LPB-1Booster - beavis audio
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+ - + - + - + - a b c d e f g h i j 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 25 26 27 28 24 29 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 25 26 27 28 24 29 30 a b c d e f g h i j 100nf 390Ω 100KΩ 1MΩ 10KΩ 100nf sw sw C1 100 nF Input R1 1MΩ 9v DC+ Q1 2N5088 E C B VR1 A100K (Volume) R4 100KΩ R2 1MΩ R3 10KΩ R5 390Ω 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 2N5088 E B C revision: 1.0 ● 28 may 2008 ● © 2008 beavis audio research
Transcript of LPB-1Booster - beavis audio
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a b c d e f g h i j
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
