LM1876, LM4765 with PSU based on pinkmouse

pra3718 · 14th October 2012, 03:01 PM

Chip amp is based on pinkmouse pcb, nothing new here. But I am using first time twin rectifier bridge.

1. 1000uf at power supply and 1000uf at near pins.

2. Same power supply may be use for active crossover with 78xx, 79xx

3. I am going to try for LM1876.

AndrewT · 14th October 2012, 03:14 PM

the HF decoupling must be small and must be very close to the power pins.
If the caps are not small then they can't be fitted very close to the power pins.

The MF decoupling does not need to be quite so close because the HF decoupling fills out the gap between initial demand and the reaction time of the MF decoupling. But the MF stills need to be fairly close. Big caps prevent this closeness.
Most recommend MF decoupling of around 100uF to 220uF, 1mF is rather unusual for MF.

If you plan 1mF as well as 100uF and 100nF, then OK but do install them at the most appropriate locations so that they each can do their job well.

1mF of smoothing is unusually low. Even Peter uses more for his rather different implementation. 4m7F to 15mF is more usual for smoothing.

pra3718 · 15th October 2012, 04:15 PM

@AndrewT, Normally I use speaker ground is powerground. Powerground and single/input ground connect with 1R 1/4 watt resistor. Just for try I used speaker ground from single/input ground it's sound good but 1R resistor running hot. If I use bigger 5 Watts resistor then should I think it would run for log ?

Best Regards.

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14th October 2012, 03:14 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	the HF decoupling must be small and must be very close to the power pins. If the caps are not small then they can't be fitted very close to the power pins. The MF decoupling does not need to be quite so close because the HF decoupling fills out the gap between initial demand and the reaction time of the MF decoupling. But the MF stills need to be fairly close. Big caps prevent this closeness. Most recommend MF decoupling of around 100uF to 220uF, 1mF is rather unusual for MF. If you plan 1mF as well as 100uF and 100nF, then OK but do install them at the most appropriate locations so that they each can do their job well. 1mF of smoothing is unusually low. Even Peter uses more for his rather different implementation. 4m7F to 15mF is more usual for smoothing.

15th October 2012, 04:15 PM	#3
pra3718 diyAudio Member Join Date: Jan 2009	@AndrewT, Normally I use speaker ground is powerground. Powerground and single/input ground connect with 1R 1/4 watt resistor. Just for try I used speaker ground from single/input ground it's sound good but 1R resistor running hot. If I use bigger 5 Watts resistor then should I think it would run for log ? Best Regards.