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5F6A woes
A few years ago, I've had my tech build me a 5F6A with Alpha pots, Sprague caps, the works, down to spec, except for a solid-state rectifier and a somewhat cleaner output transformer with 4 and 8 ohm outputs. As he's usually very busy, and in the meantime I got quite handy with a soldering iron and a multimeter, I thought I'd give it a shot and try to solve these problems myself - with the help of your knowledge, that is. Here's the deal:
1) There's a popping noise whenever I stomp on a true-bypass pedal, and it doesn't happen with the same rig through a different amp (tube or solid-state). I've measured the input impedance, and it's missing 1M by a hair (997K), so this shouldn't be the problem. Any ideas?
2) I've rehoused the circuit in a nice pine open-back combo and, despite the popping, am loving it to death. But when I took it to its first gig rehoused this Saturday, something pretty weird happened. Halfway through a solo, the volume dropped, becoming barely audible, even with my ear glued to the speakers. All tubes were glowing, everything seemed to be right, just the volume was ridiculously low even with both channels jumpered and/or cranked. I messed with the controls a little, checked whether the tubes were securely placed, and suddenly it came back to life. 2 minutes later, it died again, so I grabbed a friend's HRD and made my way through the gig. I'm using two 30W Fender 10" AlNiCo blues, and although speakers lose some power on an open cab, I don't think that is the problem - I never had any issues before the rehousing.
Yesterday I took it to rehearsal, plugged it, let it warm up, played one song, and in the middle of the solo of the second one the same thing happened. I stopped playing, turned the controls up and down, got it to work again, but it stopped again 2 minutes later.
I'm pretty sure it might have something to do with either the vibration (as it is a combo now and wouldn't have any issues on a head/cab configuration) or the heat (the tubes were placed horizontally in the head, now they are vertically placed, upside-down). There is also the possibility of something coming loose during the rehousing. The tubes are tight in their places, so it must be something else. What should I be looking for?
Thanks a lot you guys. Please help a brother out. It's pretty frustrating to have a gorgeous-sounding amp for 3 minutes and then nothing.
-Gustavo
1) There's a popping noise whenever I stomp on a true-bypass pedal, and it doesn't happen with the same rig through a different amp (tube or solid-state). I've measured the input impedance, and it's missing 1M by a hair (997K), so this shouldn't be the problem. Any ideas?
2) I've rehoused the circuit in a nice pine open-back combo and, despite the popping, am loving it to death. But when I took it to its first gig rehoused this Saturday, something pretty weird happened. Halfway through a solo, the volume dropped, becoming barely audible, even with my ear glued to the speakers. All tubes were glowing, everything seemed to be right, just the volume was ridiculously low even with both channels jumpered and/or cranked. I messed with the controls a little, checked whether the tubes were securely placed, and suddenly it came back to life. 2 minutes later, it died again, so I grabbed a friend's HRD and made my way through the gig. I'm using two 30W Fender 10" AlNiCo blues, and although speakers lose some power on an open cab, I don't think that is the problem - I never had any issues before the rehousing.
Yesterday I took it to rehearsal, plugged it, let it warm up, played one song, and in the middle of the solo of the second one the same thing happened. I stopped playing, turned the controls up and down, got it to work again, but it stopped again 2 minutes later.
I'm pretty sure it might have something to do with either the vibration (as it is a combo now and wouldn't have any issues on a head/cab configuration) or the heat (the tubes were placed horizontally in the head, now they are vertically placed, upside-down). There is also the possibility of something coming loose during the rehousing. The tubes are tight in their places, so it must be something else. What should I be looking for?
Thanks a lot you guys. Please help a brother out. It's pretty frustrating to have a gorgeous-sounding amp for 3 minutes and then nothing.
-Gustavo
) and nothing happened. So I went to practice with it anyways, and decided to try the stupidest workaround possible: turning the amp upside-down. And, to my surprise, the thing worked for 3 hours straight, flawlessly. So I'll try to tighten up those tube sockets and see how that works out.
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