Electro Harmonix LPB-1 Clone

My next DIY pedal was an Electro Harmonix LPB-1 clone I built in October 2011.

The LPB-1 or Linear Power Booster was the first pedal EHX made in 1968. It’s a pretty simple design, with one transistor used to boost the signal. It’s great for pushing the preamp in your amp into overdrive. It has 7 components and one knob!

Here is the layout I used: http://diy-layout.com/25

I didn’t have a 2N5088 transistor, so I chucked in a 2N4401 and it worked fine. Once it was built and working, I thought it would be cool to try and get it to fit into a tiny 1590A enclosure – about 9cm x 2.5cm.

IMG_3234 IMG_3445
It all managed to squeeze in nicely – but then after playing with it for a while, I decided to mod it to get a different sound from it. Electro Harmonix make a pedal called the “Screaming Bird” which is a treble booster – and apparently it’s pretty much the same as the LPB-1 with a couple of components changed. I worked out that if I change the value of the caps, I can make my LPB-1 boost the high frequencies – turning it into a trebel booster. By adding a little switch to the side, I can change between stock LPB-1 mode and Screaming Bird mode. I only just managed to get the switch and the 2 extra caps to fit in there!

Here’s how I wired up the switch:

switch between components

When the switch is up: C1 = 100nF, C2 =  100nF
When the switch is down: C1 = 2.2nF, C2 =  27nF

IMG_3592 IMG_3794 IMG_3772

So, that was my second build – works great and it was heaps of fun experimenting with different cap values. I also came to the realisation that sometimes it can be cheaper to build you own pedals than to buy them. I’m really hooked now…


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