Amped up
Well. I've been playing for a whole weekend now so I'm going to declare success on my amp surgery! :)
A few weeks ago I found a used Blackstar HT5R really cheap and got it. It's a big step up from my digital practice amp. Though at the volumes I like to practice at, the gain knob was still really fiddly without a lot of range. I'd already read that I could swap out the pre-amp tube and take away some of the top end crunch and give me more space at the bottom end, so I replaced the tube with a JJ 12AT7.
I started getting a buzzing noise at low gain when I turned it back on, so I swapped back to the other tube and tried again. Same issue. Next I tried reseating the power tube. Like a pro I managed to fold a pin on the power tube. This made the amp make a thumpy tremolo sound when I turned it back on (basically one side of the push pull was no longer getting power) It also made the tube fantastically hot. So I shut it down, let the tube cool and pulled it, discovered the folded pin aaaaand snapped it off.
Called frantically and found a shop still open at 6PM on a Friday that had two old tubes that would work in place of the one I broke and amazingly only wanted $6 each for them. Got them, biased the power tube (measured a voltage and adjusted a pot) and... No more buzz and a much more warm and bluesy sort of sound. Hurray! And what's more, the combination of the JJ pre-amp tube and an old Westinghouse 12BH7A ended up sounding really good together. Granted, I'm only at about 10hrs of play time so far but nothing is unduly hot or changing tone in undesired ways.
Also, I have to say. While this is the first amp I've ever taken apart, I really really like the construction. It was made to be monkeyed with. The head is a completely discrete unit inside the combo box. You could lift it out, add a cover to it, and have a head and separate cabinet with no other modifications. The board layouts and wiring are all beautifully clean.
A few weeks ago I found a used Blackstar HT5R really cheap and got it. It's a big step up from my digital practice amp. Though at the volumes I like to practice at, the gain knob was still really fiddly without a lot of range. I'd already read that I could swap out the pre-amp tube and take away some of the top end crunch and give me more space at the bottom end, so I replaced the tube with a JJ 12AT7.
I started getting a buzzing noise at low gain when I turned it back on, so I swapped back to the other tube and tried again. Same issue. Next I tried reseating the power tube. Like a pro I managed to fold a pin on the power tube. This made the amp make a thumpy tremolo sound when I turned it back on (basically one side of the push pull was no longer getting power) It also made the tube fantastically hot. So I shut it down, let the tube cool and pulled it, discovered the folded pin aaaaand snapped it off.
Called frantically and found a shop still open at 6PM on a Friday that had two old tubes that would work in place of the one I broke and amazingly only wanted $6 each for them. Got them, biased the power tube (measured a voltage and adjusted a pot) and... No more buzz and a much more warm and bluesy sort of sound. Hurray! And what's more, the combination of the JJ pre-amp tube and an old Westinghouse 12BH7A ended up sounding really good together. Granted, I'm only at about 10hrs of play time so far but nothing is unduly hot or changing tone in undesired ways.
Also, I have to say. While this is the first amp I've ever taken apart, I really really like the construction. It was made to be monkeyed with. The head is a completely discrete unit inside the combo box. You could lift it out, add a cover to it, and have a head and separate cabinet with no other modifications. The board layouts and wiring are all beautifully clean.