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Having a blast with my recently completed TC-15! Just to pass along some info and favorite mods:
1) Having really good luck with a Winged-C brand EF-86 tube (tried another by EH and it was problematic).
2) Love the compression on EF-86 channel with the suggested mod of R33 to 220K and R34 to 1M. With the original grid resistors, the EF-86 channel sounded very much like the 12AX7 channel. Now with new grid resistors, it's got a great, sustaining compression that reminds me of the Vince Gill and Brad Paisley Tele sound.
3) Decided to change up the tone controls a bit. I put a Matchless Spitfire-style tone on the EF-86 channel... 1-meg pot with .01 cap to ground... then I modified the contour switch to 3 positions and put it in the 12AX7 channel as a mid control. Using a pot in place of the R10 10K pot, I found that I liked the mid-boost at 10K, 15K and 20K. Put those values on the contour switch... and now I can switch-in the standard 10K mid value, or "hotter and hottest" mids with the 3-positions. I located the switch in the channel's low gain input hole - I never used it anyway.
I have an original 67 Fender Princeton Reverb, an R.I. Fender Bassman with a point-to-point board and a kit-built 18 watt TMB... but now the TC-15 is my favorite of the bunch. Thanks for a great kit, Trinity!

I really like that EF86 screen grid/divider mod too!

-The cascade mod for the 12AX7 channel is cool, it's been done a couple times. Search for it
-You can use the boost switch at the back to do all kinds of things, add bypass caps, change the value of bypass caps, change cathode resistors, etc.
-VRM
-I found the stock values for the bright caps didn't suit me so I lowered them, might be forth considering.

Some other cool potential mods...effects loop, reverb, switchable rectifiers, choke, etc.

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http://pdfelectronics.com

I like the RFT I currently have in mine. I tried a JJ at first... meh... I thought it sounded good until I put the RFT in there!



I'll have to give that a try.




Ditto!

Use a bigger value cap in the cut . Even double it

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

So many amps are a "one trick pony"... but this TC-15 does just about everything well. Very inspiring!

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Tried a new mod this week... found it online: a "squish" control on the EF86 channel. Works to add compression and drive without much distortion... much to my liking. Out of pin one of the EF86, find a .1uf cap to ground. Between the cap and ground, add a 500k pot... cap to pin one (on the pot)... with pot pins two and three to ground. Simple - and it sounds great!

That's cool, where did you find that one?

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Think I saw a mention on AX84.com... but had to Google it to find more info. There's also a video on Youtube of a guy playing a homemade amp with the "squish" mod on an EF86.

Here's a link to the YouTube video I mentioned: https://www.youtube.com/watch?v=5gnbda0FyTc

Found a new favorite mod for TC-15... a "Daisy-Chain" switch. Found it on an amp schematic shown here: https://taweber.powweb.com/store/lenora_schem.jpg
I didn't use the crunch switch, so I subbed it for this mod. Daisy Chain allows stock inputs in one switch position... and both channel inputs blended together (from channel one input) at the other position. I really liked the sound of combined channels (using an external a-b-y switch box...) so I thought the daisy chain would make it even easier - with less 'stuff' to carry around. It sounds fantastic! Combining the mid-heavy channel one with the bass and treb of channel two gives many more tone possibilities than either channel played alone. And now they're both there, by simply plugging into channel one and flipping the daisy chain switch! When you check the link, there's also a layout that shows exactly how to wire the switch. Had to change ground wiring on the Channel two input to make it work. Try it and have fun everyone!

Agreed very cool mod. The channels work nicely when blended

I prefer an A/B box though so I can switch on the fly.

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http://pdfelectronics.com

Doing by ABY pedal is my choice to, but a cool mod to put on a pul switch on the front perhaps.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps