I would like to share with you my new home made chip amp. Its based in a LM3886 chip.
I made the housing all in steel plate, very cheap and easy to find. The painting is in epoxy powder:
Everything assembled inside the housing. I assembled the amp circuit and power supply in a acrylic plate, witch is easier to drill and fix with bolts and nuts.
Two chips for stereo, one chip for subwoofer:
Power supply: an old transformer from a vintage receiver and two 10000uF 63v EPCOS capacitor hidden under the board.
Rear view. Heatsink visible for style an cooling.
Amp board:
Front view with stereo VU meter. The knob isn’t functional yet, but it is intended to control the subwoofer level. Instead using a regular LED for power on, I used a LED inside a optical relay box and connected to the front panel using a fiber optic. Very distinctive and bright.
I used the project shown in www.chipamp.com , and this power supply:http://www.chipamp.com/docs/lm3886-manual.pdf
It sounds very nice! I measured around 55w @ 8 ohms using 33V per rail
I made the housing all in steel plate, very cheap and easy to find. The painting is in epoxy powder:
An externally hosted image should be here but it was not working when we last tested it.
Everything assembled inside the housing. I assembled the amp circuit and power supply in a acrylic plate, witch is easier to drill and fix with bolts and nuts.
An externally hosted image should be here but it was not working when we last tested it.
Two chips for stereo, one chip for subwoofer:
An externally hosted image should be here but it was not working when we last tested it.
Power supply: an old transformer from a vintage receiver and two 10000uF 63v EPCOS capacitor hidden under the board.
An externally hosted image should be here but it was not working when we last tested it.
Rear view. Heatsink visible for style an cooling.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Amp board:
An externally hosted image should be here but it was not working when we last tested it.
Front view with stereo VU meter. The knob isn’t functional yet, but it is intended to control the subwoofer level. Instead using a regular LED for power on, I used a LED inside a optical relay box and connected to the front panel using a fiber optic. Very distinctive and bright.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I used the project shown in www.chipamp.com , and this power supply:http://www.chipamp.com/docs/lm3886-manual.pdf
It sounds very nice! I measured around 55w @ 8 ohms using 33V per rail
I have never have built a chip-amp; but the conventional trend is to mount
the feedback resistor onto the leads of the chip itself or on the
board as close to the leads as possible (for stability). It is entirely
possible that the new generation of chip-amps are far more immune.
But it works. . . "don't fix it if it ain't broken!"
Found an interesting article on the internet about using a T-Network
for the feedback path instead of a simple resistor. . .interesting!
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone7.html
the feedback resistor onto the leads of the chip itself or on the
board as close to the leads as possible (for stability). It is entirely
possible that the new generation of chip-amps are far more immune.
But it works. . . "don't fix it if it ain't broken!"
Found an interesting article on the internet about using a T-Network
for the feedback path instead of a simple resistor. . .interesting!
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclone7.html
Speed is not the problem. Longer paths result in higher impedance, meaning the resistance, capacitance and inductance are increased. This causes phase shifts which may result in instabilities. The feedback loop is especially critical because we're talking about the return path of the signal. Thus, the feedback loop should be kept as short as possible.
Say, you don't experience any motorboating on your amp? Just curious...
regards,
Dan.
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