Question for Sluckey

[kagliostro]

Hi Steve

I have this pdf file from your inventiveness

Marshall_Dual_800_2204_PDF

and I need a little clarification about the junction you labeled "Maybe???"

Thanks

Franco

[sluckey]

The two channels are mixed together using that 470K resistor referenced by NOTE 5 on the schematic. The dark red jumper is used in this case. But if that 470K is not needed, install the silver jumper to short out the 470K. Just leave the dark red jumper and the 470K on the board.

[kagliostro]

Thanks Steve

If I understand correctly

if the action of the 470k resistor is necessary

the red jumper and obviously the resistor are on the board

but if the action of the 470k resistor isn't necessary

the red jumper and the 470k resistor can be on the board and is sufficient to add the silver jumper

---

One clarification

the silver jumper is only the horizontal portion
and the other piece (near vertical) on the right of the silver junction on the layout
is present in every way

Correct ?

Grazie

Franco

[sluckey]

the silver jumper is only the horizontal portion
and the other piece (near vertical) on the right of the silver junction on the layout
is present in every way

Correct ?

Yes, that's correct.

You may be more interested in this updated layout for a complete amp, rather than just the preamps...
http://home.comcast.net/~seluckey/amps/misc/Marshall_Dual_50.pdf

[kagliostro]

Grazie Steve

for the answer and for the schematic but .......... no   

The interest is about the preamp

A friend asked for something to build with less W than a 2204 but like a 2204, so my proposal for him was your double preamp and for PA the PA of your Stuffed Vox with a pair of el84 final tubes 

for those who do not know your labors (people if you have never seen before, give a look here  )
http://home.comcast.net/~seluckey/amps/vox/Vox.pdf



and ..... as we are here ..... what do you think about this mix ?

Franco

[sluckey]

and ..... as we are here ..... what do you think about this mix ?

Great minds think alike. That's exactly why I designed that layout. Still haven't actually done it yet though.

[kagliostro]

You are too kind

Franco

[sluckey]

I knew I had an updated preamp only version. Finally found it. This version shows a single input jack and a DPDT Channel select switch. The physical layout of the Plexi and 2204 preamp circuits has been changed, resulting in better (IMO) wiring between board, control panel, and tubes. You may prefer this version...

[kagliostro]

Many thanks my friend 

K

[Ed_Chambley]

I knew I had an updated preamp only version. Finally found it. This version shows a single input jack and a DPDT Channel select switch. The physical layout of the Plexi and 2204 preamp circuits has been changed, resulting in better (IMO) wiring between board, control panel, and tubes. You may prefer this version...

Very cool, as I have not seen this.  What PT would you suggest for this preamp?  Would a fender reverb tranny do it?

[sluckey]

I would use a 275-0 with a bridge or 275-0-275 with conventional full wave diodes. Don't need much current. I'd be shooting for about 375VDC at the first cap, then small Fender choke, cap, resistor, cap, resistor, cap.