la2a reissue with jensen on input no compression...

undoing a mod for a coworker cause it didn't work. He followed the jensen diagrams note for note but with the jensen input transformer in and their new value for r5, it would not compress audio at all. Plus the with the jensen there was ground hum.

now I am thinking it's either the fact he left the original transformer in place and was using it's secondary connection posts as the hook p for the jensen jt-11p-1

or something was not  recalibrated?

with the stock transformer and r5 resistor value the unit behaves as normal.


edit:  had to replace the 12bh7 tube which went out.  currently has stock transformers in unit. unit is working well.

wait none of that made sense. well sort of.  here is the deal. a coworker started to mod his la2a reissue. pots were replaced with  stepped attenuators. he then put in a jensen 11p1-1 as he wanted to replace the input transformer. unit  didn't compressed but passed audio and there was hum.  He had ran the connections to the secondaries on the transformer as they have pins and such.  I unwired the jensen and wired  back in the stock transformer. I had the same results of passes audio but no compression and ground hum.  I ended up replacing the 12bh7 to get the unit hum free and compressing again.

so the secondaries were in parallel?

yes. but only the primaries of the jensen were connected... anyway turns out his whole problem was a faulty 12bh7. once that was corrected, rewired in the Jensen for him properly. it was given a through listen and to be honest the sound of original reissue transformer was  in the opinion of all involved much better.  something about the step up.  anyway decided to give me the jensens. not bad I say.