Was wondering what you guys were using for tubes and speakers. Are these Expression Amps anymore sensitive to tubes than a Fender or Marshall?  We played ours for the first time. And when we got the volume past half way things got bad. No more gain or volume. The tone gets muddy and there is a kind of high pitched, swirly kind of noise. Have never really heard this before. Not a micro phonic tube, it is much different than that. I guess oscillation is a possibility. But the lead dress and workmanship on this amp seem so well done that I do not think that could be it. I suppose preamp tubes would be the easiest place to start. Perhaps I will just go through them one by one. Any of you other guys hear this when you get your Expression opened up?
Thank You

I get the same kind of noise when mine is driven. The better output tubes lessen it and I did try some Mullards that removed it alltogether. But I'm now running Siemens and like them best.
I'm going to try input tubes and then try moving wires around, something may be crossing something that shouldn't.
Please post if you find a remedy.

I recently built my TW Express and it is really a fire breathing monster!
Have experimented with several tube sets including: 6v6, 6CA7 and EL34s.

Judging from the TW clips on YouTube, the original TW cleaned up amazingly and could go from clean to insane with the swell of one's guitar volume. The main problem with the TW Express by default is that it is way over gained, there is no possibility of cleaning up or dialing in any workable tone past volume one (7:00). I would seriously bring this to Nik's attention however I have never played through an original TW and Nik is god in some circles

Here is an original 1989 TW:

I was a little discouraged until I experimented with several preamp tube configurations I have found something that is more versatile from liquid lead to clean. Try using a Tung Sol 12ax7 in V1 and an EH12AT7 in V2. This brought down the gain by 40%. You can further reduce the gain using 12AU7. Check out: http://thetubestore.com/gainfactor.html  The newly designed TungSol 12ax7 have no discernable microphonics! You can tap the EH or JJ 12ax7 and hear how microphonic they really are.


In my experience, I'd further recommend humbuckers as single coils don't drive the TW that well.

Having built the TW I later installed the PVIMV Type II, I personally like the sound of the 6CA7 biased at 40ma. They have a lot more bottom than the EL34s and sound great through my Marshall 4x12 with greenbacks. This is indeed TW nirvana.