A-40 Transformer


So, AudioXpress sells boards for the A-40. There seems to be active builders of the A-40 (?). What tranny are you using?

I can't find a Signal 88-8. 2 custom pieces are going to run me a few hundred. If that's what I'm looking at, cool. But, I would prefer to know what (stock?) iron could be used.


Signal doesn't list the 88-8 anymore but they do list an 80-8 that would do fine. However, their transformers are simply too expensive these days.

I've built 2 A-40's using the 88-8. If I were buying transformers for a new A-40 project I would buy 2 Avel 330VA 25-0-25 toriods from PartsExpress. They're $47.00 each. The voltage is a bit high but it gives you an opportunity to build a CRC or CLC power supply and then end up with the voltages you need.

Hi Aaron,

The Avel 330VA 25-0-25 toriods that GL recommends will do just fine for your a40 - one per channel. I had John from Victoria Magnetics custom wind a 600VA toroid for me with 4 secondaries, each rated at 24v 6.25A. I think it cost somewhere near $100. It gets a little warm after hours of use, so you might want to consider 350VA per channel.

After rectification and 65,000uF of capacitance, I get rails that run at about 32v - a little higher than specified, but not a problem at all. I have a web page written up on my a40 with lots of construction details here: http://www.facstaff.bucknell.edu/esantane/movies/a40.html