops to discuss this topic. I also amended that to say that one other grasped the concept, that was you, but now I retract that. Not that you care or should. Just saying if you are waiting for an answer or defense don't hold your breath.
I took along a simple generator, RIAA inverse box and dual voltmeter. I did a quick sweep and found even in the less expensive units the EQ was dead on.

@lewm: perhaps I am misinterpreting what you said regarding conforming to RIAA but it appears all the phono stages except one measured spot on in reference to RIAA EQ.
Also, as I posted previously when I first linked to this event the phono mentioned by Roger that using his test method did not measure accurately was not part of the shootout.
Apparently it wasn’t clear that what I meant was that **I** have read widely on relevant subjects.

Doesn't change the opinions on my end.           
BTW, @clio09 Your comments about Al are un-called for.

I respectfully disagree. On another point, I am glad to see you are continuing to post your thoughts on this topic and look forward to Roger's response. It's all Latin to me but maybe I will figure it out at some point.
In my 40 years as an audiophile, and one who is fairly widely read...
Widely read by whom? If you are going to take on someone like Roger let’s start with those facts. I sincerely hope you don’t mean your posse of Audiogon minions because quite frankly I would consider that down right embarrassing.

These are sincere questions, aimed at establishing the facts of the matter once and for all.

Since when did you become the fact police? Really, such an authoritative comment. You actually think Roger cares that you called him out? I think your insider status here might be making you feel a bit larger than life. Don’t think I don’t know what is going on as the logical progression of your comments are very familiar to me, and specifically regarding the Westerlex equipment. Furthermore, don’t let it get to the point of me further calling that out here.

Let’s get right down to some real facts. We have two people on this thread with engineering degrees from reputable institutions and who in addition to being published are experts in their field of work. Their products (both of which I own by the way) are highly reviewed and well received by the industry. What have you done lately? Oh that’s right, you are an audiophile who is widely read. Let’s take it a step further, an audiophile with an engineering degree, and to my knowledge has never put their knowledge and experience on the line manufacturing and selling their designs. Please correct me if I am wrong about these facts (not that I care).

@rauliruegas: I for one appreciate your efforts to sift through all of the information here and especially Roger's posts. Specifically you noted what I am starting to think is one of Roger's main points which he has mentioned to me a number of times and which I quote from your post:
What I can see is that ramtubes is rigth in that the RIAA original is not the one for magnetic/velocity cartridges that needs a compensation. That orginal RIAA pre-emphasis ( two octaves ) is for displacement cartridges. So, he is rigth.
Now as for the dark points, based on my conversation with him today this might provide a bit of a clue (specifically the second sentence) which is from one of his previous posts:
The 40 dB curve that 99.9% of us call RIAA EQ is the combination of RIAA plus the EQ required for a velocity (magnetic) cartridge. Let us not be thinking that the groove itself has 40 dB (100 to 1) of EQ but indeed just 4 to 1.
I will wait and see if Roger posts to allow him to explain this. Otherwise I will try and reconstruct my notes and see if I can do justice to it.

At this point I am not terribly concerned about right or wrong, it is a situation where we may have two rights, or the status quo (the Bible as Raul puts it) versus a different way of looking at this (Roger has been known to think outside the box and I don't think he disavows the 40 dB curve). I am far from an expert, certainly won't claim to be "widely read" (or more appropriately well read) on the subject, and what is being discussed by the two people who I consider the experts here (with kudos to Raul for persevering through this) might as well be Latin to me.

What I do know is I have two phono stages designed by Roger (RM-1 and "RM-6") and both have extremely accurate RIAA measurements. Perhaps I can share more tomorrow if Roger has not already done so.
Well I’ve known Roger to pose questions when he wants to find out what someone really knows about a topic. However, in this case I think it’s more of a teaching moment. At some point this will come to a conclusion and we’ll know for sure.
It was his MP-3 that was **allegedly** tested by Roger in a recent phono section shootout.

@atmasphere: a correction if I might, the MP3 was not one of the preamps Roger tested at the phono shootout. It was tested prior to the event, which I did not attend. The phono stages tested by Roger and used at the event can be found here:

https://sanfranciscoaudiophilesociety.com/event-write-ups/phono-stage-shoot-out-january-26-2019/