Audio Systems: Automatic volume control, automatic volume control, analog world

Question
Hi Robert,

i have a CD player win which I have accumulated over 200 CD's from various sources. Therefore, they all aren't at the same volume. Is there a stand alone unit on the market that I can take the output from CD player, plug it into this unit, and then into the amp to keep the volume fairly constant? Or, is there unit can go between the amp and the speakers to balance out the volume?

Thanks for your expertise,

Don

Answer
Bingo. That's what we do. My company designs a computer that does that along with a myriad of other things. Unfortunately we only sell it commercially but we are about to license the software.

In the pseudo digital world of CD's, most of the consumer processing is analog because most people connect their CD player to an analog receiver. If you are not afraid of using pro equipment that operates in the digital domain, then you should see if there is a digital output from the CD player. If so you want to connect it to the digital input of a DSP. In a DSP you will have equalization in various modes, limiting, compression etc. Setting up the processor to provide you with the correct amount of leveling, either takes expertise or good ears and a lot of fiddling. The simpler poor mans route is working in the analog world. You would use a limiter/compressor and set the input level, threshold, compression ratio and output of the device to achieve leveling of CD's.

If you have the time and carefully read the manuals you can use any of these devices to accomplish leveling. The downside of not getting it right, are things like pumping effect on the sound. It will raise the nuances and lower the peaks of the music so essentially the level won't change. Our system... does not effect the dynamics so that everything sounds natural.