Noise Problems - Need advise

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ERM
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Joined: Thu Apr 10, 2003 1:32 pm
Location: London, Ontario

Noise Problems - Need advise

Post by ERM » Wed Jan 16, 2013 1:07 pm

After having most of my gear in storage for 3 years, I'm finally in a house and putting things back together. House has finished basement, so I have no way of knowing workmanship, although based on the cold basement, can't be great. Sorry this might be a bit long, but I'm trying to pass on as much info as I can. I just recently retired, so I'm looking forward to some listening time.

System consists of external WD drive> 800 fire wire> imac mini> BIS usb > Music Fidelity V-link 192> bc 99.5> bc507 dac> bc90 interconnects> DAR integrated or 21.1 pre-amp w external pwr supply to bc32 amp> bc92 speaker cables> Oskar Kithara speakers. Power conditioning = MR1200 + Power Company 400 + bc power bar.

The DAR is dead quiet, but will be used in a different room. The issue is with the 21.1 + BC32. Loud turn on hum and continued hum although at a lower volume. The weird part is it's worst connected to the MR1200. Getting all kinds of computer birdies, pops etc every time a song is selected or as songs are being displayed on the ipad used as a remote.

Originally had all computer stuff to PC400> power bar, with amp and pre-amp to 1200. After much connecting and playing around, ended up with the amp and pre-amp to the PC400 only. Computer/digital to power bar > mr1200. This is the quietest set up, but still some humming and turn on buzzing. The absolute worst is plugging in the external drive to the 1200. So we know where the noise is coming from.

Where do I start? The FC power cord, the PLC FX2.6, the 18X sillycone filter? All of these options? Realizing that the birdies go away when computer is not plugged in, I still get the humming and buzzing. Any other suggestions will be greatly appreciated. Due to the width of my equipment rack, I need two power sources. Thank you for your time.
Ed

k-Dub
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Post by k-Dub » Wed Jan 16, 2013 4:43 pm

Are you using Single ended (rca) IC's or balanced? Also, do you have 15amp or 20amp outlets in your man cave?

My thoughts are 1) you have a noisy tubes in the BC21.1... or 2) a ground loop between pre and amp. Now, I would NOT plug the BC32 into the 1200! I had a Furman 2400 watt balanced power conditioner, and thought every amp plugged into it, sound better into the wall here (Dynamics, bass, size of stage, hall info...). The 1200 just limits what kind of high voltage your amps see with other items like the 21.1 plugged into it... also - I still wouldn't use the 1200 for the amp by itself! just not a fan of current limited to the amps.

Soooo I would try your pre into the bc1200, amps to the wall if possible (maybe a dedicated line to the amps if possible). Also, try floating the ground on the amps if the hum is still there - keeping the pre grounded, that will tell you if there is a ground loop between the two. I am a big fan of grounding the system through the preamp - and often, if needed, floating the grounds elsewhere (esp on digital!!! - maybe doing this might remove some of the popcorn issues) .

The fact the DAR is quiet tells me that is the issue - the amp/preamp interface.

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ERM
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Joined: Thu Apr 10, 2003 1:32 pm
Location: London, Ontario

Post by ERM » Thu Jan 17, 2013 8:25 pm

Hey k-Dub, thanks for the input. My system is single ended (RCA) except for the V-link to the DAC.
The room has a dedicated 15 amp circuit covering 5 plugs. This excludes the pot lights and switch. I hope I can do some wire fishing and add a dedicated plug for the system or at least the amp. Maybe one for digital and one for analogue.
I'm going to have to try another 6922 tube, as I think I'm hearing tube hiss as part of the noise. I have plugged the amp into the wall as you suggested and it has helped. The pre is plugged into the Power Company conditioner as it seems quieter there. Biggest improvement is excluding all digital from MR1200 and the PC conditioner.
I plan to purchase either the BC 6000 or Sillycone filters and PLC thingee FX 2.4, but not sure if one is better than the other.

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