Project - Zoom Guitar Amplifier modifications/Enhancements - Page 1
Forum section: electronics / projects

author: IanJ
author_rank: Unknown
timestamp: July 12, 2011, 10:40:21 pm
content: Hi all,Just a quick run down of my most recent project:-I have a Zoom Fire-30 guitar amplifier that has built in effects. However as any guitarist will tell you, those effects are best operated from a footpedal and not from the front panel of the amp.So I decided to build a footpedal with 10 or so switches on it to replicate some of those on the amp panel, and at the same time replicate the associated LED's down on the pedal also.However, I had to contend with the fact that both the panel led's and the switches are driven/read via a matrix/grid. So I'm using small relays to piggy back the panel's momentary switches, and am using opto-isolators to pick up the led drive. The led's are intelligently driven since pressing a button will cancel an led on another function/button.Also, I didn't want to run a mult-core to the pedal, so decided to employ an Arduino to do the I/O and run an I2C bus to the pedal where I'm using some I2C digital I/O extender IC's as remote I/O. This also allowed me to fit a 2*16 LCD for status functions etc.Also (yes there's more!), I wanted to ditch the existing single chip 30w audio amplifier pcb with a better one, so am using one from AmpsLab. This means the existing psu in the amp also had to be ditched in favour of something bigger and that would also power the Arduino, my own boards and the Zoom processor board.So, it's all assembled and initial power up testing has gone great, and I'm just starting the software.I'm having a blast!Here's some pics:-The original amp:The original internals. On the left the single chip audio amplifier, next to it the Psu and obviously the transformer.And here's what I've done so far:-In this 1st pic you can see the opto-isolator board, relay board, Arduino Mega, my home built Psu, AmpsLab audio amplifier board and a toroidal in the foreground. Note: The bridge rectifier is just out of sight.You can also see my wiring loom onto the rear of the Zoom processor board picking up the led drive signals and also piggy backing the switches.Here's the completed pedal getting it's first power up test. There's a 5 core cable from the pedal back the the amp via some nice lockable 5-pin DIN sonnectors.And the internals of the pedal below. Each IC is capable of 8off digital I/O, all completely addressable via I2C as input or output and very easy to use in code.Here's where it all happens, a still from my webcam in my purpose built workshop in my back garden. Actually, if you look closely, you can see me working on the above project, I'm working on the Pedal.Ian.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: July 13, 2011, 11:54:20 pm
content: Nice project.Plenty of empty space in the original box before you filled it.Have you tried a class D amp on guitar? Much less heat and a smaller PSU are very attractive in tight enclosures.Wondered also if you had given thought of using MIDI instead of I2C as your interface protocol to the pedal? Your pedal may then have been useful with recording software (NI Guitar Rig etc) as well. And it also uses 5-pin DIN with opto-coupled balanced I/O for long cable runs.

author: IanJ
author_rank: Unknown
timestamp: July 14, 2011, 10:19:00 pm
content: Quote from: DrGeoff on July 13, 2011, 11:54:20 pmHi,Thanks for the reply.To be honest, I just picked the 1st 'reasonable' amp board I could find without breaking the bank, and as far as MIDI is concerned, I chose I2C because the Arduino has is built in and it's very easy to use. I'd also use the remote I/O IC's in a previous project so knew exactly what I was doing with them.As an update, tonight I wrote 99% of the code (the wife kept the coffee coming!), and it's all basically working. Tomorrow night will see some additional features to write & tidying up of the code. There's one hardware issue I have around the opto-isolators caused by the wierd way the Zoom Processor board uses phase shifting and voltage levels to turn on/off the panel Leds.That done I'm hoping the new 10" driver arrives and I can plug the guitar in!!!Ian.

author: Unknown
author_rank: Unknown
timestamp: July 14, 2011, 10:29:08 pm
content: Great project Ian.Send a video of it singin'Cheers.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: July 15, 2011, 12:25:04 am
content: Quote from: IanJ on July 14, 2011, 10:19:00 pmIs it an open-back cabinet? Hopefully you get some good crunch with the new amp/speaker combination. Make sure all the screws are tight in the electronics section and have shakeproof washers, there's nothing more annoying than the elusive rattle when you hit the power chord!