lonestar classic 212 tweed setting issue?
- Thread starter jcd
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It is something that just started happening, it is a almost complete loss of sound, ONLY on the clean channel -the drive channel on the tweed mode is fine- definitely not designed to do that and just started happening - also, the amp has a lot of chassis and tube rattle- even for a combo - the amp is only 2 months old- I hope I made a good decision!!
Mine does this as well, but only in my house -- it worked fine in the shop when I picked it up. Oddly, it works fine until I switch channels, then when I switch back it loses almost all of the sound (it's still faintly there). The high-power setting works fine, so I've just been using that.
I thought this might have been related to the known issue where Russian 12AX7s can't handle the low filament voltages associated with the Tweed power setting, so I swapped the one Russian tube that the amp shipped with for a Chinese tube, but it didn't solve the problem. Changing one tube doesn't rule this out as the problem (I haven't had a chance to do much work on this :?), so you might check into this.
Another possibility is that this is due to low wall voltage -- I checked it the other day when I noticed the problem, and it was only about 113 volts. The manual says that the LSC wants 117. The relays that handle the circuit rerouting for the channel switching need a certain amount of voltage to trigger, so if the voltage is too low, it might not work quite right. Something else to check, anyway.
Now you've got this bugging me again :lol: -- I'm going to go see if I can figure anything else out. If I find anything, I'll make another post here.
P.S. With regard to chassis rattle, try tightening the four screws on top of the cabinet that hold the chassis in place. Just for good measure, it won't hurt anything to tighten any other screws around the cabinet as well (as long as you don't overtighten them, anyway), and that will probably fix it.
Tube rattle can be a fact of life with combos; the backwave from the speakers hammers the tubes pretty hard. On the upside, I've never seen it affect the operation of the amp, and it usually goes away with the next set of tubes. Sometimes it's the little retaining clamps that go around the bases of the power tubes that do this, in this case you can often get rid of the rattle by gently bending the clamp away from the tube slightly. I tend to prefer the spring retainers with the 'hats' that go over the top of the tube, as they're a little more foolproof, but I've never installed any on an amp with PCB-mounted power tube sockets, so I don't know if they would add stress to the board inside. Maybe someone else has some insight here?
I thought this might have been related to the known issue where Russian 12AX7s can't handle the low filament voltages associated with the Tweed power setting, so I swapped the one Russian tube that the amp shipped with for a Chinese tube, but it didn't solve the problem. Changing one tube doesn't rule this out as the problem (I haven't had a chance to do much work on this :?), so you might check into this.
Another possibility is that this is due to low wall voltage -- I checked it the other day when I noticed the problem, and it was only about 113 volts. The manual says that the LSC wants 117. The relays that handle the circuit rerouting for the channel switching need a certain amount of voltage to trigger, so if the voltage is too low, it might not work quite right. Something else to check, anyway.
Now you've got this bugging me again :lol: -- I'm going to go see if I can figure anything else out. If I find anything, I'll make another post here.
P.S. With regard to chassis rattle, try tightening the four screws on top of the cabinet that hold the chassis in place. Just for good measure, it won't hurt anything to tighten any other screws around the cabinet as well (as long as you don't overtighten them, anyway), and that will probably fix it.
Tube rattle can be a fact of life with combos; the backwave from the speakers hammers the tubes pretty hard. On the upside, I've never seen it affect the operation of the amp, and it usually goes away with the next set of tubes. Sometimes it's the little retaining clamps that go around the bases of the power tubes that do this, in this case you can often get rid of the rattle by gently bending the clamp away from the tube slightly. I tend to prefer the spring retainers with the 'hats' that go over the top of the tube, as they're a little more foolproof, but I've never installed any on an amp with PCB-mounted power tube sockets, so I don't know if they would add stress to the board inside. Maybe someone else has some insight here?
guitar-norm
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I had this problem...it was a loose rectifier tube. I just pushed it back in and it fixed the problem. Yours might be loose or bad.
Hmm -- I have a spare 5U4, so I'm going to try this tonight. It doesn't seem intuitively like it should be a problem with the rectifier, as it happens regardless of whether the rectification is set to tube or diode, but I don't know the circuit well enough to rule it out.
I did some testing yesterday, and it does seem to be a switching problem. If I turn the amp on in normal mode, then switch to tweed, channel 1 works fine until I switch, then it doesn't. I can then turn the amp off and do something else for half a day, come back, and turn it on in tweed mode, and channel 1 still won't work (but channel 2 is still fine). But, if I switch to normal mode for a second, then back to tweed, channel 1 is fine until I switch again.
I did some testing yesterday, and it does seem to be a switching problem. If I turn the amp on in normal mode, then switch to tweed, channel 1 works fine until I switch, then it doesn't. I can then turn the amp off and do something else for half a day, come back, and turn it on in tweed mode, and channel 1 still won't work (but channel 2 is still fine). But, if I switch to normal mode for a second, then back to tweed, channel 1 is fine until I switch again.
