Importance of power supplies


2005-08-17 11:05 pm
Back in the day I bought a Technics SA-AX920 Class H receiver and was more than happy with it. One day I decided I wanted to hook into a computer with digital and surround sound and all of the bells and whistles so I bought a Kenwood VR-7070. As soon as I turned it on I noticed a reduction in bass, now I wasn't sure at the time if it had better highs or weaker lows since my woofers were garbage, well so were my mids and highs honestly. But overall the kenwood sounded better, cleaner brighter etc.

Last night however I hooked up an ultracurve pro eq between the computer (S/PDIF) and the 7070 and eq'd the sub +-0.5 dB 20-125 Hz 1/3 oct, however I could only eq the computer and the tv was feeding directly into 7070 bypassing the eq, not cool.
I realized that I needed a preamp so I wired the 7070 as the preamp and the Technics as the power amp with the eq in between, all is good now.

When I powered up the system and played some tracks (same tracks as played through 7070) we instantly noticed cleaner less distorted bass (w/ flat eq now) and the drum set on the test disc actually sounded much closer to a live drum set whereas the sound through the 7070 sounded muddy, loose and compressed. The cone was not controlled by the 7070 as well either.

My theory about this is based on some experience with old welders vs. new welders where the old welders with big expensive heavy power supplies produced significantly cleaner welds with almost no spatter. In reference to these amps the 7070 is physically huge and the knobs, faceplate and body are all metal, it is 1/2 wider and taller and ~2.5in deeper compared to the Technics which has plastic knobs and face with a thin metal case. The weight of the 7070 is about 27 lbs and the Tech. is about 22 lbs and is focused in one corner like it has a 19 pound power supply, the 7070 seems to have a heavy case and a lightweight power supply.

Is the beefier power supply the reason for the more accurate bass or am I misinterpreting my results here?

Feel free to get technical with your answer if needed, I am an ME not an EE but I understand electronics.