LM1876T diy HiFi amplifier build, questions, PCB, components, so on..

Mihkus · 06:41 AM

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...

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.

free image hosting

pra3718 · 07:36 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 · 08:22 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...

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?

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?

22nd January 2013, 06:39 AM	#1
Mihkus diyAudio Member Join Date: Jul 2012	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... 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. free image hosting Last edited by Mihkus; 22nd January 2013 at 06:41 AM.

22nd January 2013, 08:17 AM	#5
Mihkus diyAudio Member Join Date: Jul 2012	This is LM1876T i was sure it not sealed. What to i need to to with mute function? Just leave it? Last edited by Mihkus; 22nd January 2013 at 08:22 AM.

22nd January 2013, 11:32 AM	#9
abraxalito diyAudio Member Join Date: Sep 2007 Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though... Blog Entries: 62	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. __________________ When a measure becomes a target, it ceases to be a good measure. C.A.E. Goodhart

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22nd January 2013, 07:44 AM	#3
Mihkus diyAudio Member Join Date: Jul 2012	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...

22nd January 2013, 09:30 AM	#6
Mihkus diyAudio Member Join Date: Jul 2012	Now, still like fillet... My own last result, may be totally wrong... upload foto

22nd January 2013, 09:42 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	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.

22nd January 2013, 11:17 AM	#8
Mihkus diyAudio Member Join Date: Jul 2012	Well, how about that? online photo sharing Yellow lines on pads are jumpers..

22nd January 2013, 03:23 PM	#10
Mihkus diyAudio Member Join Date: Jul 2012	Then i should use 2 separated grounds input ground and supply ground?

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