No hum from the Bluesound....
Passive preamp issues or?
I have a Nuforce STA 200 that I’ve been using with an Axiom Walker mod preamp for a while now. Other equipment is a Bluesound Node 2 streamer and a Jolida dsd dac. Nordost digital coax and Dueland Schroeder IC’s from dac to pre and pre to amp. Last night, I disconnected the preamp and ran the IC’s directly from the dac to amp, using the volume control on the dac. The change in detail and depth was not subtle. Soundstage extended beyond the speakers- everything just sounded better. However, with the high gain of the Nuforce there’s a hum in the speakers- it’s not not audible when I’m not playing anything. I’m willing to live with it, but I’m curious why the sound improved significantly by pulling the pre- should I look at better IC’s from pre to amp or is the Axiom subtracting from the sound quality?
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- 23 posts total
There it is! The problem is either the high output impedance of the Jolida at 47kohm (which is wrong for anything mind you) save the input impedance of Rogue M120 monoblocks, which are for memory 1megohm, or similar, they would give a good ratio of around 1:20. https://www.stereophile.com/content/rogue-audio-magnum-m-120-monoblock-power-amplifier-measurements Or maybe it’s the Jolida output coupling cap with that impedance, or could be earthing. But I don’t think you’ll ever find any manufacturer with a source product that has around 47kohm output impedance. Cheers George |
The high gain and low input sensitivity of the Nuforce STA200 will allow it to amplify any noise in the system preceding it ( including ac noise ). I cannot use the amp ( amps, as I own 2 ) satisfactorily with a few preamps I have lying around, as I hear a distinct hum through the speakers. The amp was designed to work passively, and this is best for it, ime. |
If the amp really has a 1MegOhm input impedanceOh dear! This is getting like a Monty Python skit. He doesn’t have an amp with 1megohm input impedance, I’m just saying that the Rogue M120 the only amp I know of that would be an "impedance match" with a tube output source like his with 47kohm impedance. And btw I’ve had the Rogue M120 here some some time, they don’t hum, with active or passive driving them Cheers George |
- 23 posts total