LM1875 PCB, Which To Use

[Paswa]

Daniel, I support daniel, nordic is good guy, I should give him credit for building the PCB. So, I added his name too. : :whack

Now daniel, finally check my PCB before etching. Will it needs any changes?

[Paswa]

Nordic, Paswa: If you are having this PCB built - please add a few and set-up a wiki for us to buy. I'm interested in at least 6 single-channel boards. And if you can add the PS to a single board this would be heaven! thanks Bob

I dont know will nordic raise his PCB for sale or not.. But I'll not make it for sell. But I'll upload the expresspcb file for them, who wanna build the LM1875 PCB. well ?

[danielwritesbac]

Okay, Nordic has pointed out a possible error in that the ground for the input is stronger than the ground for the NFB (because of trace distance).
It needs an input star ground system. Okay.
There was also some mention about solving the problem by running the ground to between the centerpoint of both NFB and input.
I haven't figured this out.

[Paswa]

once again a non-sense quetion bcoz I'm a 100% newcomer in DIY audio,, that what is NFB ?

[AndrewT]

Negative FeedBack = NFB

[Nordic]

Hi Daniel, I seriously doubt it is audiable, but on some level it is sure to be measureable, but we have many new guys in the chipamp section so t is good to show good principles and best practices, something they can fall back on when experiments fail.

Anyhow I have played with the suggestion of an integrated board, and I think it is a good one...

THe PSU included is of CLC design and is similar to the one we use in the DX amplifier range.

If there is a demand I can have some boards made..., the cost is probably lower than elsewere in the world, but you need at least ten guys to share the setup cost between, then it can be as little as $2.50 setup + cost of the board wish is way less than Olimex...

I made it so that the board can be scored and snapped off it two seperate modules are required. and can be made as a 2 channel set with the PSU on opposing sides for symmetry.



I'm going out with a band now to one of their gigs, so I probably won't be able to finish this on before tommorrow...

[Paswa]

There was also some mention about solving the problem by running the ground to between the centerpoint of both NFB and input. I haven't figured this
out.

daniel, please explain it a litle or draw or edit my attached pcb image to show me the solution.. I can't figure it out

[Iván Francisco]

Hi Nordic:
Can I drive a pair of tweeters with your design, in a triamp project, without a dc protection circuit?
Thanks

[BWRX]

Of course you could. Just make sure that your source has little or no DC offset.

[Iván Francisco]

Thanks BWRX