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I have a Kalamazoo Model 1 that's giving me some problems I hope you guys can help me suss out.
The cabinet disintegrated years ago, now it's just a head and I've modded it to suit my tastes. It sounds - when working properly - infinitely better than it did stock.
I decided that I wanted to try the Herzog line out with it, so I installed it on a piece of angle aluminum attached to the chassis. I never even got to hear how it sounded before the amp started its current weirdness. The Herzog circuit appears to have pushed something beyond its limit into quasi-failure mode. The Herzog circuit itself seems to be working fine. And I have tried disconnecting it from the amp - the odd behavior persists.
So when I turn the amp on it works fine at low volume. When I hit it hard it seems a little distorted but it always was a bit of a hothead. But then when I turn it up louder it gets a static-ey kind of distortion like something not making good contact. And then when I turn it up yet louder and hit a chord it will clamp down and completely kill the signal ... which then, if I stop playing, will return after 10-30 seconds, fading in, taking maybe a second to come to full strength.
That sounds like it could be related to the power supply electrolytics. But they appear healthy enough. There is no inordinate hum. I replaced the caps twenty years ago with 30 uF caps (all I could get locally). The amp hasn't been played all that much. I doubt it's the caps.
I cleaned all the tube sockets with contact cleaner, and tightened the contacts on the first tube. I tried replacing the preamp and power tubes (I don't have a spare rectifier tube). I went through and checked all the resistors and replaced two of the remaining original caps (the R9 330 K cap read 7.8 K!). I've replaced all of the original caps. I checked all the solder joints and re-melted most, if not all, of them.
I've hit a wall. I can't think of anything else to try. Could this be an OT problem? There is a bit of a hot smell that I can't recall noticing before. The transformer looks normal.
http://www.rru.com/~meo/Guitar/Amps/.../M1/schem.html
The cabinet disintegrated years ago, now it's just a head and I've modded it to suit my tastes. It sounds - when working properly - infinitely better than it did stock.
I decided that I wanted to try the Herzog line out with it, so I installed it on a piece of angle aluminum attached to the chassis. I never even got to hear how it sounded before the amp started its current weirdness. The Herzog circuit appears to have pushed something beyond its limit into quasi-failure mode. The Herzog circuit itself seems to be working fine. And I have tried disconnecting it from the amp - the odd behavior persists.
So when I turn the amp on it works fine at low volume. When I hit it hard it seems a little distorted but it always was a bit of a hothead. But then when I turn it up louder it gets a static-ey kind of distortion like something not making good contact. And then when I turn it up yet louder and hit a chord it will clamp down and completely kill the signal ... which then, if I stop playing, will return after 10-30 seconds, fading in, taking maybe a second to come to full strength.
That sounds like it could be related to the power supply electrolytics. But they appear healthy enough. There is no inordinate hum. I replaced the caps twenty years ago with 30 uF caps (all I could get locally). The amp hasn't been played all that much. I doubt it's the caps.
I cleaned all the tube sockets with contact cleaner, and tightened the contacts on the first tube. I tried replacing the preamp and power tubes (I don't have a spare rectifier tube). I went through and checked all the resistors and replaced two of the remaining original caps (the R9 330 K cap read 7.8 K!). I've replaced all of the original caps. I checked all the solder joints and re-melted most, if not all, of them.
I've hit a wall. I can't think of anything else to try. Could this be an OT problem? There is a bit of a hot smell that I can't recall noticing before. The transformer looks normal.
http://www.rru.com/~meo/Guitar/Amps/.../M1/schem.html
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