Bay Area Thrash Mod V2

[Beyond Black]

This reminds me of something. In Junior high, I got all the girls to sign a petition to end women's suffrage.

I thought it was funny at the time, but it was tough to get a date for awhile

 

[Beyond Black]

Mod sounds great Mike!

 

[mnemonic]

That sounds badass. Have you tried it though your v30 cab?

 

[Racerxrated]

Great sound! More modern-ish, and tighter....

Highly recommend Mike as he does GREAT work!

 

[Jimty]

That sounds awesome - just a great sound all round. Congrats!

 

[shadow]

tl;dr
A stronger, healthier sounding amp; tighter, thumpier, faster low-end tracking; less noise; less ghosting; and keeps the amp from motorboating.


In more detail, filtering does a few things:

1. The preamp is DC powered. The rectifier in a guitar amp converts AC to pulsating DC. A byproduct of this is ripple and noise (120 Hz hum). The main reservoir filter caps charge on the voltage peaks and discharge to the rest of the circuit during the valleys. This smooths the AC ripple riding on the DC supply. So more filtering generally yields lower noise and a smoother DC supply to each gain stage in the preamp. Ghosting typically happens when a note creates harmonic dissonance with this 120 Hz ripple. Reduce the ripple, eliminate the ghosting.

2. Filter caps act as a local energy reserve. Heavy, loud, dynamic playing requires a lot of immediate power to keep the low end tracking fast and tight. When you dig into a heavy chuggy chuggy riff (especially in lower tunings) the power section draws a large current. The rectifier and power transformer can't typically keep up. So filter caps supply the missing power.

3. Filter caps help decouple each gain stage. The B+ line supplies high voltage to each gain stage through a series of dropping resistors. Without filter caps at each of these power supply nodes, the gain stages would share a common impedance path and common filtering. By decoupling each gain stage via dropping resistors and individual filter caps, the caps shunt any stray signal riding on the DC line to ground. Without this filtering, the amplified signal from one stage could modulate and feed back into another stage, causing low-freq. oscillation (motorboating).


In a vintage amp, designed for lower gain rock... this stuff isn't a huge issue. When you start adding more gain and more gain stages and you start playing heavier, faster music, a circuit designed to play classic rock starts to fall apart.

Todd Langner never added individual, decoupled filtering to the extra gain stages in his Marshall mods. At least not that I've seen. And neither do most techs who do mods. When most techs add gain stages, they install another tube and then just wire everything up in series with the existing gain stages. So you end up with FOUR gain stages all sharing common B+ supply node and one 50uF filter cap. This creates all sorts of problems. It's better to install additional filtering for each stage. Takes more time, more work, more effort. But if you're gonna do something, do it right.

This is also why attractive plug-and-play "mods" that you plug into a tube socket only get you so far...

Lots of good info, thanks!

 

[shadow]

Thanks! New Greenbacks

EDIT
Actually, those might be G12H-75 Creambacks. I have two identical Bogner cabs. One with Creambacks and one with Greenbacks. I recorded another video with Greenbacks for comparison.

Back in the 90's I remember pluggin into a JCM 900 after reading all the ads ("it goes to 20!"), thinking, "where the FUCK is all this gain they're talking about?!" I don't think anyone could say that about this punishing level of glorious gain in this super mod. Nice.

 

[FourT6and2]

Back in the 90's I remember pluggin into a JCM 900 after reading all the ads ("it goes to 20!"), thinking, "where the FUCK is all this gain they're talking about?!" I don't think anyone could say that about this punishing level of glorious gain in this super mod. Nice.

lol yeah I don't think any more gain in a circuit like this could even be useable. It's already plenty. The gain is at 1:00 in this clips, btw.

 

[Jimty]

lol yeah I don't think any more gain in a circuit like this could even be useable. It's already plenty. The gain is at 1:00 in this clips, btw.

Sounds great the way you had it. Recently I seem to be playing with less gain across all my amps - still plenty, but definitely preferring to retain more and more string clarity these days. Really don’t like it when amps get too gained out and mushy.

 

[PDC]

The photos of your work and the clips of the finished product are just incredible. If I was in the market for an amp, I would not be shopping new. I'd be finding the cleanest donor amp I could get my hands on and shipping it out to you.

 

[Detroit1973]

It made sense when I wrote it, lmao.

But I have a lot of wisdom to share. I just made a custom tshirt also.
View attachment 457958

Jesus spits his holy water in your butthole.

 

[FourT6and2]

One more clip before I have to ship the amp back to the owner. I'm gonna miss this one. Sounds absolutely incredible. I'm only doing this V2 version of the mod going forward. I like it way more than the historically correct version that stays true to what Langner was doing back in the day.

 

[ners]

Sounds so sick. Almost like an SLO? I don't know shit about this type of mod, but I'm into it.

 

[Cless357]

Sounds great ! Which one do you prefer between this one and your Jose mod ? How do they differ on real, in terms of gain, tightness, feel... ?

 

[FourT6and2]

Sounds great ! Which one do you prefer between this one and your Jose mod ? How do they differ on real, in terms of gain, tightness, feel... ?

One has less gain, more string clarity, brighter, more snarl and grind.
The other has more gain, more saturation and compression, chewier/juicier feel, more searing high mids and treble.
Both are incredible Need both!

The room clips of both are fairly accurate. Here's the Jose for comparison:

 

[Anje]

Bumping this thread as I saw the latest great video from Mike of the '71 Marshall ST he's selling, and that made me wonder:
how is this mod sounding & feeling VS an early 90's Soldano SLO or Mesa Dual Rectifier?

 

[Exo-metal]

I can only speak to the mesa since never played through a soldano. The recto isn’t as tight as fast as the Super Tremolo. There's more squish to the notes playing the recto and we never play the mesa unless its boosted. They are completely different in their delivery, the wall of sound vs more immediate.

 

[FourT6and2]

Bumping this thread as I saw the latest great video from Mike of the '71 Marshall ST he's selling, and that made me wonder:
how is this mod sounding & feeling VS an early 90's Soldano SLO or Mesa Dual Rectifier?

Yeah, what Exo said. But also the Recto sound is low-mid voiced. More compression, more saturation. This mod, specifically to the Super Trem (not an 800), is more airy. There's more breath under the notes due to the vintage iron. And the voicing is much more focused in the upper mids. It's still a Marshall after all...

 

[thrashinbatman]

Bumping this here with some clips now that I've gotten it back. Man, he did WONDERS on this thing! it is absurdly nasty, and LOUD. anything past 9 o clock on the master volume is loud enough to drown out a drummer. the gain here is at 6; it's unreal how much gain is on tap. even at 3 it's still noticeably high gain.

here's me jamming it with some riffs from my band as well as some Exodus riffs. really quick and dirty, didn't bother tuning lol. running it into an IR of an Engl cab with V30s, miked with a SM57.

 

[reignman454]

Honestly the amp rips... Should list out the components one reply at a time