Help! Looking schem for 2 channel JCM800 type with channel switching

[Backwoods Joe]

Sorry I can't remember the name of the schematic, but someone on this board has a schem for a 2 channel JCM800 type with channel switching that is tried & true. THX,  joe

[sluckey]

Are you maybe referring to my Marshall Dual 50? Look in Hoffman's schematic library.

[Backwoods Joe]

Sluckey the schematic i'm thinking about has a master vol for each channel

[sluckey]

I seem to remember that. I think each channel also had it's own tone stack? I don't recall the particular thread though. But if it was on this forum you should be able to find it using the search button.

[Backwoods Joe]

Yea it was two complete separate channels & it used relays (for & aft) for switching.

[VMS]

I found this thread but this one has shared tone stack so not sure if its the one you were looking:


http://el34world.com/Forum/index.php?topic=24600.0

[tubenit]

I simply modified Sluckey's Dual Marshall so each side has it's own tone stack.  On the attached SCH file there is a second page with the B+ rail, bias and PT.  I haven't built it but see no reason why it shouldn't work well.

With respect, Tubenit

[Auke Jolman]

Hi All,

Looking at the schematic Tubenit shared with us, I wonder if it would be possible to switch between the 2 preamps right after the CF and eliminate V4?

[tubenit]

Sluckey's dual plexi does that very thing.  However, the original poster was wanting two channels with each having a tone stack. 

With respect, Tubenit

[Auke Jolman]

Hi Tubenit,

I think I messed up with what I wanted to ask. Therefore here's a schematic (quick and dirty) with my idea.

[sluckey]

The switch connected to the cathode will have big DC voltage on it.

[Auke Jolman]

Thanks Sluckey, now it makes sense to not do it that way!

[VMS]

Hi All,

Looking at the schematic Tubenit shared with us, I wonder if it would be possible to switch between the 2 preamps right after the CF and eliminate V4?

That cf can drive multiple tone stacks, you can do it like this. Similar to JVM models.


https://el34world.com/charts/Schematics/files/Marshall/Marshall_jvm410_sch.pdf

[DummyLoad]

concept - dual 2004/1987 circuits with separate preamps all the way to the LTPI.

from the LTPI to output stage it is essentially the same circuits for both models. UL output depicted. 

a complex build for sure and not one for a novice builder. no layout provided - meld from the many existing layouts. respectfully, if you can't create your own layout, then probably something you shouldn't tackle. 


--pete