Pot help needed

soundbabe · 4th April 2010, 12:59 PM

Hi guys,

Sorry I am a newbie In the field of amplifiers, So sorry If my questions are stupid.

I have designed a stereo amplifier using 2 LM3875. Now I want to know the miniumum of potentiometers I need for a such amplifier?
my guss is that I need a dual gang pot for Left/ Right speakers, and maybe another pot (do not know which kind) tp control the volume of both speaker simultaneity, right?? Any other pot needed?
for now I have no intention to add a tone control in my design.

Thanks a bunch for any help?

jethari · 4th April 2010, 01:38 PM

If you're not going in for any tone controls, then all you need is a volume control. You can either use a ganged pot to control the levels of both channels at the same time or you can use two single pots to control the the channels individually.
Hari

ChrisA · 4th April 2010, 05:03 PM

The minimum number of pots is two. A simple pot is used on each channel for L and R volume control. But then it requires two hands to control the amp's volume. If you don't like using two hands you could use one dual gang pot for one-handed control.

But with the dual gang volume control you can't adjust the relative volume of the two channels. So you may (or not) want to add a "balance control" which is just a dual gang volume control with linear taper and one side wired "backwards".

A lot depends on what controls, if any you have on the preamp.

I'm working on something now that will only have trim pots inside and zero external controls. Think about how you will use the amp

Many people will use the two handed system because it uses the minum number of parts and every part adds noise and degrades sound even f just a lttle and every part certainly adds cost and work to the project.

AndrewT · 4th April 2010, 05:09 PM

an integrated amplifier, containing both the pre-amp and the power amp has a volume control.
A power amp normally has no volume control.
All the control functions are usually in the pre-amp.

WWWJD · 4th April 2010, 11:53 PM

I used a 10k dual gang Alps pot for mine; works great, no ill effects.

I don't have a preamp. Built mine to accept RCA inputs or Bantam DAC USB from my PC. (selectable)

4th April 2010, 12:59 PM	#1
soundbabe diyAudio Member Join Date: Feb 2010	Pot help needed Hi guys, Sorry I am a newbie In the field of amplifiers, So sorry If my questions are stupid. I have designed a stereo amplifier using 2 LM3875. Now I want to know the miniumum of potentiometers I need for a such amplifier? my guss is that I need a dual gang pot for Left/ Right speakers, and maybe another pot (do not know which kind) tp control the volume of both speaker simultaneity, right?? Any other pot needed? for now I have no intention to add a tone control in my design. Thanks a bunch for any help?

4th April 2010, 05:09 PM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	an integrated amplifier, containing both the pre-amp and the power amp has a volume control. A power amp normally has no volume control. All the control functions are usually in the pre-amp. __________________ regards Andrew T.

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4th April 2010, 01:38 PM	#2
jethari diyAudio Member Join Date: Apr 2002 Location: Mumbai, India	If you're not going in for any tone controls, then all you need is a volume control. You can either use a ganged pot to control the levels of both channels at the same time or you can use two single pots to control the the channels individually. Hari

4th April 2010, 05:03 PM	#3
ChrisA diyAudio Member Join Date: Jan 2008	The minimum number of pots is two. A simple pot is used on each channel for L and R volume control. But then it requires two hands to control the amp's volume. If you don't like using two hands you could use one dual gang pot for one-handed control. But with the dual gang volume control you can't adjust the relative volume of the two channels. So you may (or not) want to add a "balance control" which is just a dual gang volume control with linear taper and one side wired "backwards". A lot depends on what controls, if any you have on the preamp. I'm working on something now that will only have trim pots inside and zero external controls. Think about how you will use the amp Many people will use the two handed system because it uses the minum number of parts and every part adds noise and degrades sound even f just a lttle and every part certainly adds cost and work to the project.

4th April 2010, 11:53 PM	#5
WWWJD diyAudio Member Join Date: Apr 2010	I used a 10k dual gang Alps pot for mine; works great, no ill effects. I don't have a preamp. Built mine to accept RCA inputs or Bantam DAC USB from my PC. (selectable)

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