Speaker config - advice

Darren

I have an old white Marshall 800 4x12 cab from around 82 which originally housed G12-65 speakers (which I still own) My main amp is a JMP2203 from 1980 which I love, but I find the 65's can be a little overwhelming in the low end when I play straight in (no pedals engaged)

I decided to swap out the bottom two for 2x Vintage 30's - that did help tighten up a little. I then tried 2x G12m25's on the top with the V30's - the low end is much better now but I notice this fizziness in the tone and the high end is quite brittle to the point where I have really dialled back the presence and treble on the 2203 but still can hear this fizziness.

I don't play quiet - I'm able to get the master volume to 3-3.5 at home.

Would that be from the 25's or am I hearing more of the V30's now?

Also would a 65 (bottom) 25 (top) be a good combination?

Thanks,

Darren

ICBM

G12M-25s in a single 4x12" with a 2203 is not a good idea if you're not playing quietly.

If you didn't notice the fizz before and you do now, it's the 25s. They can do that, especially if they're not broken in yet.

Personally I have no idea why you'd find G12-65 have too much bottom end though, I would probably run that amp and cab with the bass up full... I assume you're running it at zero?

Darren

ICBM said:

G12M-25s in a single 4x12" with a 2203 is not a good idea if you're not playing quietly.

If you didn't notice the fizz before and you do now, it's the 25s. They can do that, especially if they're not broken in yet.

Personally I have no idea why you'd find G12-65 have too much bottom end though, I would probably run that amp and cab with the bass up full... I assume you're running it at zero?

I bought the 25s recently - seller said they were approx. 7 years old, absolute mint condition. Not 100% sure if they are broken in as they look like they have had very little to no use really.

When I'm using my SD-1 up front I find the 65s great as the pedal tightens it all up.. It's more when I play the amp with no pedals engaged I find the low end to be a little much. My settings are Pres (4) Bass (4) Mid (6) Treb (6) Preamp (6)

Maybe a trip to the doctors for my ears to be syringed will help!!

ICBM

Turn the bass to 0 and then see if there’s still too much before you do anything else. If that doesn’t fix it, turn the mid up full. If that *still* doesn’t fix it, turn the treble up a bit and the presence down if necessary. If that’s still no good... maybe you need different speakers.

But G12-65s are the best speakers ever made to go with a 2203.

PolarityMan

Im never sure about mixing speakers....which one are you going to put the mic on? Well why not just use 4 of that one?

ICBM

PolarityMan said:

Im never sure about mixing speakers....which one are you going to put the mic on? Well why not just use 4 of that one?

It gives you the options, as well as a better sound from the whole cab on stage.

Darren

ICBM said:

Turn the bass to 0 and then see if there’s still too much before you do anything else. If that doesn’t fix it, turn the mid up full. If that *still* doesn’t fix it, turn the treble up a bit and the presence down if necessary. If that’s still no good... maybe you need different speakers.

But G12-65s are the best speakers ever made to go with a 2203.

Thank you for the tip @ICBM - I should also add which I forgot to mention in my initial post is that I removed the bright cap over the preamp pot a few years back. At the time I preferred the amp without it, I can't remember the value of it and I don't think I have it anymore?

PolarityMan said:

Im never sure about mixing speakers....which one are you going to put the mic on? Well why not just use 4 of that one?

I know what you mean.. I don't play live or record to be honest, just a home hack.

ICBM

Darren said:

Thank you for the tip @ICBM - I should also add which I forgot to mention in my initial post is that I removed the bright cap over the preamp pot a few years back. At the time I preferred the amp without it, I can't remember the value of it and I don't think I have it anymore?

500pF (470pf in New Money ). Put it back, they very much do need it and the amp will definitely be too bassy without it.

Tip - when you remove a bright cap, only undo one side of it. That will take it out of the circuit just as effectively, and you can put it back more easily .

Darren

@ICBM I found the original bright cap that was in there, it's a 1000pf. By the value I'm guessing is why I originally found the amp too bright a few years ago and took it out.

Good friend of mine is sending me a 470pf to try. I've also reinstalled the 65s ready for when the new cap arrives. 

ICBM

Yes, my mistake - the one on the resistor is 470pF, the one on the pot is 1000. 470 is still better on the pot.

Modulus_Amps

If it is still not tight enough try changing the first coupling cap to 0.0022uf - 0.0047uf, that will make it tighter.