[243] Wah Pedal Buffer

Date: October 10th, 2008 | Comments : [16] | Categories: amps, DIY.

Wah Pedal Output This is the basic output stage of a typical wah-wah pedal. You can see that the pot that controls the bandpass frequency is connected not only to the output jack but also to the input of a buffer transistor that feeds back part of the signal to the first stage.

This will make the wah sensitive to the load that is placed on its output. It can also cause an adverse reaction with a low impedance input of the next stage, such as with a fuzzface type cicuit. The FF can break into oscillation with the frequency changing as the wah treadle is moved.



[218] Tillman Fet Preamp

Date: September 27th, 2008 | Comments : [1] | Categories: amps, DIY, power.

Tillman Fet Preamp

The Tillman jfet booster circuit is widely known in the DiY effects community and often recommended for certain guitar fx applications. I recently saw the circuit posted on a guitar forum and realized that it could be built on my Multi-Purpose pc board.

I’ve modified the instruction page for the pcb to show how to use it to build the Tillman. The instructions and parts list are on the site that is emailed to everyone that buys one of the boards. Ordering info:

AMZ MultiPurpose PC Board


[159] Quick Rat pedal mod

Date: September 14th, 2008 | Comments : [18] | Categories: amps, DIY, power.

Rat2 schematicThe Proco Rat has become a classic pedal that has a legion of fans among guitar players. I have 3 of them, two Rat2 and a Turbo Rat.

The Rat is designed to have a large amount of gain and a significant treble boost. This is part of what gives it a characteristic sound, but also makes some players dislike the tone it produces.

The resistors R6 and R7 along with the capacitors C7 and C6, are the main determining factors for the low frequency rolloff.



[74] Epi Valve Jr. mods

Date: March 1st, 2008 | Comments : [5] | Categories: amps.

Epiphone Tube Amp

The slightly dusty pcb from my Epiphone Valve Jr. amp…


[59] Epiphone Valve Junior mods

Date: December 7th, 2007 | Comments : [6] | Categories: amps, tubes.

Epiphone Valve Jr. head

My new Epiphone Valve Jr. amp head



[54] DiY Online Construction Articles

Date: November 7th, 2007 | Comments : [1] | Categories: amps, DIY.

audioxpressaudioXpress is the only do-it-yourself audio magazine currently published in the USA. I’ve been a subscriber since the late 1970s and have a nice collection of back issues.

Their web site has plenty of free info so check it out… better yet, subscribe today and support DiY!


An example of a recent project is the Hybrid Valve MOSFET SE Amp by Stephen Moore, published in the Oct and Nov 2007 issues. They are online for free download:




[47] Vox amPlug Headphone Amp

Date: September 28th, 2007 | Comments : [2] | Categories: amps.

Vox amPlug amp

Vox amPlug Headphone Guitar Amp


[36] Epiphone Valve Jr.

Date: August 2nd, 2007 | Comments : [20] | Categories: amps.

Epiphone Valve Jr. head

My new Epiphone Valve Jr. amp head



[7] Retro power amp

Date: May 19th, 2007 | Comments : [1] | Categories: amps.

This has to be the cool project of the month… it has a bit of a “steampunk vibe” with the copper panels and screwheads… very cool. You can read more about this unique amp at the link shown below.




AMZ Home Page

Guitar FX PCBs