LM1876

[pra3718]

Accepted solutions.

1) Ground Pin 5,10 shifted to power ground.
2) Zobel shifted to decoupling ground.
3) RF makes low input voltage, So instead of using RF I put 220pf between input pins. Pls. describe RF & 220pf (between input pins) functionality.
4) Lower value resistor sounds good to me. but it cut low bass. with the same value resister Post # 17 I can fit 2.2uf input cap. Anyway, now I have selected standard value resistor.
5) I am using 4R speakers and power supply voltage is 20VDC(+/-) I read datasheet and found if I increase supply voltage it produce heat instead of producing output-power. So I can get 22W of continuous average output power with less than 0.1%THD.

 

[pra3718]

Post # 21, is accepted solution, One confusion is there, Rin (47K) is important when Amp played without crossover. But not necessary with active crossover. Amp sounds good without those. WHY ?

 

[Robert Kesh]

Some of your caps are in backwards.

 

[pra3718]

Some of your caps are in backwards.

Sorry, not got it.

 

[AndrewT]

So instead of using RF I put 220pf between input pins. Pls. describe RF & 220pf (between input pins)

I don't like this solution. It increases the risk of amplifier misbehaviour, due to adding capacitance to the -IN Pin

Some of your caps are in backwards.

Power supply or feedback?

 

[Robert Kesh]

Power supply or feedback?

I'm sure if you look at the pcb and the amended pcb, both on this page, you can work it out for yourself.

 

[pra3718]

I don't like this solution. It increases the risk of amplifier misbehaviour, due to adding capacitance to the -IN Pin

Todays Job, RF added 220pf and between input pins removed.

 

[pra3718]

how to wire dual mono lm1876

Confusing part is 1R resister join clear & dirty ground. Configurable at Chip-amp or power supply. I tried my own way.... Pls comment.

 

[pra3718]

One channel Left-only build. Sounds good. There is not turn-on-off Noise detected when source not connected. Turn ON/OFF Noise is there when USB-DAC (Source) connected. So Noise coming from DAC ?

 

[AndrewT]

How about adding diodes across the 1r and across the DC blocking cap/s in the NFB and across the the power rails via PG and across the power rails via output/s rail?

Remove that loop in the signal routing. The Signal Return is half a mile from the signal hot !!!!!!!

 

[pra3718]

Remove that loop in the signal routing. The Signal Return is half a mile from the signal hot !!!!!!!

Updated.

I tried couple of times powered ON/OFF with source and without source connected. The speaker says I have powered ON. And sometimes silence. ( I should not call it POP )

When I need complete silence, I will have to use Amp's MUTE pin. I stared googling.... and found following link. I don't understand whether this circuit would work or not. But yes I can copy it. What is your opinion ?

ʹÓÃLM1876ÖÆ×÷СÐ͹¦·Åµç·ͼ -ÒôÊÓƵµç· -µç×Óµç·ͼÍø-µç×Ó¹¤³ÌʦҡÀº-רҵµç×ӵ緷¢²¼Õ¾

 

[Adi_007]

is enought a 18+18Vac for a bridge LM1876 or the voltage is to hight?....thanks

 

[pra3718]

is enought a 18+18Vac for a bridge LM1876 or the voltage is to hight?....thanks

LM3886 mono is good than bridge lm1876.

 

[Adi_007]

I allready have LM1876, from an old 5.1 system, and I want to use it.....

 

[pra3718]

Then, 20VDC / 1.4 = 15-0-15 AC for 8Ohm load.

 

[sofaspud]

The LM1876 is spec'd for 10V to 32V (20V-64V for single-supply) so 18-0-18 should be just about right for bridged use. I didn't run the math; it may be a tad high for effective 4-ohm load, but not so much to be a project killer IMO. Be extra generous when selecting a heat sink.

 

[riohardi0205]

hi.. may i ask your final pdf ? it's hard to get the pcb bottom for this chip. Much obliged.