3886 P2P à la Decibel Dungeon

[Tripmaster]

Hi

I have scavenge through my parts bin and have found enough parts to build a point-to-point chip amp. I will be following Nick's 3886 layout but I have a quick question regarding the value of two resistors.

Building a Gainclone chip amp with the LM3886 chip.

Earlier this year I built a pair of Pedja Rodic's discrete 27vdc regulated power supplies. Nick suggests attaching a 18-22K resistor to the negative supply pin if using a 35-37v. What value should I change this resistor to if the DC supply is 27 volts?

His diagram also displays a 47-100K resistor between the star ground and input. Is there a optimal value?



Thanks

[wintermute]

I'm using 10K with 28v rails (simply copied what briangt used).. you basically need to ensure that pin 8 gets 5mA of current or the mute will still be functioning (to a degree). The higher the resistance value (above what will allow 5mA) the more muted the circuit will be...

I've attached a graph from the datasheet, there is more info (including a formula for calculating the correct resistance value) in the datasheet.

Tony.

[Tripmaster]

Originally Posted by wintermute

I'm using 10K with 28v rails (simply copied what briangt used).. you basically need to ensure that pin 8 gets 5mA of current or the mute will still be functioning (to a degree). The higher the resistance value (above what will allow 5mA) the more muted the circuit will be...

I've attached a graph from the datasheet, there is more info (including a formula for calculating the correct resistance value) in the datasheet.

Tony.

Thanks. Sorry for not replying sooner!