JohnSwenson;528305 Wrote:
> I've measured big differences using a linear supply for the SB3, but its
> not in the signal coming out of the DAC or digital outs. The switcher
> that comes with the SB3 injects a huge amount of noise into the power
> cord which winds up in the other boxes in the system unless you have
> very good power filtration in your system. The frequencies that come
> out of this switcher are rather pernicious, they are low enough that
> most "RF" filters don't touch them and high enough that they sail right
> through the stray capacitances of most power supplies.
>
> This is not just conjecture, I've measured it several times with many
> different pieces of equipment, power bars, power filters etc.
>
> Its rather interesting that the only equipment which does a good job
> filtering out this noise is boxes which also have switching supplies.
> The switcher has filters designed to keep its own noise out of the
> electronics which also does a good job blocking the noise from the SB3
> supply.
>
> The result of this is that the effect of the noise from the SB3
> switcher in general is far more noticeable on high end gear that uses
> good linear supplies than it is with "consumer" gear using swithing
> supplies.
>
> In my system the good linear supply does make a significant difference
> with the SB3. With the SB3 supply even if the SB3 is not providing the
> signal it makes a difference, which seems a pretty good indication that
> its not direct signal related but some other vector.
>
> Just plugging the switcher is not enough to cause the problem, it has
> to have a significant load (the SB3) in order for this to be an issue.
> I have not tried just a resistor as a load to the switcher and see if
> that degrades the sound from other sources.
>
> The switcher that comes with the Touch is vastly better than the one
> that came with the SB3. With it I cannot hear any difference using the
> switcher or the linear supply. When I have the touch in the listening
> room I just use its own switcher.
>
> One test I have NOT done, but probably should is to use the Touch's
> supply with the SB3.
>
> In addition to the noise injected into the AC line there IS noise
> radiated from the wires and the supply box itself which can get picked
> up by interconnects and other boxes. My measurements show this to be
> significantly less importance than the power cord born noise, but its
> still there. If an audiophile is using unshielded interconnects (which
> are popular in some circles) this source of noise can wind up being
> significant.
>
> Th SB3 itself also radiates a lot more RF than the Touch, but thats
> irrespective of what power supply you use.
>
> So yep, using a linear instead of the switcher that comes with the SB3
> CAN make a big difference to sound. How much is going to be quite
> system dependant. For some its going to make a big difference others
> won't hear it at all and others will be inbetween.
>
> That little switcher that comes with the SB3 is so bad that it makes my
> skin crawl just thinking about it. I keep one on the floor in my
> listening room and stomp on it everytime I go in or out. I've been
> trying to come up with a good use for one, such as testing the
> ruggedness of a sledge hammer etc. That little thing is amazingly
> resiliant, I have not been able to damage it yet. A 15 pound sledge
> hammer with a really good swing would probably do it.
>
> John S.
John - thanks for taking the time to type all of this - really
fascinating stuff. This explains a lot:
1) Why I could never detect/measure any audible differences with the
different supplies - I was measuring the SB3 in isolation, so there
were no other vectors.
2) When doing listening tests, my system has a very high-quality
switching supply in the pre-amp which would filter out any crap coming
back in via the mains through that vector
3) I only use screened cables (I did once have an NVA amp that came
with unscreened cables - it also came with a self-destruct feature!)
4) I use a symmetrical choke-based mains filter for all of my
"switching" supplies (router, USB disk, HDMI Switch box, SB3/Touch)
that will stop some crud coming back onto the mains from those devices.
--
Phil Leigh
You want to see the signal path BEFORE it gets onto a CD/vinyl...it
ain't what you'd call minimal...
SB Touch Beta (wired) - TACT 2.2X (Linear PSU) + Good Vibrations S/W -
MF Triplethreat(Audiocom full mods) - Linn 5103 - Aktiv 5.1 system (6x
LK140's, ESPEK/TRIKAN/KATAN/SEIZMIK 10.5), Townsend Supertweeters, Blue
Jeans Digital,Kimber Speaker & Chord Interconnect cables
Kitchen Boom, Outdoors: SB Radio
------------------------------------------------------------------------
Phil Leigh's Profile: http://forums.slimdevices.com/member.php?userid=85
View this thread: http://forums.slimdevices.com/showthread.php?t=76496