Stereo LM3886 amp who wants to be mono!

[Gabster]

I have the Orcad Layout for the circuit above (pictured in first message...maybe you'll want to remove some caps!). If you want it, simply email me.

 

[joensd]

when i have had this problem it has been from a Ground loop or Instability in the Amp. My first recomendation is put a series resistor of about 2k between the Amp's input and the Pot's wiper, if no effect then a pair of 10 ohm resistors between each RCA jack's ground and the ground wire going to the Amp Board. make sure that the RCA jacks are insulated from the Chassis with washers. (real Importent). BTY what circuit did you use for the Bridge LM-3886 Amp?

Thanks PPL!
This finally made my amp work perfectly (the 2*10Ohm resistors).
I even had this strange hum with just a cable connected, no source. How can I understand this? The cable acting like an antenna?

Jens

 

[Squalish]

The LM3886 is just a powerful opamp.
Simply design one LM3886 as a non-inverting amp with a certain gain, and then design another LM3886 as inverting with the same gain.
The output of the non-inverting is the +ve to your speaker, the inverting is the -ve.
Easy.

Beware, you cannot power 4ohm loads with 2 bridged LM3886s as the overcurrent protection on the IC will cut in and clip the signal.
You can however, use 4 LM3886s in bridge/parallel to power 4 and 2 ohm loads.

Could you elaborate on this? Is it only at the top end of the amp's range(IE, 40 watts would be fine, 90 would clip)?