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jaylgordon 5th April 2009 02:27 PM

Need ideas for amp with 2A3, One Electron UBT-3
In the Aug 23, 2002, issue of Glass Audio, there's a neat little project for making a tube amp for a CD player, and then assembling the whole thing in a table-top radio type package ("A Hybrid Tube Radio," pp. 48-50). Long story short: I bought up all the parts, subbing in some premium pieces, and then my life got very busy. So, I have all the goodies on the shelf and may have some time to put an amp (actually, a pair of monoblocks) together.

But while I'm at it, I wondered if there's anyone out there who's used the 2A3 and the One Electron UBT-3 in a simple SE amp (I can solder and understand the basics of theory, but I'm no engineer)

Obviously schematics would be appreciated more than I could adequately thank for, but even just comments on the above-mentioned circuit and possible tweaks would also be appreciated. Note: the low power is fine, because when I still had a little "hobby time," I built a pair of horn-loaded speakers with single Fostex drivers. They sound good, although I think the current source-- an Acurus 150W amp-- is a serious mismatch.

In terms of acoustics, I have sort of a dilemma. I built a pair of active crossovers a while back (Steve Bench's design), so I had a wacky idea of the following:

[pre-amp]->[active x-over]\--->2A3 SET--->Fostex horns
\--->[Acurus amp?]--->subwoofers


[pre-amp] output 1-->[2A3 amp]-[passive xover]-->Fostex horns
output 2-->[Acurus amp?]-[passive xover]-- >subwoofer

To be honest, I'm trying to put the xovers (passive as well as active) where they seem to belong, but if I've the order ***-backwards, please let me know!

(FWIW, my pre-amp is a Melos MA111, perfect condition, with two amp outputs)



azazello 5th April 2009 04:53 PM

I can Email You schematic of my project 2A3 RCA & E180F Philips, that
sound with Fostex 206E in Hornes....if You interest ??
Output power is apr. 3 wts per channel.
One very good choice, better than my Hammonds....

jaylgordon 5th April 2009 07:58 PM

Sure. I am new, so I can't email directly for a couple days, but you can reach me at (remove space): j a y l g o r d o n @ g m a i l . c o m

Thank you so much for your help!

boywonder 5th April 2009 08:42 PM

Here is a link to Tubelab's site discussing the One Electron output transformers as well as others, not a lot of discussion, but recommended for 2A3 use.

BTW, Tubelab George sells PCB's for a 45/2A3/300b etc based SE amp on his site as well. There is loads of SE amp info there that you may find relevant for your build.

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