[peteb]

I moved a few things around on my rack and somehow introduced what sounds like ground hum coming from my speakers.  (I broke the golden rule.  don't try to fix something that is not broken)  What started out as a 15-20 minute task has now been drawn out to a 2 hr ordeal. 

The hum occurs when I power on the Bryston 4BSST.  No other components are powered on.  When I unplug the interconnects and power on the 4BSST and just leave the speaker cables connected, the hum goes away.  When I leave the interconnects plugged in to the 4BSST and power on both the 4BSST and preamp, the hum goes away.  They interconnects are Kimber Hero with WBT-01 44 RCA jacks.  When I replace the Kimber with a cheap pair of interconnects the hum goes away.

Is this hum normal since it does disappear when I power on the preamp or should I replace the Kimber interconnects?  I have a hard time to believe that both Kimber interconnects are somehow damaged since when I connect one at a time, the hum appears.

 I never liked the RCA connectors since they don't seem to make good connection with the Bryston jacks.  I think it's time for some XLR balanced interconnects.

Thanks in advance for any suggestions you can provide.

Pete     

[vegasdave]

I moved a few things around on my rack and somehow introduced what sounds like ground hum coming from my speakers.  (I broke the golden rule.  don't try to fix something that is not broken)  What started out as a 15-20 minute task has now been drawn out to a 2 hr ordeal. 

The hum occurs when I power on the Bryston 4BSST.  No other components are powered on.  When I unplug the interconnects and power on the 4BSST and just leave the speaker cables connected, the hum goes away.  When I leave the interconnects plugged in to the 4BSST and power on both the 4BSST and preamp, the hum goes away.  They interconnects are Kimber Hero with WBT-01 44 RCA jacks.  When I replace the Kimber with a cheap pair of interconnects the hum goes away.

Is this hum normal since it does disappear when I power on the preamp or should I replace the Kimber interconnects?  I have a hard time to believe that both Kimber interconnects are somehow damaged since when I connect one at a time, the hum appears.

 I never liked the RCA connectors since they don't seem to make good connection with the Bryston jacks.  I think it's time for some XLR balanced interconnects.

Thanks in advance for any suggestions you can provide.

Pete     

I think you answered your own question. It sounds like the Kimber cables are faulty. They may need to be reterminated. If you know your stuff with a soldering iron, you can do this yourself.

Regarding balanced lines, yes they are lower noise, especially when you have long cable runs.

[avahifi]

If your Kimber interconnect cables are made the way most samples of them that I have experienced are (three lightly twisted conductors) then the issue is lack of built in shielding in the Kimber cables.

The Kimber cables may work just fine in some applications, but in general I would prefer full braid shielded cables (inner conductor, fine multiple stranded external ground side wires wrapped around the conductor core) just to make sure low level electro-magnetic interference is not effecting the musical performance.  In your case the hum level was too great to overlook and conventional interconnects, even inexpensive ones, showed that inadequate shielding rarely trumps silver and high cost.

I had this same issue occur using Kimber cables connecting my Super Pas Three vacuum tube preamp to the power amp.  In this design of ours, we moved the power transformer to the outside of the case on the back panel, as its hum field was causing low level hum because it was located very close to the line circuits.  This fixed the issue except when using Kimber interconnects.  Their lack of shielding picked up the hum from the transformer a few inches away.  Live and learn.

Regards,

Frank Van Alstine

[peteb]

I will bring them back where I bought them to see if they can be repaired or at least tested.   I will let you know how I make out.

The story gets better.  The 15-20 minutes has now evolved into a 5 hour marathon.  After I connected everything back up and turned on my system I noticed a large increase in bass and an overall fuller sound.  As I mentioned above, the hum disappears when everything is powered on.  Disconnecting and reconecting my cables did something that I can't explain.   It's either the cables or the preamp just likes it better on the top of the rack.       

[rpmartins]

My brand new 4bsst² makes speakers hum when on, whatever the IC cables I use or even if there is no IC connected 

Is it a malfunction?

[peteb]

Is the noise you are hearing ground hum?  Is it a buzzing sound?  Does it disappear when you power everything on?

you should be able to power everything on, increase the volume on your preamp and detect very little noise coming from your speakers if any noise at all.  If your system is silent during this test, you can be assured that there is no electrical interference being introduced when playing music or any other material.  If the hum is present when every thing is powered on, it is present when your are listening to music and not good.

When I power everything on and crank my volume my system is completely silent.

I am the last person to be giving advice and I am just basing my feedback on personal experience.

You may want to talk to your dealer.

Good luck.

[Johlke]

I don't have a recommendation, just some commiseration.  Like you, a while back I re-arranged my listening room and when I was done I had a bunch of "hummmmmmm" coming from my system.  After a bunch of checking and re-connecting and switching cords and cables I narrowed it down to my interconnects.  That gave me the excuse I was looking for to get some Shunyata Python Zitron RCA interconnects and voila, problem solved.  No hum and the Pythons are a noticeable upgrade.

So, I'm not suggesting laying out the long green for the Pythons, just that improperly or poorly shielded cables can indeed be the problem.   Good luck!

[rpmartins]

Probably ground loop, in my case.

a) only power amp (switched off) connected to speakers = no hum
b) only power amp (switched on) connected to speakers = slight hum (and fiss from tweeters)
c) power amp+pre BP-6 connected to speakers = louder hum (and fiss from tweeters) than option b)

The hum doesn´t get louder when increasing the volume.
The hum doesn´t increase or reduce changing cables - audioquest quartz; kimber tonic; in-akustic exzelence - or having sources (CD player, tuner) connected or disconnected.

Discovered that Cyrus III with psx-r does some very slight fiss. Probably the result of being 6x less powerful than the 4bsst²

[assafl]

Sounds like a ground loop. Try to connect all the grounded equipment to the same outlet keeping a low impedance to ground. Floating the ground (disconnecting it) helps but is dangerous. Sometimes it is enough to float the preamplifier.

Going full balanced is almost certain to resolve it (as balanced interconnects ignore common mode noise induced on both conductors). For me, going SP3 was mainly to rid once and for all the RCA connector which I abhor since it is a bad design and bad concept (all types at all price points, event the Neutrik Profi which is my favorite - if I must use RCA). The only RCA I use is for SPDIF and I'd really like to use the AES/EBU instead. But audiophilleo is RCA so I have 1 RCA connection. And no hum, even if I plug my Makita impact drill to the same outlet as the stereo.