Step Up Transformers….Are they Worth the Trouble?

Here's a question that arises when one considers the RIAA equalization error in a phono stage: What is the standard by which the error is calculated? Is it the curve described by the equations in the Lipshitz paper?  Or is it the ideal curve, which is not achieved in an analog circuit using the Lipshitz equations, where there is a flat plateau between ~500Hz and ~2kHz, sitting at 0db, flanked by straight lines from -20db at 20Hz to 0db at ~500Hz on the left hand side of the plateau, and 2kHz to 20kHz (0db to +20db) on the right hand side?  Further, what about error on the pre-emphasis (cutter head) side?  That must be a variable based on choice of cutter head, company producing the recording, and age of the recording.

I certainly yield to Atmasphere on use of tubes in phono equalization (also as a proud owner of an Atmasphere MP1), but as I understand it the reason a tube phono stage may exhibit slightly less RIAA accuracy compared to a SS phono stage is that tubes change with age. Adherence to the Lipschitz equations (or any of some other equations to define RIAA de-emphasis in a phono stage) depends exquisitely on the accurate values of the parts used to construct the circuit.  Since the plate resistance (Rp) of the tubes figures in to calculations involving impedance (R in the Lipschitz equations), and since Rp does vary slightly over the life span of a tube, the RIAA error reported by a manufacturer probably has to be a bit wider in order to take that into account.  Transistors don't change in that parameter.

This is why we use passive EQ; as the tubes drift the actual EQ does not. For passive EQ you need a series resistance; we have that value set high enough that it dominates the equation of source impedance driving the EQ network so the tubes become irrelevant. In this manner the EQ accuracy is determined entirely by how well we're able to get the components to meet the values in the formula.

Dr. Lipshitz's math generates an EQ network that is as ideal as it gets.

On the record side, the cutter manufacturer goes to great lengths to make sure the cutter is spot on to the proper pre-emphasis. To that end the cutter head and electronics are matched and the electronics tweaked slightly to compensate variations that exist in the individual cutter head assembly. As a result RIAA pre-emphasis is extremely tight across all cutter head producers unless a cutter got separated from its original electronics. 

 

On the record side, the cutter manufacturer goes to great lengths to make sure the cutter is spot on to the proper pre-emphasis.

you have more faith in your fellow man than I do

and do you really think they get within .01 dB or whatever it is that Raul thinks is needed on this end?

 

For passive EQ you need a series resistance; we have that value set high enough that it dominates the equation of source impedance driving the EQ network so the tubes become irrelevant.

and what is "irrelevant?" Your irrelevant might be another man's terrible, although in my world I think we agree on it. 

and do you really think they get within .01 dB or whatever it is that Raul thinks is needed on this end?

@herman 

No. That spec sounds dubious. There would be no way to verify that in field testing since the margin of error in the test equipment (and inverse RIAA network used) would be higher than that. FWIW I looked on the FM Acoustic site and found things in the same pdf as the specs that weren't correct. For example they claim to make the only true balanced phono preamp, which isn't true. We've been making one since 1989. I know its a logical fallacy to assume everything in the pdf is false (and it doesn't appear that way to me) once one thing is proven false but it did cause me to be suspicious.

Dear @herman : " chasing numbers like this is a fool’s errand. There are so many errors introduced in so many stages of the process that these small deviations do not matter. "

 

" focus on things other than getting distortions down to such ridiculously small amounts, like how it sounds. "

 

Clasic posts of an audiophile but certainly not a MUSIC lover.

Yes,speakers could have several dbs deviation in room frequency response but that is not the issue.

Gentlemans as you are the " market centuries bargain " for the manufacturers/designers/sellers in the audio world where almost none takes care why or what gives me the audio item I buy for the money I paid for it and manufacturers/designers know that they do not have to make a higher quality design efforts due that no one is asking for. Their customers are way " easy " customers " easy " to let satisfied ( just as you. )

That " bargain audio market " it’s conform and with no comply about quality level true performance.

Those gentlemans like you that stay in the " bargain audio market " are the ones that impedes the audio market designs truly grow-up but only " more of the same ".

Look from everywhere and you will see that the quality audio design almost is in stand-by real situation and ( again ) manufacturers are truly happy with because audiophiles today pay 10 times the kind of money for audio units that almost has no true improvements .

However, I can see that you are not using " lamp cord " for the electrical power in your system or a simple IC wire from your tonearm and I can see that you use too a TT " diferent " mat and that you or some one made for you the TT plinth and many other things. Maybe you don’t use a protractor to cartridge/tonearms alignments and many other " maybe’s ". Why took you all that time and money with your room/system modifications including the Voxativ? or why posted those silver connectors picture?. I don’t care, you are.

 

Now, we can’t modified what already happens in the LP whole recording process but we can take care with the playback proccess and between other several " things ". the RIAA is there.

I know that you should understand that the first main subject to exist a phono stage is because is because the grooves recorded information comes with the RIAA pre-emphasis and we need some way to have the inverse RIAA eq. to translate that recorded information in our " language ", the second main reason exist a phono stage is that we need to amplify the very low cartridge signal levels. A stupid question could be: do you know why the inverse RIAA eq. needs to do it at the very begin of that signal that pick up the cartridge and before any other stage?

 

What we listen at the other end of the system chain is an accumulation of several kind of distortions/noise/resonances/frequen cy deviations and the like along the room/speakers contribution about.

Why can you change the VTA or VTF or AZ in a cartridge/tonearm combination?. Well and between other things to achieve at minimum any kind of added distortions/degradations to the MUSIC signal.

Obviously that you don’t care about accuracy where it matters " th first " and maybe you don’t care because what you have is what you like it ( btw, the swing in your unit RIAA is 0.6db ) additional I can see that you are not in favor or a cartridge signal short path but the other way around. Nothing wrong with me and neither with you but for the MUSIC tht at the ends is the only subject it matters to me.

In the same way that is critical the cartridge/tonearm accuracy alignment in even more critical way is the phono stage inverse RIAA eq. accuracy. Any single minimal discrete frequency deviation in that curve ( I already posted ) affects at least 2 octaves and its developed harmonics and affects even when you have: + 0.3 or -0.3.

 

" they get within .01 dB " yes, absolutely I shared several times that RIAA again other phono stages RIAA and do you know how looks in aa chart both channels?.

you can only see a perfect linear line as if be only one channel instead 2. Yes, near perfection and yes I’m way demanding in the MUSIC reproduction needs and yes I know you are not. Nothing wrong with me.

lewm the swing in the RIAA is the true deviation and not only the: +.

 

R.

Clasic posts of an audiophile but certainly not a MUSIC lover.

how odd you say that....I don't see where anything you posted has anything to do with loving music, only chasing numbers.

MY system produces beautiful music. That is all I care about. Yet you somehow know me? 

I posted how I got there. You can nitpick it if you wish, no problem here.

and BTW , your claim of .01 dB accuracy with your phono stage is ridiculous. Even if it could do it, you can't accurately measure it. You are embarrassing yourself by making the claim....

Good day