Step Up Transformers….Are they Worth the Trouble?

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.

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. 

'All' or most that you know of?

At any rate, I have to agree with you that 'knowledge levels and skills' is an issue. People seem to get into this sport out of desire rather than if they have the education or not.

If you take the time to read Dr. Lipshitz's paper you will see that it has nothing to do with the kind of amplification. If the electronics are designed according to the math in the paper it will have correct EQ.

Tubes units normally have really high RIAA deviation 20hz-20khz some witn a swing over 1 db and why is important this deviation?: because we are talking of a curve where any discrete frequency deviation affects around 2 octaves in that RIAA curve and the deviations exist almost in all discrete frequencies in that  RIAA . You can use tubes in any place but phono stage due that in reality makes a damage ( sever ) to that cartridge MUSIC signal. In theory the RIAA eq. in a phono stage should has 0 deviation ( only through digital we can reach that 0 deviation. ) to avoid added signal fully colorations and SS in this regards is better aproach.

Dr. Stanley Lipshitz wrote an article that shows all the math for producing a proper RIAA curve. If you do the math the curve will be accurate and this has nothing to do with tubes or solid state.

@pindac Could you explain the 'Very touchy' remark? I was simply pointing out fact. Did you take it differently? This is nothing to do with sales FWIW.

 I don't agree the Math only is the defining information that should create a shortlist of options to investigate. The end sound and how it impresses is the one element that really matters.

@pindac FWIW, math is what was used to make any audio product.  There are no audio products of any merit that don't use engineering. The thing the engineer has to understand though is how the ear perceives sound rather than how the eye perceives specs on paper. I think this quote says it all:

"If it measures good and sounds bad, -- it is bad. If it sounds good and measures bad, -- you've measured the wrong thing." -Daniel von Recklinghausen

Audiophiles tend to ignore the wisdom of this statement because so often the only specs (and math) printed has/had little to do with what we actually hear. So they feel they've been lied to, so much that they have developed a cult of misunderstanding. These days we have the instrumentation and understanding (although clearly the latter aspect is not universal by any stretch) to be able to draw a direct line between what we can hear to what we can measure and vice versa.

Would you please care to elaborate on ‘phono sections’ options / brands.

@lalitk No. But I can tell you something important to look for- to ask the manufacturer about: "What loading are you using on your LOMC phono cartridge?" If they respond with anything other than '47K' its likely that it won't be plug and play with that phono section (you'll have to play with loading) and you may get more ticks and pops on that account that sound like they are on the LP surface.

@lalitk If the very best sound is your goal then I'd would not limit my search to SUTs only! There are plenty of phono sections that can run LOMC cartridges straight in and IMO, some offer noticeably more clarity and bandwidth. 

Good point, I am focusing on ‘custom’ SUT’s that are designed specifically to mate my choice of the cart’s. 

@lalitk OK- keep in mind that if you have an SUT designed for a particular cartridge, if you change out the cartridge, you may have to change the SUT too or figure out the right loading. This will also be true to a lessor extent if you change the tonearm cable, since the capacitance of the cable is part of the loading of the transformer. 

Its these little details which are really the downfall of analog, not the performance or the sound!

So if you get a custom transformer built, ask the manufacturer for tips for loading it for best performance. If he tells you there's no such information or you don't need it, consider looking elsewhere.

All audio transformers have to be properly loaded. This is important so as to allow for the flattest and widest frequency response.

The correct load will vary with the source impedance (the cartridge) since transformers transform impedance (they don't isolate impedance!).

If the SUT is designed for a particular cartridge the right load is likely 47KOhms with a bit of capacitance (100pf is typical; that assumes about a meter of low capacitance tonearm cable). 

But SUTs designed as a generic such as Lundahl or Jensen (who publishes the correct loading values on their website) need a specific load which will be different for each cartridge used. If you don't have it loaded properly its a good bet you're not hearing what the SUT can really do.

I find that while you can get the noise floor down really low using SUTs, its more musical if you can run direct-in. But how that works with the preamp I'm using will not always be so with all preamps. So you'll have to try it and see. Just keep in mind that the loading thing is pretty important- its not plug and play in many cases!