Step Up Transformer Question

@lewm- no disagreement w/ your clarification of my wordage. Thanks.

Don't get too caught up on loading.   I don't unless there is a huge mismatch.

MC carts don't generally react to capacitance so I don't worry about that either.

I use DH Labs Pro Studio cable hard wired on my VPI terminated with AECO RCAs on the other side.

Thinking about going to solid silver.

Audioquest Fire w DBS to keep the dialectric formed…more important on the tonearm cable…. in my opinion But any AQ interconnects w DBS used should be on your list.

OP your wife is a saint…. just saying…..

when selecting said, choose one with a ending result of YES on the turns ratio…..

My Phono system already sounded great, with ’regular’ phono cables.

When I bought my long tonearm, the Russian maker almost insisted I use this Ortofon

 

That TT, I had been using a basic cable from Amazon while waiting.

I heard ZERO difference, I used two ’upscale’ din cables that came with my other two tonearms. Plugged

Might as well ask this audience... What phono cables are you using? I don't want to go crazy. Found some on eBay that look fair, low capacitance with good shielding. 

@rmdmoore I use a SoluPeak 4-way switch from Amazon. I can’t tell the difference with it in circuit, or connecting the tonearm directly. If you want to just run two carts, there is a Rek-o-Kut switch that also seems very quiet. I have a couple of them from previous iterations of tonearm numbers, which seem to grow and grow! I’d recommend the 4-way, though, as it lets you add two more! The cartridges have internal impedances of 38, 38, 10 and 5Ω. I don’t know what the turns ratio of the VAS transformer is, and you’re correct, Steve doesn’t push it. Basically, he said your ears will tell you if it’s right. If you can get him to reveal the turns ratio, please let us know.

Thanks for all the input.

@lewm I know subbing 12au7 for 12ax7 seems off but the amp is designed to take 12au7, 12av7, or 12ax7. Each has increasing gain but also increasing noise so if I can get more gain out of the transformer then maybe I can use a quieter lower gain tube. 

@dogberry I had asked Steve what I should get and he was kind of elusive. I named a bunch of different things including an Entre, and an FRT thinking to myself that this isn't technology that's changed a lot so maybe an older high quality adjustable one would be good. He said "they're too old". He told me to not get a bobs devices. I'm wondering if he was trying to lead me to to his own one that I had somehow not realized he makes. Also, what switch are you using?  I think that the higher gain SUT might sound better enough that I'd want to use it for both cartridges. I did text Steve and ask him if his SUT would be a good choice but I'm yet to hear back as it's Christmas. 

Overall, it seems to me that with a 6ohm internal impedance what I want is an SUT with more turns, probably 30 or 40, to better match the cartridge. I think that will produce more gain that what I need with the 12ax7 so going back to 12au7 and letting the transofrmer do more of the work is gonna be the answer. 

Thanks, everyone. This has been incredibly informative. Any addition thoughts are appreciated. 

4 lines from the bottom of my post I wrote “in proportion to the square of the turns ratio of the cartridge “. I of course meant “in proportion to the square of the turns ratio of the SUT”.

What has always boggled my mind is that SUT manufacturers so rarely publish the turns ratio(s) of their products. Which would make it very simple indeed to at least begin to match a SUT to a particular cartridge. Instead, and especially in the golden era of vinyl, most SUTs were given a value in ohms (see Elliot’s compendium above). Typically, the value in ohms is meant to indicate the recommended internal impedance of the cartridge to which you want to match the SUT. For example a "3 ohm" SUT is meant to be used with cartridges having an internal impedance close to 3 ohms (probably 2 to 5 ohms cartridges would work). It also means that the turns ratio of that cartridge is such that when mated to that group of cartridges will result in an acceptable ratio between the internal R of the cartridge and the input impedance that will be seen by the cartridge when using that SUT hooked up to the standard MM stage with a 47K ohm input impedance.

