So the day has come - my new GOTL arrived a few days ago, but first now I have been able to spend time with it.
This amp is totally different to what I am used to (Little Dot MKIII, Feliks Audio Elise and Euforia). It likes different tubes and tube combinations and headphones compared to the other amps, and it is so much more sensitive, like a tube magnifying glass.
If a tube isn't just perfect it will let you know. Loudly.
Started out with 6 x 6BX7. How do you figure out a bad tube among 7? In addition, when turning on the amp, there was a whole plethora of sounds that I did not hear before: pops, ticks, tinkling, howling and something that sounded like crumpling cellophane paper. And microphonics - just touching the volume knob sent the speakers into a tizzy....( Used a Tung Sol 6F8G as driver)
Oh my gosh, what did I get myself into? How can I find the offending tubes?
At first I just shook my head, then shut the thing off and went to sleep for the night. Yeah - that's the punishment for buying bargain lots of mixed tubes 6BX7 - GE, Philco (Sylvania) and RCA.
OK - next day: Time to try again. Looked over the tubes, checked for corrosion on the pins. And discovered that all of the 6BX7 tubes, no matter what brand, were made by GE. The sandblasted dots are the telltale signs.
Turned on the amp, and based on JV's advice, I just let it sit 20 minutes to warm up without headphones or speakers plugged in - the amp has to keep the pops and ticks to itself....
Turned it on with my $12 headphones plugged in. Just in case. Much more quiet, but not good. Used the balance control to confirm that the noise was in one channel. At least I just need to check out three instead of six tubes.
Tried tapping on the tubes and found one offender. Luckily, I have eight 6BX7, and put in a different one. Finally quiet. Until I touched the volume knob. Microphonics galore - must be the driver tube. Tapped on the driver tube - ouch! Tapped on the chassis, tapped on the volume knob - NYET. How can such a gorgeous looking tube misbehave?
Luckily I have another rebranded one (both are ladder plate, not RP). It did rattle, but I put it in, and no microphonics.
Finally, the GOTL showed what it can do - the best sound I have heard to date. Full bodied, great bass slam and very natural sounding - it just sounds right.
I am just getting used to the amp now. Decided on a very simple set up - a Sylvania 6SN7WGT and a pair of Cetron 6336B. Them big tubes get superhot - measured over 350F! Amazing that the chassis does not have any ventilation holes and only gets fairly warm but not hot with these tubes. As ugly as they are, I am using the socket savers to cool down the chassis (and I turned on my fan for the 6336s - the chassis is barely warm with the fan pulling away hot air).
This combination is totally silent at even loud normal listening levels and very little hum even at full tilt.
And here is today's question: How can I save the TS microphonic tube from the garbage heap? Any tricks to get rid of the microphonics? (The less expensive the better.) I read about high temperature silicon tube rings, but I'll rather buy them from a car parts shop than a Hi Fi web site - any suggestions? Or something else - heard about heat resistant silicone tape as well.
Have fun!
