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Aug 21, 2016, 08:10 PM
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Jack Crossfire's Avatar
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The Bax

Built a Baxandall tone control to try to get more treble. That did the job, but with severe distortion. The LM324 wasn't up to the job. The next step is an LF353 on a carrier board. The multiturn pots are quite impossible to center. Given the schematic for a Baxandall, simple resistor calculations give 40k when the pots are centered even though a standalone pot would give 50k. Fortunately, the only useful setting is maximum bass & maximum treble.

This is the only audio circuit the LM324 has had any problems with & the internet approves its use. Anyways, the virtual ground shows a bit of instability typical of the LM7805. Thought the distortion 10 years ago was caused by servos, but clearly it's not a perfect regulator. With the bass set to neutral, the distortion is more bearable than not having any treble. Would say the high end from the 1980's amplifier & Bax is clearer than the HTR-5230, but a true comparison with the HTR-5230 is impossible because it's dead.

Hollens family music is good at reproducing the distortion, because they have the high pitch voice & bassy piano.
Last edited by Jack Crossfire; Aug 21, 2016 at 10:36 PM.
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Aug 22, 2016, 12:21 AM
Waste Nothing
RickC_RCAV8R's Avatar
What are you trying to do with this project ? A rolling rc ghetto blaster ?

Try the BiFet OpAmps . Roll off everything above 12K at a slope of at least 12Db / octave . Have you ever tried an NDFL amplifier as a front end pre-amp ? Nested Delay Feedback Loop .

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