Home Forums Design and Building 2 Stroke Amplifier Design and Building Hammond PT for a Two-Stroke (Rev 2) Amp? Reply To: Hammond PT for a Two-Stroke (Rev 2) Amp?


Just chiming in on this old thread to confirm the 290AX works fine. I just swapped the AES 022772 PT that I used initially for the Hammond 290AX to try to compensate for the high line voltage at my house (125VAC), which was presumably resulting in a pretty high B+ of 425VDC with the AES PT. To get the B+ down, I used the 275VAC secondary (red/white pair) instead of the 325VAC secondary (red pair). It brought the B+ down to 375, which is still a little high, but seems tolerable. I’m not finding the 290AX to run hot at all, yet. I’ve only had it cranked (volume on 8-12) continuously for about 30 min at most. It only got slightly warm. The amp is getting a great grinding tone around 5-10, then starts to melt down past that. When it’s wide open it starts compressing like crazy, kinda like a fuzz pedal, and cutting out slightly. Think Neil Young, but maybe even worse. 🙂