GroupDIY

General Discussions => Drawing Board => Topic started by: Norbert Wilkins on January 24, 2006, 01:43:15 PM

Title: Hacking old all-in-one hi-fi unit
Post by: Norbert Wilkins on January 24, 2006, 01:43:15 PM
Hi there. First post from me and I am hoping that I might be able to find someone to answer the following daftoid question. I have a moderate level of home construction ability but this is beyond me.

I have an old Pye music centre, bought in the mid to late 80s that stood me in relatively good service for a number of years but has long since been replaced by better kit. The turntable was mechanically noisy, the cassette heads permanently out of alignment and the controls crackled horribly at every touch but for some reason I could never bring myself to throw the old beast away. It is under the desk I am currently sitting at, wrapped in a protective bin bag.

A great many of the vinyl to cassette transfers I made using this unit sound better than the original vinyl records, with an added sense of presence and vitality. I assume that this is primarily down to the action of the built in automatic level control, which cannot be overridden in normal use. As I am keen to build or locate both a tracking and a mix-buss compressor for home studio use I was wondering if anyone thought I might be able to use part of the circuitry from the Pye audio centre as an experimental preset stereo compressor? Does anyone know what this part of the circuit is likely to look like, and how easy would it be either to replicate that section on a breadboard or hack the entire circuitboard to offer stereo in and stereo out?

I figure that if I take the second option, I could, by means of miniature audio transformers or op-amp buffer stages apply a signal directly to the external inputs and by hardwiring the switch configuration derive a buffered output signal from the wires feeding the tape record heads, which may or may not require an extra level of amplification or attenuation. I figured that if I took this approach I could add a gain control (and replace the balance control with two matched resistors) at the head of the signal chain and thereby achieve some measure of control over the operation of the unit, and also rehouse the existing power supply as mains power is something I have not yet attempted in my projects to date.

Does anyone have any thoughts or advice concerning this?