Need Help diag. 102 Build

[Baddog01]

Sounds like he needs a different transformer

[groovtubin]

The OT is a T026 from Allen amps. A great OT, but not really high output. I finally figured out what is going on, I think. If I use 6V6's, no problem at all. If I use 6l6's, a little bit of problem, but almost gone. The 7591's accentuate the problem drastically. So, it may be a saturation issue.

I am going to experiment a little more and call it a day...

try 100K bias resistors, c if that helps!

jim@OA

[Sone Aura]

No wonder it was having problems! That transformer is down in the Tweed Deluxe & Deluxe Reverb territory. I am rather surprised it did not cook itself. If you were using modern production 7591s that creates some minor more issues, but trying to run anything much more powerful than an old 6L6G or 6L6GT at more than 25-30 watts is going to create problems with that transformer. The primary Z is way too high for a 7591, and even worse for a 6L6GC. A 7591 has a higher plate resistance so, "if" I was going to stay with a 7591 I would want around 4500-5000 ohms primary. 7000? That is a pretty good mismatch! Modern tubes like 7027s, 6973s, and 7591s are pretty mediocre-crappy too. The OT in that amp has a primary Z of around 7K. Over the years, Deluxe amps had a pri Z between 6.6K-8.4K Ohms @ 1000 Hz. You definitely want something larger and and a primary Z closer to 4000-4500 Ohms. If you want to do the old Diaz SRV thing, get a 2K-2.2K ohm 100 watt OT for a Showman or Twin and put an 8 ohm load on the 4 ohm tap. You don't "need" to pay extra $$ for an "SRV" OT. I'd have to say, I am impressed that the Heyboer T026 held up. Even if it did over saturate and sound weird, the fact it still made any sound at all, without making smoke, is still kind of impressive. 7591s are okay but more suited for Gibsons, & Ampegs! Try either the low power Twin or Bassman Super Reverb from Mojo. One is 4ooo ohms the other is 45oo pri. The Showman & Twin OTs are okay, but double your load for the secondary tap.

[fusionbear]

So, the resolution was to run 6L6's but adjusting the output impedance connections from 16 - 8 for 6V6's to 8 - 4 for 6L6's. The 7591's just did not work regardless of how I tried...