Appetizer - Mods for Accurate 2555 Sounds

[andrewsrea]

I bought a Marshall 2553 (50w, small head) Jubilee brand new in 1987 and have worked on a few 2550's. IMHO, Appetizer is an improvement on the Guv'nor pedal and these mods will get you 'on the money' when playing through a Fender style amp, especially through a 4x12 (schematic and pics below).

I call this 'AMI 2553 Jubilee'. Cerakote grey paint and laser graphics next week.

- Socket IC1. RC4558 will produce John Sykes' Whitesnake tone / LM833 will provide a Slash AFD tone.
- R3: 2K7 (originally 2K2) to shift the gain tone roll off to 590Hz.
- C3: 330p (originally a 120p).
- D1: Yellow LED vf = 1.87v / D2: Red LED vf = 1.69v. (Jubilee's are slightly asymmetrical, especially on the drive channel). I used sockets to be able to change,
if the mood strikes, bit this combo is really stellar!
- C12: 1n5 (originally a 470p). This design has way too much bitey treble and this makes the tone knobs more usable.
- Add: 100nF (25V or higher - I used commonly found 100v and attached at D100 and the 'ground' wire - see pic). This helps takes care of the high-speed
chatter from switching supplies or an inferior charge pump.

Bonus:
- Add charge pump and switchable 9V ('50w') to 19v ('100w') mode using mini DPDT. I used an ICL7660CPAZ, but you can also use a TC104SCPA (pictured
next to the stomp switch on the gut shot. 50w mode has more compression and harmonics and 100w mode is more in your face (AFD).
- Substitute bi-color Yellow (50w) & Red (100w). Replace 'CLR' resistor with 5K or 10K trim to dial in brightness of the LED. Note I placed that LED in
a mount, next to the stomp switch and not as suggested on the PCB.

Let me know what you think, if you build with these mods!

 

[Nostradoomus]

You can also build this on the guvernator/guvnor board because they’re literally the same pedal barring 1 cap value

 

[andrewsrea]

You can also build this on the guvernator/guvnor board because they’re literally the same pedal barring 1 cap value

Agreed. I think I noted four differences:
- The layout on the Appetizer is more spread out, IMHO lending to less risk of eddy currents or inductive oscillations (pointed out by Robert, the engineer)
- C6 is 68n (Appetizer) vs 330n
- C100 is 10uF (Appetizer) vs. 100uF
- 'Treble' pot is linear taper on the Appetizer and audio taper on the Guvornator

 

[Giorfida]

I bought a Marshall 2553 (50w, small head) Jubilee brand new in 1987 and have worked on a few 2550's. IMHO, Appetizer is an improvement on the Guv'nor pedal and these mods will get you 'on the money' when playing through a Fender style amp, especially through a 4x12 (schematic and pics below).

I call this 'AMI 2553 Jubilee'. Cerakote grey paint and laser graphics next week.

- Socket IC1. RC4558 will produce John Sykes' Whitesnake tone / LM833 will provide a Slash AFD tone.
- R3: 2K7 (originally 2K2) to shift the gain tone roll off to 590Hz.
- C3: 330p (originally a 120p).
- D1: Yellow LED vf = 1.87v / D2: Red LED vf = 1.69v. (Jubilee's are slightly asymmetrical, especially on the drive channel). I used sockets to be able to change,
if the mood strikes, bit this combo is really stellar!
- C12: 1n5 (originally a 470p). This design has way too much bitey treble and this makes the tone knobs more usable.
- Add: 100nF (25V or higher - I used commonly found 100v and attached at D100 and the 'ground' wire - see pic). This helps takes care of the high-speed
chatter from switching supplies or an inferior charge pump.

Bonus:
- Add charge pump and switchable 9V ('50w') to 19v ('100w') mode using mini DPDT. I used an ICL7660CPAZ, but you can also use a TC104SCPA (pictured
next to the stomp switch on the gut shot. 50w mode has more compression and harmonics and 100w mode is more in your face (AFD).
- Substitute bi-color Yellow (50w) & Red (100w). Replace 'CLR' resistor with 5K or 10K trim to dial in brightness of the LED. Note I placed that LED in
a mount, next to the stomp switch and not as suggested on the PCB.

Let me know what you think, if you build with these mods!

Did you find the stock appetizer to be lower gain than the Guvnor? I have one of each, and side by side the Guvnor is significantly higher gain.

 

[andrewsrea]

Did you find the stock appetizer to be lower gain than the Guvnor? I have one of each, and side by side the Guvnor is significantly higher gain.

I also have the PedalPCB Governator, and I can answer that with a 'yes' and 'no.'

The Appetizer (without my mods) has more high-pass (low cut) going on and uses a RC4558 which, IMHO has a perceived gain structure difference. So, I can understand hearing less gain with it versus the Guv'nor circuit. My mods reduce the gain a little but will accept a boost pedal in front better for more gain, if required. A TS sounds really good for that.

 

[Giorfida]

I also have the PedalPCB Governator, and I can answer that with a 'yes' and 'no.'

The Appetizer (without my mods) has more high-pass (low cut) going on and uses a RC4558 which, IMHO has a perceived gain structure difference. So, I can understand hearing less gain with it versus the Guv'nor circuit. My mods reduce the gain a little but will accept a boost pedal in front better for more gain, if required. A TS sounds really good for that.

That makes sense. I was leaning on the fact my appetizer used 3mm LEDs and my Guvnor build (tonepad) used 5mm. Never thought to look at the tonal character difference.
That said, my TP Guvnor is housed in a 1590bb along side a TS9 board as a dual pedal… so yes, I fully agree it works well goosed by a TS!