PT sub with higher B+

[Randall]

The AB763 SR schematic shows 360v - 0 - 360v, which is 720 CT. According to the Hammond site the 290DX is listed as 'lower plate volts' at 650 CT for Tweed and Brown Bassmans and such with the 8087 PT. The 290D2X is the 710 CT which is closer to the schematic, and shows to be a replacement for the 125P5D, (022798) shown on the schematic.

I actually contacted CED about this, thinking their site is wrong. They said they'd check it out.

[Leo_Gnardo]

The AB763 SR schematic shows 360v - 0 - 360v, which is 720 CT. According to the Hammond site the 290DX is listed as 'lower plate volts' at 650 CT for Tweed and Brown Bassmans and such with the 8087 PT. The 290D2X is the 710 CT which is closer to the schematic, and shows to be a replacement for the 125P5D, (022798) shown on the schematic.

I actually contacted CED about this, thinking their site is wrong. They said they'd check it out.

FWIW checking the operating situation in the Sup Rev I had - got 36 watts at clip. Hi voltage 440 at no signal, 395 @ clip. Perhaps a smidge on the low side. Amp sounded fine, owner's happy and all is good with the world. I've seen these amps turn out more power, and less, with original PT & OT. Owner is a mature fellow, probably not going for that last watt possible. And if the repair sees us through, both he and I will be pushing up daisies before it needs another iron supplement.

Funny thing I was considering another cheaper ($85) PT intended for tweed Bassman but reasoned it would leave the Super Reverb lacking all its potential power. With the 290DX I think I found a very acceptable compromise, also saved 60ish dollars. Might even benefit from longer cap & tube life when they're not stressed with maximum voltage possible.

When/if CE gets back to you please let us know what they have to say. TIA!

[Randall]

CED Sales only thanked me for bringing it to their attention, and said they would run it by the tech dept. Doubt I will hear more than that from them.

I installed the 290D2X. Amp is putting out ~38 watts before clip, with 470v on the plates, only 10v more than the schematic. I am happy with that. I think it is named D2X because it has a second 610CT winding as well as the 710CT.

[Leo_Gnardo]

I installed the 290D2X. Amp is putting out ~38 watts before clip, with 470v on the plates, only 10v more than the schematic. I am happy with that. I think it is named D2X because it has a second 610CT winding as well as the 710CT.

Sounds like a good fit. Hm... $60 for a tap on the HT windings. An expense I could do without, but if it's the only quickly available choice...