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Best Step-Up Transformer(s) for Koetsu Cartridges

Erocka2000

pfm Member
Hey folks, I posted this on another forum, but figured I'd cast a wider net to increase responses.

I currently have a Koetsu Urushi Sky Blue mounted on a Jelco TK-850S/Technics SL-1200G. I absolutely love it. Just an incredibly natural sounding cartridge, with zero listener fatigue, where one can listen for hours (and I do). I recently purchased a classic tonearm (a more detailed post on that will follow once I have it installed on the 1200G), which is said to be quite possibly the best tonearm ever for Koetsu cartridges.

That said, I'm currently using an Audio Note AN-S2 SUT going into the MM input of my Luxman CL-38uC preamp. It sounds great, but it has me wondering if there are perhaps, even better SUTs for Koetsus out there.

I've done plenty of research and there honestly isn't that much out there. Threads on various forums show promise in that their original poster had the the same question as mine. But the threads quickly lose focus on the subject and just become people talking about different Koetsu cartridges and drooling over some of the pricier stone bodies variants that some users own versus discussing SUTs.

I've read that Koetsu's own SUT is just so-so. Nothing that really leaps out at you, and others mention it's a tad boring. I've seen mention of Bob's Devices Sky20, but again, some people love it, others say it is sometimes grainy. One thing that seems pretty all around favorable are SUTs that use Hashimoto transformers. Unfortunately, I can't seem to find any new SUTs that use Hashimoto transformers. So if anyone knows of current production SUTs that use Hashimoto transformers, please let me know.

So, any of you Koetsu owners out there, what has been your experience with SUTs and have you found one that is just magnificent with your Koetsu?
 
I have an hand built SUT based around a pair of 1:16 Partridge transformers serving a Koetsu Rosewood into an Icon Audio PS1. I think it all sounds great. The loading works out at 186Ohms.
 
Hashimoto’s were superb for me with a Rosewood Signature. Even better was a Phasetech T1 although that’s extremely rare outside of Japan.
 
I am currently going through all the SUT considerations as well. I have borrowed an EAR MC4 and a Tron Convergence Signature MM and it sounds superb. I have also used the MC4 with the newish EAR Phonobox and hands down MC4/MM on the Phonobox is a huge improvement over the internal transformers.

I have been talking to the Australian distributor of Audio Note and will hope to have a listen as soon as we get out of lockdown here in Sydney.

The other SUT which I would love to try is the Auditorium Hommage T1 - it gets great reviews. The other consideration is to go up the Audio Note chain.
 
Don't know much about Koetsu cartridges but I would second the endorsement of Partridge Transformers. Bought mine from a guy in Milton Keynes who advertises regularly on ebay and mounted them myself.
 
I have an hand built SUT based around a pair of 1:16 Partridge transformers serving a Koetsu Rosewood into an Icon Audio PS1. I think it all sounds great. The loading works out at 186Ohms.
Do they have markings on the transformers so that you can check for authenticity?
 
FWIW I have a Red Sig and it sounds wonderful with whatever SUTs are used in a Tron Convergence MC and an Allnic H1201 on the 113ohm setting (never tried separate SUTs - don’t understand enough about it).
 
That said, I'm currently using an Audio Note AN-S2 SUT going into the MM input of my Luxman CL-38uC preamp. It sounds great, but it has me wondering if there are perhaps, even better SUTs for Koetsus out there.

My advise would be to keep the AN-S2 and get a better preamplifier if you want to improve the sound of your vinyl. That is if you don't what to change the turntable and tonearm. The SUT is not the weak link. Also I would avoid any of those old US made SUTs as there are significantly better ones made today.
 
I use a Silvercore SUT into a EAR Yoshiono 834MM stage, goes very well with my Kiseki Purple Heart.
 
My advise would be to keep the AN-S2 and get a better preamplifier if you want to improve the sound of your vinyl. That is if you don't what to change the turntable and tonearm. The SUT is not the weak link. Also I would avoid any of those old US made SUTs as there are significantly better ones made today.

You should read some reviews on the Luxman CL-38uC. You'd see that the internal phono stage is quite capable. Even Art Dudley said that the CL-38u (previous version) gives up very little to his esteemed Shindo Masseto: https://www.stereophile.com/content/luxman-classic-cl-38u-preamplifier

And my turntable and tonearm are absolutely fine, even before I install the new (vintage) tonearm I just bought, which will bring it up to another level.
 