The turns ratio is equal to the voltage step-up ratio. A SUT with a turns ratio of 1:10 will increase the output signal V of the cartridge by 10-fold. Etc. The resulting impedance seen by the cartridge will be equal to the input Z of the phono stage (47K ohms) divided by the square of the turns ratio (100, in this case). So the cartridge sees 470 ohms (47,000/100). Since you want the ratio of the internal R of the cartridge to be about 1/10 of the input impedance of the phono, you can see that any cartridge with an internal R of less than 47 can drive a 1:10 SUT. Nothing explodes if you break the rule of thumb. The actual loss of gain and high frequency response that occurs when the match gives you a ratio less than 1:10 is on a continuum, losses get gradually worse as the ratio approaches 1:1. At a ratio of 1:1, 50% of cartridge output goes to ground instead of driving the phono stage, and there is audible loss of HF response, due to input capacitance.

Back to our "3 ohm" SUT. A theoretical cartridge with an internal R of 3 ohms can drive a net 30 ohm load before you cross the line of the 1/10 rule of thumb. In order to create a 30 ohm load, you just have to work the formula for the load seen by the cartridge backward. I calculate 1:40. A cartridge with a 3 ohm internal R can drive a SUT with a step-ratio (voltage gain) of 1:40 into a 47K load, if you want to rigidly obey the 1/10 rule of thumb.

By the way also, an ideal SUT or any transformer does not have an impedance per se. Transformers merely reflect the impedances from secondaries to primary windings, or vice-versa. I wondered that Elliot mentioned there are SUTs that let you choose both voltage gain and impedance. That can only be done if the SUT has built in resistors typically across the secondary, which would be in parallel with the standard 47K load.

Whart, you wrote, "My dumbed down approach is to look at the internal impedance of the cartridge and multiply by 10 for the load seen by the cartridge. The secondary (or output) from the SUT will be 47k."  In your first sentence, I suppose you mean that you multiply by 10 to determine the (minimum) load that should be seen by the cartridge.  I agree. In your second sentence, you may be confusing others.  The secondary is connected to a 47K standard load at the input of an MM stage. The SUT acts on that impedance to reduce it as seen by the cartridge, in proportion to the square of the turns ratio of the cartridge.  I am guessing you know this but there is a semantic disconnect in what you wrote. I point it out only so others will not be confused.

Good point on asking Steve Leung, there @Dogberry. I also would not underestimate the N Clayton builds- I needed something not spendy for my vintage system based on old Quads and was using a VAS Franken-Denon cartridge Steve put together. Clayton may be taking a few days off for the holidays- but offers blue Cinemags, as well as vintage transformers. There is also a guy on SHF who custom builds some old stock Altec Peerless- he used to work at Altec and had a stash.

I remember first looking at SUTs years ago when I was still running an ARC SP-10 --it had gain, but the preamp was notorious for microphony. At the time, I was trying to find the elusive Expressive Technologies unit- no go.

I use an Allnic phono with built in SUTs on my main system- readily adjustable with the turn of a knob. I like that feature-there are differences in sound based on the settings. My dumbed down approach is to look at the internal impedance of the cartridge and multiply by 10 for the load seen by the cartridge. The secondary (or output) from the SUT will be 47k.

On the cables, I do use the high end spread in the main system, but on the vintage system, use Analysis Plus -- well made, cost effective, and suitable for a system of that period. 

Good hunting.

 

You could do worse than ask Steve Leung whether his VAS transformer would suit your cartridges. I have the MkI version (there is now a MkII) and I have four low output cartridges feeding it through a switch (LP-S, Ruby 3 mono conversion, Ortofon Kontrapunkt C and a Soundsmith Sussurro MkII ES - the last is a low output MI cartridge). I'm very happy with it, even if I don't begin to understand how to calculate whether it is the "right" SUT for any of them.

Ortofon T30 SUT

Simple right? It is, AFTER you have the chart of answers!

