Digitally-controlled stepped attenuator?

[Spasticteapot]

Hello, all!
I'm currently working on getting parts for a gainclone, and wanted to try getting a stepped attenuator for use for volume control, possibly in a preamp.
However, instead of using the standard-issue rotary switches, I'd like to try using a set of resistors and relays controlled by a microprocessor. (I'm also learning how to program these.) Using a remote, one could control which resistors were connected; by using a bunch of relays with SPST connections, they could be moved in and out of the circut. (When the relay's on, it would bypass the resistor).
Would this work? Also, could I use a set of relays for an input selector circut? I've got some PIC microcontroller gear, and it looks like might be easy (and fun!) to make a fancy-pants remote control system for a pittance. (10$ for the microcontroller, a few $ worth of transistors, and some relays harvested from old modems is all I'd need!)
Also, this might work rather nicely in conjunction with a built-in computer. I've got a small industrial computer board which would fit inside half of an old CD player enclosure quite nicely; with a gainclone on the other side and a DVD drive, I'd have a nifty little HTPC!

 

[VEC7OR]

To get your mind started:
http://www.mhennessy.f9.co.uk/preamp/analogue_research.htm
http://www.diyaudio.com/forums/showthread.php?threadid=21198
http://jos.vaneijndhoven.net/switchr/design.html

I'm also doing a similar project, you might wanna look here too http://www.diyaudio.com/forums/showthread.php?s=&threadid=74549

 

[myhrrhleine]

You might consider a digital pot.
Many IC manufacturers make them.
As for relays, why not use a IC switch?
4016 and 4066 (I think) are the part numbers.
An article by Doug Self showed them to be rather low distortion when used in a shunt configuration.

 

[Spasticteapot]

You might consider a digital pot.
Many IC manufacturers make them.
As for relays, why not use a IC switch?
4016 and 4066 (I think) are the part numbers.
An article by Doug Self showed them to be rather low distortion when used in a shunt configuration.

Interesting. I'd like to try two digital pots; can you point me to a simple circut? I'd like to do most of the stuff digtitally; that way, I can use a microcontroller and remote control on the cheap.
The chip switches also sound like an interesting idea.

 

[myhrrhleine]

Interesting. I'd like to try two digital pots; can you point me to a simple circut? I'd like to do most of the stuff digtitally; that way, I can use a microcontroller and remote control on the cheap.
The chip switches also sound like an interesting idea.

http://www.analog.com/UploadedFiles/Data_Sheets/101658858AD5290_0.pdf

 

[DcibeL]

There are several IC's like the PGA2311 which are basically a stepped attenuator in a chip. Easily controlled by a microcontroller.