2. tech-talk
  3. 1076618642

Not a ground loop hum???

I thought I had a ground loop hum, given that with my pre, cdp and amp all on, without any music playing, there is a hum emanating from my speakers. Following the advice seen here and elsewhere, I went out and got some cheater plugs to try and hunt down this annoying and, at times, distracting hum.

My system comprises: Anthem CD-1 (with DH-Labs power cord), Blue Circle BC21.1 tube pre (with BC62 pc), BC22 amp (Zu Cable BoK pc), Rune loudspeakers by Zu Cable (hooked up with Zu Cable Libtec speaker cable), Blue Circle MR1200 balanced power line conditioner/distributor (Zu Cable BoK pc), and van den Hul D102 MKIII interconnents.

Well, with the three components' power cord fitted with a cheater plug and all plugged into the power conditioner, the hum was still present, same intensity, volume, etc. Removing the cheater plugs one by one starting with the cdp, then pre, then amp, there was no reduction in the hum. In fact, I think I may have heard it get worse at one point.

Any ideas out there as to the cause of the hum? Maybe the tubes in the system are the culprit. There is a pair of Siemens CCa (6922 type) with Pearl tube coolers installed in the pre, and the tube in the cdp is a Telefunken CCa with a tube cooler.
mghcanuck
sean
6,231 posts
 
Max: Why don't you call up Blue Circle and let then know what is going on. If you don't have a local dealer that you purchased it from, BC should cover the bill on shipping both ways since this whole mess was due to their lack of quality control to begin with.

Other than that, i'm glad that you were able to figure out what was going on without losing too much hair or sleep : ) Sean
>
brooksl
129 posts
 
Max, I have one of those devices that you plug into outlets to diagnose several problems. When I plugged it into my Balanced Power Technology 3.5, it told me that there was a faulty ground. I called Chris Hoff. He said that balanced power confuses the device. He also said the most common results are reversed polarity and improper ground. So, your Blue Circle unit may be functioning properly.
redwoodgarden
150 posts
 
Do you have dimmer switches anywhere in your home? If yes, try turning them off, and see if that makes a difference. That suggestion solved all of my problems last year.
sean
6,231 posts
 
Balanced power WILL play games with an AC polarity tester and is the sole exception to what we think of as "proper AC power". Anything else should have a very specific hot, neutral and ground ( as far as i know ). Sean
>
mghcanuck OP
116 posts
 
I had sent an e-mail to Blue Circle and the response was as Brooks1 and Sean have indicated. Balanced power outlets will indeed show reversed hot and neutral or other icorrect wiring, because there is 60V coming from the neutral and 60V coming from the hot in relation to ground.

Blue Circle insists that it is likely really dirty incoming AC causing mechanical noise in the transformers of the MR1200. I'm back to my question of why bother with this relatively expensive power conditioner to prevent noise in the stereo components only to have the conditioner make noise.

I've swtiched over to the $200 Monster HT1000 power bar that was lying around since I received the $750 MR1200. Guess what, no noise from the HT1000. This just ticks me off.

Next week we move into our new house, so I'm really eager to see what kind of results I will get from these two units plugged into the dedicated line I had installed. Will the MR1200 continue to hum? Will the Monster piece mash the Blue Circle again? Enquiring minds want to know! FWIW, I'll post my findings in a few days and continue to ponder Chris VenHaus' solution of wiring two 0.47uF 600V Auricaps in parallel in the dedicated outlet if the MR1200 is still noisy. Has anyone out there tried the latter yet?

Thanks again to all for your comments and ideas.

Max
More to discover