Stock power tubes for a 4210 in 1987?

[marshallmel]

Just grabbed a 1987 4210 combo and it doesn’t sound the greatest. I know the earlier ones for the US market came stock with 6550’s but around 86 I believe they went back to EL34’s. This one has 6550’s but the retainers are bent out like someone tried to force them which leads me to believe they were changed at some point. I’m wondering if they just shoved them in there without changing anything? It’s unusual because the amp sounds dark and scooped. Speaker is the stock G12M-70 that sucks.

 

[ChurchHill]

Could be, not sure exactly when they switched back, but think it was around that time. The retainers probably weren't changed just for the US market, or they could've been replaced at some point during the amp's life.

I'd start by checking the bias. That could be off, anyway, and would effect the sound even if is setup for 6550s. There's only one or two resistors in the bias circuit that would need to be changed and that's only if you can't get it to bias correctly.

Edit: At least I think the above is right off the top of my head. If you don't know how to check the bias, take it to someone who does. It is worth it and needed to keep the amp sounding its best.

 

[marshallmel]

Could be, not sure exactly when they switched back, but think it was around that time. The retainers probably weren't changed just for the US market, or they could've been replaced at some point during the amp's life.

I'd start by checking the bias. That could be off, anyway, and would effect the sound even if is setup for 6550s. There's only one or two resistors in the bias circuit that would need to be changed and that's only if you can't get it to bias correctly.

Edit: At least I think the above is right off the top of my head. If you don't know how to check the bias, take it to someone who does. It is worth it and needed to keep the amp sounding its best.

I’ll be taking it to my guy on Monday. I like to give him a starting point on where to look. Thanks for the reply.

 

[ChurchHill]

Cool. It may need a cap job if the electrolytics haven't been replaced, but that's pretty standard for an amp that age. I've got a 2205, same amp just the head version. Very different from a 2204/2203, but still very much a great Marshall. Hope you enjoy yours as much as I do mine!

 

[fusedbrain]

2205/2210 2 channel jcm 800's never came stock with 6550's as far as I know.
The reason that the tube retainers are bent out is that you do not want to ground the metal base of some 6550 tubes, or your gonna have issues.

Get your tech to load it up with El34's and bias it properly, and make sure the bias feed resistors @ the phase inverter are the correct value. ( 220k )
There might have been a resistor change, or a parallel resistor added in the bias circuit, in order to bias the 6550's, but your tech should pick that up and sort it out.
And put a proper speaker in there.
Those g12m 70's are crap.
I wouldn't pass judgment on the amp until its loaded with the right tubes, biased properly and played through a decent sounding cab with Greenbacks, V30’s or 65's.

Edit: yeah, a cap job would probably be a good idea too, while its at the shop

 

[napalmdeath]

2205/2210 2 channel jcm 800's never came stock with 6550's as far as I know.
The reason that the tube retainers are bent out is that you do not want to ground the metal base of some 6550 tubes, or your gonna have issues.

Get your tech to load it up with El34's and bias it properly, and make sure the bias feed resistors @ the phase inverter are the correct value. ( 220k )
There might have been a resistor change, or a parallel resistor added in the bias circuit, in order to bias the 6550's, but your tech should pick that up and sort it out.
And put a proper speaker in there.
Those g12m 70's are crap.
I wouldn't pass judgment on the amp until its loaded with the right tubes, biased properly and played through a decent sounding cab with Greenbacks, V30’s or 65's.

Edit: yeah, a cap job would probably be a good idea too, while its at the shop

Yeah, those were definitely EL34's stock. I had a 2205 myself. Bought it used on TGP about 20 years ago. Had old school real Svetlanas before they were =C=. Amp sounded fantastic.