SUT Info Charts I gathered

 

Chart 2: Cartridge Column: my AT33PTG/II cartridge’s 0.3 mv signal strength and 10 ohm coil impedance is shown just change it to your cartridge’s numbers

When Considering a SUT or it’s setting: I start with Impedance shown to MM Phono Input, then check which xFactor ____? gives that result. Enough or Too Much gain?

The Bottom of Chart 2, Right Column: select the impedance ____ ? you want shown to the MM Input (guidance: cartridges coil impedance x10)

then go left, see if the Gain in DB of that xFactor is ENOUGH or TOO MUCH.

........................

Note: Calculated Signal Strength: Allow for a bit of loss, I just guess a little lower

 

 

SUT (they are tricky, I got help here, did research, scratched my head, learned this).

Consider selected and future MC cartridges when choosing a SUT (or phono stage with MC):

You need to know both the cartridge’s signal strength AND it's coil's impedance to know what range of xFactor (enough but not too much gain) and that xFactor’s resultant impedance (that will be shown to the MM Phono Input).

Thus you want a SUT with several options of gain (xFactors) AND each of those xFactors give a RESULTANT impedance that will go to the Phono Stage's MM input (separate or in a Preamp).

Some equipment has independent options for gain and for impedance, they usually cost more, but are needed for some MC cartridges with signal strength/coil combos that need that separate adjustability. Best flexibility for unknown future cartridges.

…………………………………

FORMULAS

GAIN = xFactor  = +____db.      

xFactor squared = _____?

RESULTANT Impedance ‘shown’ to MM Phono Input _____? 

47,000 (common MM phono stage is 47K) divided by xFactor squared ____ = impedance shown to the MM phono input (check your equipment’s MM Phono Input impedance, some not 47k)

The guidance for impedance shown to 47,000k is cartridge coil impedance __  x10.

……………………………………

example: for current and future MC cartridges (including my friend’s cartridges we listen to here): I chose Vintage Fidelity Research FRT-4 to get PASS and 4 optional xFactors and their resultant impedance

Some/this SUT’s face numbers are confusing, I had to find the specs to know what the face settings meant: how much gain/resultant impedance shown.

PASS (for MM or High Output MC) bypasses transformers, unchanged signal to MM input

Face 3 ohm = xFactor 35.84 (+31db). 35.84 sq = 1,284. 47k/1,284 = 37 ohms shown to MM input

Face 10 ohm = xFactor 20.68 (+26db). 20.68 sq = 428. 47k/428 = 110 ohms shown to MM input

Face 30 ohm = xFactor 18.27 (+25db). 18.27 sq = 333. 47k/333 = 141 ohms shown to MM input

Face 100 ohm = xFactor 10.55 (+20db). 10.55 sq = 111. 47k/111 = 423 ohms shown to MM input

Luckily for me, it also has 3 tonearm inputs, front selectable.

.....................................

this shows it (ding in face panel) (price a bit low due to that)

 

 

...............................

Entre ET-100 is similar (black or silver)

 

 

Other SUTs with flexibility can be found

IF you or anyone wanted a New MM/MC Phono Stage with Options, Project makes several among other companies

 

Can you boil down your questions to two or three sentences ?

The only thing I’m sure of is DON’T replace a 12AX7 with a 12AU7.

 

I got my 1254's as apart of a Group Buy during COVID. The report was these were Hand Wound Versions due to the workforce being very limited. I got these for approx' $300 shipped to the door. The final build was approx' £400 inclusive of Pure Copper Low Eddy RCA's used on the chassis. 

The Hashimoto SUT built to a very similar Spec' was short of £500

Both prices are in keeping with the monies the OP is considering, It is not known if a from scratch build is something they would consider.

My encounters with Pure Copper Low Eddy RCA's in use, is generating the notion making the use of such connectors is a must for any DIY Builds or Upgrade Works undertaken.

To get the full benefits, Cables used with the Chassis Mount Low Eddy RCA's are noticeably better when terminated with Low Eddy RCA's as well. 

Ortofon makes great SUTs at very reasonable prices. Most SUTs are severely overpriced. If you are good with a soldering iron. Sowter Transformers of England makes first class naked transformers which can be mounted in their own chassis or better yet inside a phono stage or preamp ( no interconnects!)

