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....Thanks to the AX84 Project (www.ax84.com) I have built my own tube guitar amp......

The AX84 - P1 is a low power tube guitar amp.
It features a 12AX7 (or ECC83) in the preamp stage, and a single-ended EL84 for the power stage. The output power is (I think) between 4 and 5 Watt.

MY P1

My amp is basically an AX84-P1, rev.10, lite version, which I have modified by adding a small , solid-state tremolo unit.
That's why I call my amp: Tremotube
This amp is also small sized: 33X23X22 centimeters. .
Here are some photos and the schematics with my mods.
(Of course, I'm not the expert, you can find information and help on the AX84 site and discussion forum, see at http://www.ax84.com).
I want to thank the friends at the AX84 discussion forum (especially Chris, Kursad, Carl, Glenn...) and friends outside the forum (Alessandro) that helped me a lot.

Front view The guitar is an old Ibanez PF200, Gibson-style (....unfortunately, ONLY the style...) You can see the tubes in operation from the amp's top grille.


SCHEMATICS


The amp schematics The power supply schematics

MY MODS


The mods to the amp:
an extra grille resistor on the 1st preamp stage
an extra resistor in series with the volume pot
an extra resistor in paralle with the 2nd preamp stage anode resistor
These mods where to get some less distortion...
an extra capacitor on the 1st preamp stage cathode
This mod is to get more bass
I know the mods are 'unusual'. There were some constraints, as I built the amp circuit on a PCB. So my suggestion is: DO NOT USE PCB, because it will be difficult to modify and fine-tune your design.

The mods to the power supply:
DC supply for the preamp filaments (definitely kills the filament hum)
I've been playing around the power supply for a long time, trying to kill the filament hum. I've tried with different grounding, bleeding resistors, filter caps etc. I think the ECC83 is defective, by the way I finally decided to go for the DC filament supply.

Comments? Mailto: ciccio.mario@mailcity.com