Welcome, Guest. Please Login or Register
Decware Audio Forums
10/24/14 at 08:03:12


Pages: 1
Send Topic Print
Hum issue with Torii II (Read 2141 times)
JimR
Verified Member
**




Posts: 11
Hum issue with Torii II
12/08/08 at 02:16:08
 
Hi,

I recently bought this Torii II amp from a guy on agon and while the amp appears to be in excellent condition and sounds superb with my custom single driver speakers.

The one ongoing problem is that there is a fixed, low-level hum coming from both vhannels, but slightly more of it from the left channel.

I've done everything an experienced tube audiophile would do, including swapping tubes, cleaning sockets, disconnecting sources, re-routing power and signal cabling, etc., but the hum persists.

I can hear it at a low level sitting about 7.5 feet away and while generally not audible for a lot of music, it is quite prominent in quiet passages in some orchestral and acoustic musics.  Bottom line is that it shouldn't be there, and I'm out of things to try with the exception of an isolation transformer to block any potential DC on my AC line.

I have also not heard from Decware on this since the last email which simply pointed me to the link to the white paper on debugging hum issues.

I suspect that the transformers are buzzing a bit (as I can hear them) and rattling the elements of the rectifiers and possibly the output tubes because after all the tube swapping, etc. the only thing that made any difference at all was going to a heavier gauge, shielded power cord, and that had only a minimal positive effect.

Are there any known problems with this amp and AC power with DC offset, or do I have something seriously wrong that will require me to ship it back to Decware.  Either way, I'd really like to get on with this because I am ultra sensitive to hum and hiss problems -- and it's been a long time since I had a tube amp that did either.

Thanks,

Jim
Back to top
 
 
  IP Logged
buzz
Seasoned Member
****




Posts: 393
Re: Hum issue with Torii II
Reply #1 - 12/10/08 at 00:16:57
 
Jim R from Colorado? From your description you have a ground loop. A quick way to check for the offending piece of equipment is use a ground lift cheater plug at the wall socket of each component, one at a time until it disappears. I just use an old IEC cord with the ground prong pulled out of the plug. The best way to totally eliminate loops is to make sure signal ground only connects to earth at one point in your entire system.

Best wishes,
buzz
Back to top
 
 
  IP Logged
Jason
Senior Member
***




Posts: 68
Re: Hum issue with Torii II
Reply #2 - 12/10/08 at 02:19:16
 
Believe it or not, I actually had an intermitent hum with the Mk II that I finally traced back to the electronic light dimmer in the room.   Totally seperate circuit too.  I could hardly believe it when I found it, especially after all the work isolating everything in the rack.

Jason
Back to top
 
 
  IP Logged
Pages: 1
Send Topic Print