lpb-1booster - beavis audio
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100n
f
390Ω
100KΩ
1MΩ
10KΩ
100n
f
sw
sw
C1
100 nFInput
R11MΩ
9v DC+
Q1
2N5088
E
C
B VR1
A100K
(Volume)R4100KΩ
R21MΩ
R310KΩ
R5390Ω
C2
100 nF
output
LPB-1Booster
The Electro-Harmonix LPB-1 booster is an old design dating back many
years. It’s simplicity belies the fact that you can get great sounds out of
just a few parts. The single transistor does all of the work. R2 and R4 set
the bias level, C1 is the input cap, and C2 is the output cap.
beavis board project
A100K
Volume
in
out
Mods!The C1 capacitor filters the input signal. The 100nf part is large enough that bass
content of the input signal is preserved. But what if you want to remove bass
content? In other words, make a treble booster instead? Simple: lower the value
of C1. Try values from 50pf to 22nf.
You can increase the amount of headroom (how loud you can go before the
signal starts to clip/overdrive) by increasing the input voltage. If you have a 12
volt DC adaptor, plug that in to experiment.
You can lower the gain of the circuit by using lower gain transistors. Try any of
the bipolar silicon NPN parts in the parts stash. Be sure to check the pinouts!
1MΩ
2N
5088
E
B
C
revision: 1.0 28 may 2008 © 2008 beavis audio research