You should read some reviews on the Luxman CL-38uC. You'd see that the internal phono stage is quite capable. Even Art Dudley said that the CL-38u (previous version) gives up very little to his esteemed Shindo Masseto: https://www.stereophile.com/content/luxman-classic-cl-38u-preamplifier

And my turntable and tonearm are absolutely fine, even before I install the new (vintage) tonearm I just bought, which will bring it up to another level.

I am sure the Luxman is quite capable but I am highlighting your weakest link. I doubt you will find a better step up unless you drop a significant amount of money on one and even then it doesn't mean its going to be a great SUT. With all due respect, I don't need to read reviews. I can pretty much tell what a product is going to sound like just by looking at the circuit, the layout and the parts used. Having had original Luxman and Shindo amps through our workshop (and repaired them) over the years they are OK but they are nothing really special, quite warm and coloured sounding when compared to a good designed preamp. Also, just hope and pray you don't get problems with the valves as they were all designed around a certain type/collection of valves/tubes chosen by Ken, some of which are unobtainable today...
 
I am sure the Luxman is quite capable but I am highlighting your weakest link. I doubt you will find a better step up unless you drop a significant amount of money on one and even then it doesn't mean its going to be a great SUT. With all due respect, I don't need to read reviews. I can pretty much tell what a product is going to sound like just by looking at the circuit, the layout and the parts used. Having had original Luxman and Shindo amps through our workshop (and repaired them) over the years they are OK but they are nothing really special, quite warm and coloured sounding when compared to a good designed preamp. Also, just hope and pray you don't get problems with the valves as they were all designed around a certain type/collection of valves/tubes chosen by Ken, some of which are unobtainable today...

I guess we'll have to agree to disagree on how good Luxman and Shindo preamps are. I don't see the Luxman as my weakest link. Do be honest, I don't really have any weak links (in my opinion) in my system. I was just asking about SUTs to see if I could maybe squeeze the last bit improvement out of my analog rig. If I can't, no worries, as it sounds fantastic the way it is. Also, my Luxman only uses 12ax7 and 12au7 tubes, so hardly unobtainable. And not everyone likes a neutral or analytic sound. I actually prefer warmer sounding systems as long as resolution doesn't suffer, which in my system, it does not.
 
No problems here. Just doing some due diligence. I mean, that's what audio forums are for, are they not?
SUTs are a product of a bygone era, when high gain, low noise amplification was hard to come by.

They are essentially unnecessary today - an archaic product fulfilling a boutique niche - perhaps like a cartridge warmer products that came up in another thread.
 
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SUTs are a product of a bygone era, when high gain, low noise amplification was hard to come by.

They are essentially unnecessary today - an archaic product fulfilling a boutique niche - perhaps like a cartridge warmer products that came up in another thread.

It depends on how natural and realistic you want your music to sound. You can't get a gain stage (20db to 30dB) more simple than an SUT that also is extremely low noise. Simply put, its wire with gain...
 
F.w.i.w., I have a Urushi Vermillion (lower output). Both that, a Benz Ebony and T. Proteus sing through my EAR 912 pre., which I believe has the trannies and performance not far short of EAR's top SUT. I've never been into SUTs, relying instead on previous s/s stages. I wonder if the extra cost, complexity and interconnectivity of SUTs is such a viable route these days.

The m/c stages of EAR's pre's are generally considered to be excellent, and it may be that others, and SUTs, just offer a different flavour rather than out and out s.q. improvement. Just a sceptical thought ! ;)
 
F.w.i.w., I have a Urushi Vermillion (lower output). Both that, a Benz Ebony and T. Proteus sing through my EAR 912 pre., which I believe has the trannies and performance not far short of EAR's top SUT. I've never been into SUTs, relying instead on previous s/s stages. I wonder if the extra cost, complexity and interconnectivity of SUTs is such a viable route these days.

The m/c stages of EAR's pre's are generally considered to be excellent, and it may be that others, and SUTs, just offer a different flavour rather than out and out s.q. improvement. Just a sceptical thought ! ;)

All of EARs phono stages use SUTs Mike!
 


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