Marsha.

[JakeFuzz]

Been working on this one for quite a while. I noticed Juan had a similar project going and I think his graphics are a little better than mine .

This is a full voltage tube pre-amp modeled after the Marshall 1959 and 1987 plexi amps. This is the normal channel input which I am now thinking is a mistake and will probably start transitioning back to the bright channel. I am getting a little oscillation at high gain so I am going to put the 47pf cap from plate to cathode in on the last gain stage to see if that helps. Sounds very Marshally and dark (stupid normal channel). PTP wiring is probably the ugliest and biggest PITA style I have seen. I included a phase inverter approximation using the last half of a tube by running the tonestack into a typical 12ax7 gain stage. I may need to tweak around with those values as well. Uses all parts from Weber including their 12VAC to 260VAC transformer. The first half of the amp runs at 350V and the second half of the amp at 380V (at the top of the plate resistors). The heaters are run in series by a 12 volt regulator (hoffman amps). There is slightly less filtering than the actual 1959 because I couldn't fit anymore capacitors inside this enclosure! Knobs will be switched out to the Marshall brass knobs on my next SB order. Enjoy!

[jtn191]

woa 

looks like my last sunking but with mucho mucho mojo!
I'm subscribing just in case ya want to share some sound clips & schems/layouts

[JakeFuzz]

Haha, thanks. Definitely sound clips to come when I can get it sounding the way I want it to. The sound is there it just needs a little tweaking. I am not sure about layouts though. I can certainly make a layout for the power supply, but the PTP wiring itself was pretty much a 'make it fit and make sure it isn't shorting' sort of thing. The amp is almost a direct copy of the 1959/1987 pre-amp up to the 22nf cap going into the phase inverter. From there I just added a 1M grid reference, and had that going into a standard Fender 12ax7 stage (1.5K/22uF cathode setup) with another 22nF coupling cap off the plate to the 1M volume control.

[sgmezei]

HO-LY CRAP!!!! That is badass.

[jimmybjj]

Awesome, great job Paul!

[slimtriggers]

That is incredible!   

[murdog47]

Wow! Love it!

[DutchMF]

WOW! So freakin' cool! 

[JakeFuzz]

Haha, thanks guys! Now I expect to see a lot more tube pedals here in MB because these transformers only cost $20   

My next project (besides finally finishing up the lightning) will be an all tube compressor... maybe.

I got so excited when testing this I 'accidentally' started playing too loud and my neighbors called management  lame, a man should be able to play his instruments at 4:30 in the afternoon. BTW this thing has an insane amount of volume boost, I think unity is slightly less than 9 o clock!

[gtr2]

Beautiful!



Josh

[icecycle66]

Kudos, dude. That's cool as anti-hell.

[alanp]

If you do this again, you might want to consider using capacitor cans on the top (Marshall style!), either with 50uF+50uF cans, or a 40/20/20/20uF one. It would give you more room to work with components underneath.

[stecykmi]

oh man, an all tube comp sounds awesome, keep us updated on that one.

beautiful build, i'd love to see a schematic!

[JakeFuzz]

If you do this again, you might want to consider using capacitor cans on the top (Marshall style!), either with 50uF+50uF cans, or a 40/20/20/20uF one. It would give you more room to work with components underneath.

Definitely, I did have a lot of extra space on the top. Cap cans would have been the way to go for this. I didn't know they made 4 caps in one can, that's awesome.

oh man, an all tube comp sounds awesome, keep us updated on that one.

beautiful build, i'd love to see a schematic!

Ill draw up a schematic this weekend. Part values are still moving around until I find a good balance between the normal and bright channels. The tube comp was actually my mixing engineer friend's idea. He has a couple of model numbers he really likes to use on guitar tracks so when I am ready I will get the info from him.

[rullywowr]

Wow man, that's righteousness there. I am inspired to make something similar now...