2. amps-preamps
  3. 1332600947

Hum from both speakers...This is New Please read.

Hi All, I would like to say I am new to channel after a long recovery from mid-fi! I am building a system in my home office. It consists of; Jolida 302crc (new tubes tried ), Jolida glass FX Dac, Jolida jd9, Rotel 2500 turntable..., pioneer elite pd65. Monitor Audio Silver RX2, Epos M Sub.
AQ rocket 88 speaker cable, AQ IC's.

So, the Jolida 302 is new. Since the first setup there has been a hum from both speakers. For the last month, I have been going insane throwing time and money at the problem. I have read, I think, every post on audiogon bout hum and the related links connected to other sites.

So, this AM, I am chasing the problem again, and I noticed that when I disconnect the negative speaker connection on the right speaker it goes away. Dead silent. Plug it back in and It returns. If I do this on the left speaker, it does not go away. Thes are biwired speakers and the hum only goes away on the right speaker, negative, low Freq posts. If I switch speaker sides, hum is still there but removing the right negative does nothing.

So,

Is it the negative speaker post on the amp?
Is it the negative speaker post on the speaker?
Is it the cable?

Could the ground in the amp or the speaker be loose on the right neg. post?

I know this subject has been beaten to death, but I think I am going to need counseling if I don't solve this.

Thanks in advance,

Troy
plosive
grimace
624 posts
 
Yeah, if you find an answer please post it. I've had the same problem with a Cary
v12r for a couple of months now. Sent it in to Cary for what wound up being a very expensive service (cap upgrade) and they could not duplicate the hum AND it was still there when I got the amp back. Switching to the 4ohm taps helped some. Curious to hear if you can fix yours.
hifigeek1
770 posts
 
Sometimes it's a ground loop involving the subwoofer. Have you tried unpluging the subwoofer from the wall?? Sometimes the audio isolator works at the rca inputs to the sub if you're running it passively.
wolf_garcia
4,650 posts
 
Ground "floating" often fixes this sort of thing...I use my REL sub "floated" (it has a switch for this)...works fine and the whole system is hum free. I also use a PS Audio Humbuster to keep DC crap out of the main amp (currently a Jolida 502P).
atmasphere's avatar
atmasphere
7,068 posts
 
That does sound like it could be a ground loop problem, but if so it has something to do with the subwoofer. If you unplug the subwoofer from the wall that should manage the hum.

If not, then my 2nd theory is that there is a wiring bug in the output section of the amplifier.
plosive OP
16 posts
 
First off, thanks for all the responses! I tested so many different things yesterday, my head was numb by about 11pm PST. So to know avail, I could not make it go away. Even with cheater plugs on everything and nothing!!!!! Different plugs around the house.... My neighbors house!

So as I sit now, the AMP is now making it's way to the very kind and awesome tech's at Jolida. While it is there having it's hum chased down and killed, I am having the rest of the upgrades done and will be going to KT88 tubes when it gets back.

So for now, I have plugged my 1976 Pioneer SX 850 receiver again and I stand with my mouth agape at how great it really does sound!!!! Clean, smooth, rich, warm and vintage!

I may have to consider keeping it as the preamp and see how that works out.

Thanks again all and I will update when the traveling AMP returns home.

Troy
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