Gainclone sucking back Current - Page 2

Tensop · 12th May 2004, 05:05 AM

isnt mute meant to be coupled via a resistor and capacitor to -VE, not gnd?

janneman · 12th May 2004, 06:06 AM

When you bridged C3, the input cap, you made it a DC amp. Any stray DC from the preamp or whatever you drive it with is amplified. The advice given was NOT to take out C3, but to put a resistor from the +input to ground (22k was suggested). That will solve the unbalance in bias while still maintaining the AC coupling.
Be really carefull by doing random things, unless you fully understand the implications. The chip amps may be cheap, the speakers probably not.

Jan Didden

rayban68 · 12th May 2004, 03:18 PM

Yes, I was supposed to move R5, not short C3, but as it was easier to short C3 I did that instead. I figured that it wouldn't cause too many problems, since C7 ensures unity gain at DC. I also tried to connect a speaker with the input shorted and get the same results.

I will fix it properly (move R5, unshort C3) on my lunchbreak today and see if that helps at all.

I believe that R1 couples mute to -Ve and C1 to ground, as shown in the datasheet.

Thanks

peranders · 12th May 2004, 03:28 PM

Mr. rayban, in cases like yours and in many other also, I really recommend you to read the datasheet first and all application notes before you trust an unknown website and circuit design. Start with comparing and make up your own opinion. It can be hard to understand what the datasheet says but at least there usually is a typical application and connection.

Normally you have good info there to start with and if you want you can tweak" the design.

rayban68 · 12th May 2004, 03:58 PM

I thought I had read all the materials

This circuit is identical to the datasheet (other than my mixup with R5 and C3 which is now corrected)

I don't really want to tweak the design, well not yet anyways

, I just want to make it work properly.

12th May 2004, 06:06 AM	#12
janneman diyAudio Member Join Date: May 2002 Location: Where Germany, The Netherlands and Belgium meet Blog Entries: 6	When you bridged C3, the input cap, you made it a DC amp. Any stray DC from the preamp or whatever you drive it with is amplified. The advice given was NOT to take out C3, but to put a resistor from the +input to ground (22k was suggested). That will solve the unbalance in bias while still maintaining the AC coupling. Be really carefull by doing random things, unless you fully understand the implications. The chip amps may be cheap, the speakers probably not. Jan Didden __________________ /Another new issue: Linear Audio Volume 3!

12th May 2004, 03:28 PM	#14
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	Mr. rayban, in cases like yours and in many other also, I really recommend you to read the datasheet first and all application notes before you trust an unknown website and circuit design. Start with comparing and make up your own opinion. It can be hard to understand what the datasheet says but at least there usually is a typical application and connection. Normally you have good info there to start with and if you want you can tweak" the design. __________________ /Per-Anders (my first name) or P-A as my friends call me

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12th May 2004, 05:05 AM	#11
Tensop diyAudio Member Join Date: Jul 2003 Location: Chapel St.	isnt mute meant to be coupled via a resistor and capacitor to -VE, not gnd?

12th May 2004, 03:18 PM	#13
rayban68 diyAudio Member Join Date: Mar 2004 Location: Prince George, BC, Canada	Yes, I was supposed to move R5, not short C3, but as it was easier to short C3 I did that instead. I figured that it wouldn't cause too many problems, since C7 ensures unity gain at DC. I also tried to connect a speaker with the input shorted and get the same results. I will fix it properly (move R5, unshort C3) on my lunchbreak today and see if that helps at all. I believe that R1 couples mute to -Ve and C1 to ground, as shown in the datasheet. Thanks

12th May 2004, 03:58 PM	#15
rayban68 diyAudio Member Join Date: Mar 2004 Location: Prince George, BC, Canada	I thought I had read all the materials This circuit is identical to the datasheet (other than my mixup with R5 and C3 which is now corrected) I don't really want to tweak the design, well not yet anyways , I just want to make it work properly.

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