SV20C plugged in without speaker load :(

Baldy1979

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Just bought an SV20C amp from a friend and I accidentally hooked up a TwoNotes Torpedo Captor X attenuator to it incorrectly and took it off standby without a load attached to the speaker output.

I connected the SV20C effects loop send to the attenuators speaker input, then the attenuators speaker output to the speaker.

SV20C effects loop send --> Attenuator speaker in, attenuator speaker out --> speaker

I took it off standby and put it on High mode and and strummed but wasn't getting any output so I increased the amp volume almost to 80/90% until I heard a really faint guitar signal coming from the speaker. Then I turned it off and checked the connections and realized my error :( Total amount of time that it was powered up off standby and strumming was maybe 2 minutes.

My question is since the guitar signal was being routed out through the effects loop send and bypassed the power-amp section could this have done any damage to the output transformer or any other components in the amp?

Any feedback would be greatly appreciated!
 

PelliX

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Welcome to the forum!

My question is since the guitar signal was being routed out through the effects loop send and bypassed the power-amp section could this have done any damage to the output transformer or any other components in the amp?

Yes, cranking a valve amp without a load can kill your output transformer (and more, but mainly the transformer). Sending your FX loop into the attenuator seems safe to me, at least, I can't see anything getting hurt.

What about the amp, though? With a speaker attached, does it work? That's the question.

EDIT: Come to think of it, you might be lucky in that you were sending signal to the FX loop, but presumably the FX return was empty. That means the power stage would have been 'more or less' idle the whole time. Not good for an amp, but still.
 
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Old Punker

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Just bought an SV20C amp from a friend and I accidentally hooked up a TwoNotes Torpedo Captor X attenuator to it incorrectly and took it off standby without a load attached to the speaker output.

I connected the SV20C effects loop send to the attenuators speaker input, then the attenuators speaker output to the speaker.

SV20C effects loop send --> Attenuator speaker in, attenuator speaker out --> speaker

I took it off standby and put it on High mode and and strummed but wasn't getting any output so I increased the amp volume almost to 80/90% until I heard a really faint guitar signal coming from the speaker. Then I turned it off and checked the connections and realized my error :( Total amount of time that it was powered up off standby and strumming was maybe 2 minutes.

My question is since the guitar signal was being routed out through the effects loop send and bypassed the power-amp section could this have done any damage to the output transformer or any other components in the amp?

Any feedback would be greatly appreciated!

As @PelliX suggested with your SV20C shut down, disconnect it from your attenuator and connect a speaker to your amp, power up and see if your amp works. You may have dodged a bullet because there was no input signal to the SV20C's output stage. I once accidentally powered on a small amp w/o a speaker attached and it was fine. Like you, I had no input signal going through it.
 

V-man

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The biggest Enemy of a load-less valve amp is volume. As a rule, never do it, but an impedance mismatch/load-less switch on occurring will be far more likely to blow an amp at higher volumes than it ever would at low-0 volume.

if you have something like a captor or switch heads with cabs a lot, the smart rule is to flip the volume down to zero and slowly bring the volume up each time you power on/off. That way you’ll know you forgot to attach the speaker by/before volume 2, and can hit standby immediately to rectify the issue.
 

marshallmellowed

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If the amp is still working, you're good, play on and remember to check things carefully next time. Some colored tape can help with plugging things into the right place. The fact that you had the signal routed out via the FX Loop is a good thing, as the power amp was basically sitting idle, even though you cranked the volume up.
 

PelliX

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if you have something like a captor or switch heads with cabs a lot, the smart rule is to flip the volume down to zero and slowly bring the volume up each time you power on/off. That way you’ll know you forgot to attach the speaker by/before volume 2, and can hit standby immediately to rectify the issue.

Power? That's what the standby switch is for - standing by while you plug in more cabs... :D
 

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