@greg7 - I was chasing a seriously annoying noise floor issue for the better part of a year and solved it just a couple weeks ago with a low capacitance isolation transformer. When I say my problem is solved, I mean it completely knocked out my noise issue, and I have a very near field arrangement with this system. First, a description of my system, then a description of the process I underwent to deal with the noise issue (with links):
My system: Luxman CL-38u SE tube preamp > Atma-Sphere M60 tube monoblocks > Proac Studio 1 monitors situated in a near field arrangement with ~3.5 feet of separation (in this system I essentially listed to ’open air’ headphones, and it sounds amazing to me)
My story:
I had a relatively low volume noise floor that wouldn’t likely be all that bad to most people, but annoyed me to no end, perhaps because it was accompanied by a low volume buzz that was worse in one amp than the other. After reading some ground loop chasing tips.....
-I found an
online tone generator and matched the buzz (60hz sawtooth)
-I found a rather lengthy forum thread that discussed the use of a low capacitance isolation transformer to solve issues brought about by bad AC supply (
start here - I think I saw a thread perhaps started by you). It’s apparently essential to use a low capacitance transformer for for this type of application (the forum thread I read goes into the ’whys’ of this).
-I purchased a
cheap power monitor to confirm power needs, and luckily found my collective system only draws ~610va at idle, and rises to ~mid-700va at peak (one of the benefits of a near field system).
-I took a chance with a few hundred dollars on a Topaz 1kva unit, which completely knocked out both my white noise and buzz issues. In truth, when I put my ear literally an inch from each driver (tweeter and midwoofer), I can hear a very low level of buz, but it’s VERY low and absolutely inaudible at listening position. For a tube system, it’s essentially dead silent.
Here’s a link to another
forum thread that talks of the Topaz unit, but it appears these are branded under different names. I purchased mine through the E-b auction site and it was a very smooth transaction.
If you take this road, be sure to pay attention to what power your system demands at peak (here's the
spec sheet for a 0.0005pf unit under the brand name 'Daitron'; I purchased a 0.005pf Topaz model and it does the job fine). I have all of my audio components set up via the transformer with isolation between the computer and DAC, but depending on your system and needs, you may not need to put everything on it. I might not either; I only recently set it up and still have some experimentation to do....
Good luck!
