JPF Prototype Nimrod 100W Bass / Guitar Amplifier

Here are some photos of the 1st prototype of a 100W bass / guitar amp.

The amp was initially designed as a bass amp (mainly for my use!), but there was some interest in the design from a couple of guitar players, so we will develop a guitar version of this amp too.

The amp fits into our standard head shell and will weigh in at a fairly manageable 14kg.

We have used the same pre-amp topology as used in our other amps, but with the addition of a defeatable active mid cut/ boost control. Like the control on Ampeg amps, this uses a tapped inductor to allow selection of 5 different frequencies to cut or boost.

This version on the amp uses 2 x KT88s to deliver 100W, but the next iteration of the design will be capable of using either KT88s or 6550s.

Anyhow, here are the photos.

Front (no control panel yet!)



Rear. 2 x KT88s




Tapped inductor, custom wound by Sowter Audio Transformers. Mu metal screened for low hum.




Gut shots showing the layout and wiring.


NimrodGutshot Nimrodboard

This entry was posted in Amp building, Bass Amps, JPF Amps. Bookmark the permalink. Both comments and trackbacks are currently closed.