Stereo amplifier with bass booster

Thread Starter

stringskipper

Joined Aug 1, 2008
3
Hi everebody! First of all i need to apologize on my english, it's not very good
and if i make some mistakes i hope you will understand it
I'm interested on some ideas about this project.
(all solutions and diferences among them)
I have allready started this and a i have some problems.
The basic idea is to create audio amplifier which amplifies
all audible frequencies, and add some circuit which will
amplify bass frequencies. (few decibels). All with op-amps.
So, the (ideal) amplitude characteristic will look like this -->(picture 1)
(gain in bass range must be adjustable)
I have create this circuit --> (picture 2, this is
just one block, not stereo),
but this don't do the work! I tried to place filter
circuit in other part of feedback (parallel with R1, of course
with changed values for R-C), but
still it's the same result...--- no bass frequency change!
I'm using LM1877.
(I put these values just for the testing, so the critical
frequency is set to 1 KHz. In real circuit i need to
amplify frequencies from 30 Hz to 170 Hz, without loss of
high frequencies and overall volume).
I'm very grateful on all answers, ideas and explanations.
 

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Audioguru

Joined Dec 20, 2007
11,248
Your schematic is a fuzzy JPG file type instead of a very clear GIF or PNG file type so I can`t reed the IC`s pin number.

The inputs of the LM1877 must have a resistor connecvted to the bias pin 1. Pin 1 must have a capavitor to ground.

The resistor from pin 7 to ground and pin 8 to ground must be in series with a capacitor to ground.

These things are shown in the datasheet.
 
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