Thursday, April 12, 2012

Amp pedals - The ROG Professor Tweed

After trying a few fuzz designs I started investigating the gear chain of some of my favorite guitar legends and I realized that although the fuzz pedals are a critical part of the chain there are other components which are just as cardinal as the pedals. There is the brain, the heart, hands and fingers and feel of the player. There are the strings, obviously, but once the vibrations are created they are turned to electric current through the pickup coils which are the first major factor in the sound. Mostly you can hear the difference between single coil pickups and Humbuckers. After that you have the pedals, the amp, the cabinet and speakers and the room, microphones and recording gear.

It seems after building some fuzz pedals the next gain stage is the amplifier. I have to give a big credit to the RunOffGroove website from which I learned so much. The guys over at ROG have some fantastic designs of circuits utilizing solid-state FETs to emulate the behavior of driven tube gain stages. With this they designed some serious emulations of classic amps by Fender, Vox and Marshal.

As part of my Fuzz Quest I started off with the simplest design of a classic Princeton amp so I built the Professor Tweed. It sounds like a late 50s amp which can go from clean to overdrive through the input GAIN knob. This was the first time I understood the difference in voicing quality and character between an overdrive and a fuzz. A fuzz is really over-the-top distortion which changes the original sound completely. The overdriven amp stage is softer and crunchier. Although the pedals sound great together with the fuzz boosting the input of the amp pedal, you can use the amp pedal alone as a great overdrive for guitar or Harmonica and it really gives you great classic Blues and Rock'n Roll tone. I have to say that the Professor lacks some sparkle and I always keep its TONE control on max. The mo' bass switch is a nice addition too. I ended up using additional tone control pedal after it to give it more sparkle. Also it sounds better with single coils than with Humbuckers. Humbuckers tend to have higher ouput level and drive the pedal to distortion even at low gain settings. You can get the schematic here.

In the next few posts I'll dive some more into overdrives as it really is part of the story.

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