[tg3]

Do the AKSA amps need a 4-wire transformer secondary, or will a 3-wire work ok? Found a great deal on toroids, but they are 3-wire.

[AKSA]

The 55W AKSA needs a center tapped transformer of 25-0-25 Vac;  the 100W needs the same at 35-0-35 Vac.  

Generally, these are four wire affairs;  that is, two separate windings, each of 25 or 35 Vac.  The start of one winding is paired with the finish of the other to make a center tap.

A few transformers, mostly EIs, are made with the start of one winding attached internally to the finish of the other.  This is a single wire, the center tap.  If you have one of these, it will do the job fine, but you need to check the voltage output to ensure that from the outer wires the voltage is either 50Vac or 70Vac, and not 25Vac or 35Vac, which would indicate the windings are in parallel, not series.

tg3, can you share with us this 'find'?    

Cheers,

Hugh

[tg3]

ApexJr (www.apexjr.com) had a special for 25-0-25 toroidal transformers that were surplus from Defintive Technology - USD$25, and I grabbed a couple for a planned AKSA 55. I have misplaced the specs, but they were a bit more than the 160VA that you consider optimum.