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Luxman Class A Integrated Slight Buzzing Noise

Hello--

I just purchased my first class A amp--a Luxman 550ax--from an AG member recently. I noticed this morning that when I get close to the amp while it is turned on there is a slight buzzing noise coming from the unit. If looking directly at the top of the unit it seems to be coming from the right middle of the unit. Doesn't seem to affect anything with my Harbeth speakers and I only hear it from a couple feet away. I was wondering if this is normal for a class A amp. Anyone with a 550 or 590 have this issue? Any ideas what could be causing it? I have it plugged into a Richard Gray 400 Power Center using the stock Luxman two prong JPA1000 polarized power cord.

Sources are a PC connected USB to a Fostex HPA8C DAC connected to the Luxman with Transparent Audio Link 100 RCA cables.

Thanks,

Dave
ddinkel

Showing 2 responses by twoleftears

twoleftears's avatar
twoleftears
5,320 posts
 
Deedo--I have found your posts very interesting and illuminating. Transformer hum and buzz has, off and on, bothered me for years. All the way back to when I owned an Adcom 535 (long time ago). I had a big Nackamichi for about a day (re-badged Threshold), that also hummed. And a big Sony from the old ES line that didn't. I had concluded that it was crap on the line coming into the house, combined with the design of the transformer--i.e. that toroidals were a lot more prone to it than other shapes/designs (the Sony had EIs). I've steered away from toroidals for a long time, first with a Cary and now with an Ayre. (I discarded Plinius as an option because there was a lot of anecdotal evidence on line about humming.) The idea that it all depends on the size/weight, the materials, and the exact construction, rather than the basic shape/configuration, is something of a revelation.
twoleftears's avatar
twoleftears
5,320 posts
 
Well, yes and no.  *Some* hum is caused by a ground loop, and *some* hum is caused by DC on the line, and both of these are cured fairly easily.  Check out this guide.

https://www.psaudio.com/ps_how/how-to-find-and-fix-hum/ 

However, there are *plenty* of instances where these fixes and others will not touch the hum.  Usually it has to do with the design or quality of manufacture of the transformer, or some strange interaction between the transformer and your AC.

There were a number of reports on the net of Luxman integrateds humming; if it weren't for this I would probably own one right now.  It you get this far, it's usually not fixable.  Live with it or move on.

See also the discussion somewhere in the thread "ask Ramtubes a question".
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