Tech Tips and Amp Mods

This page is a "work in progress" so drop by from time to time to check out the latest tips and mods. Last changed: October 2008

Pedal Tips

In this section we will talk about different pedal designs and how to patch them into your rig.

Overdrive and Distortion Pedals

What makes Overdive/Distortion pedals different and why is it so hard to get it right.

It all gets down to the three main parts of the pedal, the Pre-EQ, the distortion circuit and the Post-EQ. Too much Pre-EQ will make your guitar thin and scratchy and not enough will turn it into fuzz.

The "scooped mids" and "treble cut" Post-EQ circuits are used alot in Overdrive/Distortion pedals. With the scooped mids circuit you will get a great crunch rhythm sound, (G2D Classic). With the treble cut circuit you will get a slightly mid focused tone, which is great for soloing, (G2D Custom OD).

Generally speaking, the more drive you use, the more Pre-EQ and Post-EQ you need, so if you are looking for an open sounding pedal, then try the lower gain models on the market, (G2D Cream-Tone).

General Patching Rules

Overdrive pedals should be first in your chain, followed by Distortion pedals, then effects pedals.

Compressors in front of Overdrive pedals will increase your drive and raise noise. Compressors left on after Distortion pedals will choke your solos.

Some guitarists have the Wah pedal before the Overdrive pedal to soften the wah effect. Others modify the amount of wah effect and place them at the end of the pedal chain.

The last effect pedal in your chain will be the most dominant effect. Tuners should go at the very end of the chain.


Amp Mods

The Fender / Marshall tone circuit is
responsible for most of your amps tone.

In the section we will talk about general amp mods (not using pedals) and mods that make amps work better with pedals.

I am going to upset a few people out there....
The resistors and capacitors that make up your amplifiers circuit, have more effect on the tone of your amp, than just the valves alone.

I have to warn you here, my favourite amps are the Fender Twin for clean, the JMP/JCM Marshall for crunch and the early Mesa Boogie for soloing.
So.... some of these mods may come out sounding similiar to one or two of these amps.


Fender Amps

Fender Twin/Super

To get more mid focus raise the value of the MIDDLE pot from 10k to 25K.
To lessen the jump in the bright switch, change the 120pF to a 47pF.
If you find the Vibrato channel still too bright, then remove the 10pF from across the 3.3M resistor.
Remove any chrome dome speakers immediately !!!!

Other Models

Fender released a series of amps with an overdrive circuit after the tone circuit. You can pick this type of overdrive, as the MIDDLE knob increases the drive and the BASS knob turns the sound into fuzz. Not much can be done to sweeten this design. Your best option is to use an overdrive pedal with the amp set to clean.


Marshall Amps

Non Master Volume Amp

What can I say.... the difference between the two channels is EXTREME.
Simply removing the 470pF cap across the 470K resistor in the mixer circuit will make this amp more usable.

To make this amp more pedal friendly:
- remove the 33uF from the cathode of valve 1a
- remove the 0.68uF from the cathode of valve 1b
- remove the 0.005uF bright cap from "VOLUME 1"

Master Volume Amp

To make this amp more pedal friendly:
- remove the 0.68uF cap from first stage cathode
- remove the 0.001uF bright cap off the volume pot

This is a taste thing... to set the overall brightness of the amp, remove one or both 470pF caps across the 470K resistors. Try this setting with your favourite overdrive pedal engaged.

The Tone Circuit

Theses modifications are well worth trying.

To sweeten the top and bottom end of both "Non-Master" and "Master Volume" models:
- change the 470pF on the top of the Treble control to a 220pF
- change the 33K/56k on the bass circuit to a 100K

An effects loop can be added after the master volume and before the phase splitter. In the past I have added a simple FET circuit internally to lift the return level into the splitter stage. This circuit can be mounted on the Send and Return sockets and powered from the bias tap.


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