Yes, any power supply could create an EMF field that the modules could pick up and some transformers, particularly the rectangular EI lamination type, shouldn't be within several feet of the rack. there are several issues and means of tackling them. The other critical factor I guess is shielding, any tips on techniques that have worked for noise/hum issues?Hi
Geoff, do you think the PSU below will work? I'd allow at least 1 amp for two modules (1073's draw 122mA each) and at least 5 amps for a rack of 8.Īll respect to companies that rack these pres but I have heard rumours that on occasion the PSU's mounted inside the rack have actually created noise problems. I'm amazed at how tiny some power supplies are for racks of modules. So there's not really an audiophile power supply per ce, just very good ones with adequate current capabilities and minimal noise or ripple.
if it measures -60dB (1mV) that's too much. Gobs of current headroom to accommodate the switch on surge of all those electrolytics charging up.Ģ. If you don't recap the modules in their lifetime and the electrolytics lose their efficiency you can get a situation where the signal in the output stages modulates the power rails, which is picked up in the feedback, and leads to "motor-boating" instability/oscillations.ġ. So, if you don't have gobs of capacitance after that 12 ohm resistor, then the noise and crud on the power supply can get into audio via the feedback. If we take the 1073 as a classic example, one of the biggest flaws in its design is that it takes the negative feedback for the output stage from the collector of the 2N3055 which puts it the primary winding impedance and a 12 ohm resistor away from the dc supply. IMHOĬan anyone give me your experience about how much the quality of a power supply affects the sound of a preamps like 1073 or 1081?Īre there audiophile level power supplies available? If so, can anyone tell me where I can get more info on these and where to buy? I've heard expensive power cords that make a difference. I know every stage and component of audio equipment affects the overall sound quality.