FS Redboy SUTs

For Sale


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I build step up transformer boxes (SUTs) with different vintage input trafos and release them into the wild as a way to feed my hifi habit. I generally post them here, first; you may see them listed elsewhere on occasion.

These SUTs are entirely handcrafted by me, one or two or a few at a time. A lot of work goes into these little things! There's no automation involved; nothing is outsourced. I get weirdly hung up on aesthetics -- it's important to me that the wiring on the inside be as neat as possible, even if nobody ever sees it. It's all very labor intensive and inefficient from a "business" perspective... but fortunately this is just a hobby and I'll keep doing it as long as it's fun.

I use the best parts I can find for the price. Here are the build highlights in "standard" configuration:
  • gold-plated RCA connectors
  • high purity "six 9's" Japan 6N OCC solid core copper wire 24awg (0.00009% pure copper) or
  • NOS Western Electric wire, fresh off the spool
  • Teflon insulating tubing
  • TRT Wonder Solder audiophile grade solder
  • NOS USA ground lug
  • High quality sockets, new production or NOS when possible
  • aluminum enclosure for additional shielding
  • stainless steel hardware


(Available inventory is based entirely on which transformers I have on hand and whether I have free time to build SUTs.)

UPDATED 07/14/2023

Some unusual offerings this time...

- - - - - U T C B-4566 - - - - -

(A11 in OEM case; see this post) ~1:15 $575


- - - - - R C A MI-12399 - - - - -

RCA MI-12399 ~1:14 gain $485 (This one's SOLD but I try to keep these "in stock"; the transformers aren't usually as shiny new)
More photos here



(The units below have been sold and are no longer available)

- - - - - T R I A D A-10 J - - - - -




- - - - - P E E R L E S S 4611-8 - - - - -



- - - - - U T R A D 2569 - - - - -

photos and see this post


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At some point I'm going to want a second SUT - one per arm y'see. All of the carts I'm running are between 0.18 and .4 mV and seem to be equally happy on the Microtran. The AT33PTG/II just arrived. Not sure what that one would want yet.
I really ought to get me one...if just to have on hand for later on.
I 2nd this, you really should get you one. They're so useful, especially if your phono stage sounds great with MM. I've never had the best luck with SUTs but these have been painless and remarkably resistant to noise/hum/buzz that many get from not liking where they're placed.
Just PM'ed Nate!
I don't think you'll be sorry. If it doesn't work out, there's bound to be somebody who'd want it. I've used the MicroTrans with a few carts here, mostly an AT OC-9ml/2 and Shelter 501mkII and both sound better with it than they've sounded in any other context. It especially likes the AT, giving it a body and color that it can sometimes lack...resulting in what, to me, is the almost perfect cartridge. Best of luck!
And the AT is what I'm considering using...as I've been so pleased with the three AT MM carts I've had so far.
The OC-9ml/2 has a similar vibe to my old Signet MR5.0, which had a similar vibe to the AT-150mlx I had, though I think the OC-9 just has more of what is good about them. I didn't love it for a long time, it languished in my spare cart box, but came into its own with this SUT and the very light Technics EPA tonearm I had it on recently. That said, I'm listening to it on the heavier Sound ST-14 tonearm I just posted about, and it sounds ok there too. It's fairly high compliance, though and can get a bit off-sounding, flat, with a heavier arm like the VPI arm I originally tried it on.
It arrived today! I'm all excited.....now to get a cart in here! :over:
What kind of increased output can I expect to have with the 1:16 ratio trannies with .4mV going into it?
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It arrived today! I'm all excited.....now to get a cart in here! :over:
What kind of increased output can I expect to have with the 1:16 ratio trannies with .4mV going into it?
Cool! 1:16 ratio is equivalent to about 24dB gain. With your .4mV in, you get about 6.4mV output (0.4mV x 16).