LM3886 Balance Control

I'm assembling a two-channel (stereo) chipamp LM3886 kit following the user guide and am looking for a simple way to control the balance between L and R channels. For volume control I am using dual-ganged 25K pots on the amplifier input as recommended in the amplifier board schematic. As for balance control, my first thought is to use another pair of dual ganged pots, each between amp IN and GND (a CW turn attenuates one channel while increasing gain on the other, a CCW turn does the opposite) but it is not clear to me how well this will work or whether it is a good idea. Any suggestions? :rolleyes:


2011-11-17 3:49 pm
There are some very simple ways to implement a balance control if you don't want to add extra amplification into your design.

The simplest way is to use a dual linear track pot with each half wired in reverse to the other (ie one side is increasing in resistance as the other is reducing). One side can be connected from the wiper of the Left volume pot to ground and the other side from the wiper of the Right.

With the "Balance Pot" in its centre position, both sides will be attenuated equally. As you move the pot off centre one side will attenuate more than the other, and at the extreme ends of the pot one channel will disappear completely.

You will lose a bit of gain but that can be recouperated in the other stages.