Correlation-Sound and Power Supply Config

[fmak]

I have been playing around with a RMEADI-2 ADC/DAC, which takes both dc and ac supply via a LM2585 Chip and a 100kHz switching PS.

The unit claoims to have a high quality switching PS at 12V 1.25A but this sounds aweful compared to battery which gives the most relaxed sound. An LT1085 12 V regulators sounds quite good if a bit opaque. A 12 1A ac supply sounds surprisingly nice and quite open. A 20V unregulated dc supply doesn't sound brilliant - even thicker than the LT1085 unit.

To see what might be going on, I did some qulaitative measurements of the dc feeds inside the unit; the regulated 15V supply for the opamps and two 5V regulated feeds to the adc and dac sections.. With the ac supply, there were around 3mV ripple in these feeds. With the LT1085 supply, these had diminished to the instrument noise level of around 0.79mV. I used a Fluke Scopemeter with a 1MHz bandwidth.

The interesting points in this is the correlation between subjective changes in sound quality and the types of supply and their associated ripples. This is inspite of multiple regulation built into the unit.

When I get round to it, I shall do some measurements with my ac millivolter that can go down to 1uV 1MHz bandwidth, particularly with a battery supply and try to tie it with listening impressions.

[Htguy]

HI,

Very cool stuff here. Looking forward to more on this.


God bless...

Mark