EL 84 circuit

[sluckey]

The 272X seems a bit light duty but if I had one in hand, I would certainly give it a go. If I had to shop, my choice would be 270DX. And for OT, I would use the 1650FA. These two transformers look good together and sound great in any 2xEL84 push/pull amps. I've used both of the transformers and really like them.

But, my first choice would be this AO-39 on eBay. Good price. Probably even get it cheaper. It ain't gonna last at that price.

[DavidN]

Steve: I took on the Dual Lite project and got it all assembled. It has been a fun project and great learning experience. Please see picture. I used Rob Robinette's startup procedures and found that there is no DC power at v5 pin 7 where the output transformer connects. Pin 7 at v4 is 472 v DC. By the way this is at startup with only the rectifier tube installed. There is no continuity between the output transformer secondary's and I assume therefore that I will need to find another output transformer. I am still new to this obsession and I see transformers for TMB18 and VOC AC15. Can I please ask for a recommendation for an output transformer.

David

[DavidN]

Apologies, I didn't see that this discussion went to a second page and you had already answered this question. I will get a replacement and get this project completed. Thanks again for your amp information

[sluckey]

I already gave a recommendation for an OT in my previous post.

I'm looking at your gut shot pic and the OT wiring looks strange to me. I see two grommets for the OT wires. Seems strange that both primary plate wires did not pass through the same grommet. I suspect you have wired a secondary lead to V5-7. Double check and confirm that you have wired the OT correctly.

[johnnyreece]

I'm looking at your gut shot pic and the OT wiring looks strange to me. I see two grommets for the OT wires. Seems strange that both primary plate wires did not pass through the same grommet. I suspect you have wired a secondary lead to V5-7. Double check and confirm that you have wired the OT correctly.

+1 on this. Hard to tell the wire color on those old radio trannys. It might be you've mistaken one color for another. Definitely worth verifying what's what with your meter.

[DavidN]

I do believe that you gentlemen were right about the wiring being wrong but when I tested the output transformer and it was bad. I replaced it with the Hammond as recommended and went through startup. Checked the bias and I ended up changing out the cathode resistor to a 250ohm and it has a calculated tube dissipation of 93 percent. The amp sounds really nice on both channels. Great project and thanks for the suggestion and helping me get there. A few pictures included