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.

I agree that one does want RIAA error to be as small as practical, but I don't agree that +/-0.2db (the actual data for the Allnic, reported by Raul as "0.4db") is anything to be concerned about.  I also own Raul's 3160 Phonolinepreamp, and it's excellent too.  I don't know the RIAA error of the MP1, but it's probably wider than that of the 3160. I don't hear that as a problem; I don't hear it at all when comparing the two.

“Loading on the input side”.  Does that mean using a resistor across the primaries of the SUT (which on its surface sounds like a bad idea) or what? Dave is a great outside the box thinker.

exactly. https://myemia.com/SUT.html

https://myemia.com/Loading.html here's a discussion

anybody else having issues with this thread? Unless I go to my responses page I can't see the latest updates

I agree that one does want RIAA error to be as small as practical, but I don't agree that +/-0.2db (the actual data for the Allnic, reported by Raul as "0.4db") is anything to be concerned about.  I also own Raul's 3160 Phonolinepreamp, and it's excellent too.  I don't know the RIAA error of the MP1, but it's probably wider than that of the 3160. I don't hear that as a problem; I don't hear it at all when comparing the two.

agree completely. How much error is introduced on the production side? Does the deviation of  EQ applied in the electronics that drive the cutting head approach such small amounts, or the other errors introduced in the cutting process?  I'll answer that...... no. Your speakers in room response introduce many dB of deviation, etc. At some point you have to focus on things other than getting distortions down to such ridiculously small amounts, like how it sounds. 

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.