Guitar Pedal Projects. Top 5 in DIY With Forum Support!


Post Reply
Forum Home > Layout Gallery - GuitarPCB Build Documents, Mods and Tips > After Blaster

Site Owner
Posts: 8793

Here is our final version v4 of the After Blaster Gain Stage add-on board.

You may use included dip switches for bypass, use a DPDT switch or simply leave it on.

AfterBlaster - 3 in 1 Tonal Enhancement Circuit - Easily add extra gain to any circuit!

The AfterBlaster is a cool THREE-IN-ONE circuit that provides several useful functions. It is a handy bypass footswitch wiring board with a status LED. It has a switchable boost circuit that provides a very noticable boost enhancement for any circuit . It can also provide a final tone balancer to attenuate the output level of any circuit. Or anything in between!


Build Document


Always check for updates in the Layout Gallery before building any circuit.

Each board will include a pair of dip switches!

Also included is a 100k Trimmer pot.



Install the Dip Switches and  Trimmer as seen in the photo above.



For those interested in making an enclosure mounted switch & control knob see schematic and video below:

See After Blaster in use with this Video Demo

You need Adobe Flash Player to view this content.

December 29, 2015 at 11:32 AM Flag Quote & Reply

Site Owner
Posts: 8793

Aside from using the on-board Dip Switch and Trimmer (some people prefer the set and forget method) you may use a DPDT switch and potentiometer for mounting on the outside of the enclosure. Keep in mind that the potentiometer should be at roughly 2:00 for unity gain and higher for boost and clarity. It can also be used to cut the volume as well below 2:00 if needed.

Another Mod is to install a 2N5457 for a bit more grit when turning it up than a cleaner MPF102 will provide. As usual Bias from 4.5v to 6v. to suit your rig and ears. You will need to socket R4 and find the correct resistor.

If you wish to try a J201 (even more available grit) you will have to socket and adjust R1 and increase as well as possibly socketing R4 and adjusting till you can attain in roughly 4.5v to 6v. on the Drain leg of each transistor.

As always "socket and see" what you like. When using sockets this allows you to easily make changes without ruining the board by desoldering etc...

January 6, 2016 at 9:42 AM Flag Quote & Reply

Site Owner
Posts: 8793

Courtesy of Billy:

Here is a description and diagram to show how to add an After Blaster to any GuitarPCB board with on-board foot-switch such as the Mastadon Fuzz, D.S.O.T.M etc...

Put jumpers on the board to bypass the switch part.

Shown here in green:

Add your +9v and ground as per the After Blaster build doc wiring diagram don't install R8 the CLR  (won't do any harm if you've already installed it) or an LED on the Main board instead install them on the After Blaster board and you can use a pot to turn the After Blaster up or down when active and a DPDT switch to externally control the After Blaster.

January 18, 2016 at 12:54 PM Flag Quote & Reply

This topic is closed, no additional posts are allowed.