Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tricalibur on April 27, 2024, 02:47:34 pm
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Greetings, I'm posting this in a few different spots trying to find an answer.
I own a few Soldano heads and recently acquired a BAD SLO100 used. Sadly, it's experiencing some issues. Apologies for the long post, but I'm hoping to avoid the usual comments/solutions, as I've explored those already. Here we go:
The amp sounds great but has an intermittent issue that’s been tough to pin down. Occasionally, when first striking a chord on the Overdrive channel the amp will have a weak signal before the full tone comes through, making the signal go from rather weak to audibly being louder. Sometimes the signal will briefly shrink away during play, which is really distracting, and then come right back. However, confusingly, sometimes the amp seems to behave relatively normally with little intermittent weak signal issues.
I would prefer to use the amp with JJ 6L6 tubes, unfortunately when I switched to those it made the signal cutting out issue even worse. Worse still, it introduced a loud oscillation, making the amp virtually unplayable. I am capable of checking and adjusting the bias. I did so and it fell within nominal parameters with both stock 5881 tubes and the 6L6s.
I have attempted tube rolling the preamp tubes and different sets of 6L6 tubes, but to no avail. An observation I’ve made is that channel switching greatly affects the momentary signal loss which is only righted by immediately re-strumming a chord. Sustained notes across channel switching from clean to overdrive always results in signal loss. The issues are exclusive to the Overdrive channel with the clean/crunch behaving normally, so far as I can tell. I've used D3 in all switches and jacks, but the issue persists. Even with a footswitch plugged in, toggling the Bright switch and Clean/crunch switch has a tendency to trigger the signal loss. Shouldn't the presence of the footswitch bypass those issues all together?
I’ve had the amp in with a well known local amp builder and he isolated the signal loss to the first relay which handles channel switching. However, after replacing the relay, thinking it was bad or damaged, he was ultimately unable to fix the issue and was unsure of where the signal loss originates. He ruled out an bias issues in the preamp or a failed grid leak resistor.
As you can tell, I’m very disappointed and frustrated as it’s been a dream of mine to own an SLO100. BAD was relatively unhelpful and so I’m turning to whomever I can that might know more about this issue or hopefully find someone who has experience working on the new BAD builds. Are you able to recommend anyone who may be able to help? If this is not the right place to ask, can you recommend a forum or message board where I could post instead?
I have a Avenger and a Yamaha T100 as well. Both perform flawlessly although I tend to blow tubes a lot with the masters on 7! Thanks
I'll post the videos of this issue if need be.
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From your description of your problem I don't think many people can tell whats going on with your amp. This is primarily a vintage amp forum but common troubleshooting methods still apply. If the low signal problem is only with overdrive then your power amp is OK. Intermittent problems are either temp related or connection problems. Look for a bad joint or component and flex the board little -- I would poke and prod along the overdrive signal chain to see if you can cause the amp to fault or unfault and maybe localize the problem. The SLO 100 has been around for a while but I could not locate a "BAD" SLO schematic. Consensus is "Pre-BAD" is better but Im not sure what that means. You have tried tube substitution to no avail and you need to dive into the circuit. Please be careful. Here is the SLO schematic--follow the red outline for overdrive. Jim
https://robrobinette.com/How_the_Saldano_SLO-100_Works.htm
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Thanks for the info. Just trying to cover my bases. Alex from Science was the one who opened it up and inspected the board before replacing a relay. Unfortunately that wasn't the fix!
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Alex from Science was the one who opened it up and inspected the board before replacing a relay. Unfortunately that wasn't the fix!
Who is that?