[walfredo]

Hi All,
 
Noob question:
 
I just got my first tube amp: Doge 6210.  The sound is beautiful, but more often than not there is a very annoying background noise on it, and sometimes there is a high pitched RF-like noise to it.  Any ideas on how I can "fix" it?
 
Thanks for the help!!
 
[]s
Walfredo

 

[walfredo]

Please help, people...

 

[Uncle Erik]

How often do you get the noise? Sometimes an amp will pick up your cell phone "checking in" with the local tower. The best solution is to keep your phone away from your rig.

You might also pick up noise from things that emit RFI, like fluorescent lights, dimmer switches, AC motors, HVAC systems, refrigerators, computers, CRTs, neighbors who operate amateur radio, and anything that kicks out RF. Hunting down the culprit can take some time, but look around and consider moving your rig.

You might be getting some noise from your source. If you are feeding the amp from a computer, the noise could be coming from inside your computer. They're noisy. If you have a DVD player, try connecting it to your amp and play a CD. If the noise goes away, it's your computer's fault.

Finally, you might have a ground loop. You can try plugging it into different outlets to see if that helps. A "cheater" plug (one without a ground pin) can also isolate a ground loop. I don't recommend cheater plugs for anything but testing since the ground is a rather important safety feature. If you do find a ground loop, I'd recommend finding an inexpensive isolation transformer.

Please let us know if you make any progress with the noise and what worked - it would help out others searching for information.

 

[walfredo]

Thanks, Uncle Erik!!
 
Apparently I do have a ground loop.  When I disconnect the comcast cable, the noise is greatly reduced to almost nothing.  Now I'm trying to make comcast folks to fix it.
 
[]s
Walfredo

 

[walfredo]

Ground loop solved.  But there is still noise (less than before).
 
My current theory is that the Doge has settings for 60, 300, 600 ohms, while the W1000 is a 40 ohms HP.  After the ground loop was solved, my Byerdynamics 990/600 omhs are completely silent with the Doge, which supports the theory.
 
Does this make sense?  Would an impedancer solve my problem?  (This appears in many other threads.)  Where can I can an impedancer?
 
Thanks,
Walfredo

 

[jazzy76]

Try different tubes (selected, matched, with low noise) because your headphone is high efficent.
 
Try your beyer with the audiotechnica, the total impedance will be around 300 ohm and if the noise is still here the impedance has nothing to do here.
 
Hope it helps
 
frank
 

 

 

 

 

 

 

[walfredo]

Thanks for the tip, Frank.  I tried plugging both of them and the noise persisted on the W1000.  So, ruling out impedance...
 
The noise is not horrible.  The Doge + W1000 combo is still very usable.  But every now and then something happens and the noise goes away.  It then becomes truly wonderful!!  I'd like to have it wonderful all the time. ~
 
Any ideas on what to try?
 
[]s
Walfredo

 

[jazzy76]

Ask here http://tubedepot.com/  for the best low noise and no microphonic modern production 12ax7 and buy a matched and balanced pair with a couple of matched jj el84 or Reflektor 6p14p-ev.
 
Stay away from NOS tubes for the moment.
 
frank

 

[jazzy76]

I forgot to mention that good shielded power cables and interconnects can help to reduce noise.
 
frank

 

[walfredo]

Thanks so much, Frank!!  Will do.