Author: Smeg (webcacheM01b.cache.pol.co.uk)
Date: 08-04-2002 14:56
Interesting that you mention the power supply to the opamps - is it noisy or just not supplying enough current? Looking at the squeematic there is a 3pin device that supplies 9v from the 12v supply, but i dont know what it is, I cant make out the squeematic, they are very poor scans.
I already changed a load of resistors and caps on the underside (as per steinbergs recommendations) so now I have line level in/out but there is still an audible hiss, which is terrible if the CD player is plugged in, you can actually hear whats going on inside the drive as it spins up.
I have heard that the CODEC is fairly noisy too, that it wasnt one of Crystal Semiconductor's better designs, otherwise I would consider building/purchasing a very quiet opamp which I would connect directly to the codec and bypass the existing circuitry altogether. Though I guess that if I want to be serious about recording I need to get an external device of some sort to plug into the DSP port.