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Update on Sophia EL34 amp from 2 weeks ago.

Posted by Michael Samra (D) on April 6, 2014 at 14:59:24

Before

After
You guys may have remembered when I posted a Sophia EL34 amp and we all kind of cringed at the messy layout..It isn't as bad as it looks in the photos but it's not Sophia's best work either..They have some very nicely laid out stuff and I have to admit that the physical architecture of this EL34/KT66 amp is first rate..
I want to add that even tho we criticized the direct connection in the Sophia amps,they stumbled on to something here because the elimination of terminal strips may be yielding a great sonic improvement..In the bottom circuit boards that you see,the components are directly connected to each other with the board merely holding the components..This amp was pretty easy to upgrade and they were very generous with the room to work as well.
I actually enjoyed EL34s in this amp and that included the vintage tubes but when its hooked to the big ribbons,it sounds much better with the KT66s..When it's hooked to the IMF SACM transmission line speakers,the EL34s compliment this setup very well.The IMFs are exaggerated and somewhat sharp sounding in the treble ranges but this amp with the EL34s or KT66s, make it a perfect balance and the amp really does a nice job.
While I'm not a fan of not using terminal strips,this amp with the direct soldered components seems to be on to something.
As with any amp or preamp,I did make upgrades that brought on worthwhile improvements. I installed Schottkys,Russian Teflon couplers,
35uf poly film cap bypasses on each of the 180uf electrolytics,and I put the grid stoppers directly on the sockets so they would fix the oscillation that would crop up on occasion.
The improvement is phenomenal and this amp has some very nice iron and you can run most any octal based tubes from EL34s,KT77s,KT66s,6L6gc,7581,7027,6P3S-e,and all will sound very nice.
You can always run a 7027 in a pentode amp wired for a 6L6 but not an UL amp without rewiring the sockets.
The reason I used the teflons is,I felt the amp needed a little more bite and I wanted to lift a comparative veil over the music and with the updates I did,the amp was able to do that very well.
Of the 35uf poly film caps,I used an EC Unlytic on each end with a CDE poly in the middle..The CDE and the Unlytic sound almost identical.I also changed an extension resistor that was out of tolerance..The Muse KZ bypass cap made a nice difference as well..I did have to change the power switch as it locked up but that was after I took this photo..You can see the original and the updated version.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

Edits: 04/06/14 04/06/14 04/06/14

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