my lil p2p lm3886

[wazzy]

thought i would have a go it was pretty successful, almost totaly silent at max volume, decent sound. wiring was not very neat but it worked! i put it in an old inverter case. please let me know what you think.

[madmonda]

Nice work. I just received a couple chips in the mail. I'm gonna have a go at p2p in the near future. Let's see the casework too!

[AlexQS]

Wow. Point to Point sounds like fun. What are you using for powersupply?

[wazzy]

for the power supply i used a transformer salvaged from an old 'hifi' i put it in an old ups box with 20000uF capacitance, i got about 30 volts per rail unloaded. here's the case, it's a little rough, my first go please be kind the small one on top is a lm1875 in an old external drive box.

[HIPCHECK]

I enjoy it! I like the " I did not buy it look", also. I like finding parts to use in builds also. Really like doing DIY projects and finding a use for electrical equipment that would otherwise be sent to landfills or waste. There is so much electrical equipment that needs to be put to use.

Enjoy your amps!!!

[wazzy]

recycling! only thing i bought new were the lm3886s.

[gootee]

I'm not surprised that it's quiet, because you did everything right by twisting together all of the wire pairs, so they wouldn't act as antenna loops. Great work.

Also, I love that the local decoupling caps are so close to the chips. What values did you use, there?

How long are the power and ground wires from the chips to the PSU caps?

How did you route the grounding?

Did you run additional separate ground wires from the chip input ground reference points back to the PSU ground?

Where do the speaker ground returns connect?

[lanchile]

Very nice wazzy!!! it feels good to build a diy amp point to point . Enjoy your diy amp!

[AndrewT]

Yes,
it would help us to see a diagram of how you did the wiring up.

[wazzy]

Originally Posted by gootee

I'm not surprised that it's quiet, because you did everything right by twisting together all of the wire pairs, so they wouldn't act as antenna loops. Great work.

Also, I love that the local decoupling caps are so close to the chips. What values did you use, there?

How long are the power and ground wires from the chips to the PSU caps?

How did you route the grounding?

Did you run additional separate ground wires from the chip input ground reference points back to the PSU ground?

Where do the speaker ground returns connect?

i knew about twisted pairs from a little pa experience, my thinking was that i could use smaller value 1500uF local decoupling capacitors of decent quality and then cheaper ones for bulk storage in the remote supply, the small film ones are 33nf no reason other than i had them. the power and ground wires are 350mm long, the speaker grounds connect directly to the ground plane where the local decoupling caps are, the input grounds are also connected there but with a longer line to lift the ground slightly. seems to work pretty well, i came to this arrangement by trying all different schemes, for me this one seemed to work well, less chance of loops i think. i'm not a electronics boffin, i figure stuff out with my hands. thank you for your feed back.