Advice for Power Supply - Pete Millett Balanced NuTube

I am looking for some advice, please. I need to build an appropriate power supply for Pete Millett's Balanced NuTube design.

It is likely that I will build both a line stage and headphone version. So, I'd like the power supply to support the current necessary for low impedance headphone loads. Per Pete's article, I'd prefer to run it off +/- 15V with a min current of roughly 0A200 or more per side for good measure. I'm a bit new to this. I think if I don't build it "dual mono" and use two PSUs, then I'd need a PSU that can work up to 0A400. I, like most people, seem to err on the side of more is better.

I have been experimenting with trying to model a PSU, but I am out of my depth at the moment. So, I would prefer a PSU with ready-made PCBs, a known-tested BoM, and some level of support from a forum thread and/or the designer. I don't have a lot of concerns, but many power supplies have an enormous number of rectification, snubber, and filtering choices. Board mounted transformers (similar to the WHAMMY kit) would be a plus, but I can work with a donut (or two) if the design warrants. Some designs use wall-warts or other DC supplies as the initial power source. I'm game, if they perform.

Low noise will be a priority.

Thanks in advance.

I would consider this one:

Dual/Bipolar LV-Reg

Thank you for the quick response, Dennis! That seems like an excellent option. I have (shocking, I know) a noob question or two. :D

1) The determination for the VA rating seems simple enough for the transformer. It clearly states "Use a power transformer with a current rating at least 1.8 times greater than the expected peak load current." Simple enough. So, if I go with one, then I'd want 0A400 * 120V ~ 50VA for gracious plenty.

If I do "dual mono", then 25VA per transformer, would be gracious plenty, correct?

This follows the MORE is better "rule" and multiple comments I've read that lower loading can be lower noise. I don't feel that asking for someone to make me 25VA on a 50VA core or similar would be cost effective or necessary.

2) This is a regulated supply (vs. my other supplies that float with my mains). The universal PSU and other PSUs I've seen have a bit of voltage loss in the PSU circuit. I can't find on the sales page what secondary voltage to choose based on output voltage. I'd generally assume that 15VAC secondaries once rectified would definitely more than enough (and maybe too much) for 15VDC out. However, depending on the efficiency of the circuit, 12V secondaries may be more appropriate. I'd appreciate any insight, please.

I've had good luck with the Antek shielded donuts for my other builds.

If I go with a single unit - this seems sufficient.
AS-0515 - 50VA 15V Transformer - AnTek Products Corp
(or its 12V secondary counterpart)

If I go dual mono - a pair of these may do well.
AN-0215 - 25VA 15V Transformer - AnTek Products Corp
(or its 12V secondary counterpart)


With thanks!


Dennis Hui

Paid Member
2002-08-27 7:19 pm
Toronto, Canada
Hey IAIMH (sounds like an 80s band :) ),

I would go with 50VA in both cases, just because they have a static
shield not available on the 25VA ones.

For the voltage, 12VAC look like you'll be cutting it a bit close
(Even though the +/-15V PS uses low drop out regulators, you'll still need to
budget a few volts loss), so I suggest 15VAC:

AS-0515 - 50VA 15V Transformer - AnTek Products Corp



Paid Member
2014-12-09 5:51 pm
Pete told me his PS for op amp, on his website, would work fine and that’s what I went with. Go to this link and scroll down about two-thirds of the way: LR Phono Preamp

I bought a 15+15v encapsulated transformer similar to the one pictured. There are links for a schematic and BOM and it’s an easy build. NOTE: PCBs for PS and preamp DO NOT conform to hole spacing for the pre-drilled chassis bases sold by the store. But they are aluminum and drill easily. There also is a short thread, “Building the Pete Millett Balanced Korg NuTube Preamp” that has some helpful tips. It’s in the Analog Line Stage forums. I just finished mine and am still wiring the chassis or I’d offer you a listening report. Best, Jim.