Controlling volume of an amplifier..

[Ioannis]

It looks like the people assembling that great radio, really liked what they were doing!

Imagine to have a production of this thing made by bare hands!

[ronjodu]

I wish I had seen this thread earlier as I would have given a thumbs up for the PGA2320 Volume control chip from TI. I have one of them running my Gainclone amp and couldn't be happier with it although I don't consider myself an Audiophile by any means.
I control it with 3 pushbuttons, increase gain, decrease gain and a third for Mute, all running from a 16f876.

Here are a few pictures.
The first is the PGA in action. The thing to the left is a programming dongle I use to cram stuff into the bootloader and the heavy white wire goes to a LM34 to take the temperature of the Amp chip.

The second is of the amp itself, a dual mono.
The third is a 7 segment display I'm toying with to show gain.

[ardhuru]

Not getting into the advisability of using (or not) a semiconductor for controlling the volume, my vote goes to the DS1869 http://www.maxim-ic.com/appnotes.cfm/an_pk/168

Its perhaps the simplest a digital volume control can get and has been working flawlessly for a couple of years in one of my apps.

Regards,

Anand

[ardhuru]

Realised as soon as I sent the earlier post...

The DS1869 is a single channel device.

Sorry for the irrelevant info.

Anand

[Ioannis]

The mono-stereo is a main concern. You may use another version of the same chip or two of them. What bothers me is the quality of the chip on audio content. It seems from the specs that is good for general use from dimmers to some audio control.

OK for a low spec audio preamp. But the PGA is dedicated to Hi-Fi.

Ioannis

[abidr]

Here is my approach to control volume of any amplifier, i have used DS1802 a digital pot from Dallas Semi with buttons control. No need for a microcontroller. These are schematics and layouts of the circuit, it uses five buttons mute, up, down, right, left.
I have three boards of the same. Using one of them with amy amp , a gainclone based on OPA549 and in realtime it really rocks.

[abidr]

Here is another approach, this is a pre amp and volume controller which uses PGA2310, an IR, switch to change input (a 4 input selectors) , PIC 16F876A, 16x2 LCD and rotary encoder.
Pre is complete, I have made the software in PIC Basic Pro, these days I am testing the code, once its complete I ll try to post it at the board as a help for others.