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

Showing 7 responses by plosive

plosive OP
16 posts
 
Bananas at both ends. Sub bare wire at amp to spades on sub hi pass

Thanks!
plosive OP
16 posts
 
Blk25, Thanks! I have gone through the above steps and I'm leaning towards the AMP. Nothing else changes the hum. The right negative changes on the speaker are the only way I can make it stop. ( On both speakers ) and switching the speakers lends the same results. So, the question I have now before me is.. Do I open up the AMP and have a look at the wiring (Grounds to the speaker Posts ) or Pack it up and live without an AMP for ~two weeks, I would think. Really a drag. With the new tubes in, it sounds awesome, but I can not live with the hum ( Knowing it is there kills me! )

Thanks for all the help!
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
plosive OP
16 posts
 
Minori,

Thanks for the detailed plan. I like the very structured approach and as soon as the AMP returns, I am going to try your methods.

As far as the outlets, my problem is the distance from the source. Should I purchase long PC's (~12 feet to the next outlets)? What is better, Longer power cords or IC's?

I have some freedom in the room as far as placement and I have been considering a rack on the side wall and running longer speaker cables and/or a mix of components on the front wall. This would be helpful as space is an issue up front.

The System is in my home office. If you look at my system, you can see that everything is sitting on a credenza. I am not happy with this placement.

Some components can go in the cabinet, but I would like to have the Jolida, Pioneer and the VPI Scout (Being delivered Saturday 3/30/12) visible for looks and ease of use. I also have the Jolida Phono Stage, Jolida DAC and a Pioneer Elite CD player. Behind the cabinet are all the cables and a monster HT2500 power center. Any Ideas on optimum placement would be much appreciated.

Thank you for your time already. Any help on the above from you are anyone else that would like to support a newbie, would be great!
plosive OP
16 posts
 
Wire World 7M Cable works awesome!
plosive OP
16 posts
 
Ok, I received the Jolida 302CRC back today in the form of a 502CRC (I had it upgraded by Jolida) also, I had all the resistors upgraded. This is now as good as it gets from the factory. I am now using GL Kt88's, Mullard 12AT and NE 12AX input tubes. The Jolida crew was top notch on communication and the work. The sounds is 10X what it was....

No for the HUM, They could not reproduce it. I did not send them my tubes, so they used theirs. The only difference now is the new KT88's and the resistors. I would love to know what it was, but it is very quiet now!!!

Thanks for all the help!
plosive OP
16 posts
 
The upgrades to the resistors and the settings for easy bias. Was 70.00 + Shipping. The Upgrade to all the input caps was 100.00. Mine was very new so all the Hex stuff and other upgrades came from the factory.

I will tell you this. It is a brand new AMP... The KT88's and the resistors put it in a new world.

It feels faster and has much better mid-range. The high end is more refined and bass response is tighter.
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