Power amp based on LM1875

Started by tombaker, September 25, 2013, 09:16:30 AM

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tombaker

Hi,
Has anyone made a power amplifier based around this chip (LM1875).
There is a schematic on the datasheet:

http://www.ti.com/lit/ds/symlink/lm1875.pdf

I'm looking for a power amp circuit to go after an Alto Mini-tube preamp. Just wondering if anyone has used this chip or has made this circuit.

I whipped up a small vero layout although that's probably not ideal for an amp and I would imagine the power supply would be fairly important as well.

Blue Box, Harmonic Perculator, Brian May Treble Boost, Klon Vero, Fuzz Face Germ/Sili, Echo Base Delay, CS-3 Monte Allums Mod, JLM 1290 Mic Pres, JLM Mono Mic Pres, Engineer's Thumb, A/B/C & A/B boxes, Tiny Giant Amp, Microamp

Johan

Great chip.used it many times...get a proper heat sink for it though, it produceses 6 watts of heat at idle...
J
DON'T PANIC

tombaker

awesome thanks will do.
What voltage Psu did you use and did you make a single or dual supply circuit?
Blue Box, Harmonic Perculator, Brian May Treble Boost, Klon Vero, Fuzz Face Germ/Sili, Echo Base Delay, CS-3 Monte Allums Mod, JLM 1290 Mic Pres, JLM Mono Mic Pres, Engineer's Thumb, A/B/C & A/B boxes, Tiny Giant Amp, Microamp

psychedelicfish

I made one on +-20V from a centre tapped 15V transformer, I gave up on it after problems with fried chips and instability. Make sure you have power supply filtering caps close to the chip, and the input and output caps close to the chip as well.
If at first you don't succeed... use bigger transistors!

Morocotopo

I made a power amp with the PCB included in the datasheet, the single supply one. Worked perfectly. Big heatsink. Never boxed it but should have, would be a really useful mid power amp. Íf made with vero, you should be careful with the traces that carry the high current, make them wider or something, and stick witht the datasheet grounds schem so as to avoid hum and loops.
Morocotopo

tombaker

Awesome thanks guys,
I've been considering splitting the signal into two frequency shelves and giving each shelf an amp, theres definitely a proper term for that, which escapes me right now.
By adding a crossover or two active filters before each amp will that increase the power?
Blue Box, Harmonic Perculator, Brian May Treble Boost, Klon Vero, Fuzz Face Germ/Sili, Echo Base Delay, CS-3 Monte Allums Mod, JLM 1290 Mic Pres, JLM Mono Mic Pres, Engineer's Thumb, A/B/C & A/B boxes, Tiny Giant Amp, Microamp