Author Archives: Frank

Custom Footswitch for Fender Vibroking

By Frank | Published: May 6, 2014

Here a picture of a custom footswitch we made for a Fender Vibroking.     The problem with the amp’s stock footswitch is that there are no LEDs on it to indicate which functions have been activated, so we built a footswitch with LED indicators for each feature. The LEDs can be powered either from […]

Posted in Effects pedal, Pedal building | Comments closed

Boss Pedal Repair at JPF Amps London Workshop

By Frank | Published: May 1, 2014

Here are 3 Boss pedals I’ve had in for repair at our workshop; a DM-2 analogue delay, an OS-2 overdrive /distortion pedal, and a DD-3 digital delay.     Boss pedals are, in my experience, very reliable. None of these pedals had major faults. The DM-2 (which for the uber pedal geeks was the earlier […]

Posted in Effects pedal, Effects repair, JPF Amps | Comments closed

Boss TR-2 effects pedal repair and modification

By Frank | Published: April 18, 2014

As well as repairing guitar amplifiers, we also repair and modify effects pedals. The Boss TR-2 is a good sounding tremolo pedal, but suffers from a loss of volume when the effect is engaged. This is easily cured by changing R9 on the PCB from 10k to a lower value. I find 6k8 works well. […]

Posted in Effects pedal, Effects repair | Comments closed

New JPF Sound Sample and “Rockumentary”

By Frank | Published: December 9, 2013

We now have a “rockumentary” on Youtube where I go into some detail about the design and construction of JPF amps, and there is also some footage of David PAge demonstrating the a SC15 combination. These can be accessed via our media page.

Posted in Amp building, Guitar Amps, JPF Amps, Sir Charles | Comments closed

JPF Prototype Nimrod 100W Bass / Guitar Amplifier

By Frank | Published: November 11, 2013

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 […]

Posted in Amp building, Bass Amps, JPF Amps | Comments closed

Fender Blues Junior Guitar Amp Repair

By Frank | Published: August 9, 2013

I see quite a few Fender Blues Juniors in the workshop for repair; not that they are unusually unreliable, it’s just there are a lot of them out there! However you do see many of the same faults occurring, so here’s some photos highlighting these from a recent repair. Firstly, like many amps that use […]

Posted in Amp repair, Guitar Amps | Comments closed

Aguilar AG500 Bass Amp Repair: Man vs SMD Round 1

By Frank | Published: July 31, 2013

Here’s a repair I conducted on a more modern amp, a Aguilar AG500 bass guitar amplifier, where we were dealing with the dreaded SMDs. This amp is quite an interesting design as it has a class D output stage, however unlike most class D amps it’s not ultra light. It employs a linear power supply […]

Posted in Amp repair, Bass Amps, Guitar Amps | Comments closed

VOX Night Train Guitar Amplifier Repair

By Frank | Published: June 17, 2013

Here’s some photo’s from a recent repair of a VOX Night Train amplifier. The amplifier was producing no sound. Curiously the HT voltage on the first pre-amp valve was only 95 VDC, way below spec. I removed the valves and the HT on the first valve stage was still only 95 VDC. On further investigation […]

Posted in Amp repair, Guitar Amps | Comments closed

Peavey Classic 30 Guitar Amplifier Repair

By Frank | Published: May 30, 2013

Here are some photos from the inside of a Peavey Classic 30 that I recently repaired. The amp was brought in making a ton of crackling noises and was cutting out intermittently. It had been looked at previously by someone who had concluded that the PCB had absorbed moisture (not possible), and had tried to […]

Posted in Amp repair, Guitar Amps | Comments closed

More safety earthing issues. VOX AC30 and Yamaha PA

By Frank | Published: April 10, 2013

A couple of safety earthing issues I’ve seen over the last few weeks. Here’s the safety earth from a recent repair on a JMI era VOX AC30. Suffice to say, if you were going to solder the safety earth to something, then the chassis might have been a better bet…… OK, that was a vintage […]

Posted in Amp repair, Guitar Amps, JPF Amps, Vintage amps | Comments closed