lm3886 no mute

[rtill]

hello,
curious if I don't want the mute option with the lm3886, do I just connect pins 4 and 8 together to the V- rail?

[Redshift187]

I think you should use a current limiting resistor. It's common to use a resistor and capacitor to slow down the turn on, which will (usually) get rid of turn on thumps.

[rtill]

thanks, works now! I do have a question in regards to using it as a guitar power amp coupled to a tube preamp. If I turn the volume past 2, it starts to break up/cut in and out. I am assuming my load is too big. What can I do? couple it with a 470k resitor?

[pacificblue]

Originally Posted by rtill

What can I do? couple it with a 470k resitor?

Couple what with a 470k resistor?

Is the heatsink big enough? What is the supply voltage? What is the load impedance? What value is the mute resistor? Is volume setting 2 already pretty loud?

Schematic? Photos?

[AndrewT]

why are two threads discussing the same query?

[jaycee]

Use a 22K resistor between MUTE and -V. Having none will burn out the chip.

[rtill]

found my mistake, using a 30-0-30 tranny. puts it at the edge of it's limits. Will downgrade to a 20-0-20 tranny.
One more question....
I don't want stereo - can I connect the inputs and outputs of two chimpamps and get double the watts? Stupid question, but I'm here to learn. And do they both need seperate power supplies or can they use just 1 or will there be sag unless the tranny can supply enough amps?

[Redshift187]

Yes you can, you can parallel, bridge or both (with 4 or more chips). Why don't you want stereo?

[rtill]

why not stereo? - cuz I am running a mono 4x12 4 ohm cab.
so I can use the same power supply?

[AndrewT]

if you need the power of

a mono 4x12 4 ohm cab.

then you need the power and heat dissipation ability of a discrete output stage.
An alternative would be to power EACH driver from it's own dedicated chipamp. This too will need a big sink/s if you plan sustained SPLs.