Epiphone Blues Custom 30 Crackling

[Dannyboyee82]

Sorry, I stand corrected. He explained properly to me tonight. There isn't a transistor in sight, I must have misheard him on the phone. He meant capacitor. So he narrowed it down to one or two capacitors in the reverb stage that were causing the problem, but replaced all. As for the feedback, it was being caused by another capacitor in the reverb stage that was running low, as you cranked the reverb up it would begin to feedback. He said it wasn't noticeable on the 15w setting, but on the 30w you could only get away with setting the reverb half way before it began to feedback. I'd never use that much reverb anyway, but it's good to know it is no longer an issue.

 

It is down to cheap Chinese parts. He said that overall, the design of the amp is spot on. Going on to say that it's rare to find an amp these days without some kind of circuitry behind the valves. Marshall being one, that advertises amps as valve.. when in reality they only manage the amplification of the amp, everything else is done through transistors. I don't have a clue to be honest, these were his words.

 

Anyway, thank you again Carverman.. it has been interesting and a lesson to me.

[carverman]

Sorry' date=' I stand corrected. He explained properly to me tonight. There isn't a transistor in sight, I must have misheard him on the phone. He meant capacitor. So he narrowed it down to one or two capacitors in the reverb stage that were causing the problem, but replaced all. As for the feedback, it was being caused by another capacitor in the reverb stage that was running low, as you cranked the reverb up it would begin to feedback. He said it wasn't noticeable on the 15w setting, but on the 30w you could only get away with setting the reverb half way before it began to feedback. I'd never use that much reverb anyway, but it's good to know it is no longer an issue. [/quote']

 

Thats good to know. I also have a Belton spring reverb unit in my Peavey and so far it hasn't caused any problems.

 

 

It is down to cheap Chinese parts. He said that overall, the design of the amp is spot on. Going on to say that it's rare to find an amp these days without some kind of circuitry behind the valves.

Well that's good, cheap caps aside, I'm glad that the reverb pre-post 12ax7 in this amp are actually driving the springs.

 

Marshall being one, that advertises amps as valve.. when in reality they only manage the amplification of the amp, everything else is done through transistors. I don't have a clue to be honest, these were his words.

 

Some amps have solid state (SS) echo/reverb spring/reverb plate. etc digital signal processors (DSP)

instead of discrete reverb springs..this may be what he is refering to.

Because of the complexity of the circuits in these units, they have to use ICs or transistors

and that's understandable as these units need to be compact to fit inside a tube amp.

[jefrs]

Crackling from the BC30 is a problem I had and which I cured.

 

The BC30 is All-Valve, other than a couple of diodes on the heaters and foot-switch relays, no SS at all. No DSP and the reverb tank is on the wet side (to the point of sloshing around and spilling).

 

Problems traced to two areas -

 

1) dirty valve seats: remove and re-seat all the valves. Could be faulty valve - recommend swapping out the stock rectifier anyway.

 

2) a faulty standby switch arcing: far more serious - bypass and remove the cheap and nasty standby switch, it is not needed with a valve rectifier anyway (I put a master volume into the position of the switch - see other thread).

[carverman]

Crackling from the BC30 is a problem I had and which I cured.

 

2) a faulty standby switch arcing: far more serious - bypass and remove the cheap and nasty standby switch' date=' it is not needed with a valve rectifier anyway (I put a master volume into the position of the switch - see other thread).[/quote']

 

Makes sense. If it has a tube rectifier, the rectifier has to warm up before it can function as a rectifier

and that would allow the cathodes of the other tubes to warm up at the same time before

the B+ comes on., so in this particular amp the only purpose is Stndby if you have a

guitar plugged in and don't want to unplug it.

 

However in some amps like the Peavey Valveking with a SS rectifier, it has a more useful purpose.

It's better to allow the power tubes to warm up a bit before allowing the B+ on the plate.

[jefrs]

The standby switch should NEVER be used to silence the amp if you have a guitar plugged in and don't want to unplug it. This can cause "cathode poisoning", essentially a build-up of space-charge around the grids and then premature valve failure. Always pull the input jack back to short the input for silence, or just turn the volume knob to zero.

 

Amps with a SS rectifier either need the standby for heater warm-up or like some other Peavey jobs, they have a delay on the HT. Otherwise just turn them on with the volume off and wait - this is the way olden domestic appliances were done. The standby switch has become a fashion accessory.