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-   -   My First LM3886 GC (http://www.diyaudio.com/forums/chip-amps/124111-my-first-lm3886-gc.html)

samsagaz 1st June 2008 12:53 AM

My First LM3886 GC
 
Hi guys, im using the Schematic that i found in the Datasheet of the LM3886, its how i draw it

http://www.proyectosdiy.com/_tmp/sch.pdf

and i draw the PCB using just one side in that way

http://www.proyectosdiy.com/_tmp/pcb.pdf


can someone please tellme some tips about the Sch and PCB?

i dont know if can add something to the schematic to get it sound better.

or if can fix something in the PCB, im now on this :)

Thanks in advance

Dino-Indo 1st June 2008 01:31 AM

2 Attachment(s)
Hi Samsagaz,

May I propose the attached PCB Layout..
I didn't built it myself... purchased local from an Indonesian supplier here.. but probably you could try to implement it...

It sounded really good... I'm using some Riken MetalFilm 0.5 Watt resistors and some Elna RE3 blue capacitors 1000 uF/50V (for power supply smoothing caps on C 9 and C 10).

And instead of placing 0.1uF MKM poly cap on C7 and C8 also installed additional Elna RE3 blue capacitors 1000 uF/50V on C7 and C 8 position and then putting the 0.1uF cap below of the PCB at the feet of these additional 1000uF caps...

Good Luck!!

sneih 1st June 2008 03:34 AM

hi dino i'm confuses about caps position on C3 at your picture attached!

that's show polar like + - - +

is it right position?

Dino-Indo 1st June 2008 04:35 AM

Yes..:D you are right..
I installed them back to back.. so it's become non polar (?)
Hehehe..
But it does sound good...

sneih 1st June 2008 04:46 AM

u mean: - + , -+ ?


thx!!

Dino-Indo 1st June 2008 05:22 AM

Nope... just follow the silk screen/top face of the PCB (the green one).. So the lay out will be + - - +
:D
Good luck!!

neutron7 1st June 2008 06:26 AM

If you dont need the extra few watts,

if you can still get them, the Lm3875 in my OPINION has a much smoother sound than the 3886

sneih 1st June 2008 10:12 AM

Quote:

Originally posted by Dino-Indo
Nope... just follow the silk screen/top face of the PCB (the green one).. So the lay out will be + - - +
:D
Good luck!!

thx
btw i also have this pcb n still in progress

my problem:
honestly i have 3-4 part that they included but not in pcb....
n i dont know how to install them
ex:
- C4: 47pF-50pF = that seems not in the pcb..

- C5,9,10: 100uF/50V = where i install this part? replace with 1000uf?

- R4, R6: ??

samsagaz 1st June 2008 12:24 PM

i will build LM3875 too, i wanna test diferents GC.

and want to build my own PCB in all the cases.

But i just dont know if the Datasheet schematic are the best choice, ir can be improved.

Regards

Puffin 1st June 2008 12:50 PM

samsagaz. Build a simple gainclone first, get to know the pin layouts intimately. Then start to experiment with different resistor feedback values, cap values etc.

I have just spent the best part of 2 days trying to make my second bridged gainclone (first was with LM3886's, this time with LM3875's). No sound, then lots of noise, then no signal input, rebuilt the thing 5 times ! Just got it working and it sounds fantastic (of course) I can go and eat now !.


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