Output transformer values

[Skip Hagey]

Good afternoon all, I just tested my output transformer from my AO-39 project and one side reads 205 and the other reads 181 without any load or power to it, just statically.  Is this going to be a problem or is this pretty standard?

[sluckey]

That's about the same readings I get on mine. Been working fine in my dual lite amp.

[PRR]

That's normal.

DC (ohm-meter) Resistance readings are NOT audio impedance.

Ideally the DCR would be zero. But we do not have zero-Ohm wire. The next best choice is DCR much less than Audio Impedance. As this is surely a 5,000 or 8,000 Ohm winding, and you have under 400 Ohms of DCR, that is fine.

The 205/181 difference is 13% against DCR, but under 3% compared to Audio Impedance. Against this your tubes (both outputs and drivers) have 20% variability at best. "Nothing". Especially since your speaker responds to the total average.

The DCR is "always" a little different because they wind one half, then the other. They should have the same number of turns (more important than DCR). But one winding must have a longer length around the core. Actually there are ways to equalize the DCRs, but they are expensive, and don't make a simple guitar amp sound better.