LM4780 SS Pcb - Page 6

pinkmouse · 11th December 2006, 02:32 PM

I've never bothered, I just use 5% for outputs

mhennessy · 11th December 2006, 02:32 PM

Quote:

Originally posted by CarlosT
Da**! I've never seen .1% resistors...you guys sure you're not talking about 1%?

Yes, they exist - for example the RC55Y series. And they're expensive - nearly a pound each. But the point is, you don't need to buy them - you'll be able to find enough in a batch of standard 1% components that are well-enough matched.

Quote:

Originally posted by jaste
So the low-value output resistor is hard to meashure, maybe I´ll get that one from 0.1% department rigth away tehn, or do the even exist in that tolerance?

I've never seen better than 5% for those, but who knows what's out there given enough cash? Trouble is, at those values, the component leads and PCB tracks have a comparable resistance. I was able to match up components quite well from a batch of 5% parts... I used a current source and voltmeter to make the measurements

jaste · 11th December 2006, 03:23 PM

so how important are the matching of the output resistors, should be as important as any?

CarlosT · 11th December 2006, 03:24 PM

What's an output resistor?

gmphadte · 12th December 2006, 08:57 AM

Refer sch at post #34
R11 and R12 are output resistors and u will use them for parallel mode operation only. If you want to make a stereo version do not install them.
At no time u should connect all the 3 speakers even if it is shown. U either connect the middle only with R11 and R12 installed or connect the top and bottom speakers(Left and Right) without R11 and R12.

Gajanan Phadte

pinkmouse · 12th December 2006, 09:04 AM

Quote:

Originally posted by gmphadte
At no time u should connect all the 3 speakers even if it is shown.

Indeed.

jaste · 12th December 2006, 09:56 AM

Just making sure I got it right, the thing called "J" in the scheme is just a wire to connect the two sides if you wanna go parallel?

pinkmouse · 19th March 2007, 12:24 PM

Discussion of pirate SW removed to Texas

baskiria · 19th March 2007, 12:25 PM

Thanks pinkmouse

11th December 2006, 02:32 PM	#51
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	I've never bothered, I just use 5% for outputs __________________ Al There is science, logic, reason; there is thought verified by experience. And then there is California. Edward Abbey

19th March 2007, 12:24 PM	#58
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Discussion of pirate SW removed to Texas __________________ Al There is science, logic, reason; there is thought verified by experience. And then there is California. Edward Abbey

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11th December 2006, 03:23 PM	#53
jaste diyAudio Member Join Date: Dec 2005 Location: Stockholm	so how important are the matching of the output resistors, should be as important as any?

11th December 2006, 03:24 PM	#54
CarlosT diyAudio Member Join Date: Oct 2006	What's an output resistor?

12th December 2006, 09:56 AM	#57
jaste diyAudio Member Join Date: Dec 2005 Location: Stockholm	Just making sure I got it right, the thing called "J" in the scheme is just a wire to connect the two sides if you wanna go parallel?

19th March 2007, 12:25 PM	#59
baskiria diyAudio Member Join Date: Jan 2006 Location: budapest	Thanks pinkmouse

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