Quad channel volume control

[usul27]

Hi folks,

I've finished and testet the first prototype of my 4-channel volume control. It is designed to be used in my 4-way active speaker project, but can be used for any other project. It features optocouplers for the digital control connection to decouple the circuit from the controller.
It uses a PGA4311 and a OPA1664 input buffer. No output buffer is used, because the circuit should be located near the power stage.

Control has been tested from an Arduino and from the RaspberryPi - both work well. I'm thinking about a specific controller board designed just for this project.

Any comments?

Regards
Daniel

http://www.crazy-audio.com

 

[maxw]

Very nice!

What ICs did you use for opto isolation?
What will you use for a power supply?

 

[usul27]

I'm not sure about the power supply. For the tests I'm using a small LM317/LM337 based supply: SimplePower | Crazy Audio. Right now I'm creating a similar circuit with an integrated mains transformer and 100mA LM317L/LM337L which are powerful enough for this circuit (it uses < 20mA).

The Optocouplers are standard KB817 compatible. They are rather slow, but for this application that doesn't matter. Data traffic are only 32 bit per volume change. With the current configuration they should work up to 10-30kHz, but I'm using 1kHz at the moment to be on the safe side.

 

[usul27]

Started to code the control software, it is now available on GitHub (link on my site).

 

[maxw]

Started to code the control software, it is now available on GitHub (link on my site).

The link in your signature doesn't work.

 

[usul27]

Thanks, corrected this.
The link to the project site is Quad volume controle, PGA 4311 | Crazy Audio
The Arduino code is here: Controlling QuadVol with Arduino/Sparrow | Crazy Audio

 

[maxw]

Thanks, corrected this.
The link to the project site is Quad volume controle, PGA 4311 | Crazy Audio
The Arduino code is here: Controlling QuadVol with Arduino/Sparrow | Crazy Audio

Nice one!

 

[Nisbeth]

Very nice, thanks.

/U.

 

[usul27]

The final PCB should be here in some days, but at least I finished the power supply

Trafopower

 

[usul27]

P.S. Does anybody have an idea, why these images are squeezed?

 

[usul27]

My final version is finished now. Pictures will follow soon.

 

[usul27]

 

[usul27]

More infos on this project at Quad volume controle, PGA 4311 | Crazy Audio

 

[Earfanatic]

Very well made, congratulation.
Could use a remote control, some guys ask me from time to time, some want a solution to control their volume from a smartphone. I am sure I wont do it for them, but if you have such ideas, then those young diyers would love it.

 

[usul27]

For remote control using an mobile device, you could use the Raspberry Pi as an interface. The code to control this device from a Raspberry is just a few lines of Python code. A web app to change the volume should be not a big deal. Is anybody interested in it?
Here is the code to control it from a Raspberry Pi:
Controlling QuadVol with the Raspberry Pi | Crazy Audio

 

[rsavas]

Watch out for o/p glitching/noise at power up of the PGAx3xx series devices. Muting the part at power up does not solve this issue. This was verified by TI tech support.
If you have a high gain PA powered up and connected to speakers, as you are powering up the PGA4311, you or your speakers might not like what happens!!