I’ll do some digging. I know some very technical people who have 128Bs. They might know the magic formula… or be willing to do what you mention to get the ratio. I’ll let you know what I find.

hi.i have always wanted to build 128Bs. I have not been able to because i cannot find data on the ratio of the feedback winding in the output transformer. I believe the OT was a proprietary ALTEC part so i don’t think this data is found in any catalog. If would require that someone disconnect the OT in a 128B and then measure the turns ratio. If you have this intel, pls lmk. thanks.

That’s good to know. The combination of the old and new (and the reliability that should engender) is exciting. Amplification is the touchiest aspect of vintage equipment — the most dangerous, I suppose, and yet the most coveted. What became of your Western Electric 43A Homage Amplifier? Spectacular stuff.

Hello. thank you Vincent. I don’t take orders at this time. I do sell the completed pieces however. This particular compressor has been sold.

A18 works great. Rated at +15 but i suspect it can pass more. i havent heard it distort yet. In the past i built these with +8 UTC ouncers and those are not ideal. A series should be fine. good luck.

I’ve just built myself one but sadly the original Peerless input transformer I bought for it doesn’t appear to pass signal correctly. I have an UTC A18 lying around and noticed that you used one for your build. What are your thoughts on it? Have you noticed any issues with headroom at all?

Thanks,

Matt