(a bit OFF) Sugestions for a 20w build

[fhn_lopes]

Guys, this ain't about EVH only, but I'd like to hear some thoughts.

I'm planning to build a 1x12 combo with a pair of 6V6 tubes in push-pull. It's amazing how underated these tubes are... I think they BLOW el84's by far in tone and punch, but almost no comercial amp uses them! so I have to build my own

The idea is ti be as simple as possible, but with some features too. I thought of using 2 inputs to alternate between clean/crunch and overdrive modes (bypassing one stage). very simple to do, and keeping it single channel. Maybe add a metro loop too, but that's later.
Now I want to hear ya

ONe MV or two MVs? Lar Mar? PPIMV?
I'm firm with two gain pots, thinking of one after the second stage and another after the 3rd.

Now the tone:
I want a 3 stager marshall-ish amp, but more in a bogner/friedman way.... Think of early Jerry Cantrell tones... That gain and rawness.. Of course it's a small amp and woun't get the same punch. Clean mode would be a plexi-like gain and tonewise, and the 3rd stage kicks in a good boost for that metal tones... I want it to be a bit thighter than a normal plexi too...

What do you guys recomend me for rk/ck values for the 3 stages? I'm thiking of making the boost stage the 1st one, making it easier to bypass it for the clean/od inputs.

thought of doing something crazy like 5k/no cap 1st stage, 1uf/2k7 2nd stage and .68uf/820r 3rd stage...

any thoughts?

[fivecoyote]

Sorry cant help you technically, but agree about the tubes and think it's an awesome idea man!

[fhn_lopes]

Yes, I need a smaller amp for rehearsals and small gigs... 50w and a 4x12 can be too much sometimes...plus I want a modded marshall tone but don't want to mess with my amp.... it's sounding amazing as is... jus want a high gain tone in a small package

I'd go for a randall RD20 but they are expensive here and i would have to mod it still... so better build one

[fhn_lopes]

DEcided on the amp. Going to be 3 stages from the bogner triple giant preamp with a CF instead of a 4th stage and plate fed tonestack. Poweramp is coming later. I also added a second input jumping the first stage (still need a second pot or maybe a dual pot to control both 1st a and 2nd stages).
I messed up with the schem, wich is here https://fbcdn-sphotos-h-a.akamaihd.net/ ... f6cc8e5dc4.

I think the 2nd input isn't correct, but what do you think of the overall changes?

PS Original schem can be found here http://i45.tinypic.com/qqe1k9.jpg.

[fhn_lopes]

After a while I debugged the errors I could find and added a 12000-ish channel with a CF, sharing the tonestack ... The lead channel is a 4 stager non CF just like the sharp channel of the triple giant preamp.


Poweramp is going to be push-pull with 2x 6v6, my intention is to build this into a JTM45 chassis, 1x12 combo. Schem is here, what do you see? any other errors?

sharp channel schem rev 6.png

preamp

(166.51 KiB) Downloaded 1470 times

[gloeidraad]

A few things at first sight,there is no coupling between V3 and V4
Thecathode follower in the clean channel is not right, remove couplingcap and 1m resistor and make it direct coupled just like a standard marshall. Better switch the tone stack with a relais.
I think there are some other things.

Erik

[fhn_lopes]

Thanks Erik!! Just one question: Isn't the C13 (47n) coupling between V3 and V4? (this is the stock schem I found, i just pasted it there LOL)

I want both channels to share the tonestack, but I'm considering bypasing it for the clean channel, after all, my plexi is allways with controls dimed anyways LOL. Maybe just a treble control... Or maybe a switch lifting the tonestack for the clean channel, and leaving it there if I want to.


Fixed the CF, thanks!

EDIT: just noticed now that the original schem is feeding the grid at V4 with HT, even though there's a 330k resistor, I think it shouldn't be this way, right?

[gloeidraad]

There is no signal to V4. the couplingcap is connected to nothing only to ground via 330k resistor.

Erik

[gloeidraad]

And C13 is connected to B+, so i think the schema has some errors in it

I think the top of R23 must be connected to C13 and break the connection to B+

[fhn_lopes]

yup.... that shite is wrong, now I dunno if I keep this 3 stages or 4....

EDIT: found tha error, I messed the schem up when using paintbrush

The correct is 4 stages.

[jerrydyer]

I built a 2204 but used classic tone 18 watt PT and OT.. its the coolest amp ever,,,, and it couldnt have been easier ...the 6v6 is the coolest tube......

[fhn_lopes]

Looks lice a nice amp, Jerry! Can you share some gut shots??

Actually I'm after early AIC tones and I know Jerry Cantrell used that bogner modded marshall for the early records... And acording to what I have found, that amp is based on the triple giant sharp channel... I found the schem and wanted to build it in a small pack, 18w 6v6 in 1x12 combo. Of course, added a simple plexi bright channel to it to use as a clean/crunch channel

BTW, the correct schem is here.

sharp channel schem rev 6.png

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[OnTheFritz]

I built a 2204 but used classic tone 18 watt PT and OT.. its the coolest amp ever,,,, and it couldnt have been easier ...the 6v6 is the coolest tube......

Want to build something like this for a friend. Was thinking the same X-Formers, figured it would sound awesome.
Plan on a non-master which is what he wants. Can't wait to build and hear the organic tone with NOS tubes.

[fhn_lopes]

Doing some math now on the PS for the preamp, I think those 330k plate resistors for 2nd and 3 stages are way too much, unless that diode bridge recfier was a voltage doubler, which is not. 330k would perform more than 330V of voltage drop at the plate, almost all the voltage that the usual 250V@10mA preamp trannies can generate after the rectfier.... Probably something wrong there.... what do you guys think??


OnTheFritz, a non master JCM looks cool!! After all those doubts on this triple giant schem I'm thinking on going the JCM route....

[fhn_lopes]

After all that time I'm back with some news... I've drawn a Layout based on 2 schems... Lo input is a plexi-like 2 stager and hi input is that sharp channel from bogner triple giant preamp I've posted before. Poweramp and power supply came from Mark Huss 6V6 plexi schematic. Too lazy to drawn the schem now but here's the layout... It's my first time at this so it's a bit messy... can you guys see anything wrong??