The LM4780 is just two LM3886 in one package. The biggest drawback for a new design is that the LM4780 is not made anymore.
The newest TI model of the LM3886 the mute pin doesn't work at all and the amp is always unmuted.
I am trying to see the advantage of the additional opamps that are needed for this design.
The newest TI model of the LM3886 the mute pin doesn't work at all and the amp is always unmuted.
I am trying to see the advantage of the additional opamps that are needed for this design.
Interesting about the mute!
The opamps remove any requirement for coupling caps except at the input.
The opamps remove any requirement for coupling caps except at the input.
The parallel86 is not inverting, has only one servo for both of the halves of lm4780 and uses no coupling capacitors. mod86 uses lm3886 and has no coupling caps, take a look here:
Modulus-86 Rev. 2.2: Composite amplifier achieving 65 W (4 Ω) at 0.00006 % THD.
Modulus-86 Rev. 2.2: Composite amplifier achieving 65 W (4 Ω) at 0.00006 % THD.
OK, guys. Please, please forgive an ignorant post. I purchased the red LM4780 boards that Peter and Brian designed many years ago. I assembled them, and when voltage is applied you can hear a faint turn on thump, but it will not pass a signal. I am assuming the chips are in muted mode. I am unsure of the means necessary to turn the mute function off, as indicated by the diagram on the datasheet. Pins 14 and 20 are mute function. Do I apply voltage to them, or ground them to unmute the signal path?
See MUTE MODE section in data sheet below (page 16).
As I read it, connecting to the negative through a resistor enables audio.
Good luck!
https://media.digikey.com/pdf/Data Sheets/Texas Instruments PDFs/LM4780(TABD).pdf
As I read it, connecting to the negative through a resistor enables audio.
Good luck!
https://media.digikey.com/pdf/Data Sheets/Texas Instruments PDFs/LM4780(TABD).pdf