LR-Baggs MixPro Battery elimination

I Recently bought a LR-Baggs MixPro 2 channel preamp  for my two acoustic guitars

The first one is a Alhambra NJ3A_Brillo with a homebrewed  K&K puremini system ripoff James May engineering system  using 4 small piezo’s and a larger feedback compensator.
I used cheap 16mm piezo’s,  they are really cheap, like 30 cents a piece.
I also added a Gretsch Deltoluxe magnetic and wired the system to a stereo jack

My second acoustic is a Gretsch Penguin Parlor with a Fishman UST and Preamp and a Gretsch Dearmond 2000 pickup in it.

The Piezo/Magnetic blend sounds very nice and adds some warmth to the piezo’s

But I hate batteries!!

So I tried to figure out if I could eliminate this part from the LR-baggs.
The MixPro switches on when plugging in the output mono cable.
When opening the MixPro I noticed a stereo jack input was used so I figured I could use a stereo plug and supply the 9 volt 2.7 mA power from my pedal board supply somehow.

After thorough measurements it seems that the ring and sleeve lips are used to switch the battery (-) to the ground of the MixPro.

That means I could supply the (+) trough the ring and add some trickery to the battery plug sourcing the (+) trough a salvaged battery clip with a small 33 ohm resistor.

img_20191121_202655 img_20191121_202721-1

This way I can supply my Lr-Baggs from my pedal board trough a small breakout box
Practically it is the implementation of the P3 Phantom power system


MixPro Battery Eliminator

I used a 33 Ohm resistor to be save, but a simple wire is enough.

LR-Baggs MixPro Battery elimination

Dutch PTT wire broadcast speaker VOX AC-4 Build

As intermezzo I did a rebuild from my Dutch PTT wire broadcast powered speaker amp and made it into a VOX AC-4 with some tweaks

I junked the original EL41 pair used as preamp and power amp and used a EF86 and EL84 set. I also added a power transformer since the original was fed directly using the plain line voltage. too dangerous IMHO.

The first attempt was a quick and dirty rewire of the original board and it worked Ok but there was some oscillation when volume maxed out.

I decided to rebuild it on a proper aluminum box and FR-4 carrier boards with eyelets.

That worked much better. Unbelievable how quiet this thing is.


Dutch PTT wire broadcast speaker VOX AC-4 Build

Some succes with my Line-6 Pocked Pod MIDI keyboard project

The line-6 PocketPod is a nice cheap guitar effect. It basically is an original Pod 2.0 in a smaller package , but no real MIDI interface. This means you can’t hook up a Behringer FB2020 or similar MIDI floorboards. As far as I know, there is no pedal board on which you can hook up USB based MIDI hardware available on the market. You need hardware and an OS in order to act as a MIDI host.. You could use a PC or laptop to act as host and reroute the real MIDI signals to the virtual USB hardware but that seems overkill IMHO.

Enter the Raspberry PI. the cheap credit card Linux machine. I found out that hooking up the PockedPod to the PI, the PocketPod was recognized and acting as a serial MIDI port.

I could send MIDI data to the thing using amidi and It reacted as expected. Program changes and control changes worked fine. There are plenty resources available on the Internet about Line-6 POD MIDI traffic and SysExe data and I used that as a starting point to continue my research.

I thought about using a nice box and hooking up a few footswitches, but that would increase the costs considerable and I dont want to incrrease cost for a $100 device too much, I remembered some story of using a cheap PC keyboard as footswich by removing unneeded keys. That proved to be a neat and cheap solutuin to create the $10 PockedPod footswitch. A 5$ PI zero and an old PC keyboard and some soldering should be enough to get thinks running.

I hacked an old LogiTech 250 keyboard and pulled most of the keys and made a coverplate with keyholes and a bunch of extra indicator LEDS.

The plan is to clock the LED data back to the keyboard trough the 3 status LEDS and 3 74HC595 shift registers.



Some succes with my Line-6 Pocked Pod MIDI keyboard project

PH0MB Ham & Jam

This is my first post on

Weird name eh? but that’s my HAM radio call PH0MB.
My real daily job is being a IT administrator

I’m not very active on the air, but I like to tinker and make stuff and being a ham broadened the scope and connections to fellow tinkerers.

I’m also guitarist in 50’s R&R band “Miss Behave & the Naughty Boys

Currently I’m busy working on creating a Foot controller for a Line6 PocketPod. Not just the usual up/down/left/righ key breakout found on several sites, but a real USB-MIDI solution

I use a RaspBerry PI and an old USB PC keyboard communicating directly to the PocketPod.

Source Code and project details will follow soon, but it really works very well. Support for a Volume/Wah pedal will be added and more to come.

PH0MB Ham & Jam