my paralell LM4780!

sasmit · 3rd May 2009, 06:31 AM

thought i should start a thread of my own...although a simmilar one exists by BrianGT..

sasmit · 3rd May 2009, 06:33 AM

I have made a pcb using national's art work as a guide, it may not be upto scratch..it works without any hum hiss and sounds good too.. comments welcome..

sasmit · 3rd May 2009, 06:38 AM

the pcb with components in place...a few changes have been made after the pic..decoupling caps near IC replaced with monolithic ceramics in place of film.

jamesjmcgee · 4th May 2009, 12:06 AM

I like the way the chip is mounted, thats waht i need for the system I'm building. How does it sound?

sasmit · 4th May 2009, 03:46 AM

sounds pretty good...the benchmark being my earlier amp based on TDA1514A and my Sony DHC-AZ55D. It's dead silent...no hum no hiss at all !

sasmit · 4th May 2009, 03:50 AM

btw although the way the chip is mounted will remain that way , I will be using a larger heat sink in actual use..it's twice as large.

AndrewT · 4th May 2009, 11:18 AM

have another look at the trace and lead lengths connecting C1 to C2, the HF decoupling.
The traces are too long resulting in excessive inductance.

sasmit · 4th May 2009, 11:27 AM

ya...tat ground trace is a bit long,but the caps are close the chip pins for +ve and -ve rails. I haven't had any issues though, with oscillations even with inputs open....which would occur with inductance in traces.. right ?

AndrewT · 4th May 2009, 11:58 AM

Quote:

trace and lead lengths connecting C1 to C2,

yes, the C1 & C2 decoupling are close to some of the power pins. But look how far apart they are.
The zero volts of the decoupling should be connected to each other. It's the way the currents want to flow. The decoupling is like a temporary battery for very short term transients.

kuldeepsingh · 5th May 2009, 02:14 AM

good work,

did u assembled the PCB once send by me, how did that sound compared to this reference schematic

3rd May 2009, 06:31 AM	#1
sasmit diyAudio Member Join Date: May 2006	my paralell LM4780! thought i should start a thread of my own...although a simmilar one exists by BrianGT..

5th May 2009, 02:14 AM	#10
kuldeepsingh diyAudio Member Join Date: Aug 2006 Location: Chennai, India	good work, did u assembled the PCB once send by me, how did that sound compared to this reference schematic __________________ . . .. ... ..... ........ ............. ..................... .................................. My Blog

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4th May 2009, 12:06 AM	#4
jamesjmcgee diyAudio Member Join Date: Jan 2009	I like the way the chip is mounted, thats waht i need for the system I'm building. How does it sound?

4th May 2009, 03:46 AM	#5
sasmit diyAudio Member Join Date: May 2006	sounds pretty good...the benchmark being my earlier amp based on TDA1514A and my Sony DHC-AZ55D. It's dead silent...no hum no hiss at all !

4th May 2009, 03:50 AM	#6
sasmit diyAudio Member Join Date: May 2006	btw although the way the chip is mounted will remain that way , I will be using a larger heat sink in actual use..it's twice as large.

4th May 2009, 11:18 AM	#7
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	have another look at the trace and lead lengths connecting C1 to C2, the HF decoupling. The traces are too long resulting in excessive inductance.

4th May 2009, 11:27 AM	#8
sasmit diyAudio Member Join Date: May 2006	ya...tat ground trace is a bit long,but the caps are close the chip pins for +ve and -ve rails. I haven't had any issues though, with oscillations even with inputs open....which would occur with inductance in traces.. right ?