@rmdmoore A VAS Cartridge as you are investing in, is a bespoke built Cartridge. It is being produced by an individual who's reputation is recognised for both Cart' Overhauls and Scratch Built Cart's across the Globe.

Taking time for selecting the SUT or Head Amp to support it in use will be a worthwhile experience.

Adding to your considerations for a preparation, the general consensus is to keep connecting cables between the SUT / Head Amp and Phon', as short as possible.

As you have made known, the PA 2 has a inbuilt SUT used in combination with Tubes.

My experiences had with both owned and loaned SUT's and Head Amps is that the SUT can create a range of effects to impact on the perception of the Tone being produced. The SUT depending on model in use, can be perceived as creating an increase in Richness, ranging from a subtle influence, through to a very noticeable Bloated bottom end of the frequency range.

I have less experiences with Head Amp Models, and from what I have experienced, I am able to describe the effect of the Head Amp as being much more transparent as a influence in a comparison to a SUT. A Head Amp's influence in relation to certain SUT's could be described as the Anti Thesis of such models of SUT. 

All the above is based on my experiencing a variety of Models/Designs in the home system.

The Company Sculpture A has a range of SUT's, that are offered with a broad range of winding ratio's. I have been demo'd a few Sculpture A SUT's in a system I am very familiar with and one that shares similarities to my own. 

On the day of the Demo's a Sculpture A Copper and Silver Winding SUT was loaned for the experience. The Copper Winding was a perfect match for a 0.2mv Cart', which is the resident Cart's output.

The impact this SUT had on the system in comparison to the resident SUT was quite something, the transformation of the sonic has been notable and well worth making known to others.

The Silver Winding SUT was more aligned as a match to a 0.5mv Cart', but was still able to off something quite special and as well notable for what it could present.

I am left with two questions, as new to me electronic encounters had been had. 

1, How much does the Cart' matching offer to create such an impressive demo'.    In general this will be the suggestion that will be off the most importance

2, How much does the use of a Nano Crystalline Core Metal add to the impressive sonic produced.                                                                                                        As it is not a commonly experienced material in use, it is difficult to tie this one down. 

The overall outcome is that, Sculpture A SUT's are devices on my short list to be a home trial.  

They came mounted in a chassis; the listing said it was a custom job for an audio shop.  

Didn't like the long wires so decided to re-do the chassis.

I decided to wire up all three taps, 3, 24, and 40ohm so I put them in a box I made with stuff I had around.

 

Here it is before the other RCAs came in.

James Audio was supposed to have workers from the former Tango or Tamura companies and DIY folks liked their trannies.

I saw the ones in Italy with four taps; that might make a good project.

@theflattire this is super useful information. As I said, I'm using some crappy found interconnects to go from the SUT to the phono. I have some better shielded low capacitance cables coming soon. Maybe those will solve the hum problem. Seems like Ned Clayton is on vacation based on his eBay profile so I'll check back after the holidays. Wondering about those James audio SUTs though. I found some straight transformers online but not mounted in a box. They don't appear to be octal but likely a couple different set of turns so more connections. Did someone make a box for you or did you find one already put together? 

I had Ned Clayton Cinemag 1254s for a while and it was pretty close to my Hashimoto HM-7s.  The 1254s are a couple of steps down from Bob's SKY.

Now I'm running some James Audio SUTs that I got for half the price of the Hashimotos and I'd be hard pressed to find a significant difference.

I think over the $500 range for SUTs and the diminishing returns start. I go for gain and how it fits with my phono stage; you don't want to overload it.  You can also try to match the cart load, but I don't really pay attention to all that.

Hum is a matter of placement and sometimes cables for me.

There's a good thread on SHF on SUTs under a $1000.

Hard to believe that Rodgers doesn't use some better SUTs or maybe proprietary ones, then again my Modwright uses inexpensive Lundahls mainly for the low gain and to hold costs down.