Cascaded or Non Cascaded - 1977 JMP 2204

[Fish17]

I’ve read conflicting information on when Marshall switched to cascaded preamp designs. I’m about to pull the trigger on a buddies 1977 JMP 2204 (3/1977) but I want to confirm it is the cascaded design. See below gut shots thanks in advance for everyone’s help.

Also what I’m I looking for future reference?

Anything else interesting you can tell me by these photos related to mods/changes?

 

[Purgasound]

That's the non-cascaded version. There's been some other work done, can't quite make out what the mods are but doesn't look extensive.
They're easy enough to convert to a cascaded circuit.

 

[Fish17]

That's the non-cascaded version. There's been some other work done, can't quite make out what the mods are but doesn't look extensive.
They're easy enough to convert to a cascaded circuit.

Thanks man for the prompt response.

Where is it on the board and what do I look to know the difference? I’m on the hunt for a 2204.

I want the cascade to get extra pre-amp saturation. I’m sure I can get it modded but that’s extra costs.

 

[Trouble Free]

The early 77 amps weren't cascaded. You get an extra gain stage when it is..... Also if it were the later cascaded version it wouldn't have this extra capacitor at the end.

 

[Trouble Free]

On the cascaded version you would also see a cap and resistor going from the input jacks to the first pot.

 

[Fish17]

On the cascaded version you would also see a cap and resistor going from the input jacks to the first pot.




View attachment 158714

Thank you man this SUPER helpful! This community is the best.

 

[Fish17]

There’s an early 1978 locally (4/78) but he won’t open it up so I’m not sure what the guts look like. Gotta drive 1 hour to see the inside. However it for sure will be cascaded since it’s a 78and it has the lower voltage tranny. Perhaps it has the mustard caps as well but most likely it will be chicklet caps.

 

[Fish17]

The search goes on this early 1977 is not what I’m looking for has the Mullard mustard caps and the lower voltage tranny but missing the cascade. I was paying a premium but now that it would need some work I’m walking away.

 

[Fish17]

On the cascaded version you would also see a cap and resistor going from the input jacks to the first pot.




View attachment 158714

The search goes on this early 1977 is not what I’m looking for has the Mullard mustard caps and the lower voltage tranny but missing the cascade. I was paying a premium but now that it would need some work I’m walking away.

There’s an early 1978 locally (4/78) but he won’t open it up so I’m not sure what the guts look like. Gotta drive 1 hour to see the inside. Its stock from the outside Daly caps, for sure will be cascaded since it’s a 78 however, and it has the lower voltage tranny. Perhaps it has the mustard caps as well but most likely it will be chicklet caps.

 

[dtier]

It may be a hard find as it seems they ran out of .022uf mustard caps about the same time that they came up with the cascaded gain. My '77 has the cascaded gain and the green .022s.

 

[Fish17]

It may be a hard find as it seems they ran out of .022uf mustard caps about the same time that they came up with the cascaded gain. My '77 has the cascaded gain and the green .022s.

They do exist Johan Segeborn on YouTube has a 1977 with a cascade gain but he may have modded it. I can’t tell from his photos what month it was.

 

[dtier]

They do exist Johan Segeborn on YouTube has a 1977 with a cascade gain but he may have modded it. I can’t tell from his photos what month it was.

@Trouble Free posted pic shows one as well so indeed they do exist. Mine is a USA model, perhaps that is a factor.

 

[Purgasound]

As far as the capacitors go, there's really not a discernable difference in sound between the capacitor types. Those little green Chiclets and Lego block looking ones don't look as cool but they are doing the same job as the mustards and are less likely to develop any DC leakage problems.
I like the higher voltage transformer versions personally.
Cheers