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-   -   LM1876T diy HiFi amplifier build, questions, PCB, components, so on.. (http://www.diyaudio.com/forums/chip-amps/228379-lm1876t-diy-hifi-amplifier-build-questions-pcb-components-so.html)

Mihkus 22nd January 2013 06:39 AM

LM1876T diy HiFi amplifier build, questions, PCB, components, so on..
 
Heya everyone, yesterday i ordered single LM1876T chip to change TDA7265 wihich sounds terrible, speakers are rubbish too Defender mk35 somekind of Hi-Fi they say...
Well i removed the preamp JRC4558 known as worst opamp known to man but great for guitar applications.

Now i designed single sided PCB with fillet plane ground...
Now sure if everything is okay, well... PINout taked from datasheet and also SCH
they say LM1876B pinout is shown...

Heres the PCB ive designed, may have lots of mistakes...:o

Non inverting or negative - input caps 2,5mm ones on board are hooked with ground.
Also there are few jumpers one on input other on the output side.

http://s8.postimage.org/bio9zlzrp/pcb.png
free image hosting

pra3718 22nd January 2013 07:32 AM

Quote:

Now i designed single sided PCB with fillet plane ground...
How about star grounding ? If mute=not connected then take care about pop. You don't need Rin ? Is it possible to move Cs (electrolytic + ceramic) to power pins ?

Mihkus 22nd January 2013 07:44 AM

Yeah, star grounding may be best solution, right now i have thin rail going to pin 10...
We can move everytihing on board, im new to this PCB designing thingy, well i have made few amps, DAC's, preamps and so on but making PCB with minimal amount of space and without knowing what the heck is the difference between LM1876T and B
Took pinout from B type...

pra3718 22nd January 2013 07:56 AM

Quote:

difference between LM1876T and B
LM1876T = non-isolation package.

Is that lm1876b ?

Mihkus 22nd January 2013 08:17 AM

This is LM1876T i was sure it not sealed.
What to i need to to with mute function?
Just leave it?

Mihkus 22nd January 2013 09:30 AM

Now, still like fillet...

My own last result, may be totally wrong...
http://s7.postimage.org/j63nl9x4r/pcb2.png
upload foto

AndrewT 22nd January 2013 09:42 AM

The two film caps on the +ve & -ve rails are in the wrong place.
They should be on or at the Power Pins of the Chip.

Mihkus 22nd January 2013 11:17 AM

Well, how about that?
http://s2.postimage.org/531oif5dl/pcb4.png
online photo sharing

Yellow lines on pads are jumpers..

abraxalito 22nd January 2013 11:32 AM

Using a groundfill means you'll get crap sound because the noise currents from the input socket are going via the caps (C1, C? unmarked) to gnd. Shared ground impedances suck worse than TDA7265s for sound. I get fairly decent sound out of the bass/mid driven by my TDA7265s, the tweeter sound though is very, very dull.

Mihkus 22nd January 2013 03:23 PM

Then i should use 2 separated grounds input ground and supply ground?


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