- 197 mV offfset on LA 4663

G33/33 · 12th April 2005, 06:49 AM

Friends,

I build an amp with LA 4663, and have - 197 mV offset on both channel. The schematic is taken from datasheet without any modification, only add a 10K potensiometer before input cap. What should I do to lowering the offset below 50 mV ?

I have search the archieve, but no one using this chip.

rgds,
Gede

Leolabs · 12th April 2005, 09:26 AM

what kind of chip is this????Do u operate it with dual voltage supply???

rinox · 12th April 2005, 02:43 PM

197 mV is simply nothing, don't worry about this offset.

G33/33 · 13th April 2005, 02:37 AM

Quote:

Originally posted by Leolabs
what kind of chip is this????Do u operate it with dual voltage supply???

No, this chip is designed for single supply.
You can download it's d/s from www.alldatasheet.co.kr or from Sanyo website. It sounds good enough for my ears. The output stage looks like a balance amp but may be i'm wrong about this.

Quote:

Originally posted by rinox
197 mV is simply nothing, don't worry about this offset.

Well, i can't confinced myself that 197 mv offset is nothing. Especially after reading Joe R posting about DC offset

rgds,
Gede

Tim__x · 13th April 2005, 06:26 AM

Looking at the datasheet, this chip runs into a BTL. Are you measuring the offset between output pins, or from one output to ground? Between outputs on one channel is the way you should be measuring it.

G33/33 · 13th April 2005, 06:45 AM

Quote:

Originally posted by Tim__x
Looking at the datasheet, this chip runs into a BTL. Are you measuring the offset between output pins, or from one output to ground? Between outputs on one channel is the way you should be measuring it.

Hi Tim,

I measure between output ( Output + and Output - ) on one channel, not ground.
If i measure to ground, it would be around 6,8 V with 15V supply, exactly as datasheet show.

rgds,
Gede

runebivrin · 13th April 2005, 09:11 AM

The spec sheet says the offset can be anything from -300mV to +300mV, so if you want lower offset you'll either have to change chip, or add a trim pot on the input to inject a small compensatory DC voltage.

Rune

G33/33 · 14th April 2005, 12:32 AM

[QUOTE]Originally posted by runebivrin
[B] if you want lower offset you'll either have to change chip, or add a trim pot on the input to inject a small compensatory DC voltage.

Hi Rune,

Do you mean add a trimpot after the input caps in series to the input pin or to Ground ?

I won't change the chip because I want to learn more on how to solve offset problem with chip amp

Gede

12th April 2005, 06:49 AM	#1
G33/33 diyAudio Member Join Date: Dec 2004 Location: Djakarta	- 197 mV offfset on LA 4663 Friends, I build an amp with LA 4663, and have - 197 mV offset on both channel. The schematic is taken from datasheet without any modification, only add a 10K potensiometer before input cap. What should I do to lowering the offset below 50 mV ? I have search the archieve, but no one using this chip. rgds, Gede

13th April 2005, 09:11 AM	#7
runebivrin diyAudio Member Join Date: Jul 2003 Location: Huddinge, Sweden	The spec sheet says the offset can be anything from -300mV to +300mV, so if you want lower offset you'll either have to change chip, or add a trim pot on the input to inject a small compensatory DC voltage. Rune __________________ Do wizards use spell checkers?

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12th April 2005, 09:26 AM	#2
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	what kind of chip is this????Do u operate it with dual voltage supply???

12th April 2005, 02:43 PM	#3
rinox diyAudio Member Join Date: Oct 2004	197 mV is simply nothing, don't worry about this offset.

13th April 2005, 06:26 AM	#5
Tim__x diyAudio Member Join Date: Jun 2004 Location: Edmonton area, Alberta	Looking at the datasheet, this chip runs into a BTL. Are you measuring the offset between output pins, or from one output to ground? Between outputs on one channel is the way you should be measuring it.

14th April 2005, 12:32 AM	#8
G33/33 diyAudio Member Join Date: Dec 2004 Location: Djakarta	[QUOTE]Originally posted by runebivrin [B] if you want lower offset you'll either have to change chip, or add a trim pot on the input to inject a small compensatory DC voltage. Hi Rune, Do you mean add a trimpot after the input caps in series to the input pin or to Ground ? I won't change the chip because I want to learn more on how to solve offset problem with chip amp Gede

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