Lm3875 RevC kit finished!

sumacSK · 6th December 2005, 12:45 PM

Hi all,

Here are pictures of my very first finished amp. It works really great. There is just one thing I don't understand: when I turn it off, few seconds after that it seems to turn on for a short while.
Do anyboy knows why is this?

Thank you all for your help.
Martin

sumacSK · 6th December 2005, 12:47 PM

and another one...

Russ White · 6th December 2005, 01:08 PM

Wow, thats a nice neat compact implementation. I am not sure I can diagnose your turn off problem, but I will mull it over.

Good job, I bet it sounds great.

tja · 6th December 2005, 01:47 PM

Quote:

Originally posted by sumacSK
There is just one thing I don't understand: when I turn it off, few seconds after that it seems to turn on for a short while.
Do anyboy knows why is this?

I've got the same thing with my (BrianGT) RevA. I switch it off (with the source still running) and the music dies after two seconds, only to come back from the grave after a few seconds, but just for a short while.

Take

sumacSK · 6th December 2005, 02:08 PM

Hi Take,

Yes, this is exactly what my amp is doing... Did you managed to fix it? Or I don't have to worry about it?

Thanks Martin

tja · 6th December 2005, 02:20 PM

No, haven't fixed it (I'm still in the proces of building the other channel), but I'm not too worried either. I'll be watching this thread to see if anyone has a solution (or just an explanation).

Take

DocLorren · 6th December 2005, 08:56 PM

No solution here, but just to let you know mine does the same thing and is running fine.
Maybe it has something to do with the chip shutting off after the inevitable voltage drop following a few seconds of playing music without power (the length depending on how much uF you have in your PSU), which could somehow recover in the electrolytic caps to give one more (very) short burst of music?

carlosfm · 7th December 2005, 01:04 AM

Quote:

Originally posted by DocLorren
No solution here...

Try bleeder resistors on the PSU.

DocLorren · 7th December 2005, 01:31 PM

Carlos,

That could very well be the solution although to a problem that I personally do not perceive as a one. Once you decide to stop listening, why not shut down all your equipment?
Or is there someone out there who insists that repeatedly powering up/down a GC is bad for music reproduction :-)

Nordic · 7th December 2005, 02:48 PM

Without the bleeders, if you switch the amp off regularly the capacitors stays in this neither fully charged or discharged state which is not good for them...

6th December 2005, 01:08 PM	#3
Russ White diyAudio Member Join Date: Jan 2005 Location: Nashville, TN, USA	Wow, thats a nice neat compact implementation. I am not sure I can diagnose your turn off problem, but I will mull it over. Good job, I bet it sounds great. __________________ Less pulp more juice Twisted Pear Audio.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
LM3875 Kit Finished - Could use some more bass	johan851	Chip Amps	91	31st March 2008 01:13 PM
Audiosector/Chipamp LM3875 or Mauro Penasa's My Reference RevC from Twisted Pear	blottojon	Chip Amps	14	8th March 2006 09:48 AM
LM3875-semi finished	enzedone	Chip Amps	17	16th February 2006 04:19 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

6th December 2005, 02:08 PM	#5
sumacSK diyAudio Member Join Date: Jun 2004 Location: Prague	Hi Take, Yes, this is exactly what my amp is doing... Did you managed to fix it? Or I don't have to worry about it? Thanks Martin

6th December 2005, 02:20 PM	#6
tja diyAudio Member Join Date: Feb 2004 Location: Leiden	No, haven't fixed it (I'm still in the proces of building the other channel), but I'm not too worried either. I'll be watching this thread to see if anyone has a solution (or just an explanation). Take

6th December 2005, 08:56 PM	#7
DocLorren diyAudio Member Join Date: Nov 2004 Location: Utrecht	No solution here, but just to let you know mine does the same thing and is running fine. Maybe it has something to do with the chip shutting off after the inevitable voltage drop following a few seconds of playing music without power (the length depending on how much uF you have in your PSU), which could somehow recover in the electrolytic caps to give one more (very) short burst of music?

7th December 2005, 01:31 PM	#9
DocLorren diyAudio Member Join Date: Nov 2004 Location: Utrecht	Carlos, That could very well be the solution although to a problem that I personally do not perceive as a one. Once you decide to stop listening, why not shut down all your equipment? Or is there someone out there who insists that repeatedly powering up/down a GC is bad for music reproduction :-)

7th December 2005, 02:48 PM	#10
Nordic diyAudio Member Join Date: Sep 2005	Without the bleeders, if you switch the amp off regularly the capacitors stays in this neither fully charged or discharged state which is not good for them...

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)