Controlling volume of an amplifier..

[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.

[Ioannis]

Hi abidr,

nice project with the PGA device.

As I am lacking inputs for the many audio sources I have now (Mini disks, CD players, tuners, Tape cassete recorders, Phono, Pc, Mac etc) I need a pre-amplifier with many inpusts but also have the ability to send a selected input to a recording device independently. I need to have at least 3 outputs for recording while listenting to a 4th input. A little complicated and many relays but I think I will manage it. It will complement your design nicely!

Ioannis

[falingtrea]

Heh, for controlling volume, I would figure out a way to drive the volume knob with a servo. Less issues with audio quality that way.

[mister_e]

Nah.. no need for servo... there's some motorized pot and faders already available on the market. Penny & Giles are the really first that spring to mind (for faders). Almost sure that ALPS do some as well.

[abidr]

Ioannis:
I think what you have mentioned is not very difficult to achieve, but for that you ll need a bigger PIC like 16F877A and probably two ULN chips. I intend to make an input selector with a simpler PIC like 16F84A, but insted of relays I would like to use something like MPC507A or if I want to complicate circuitary I ll use something like SSM2404.
Here are a couple of PICs of the populated pre amp its a very small size PCB like 4.5x4.5 Inches.