sporadic buzzing/humming noise from right phone (HD 650) [resolved]

[starflyer77]

I just finished building my crack+SB.  I am hearing some mild buzzing/humming noise from my right phone.  The noise is clearly audible when no music is playing and it goes away from time to time.  The noise remains unaffected by the volume control.  I am running from 110V.  In my small voltage test, the OA and OB came out as ~106V which is outside the range 75-100V.  Could one of the tubes be faulty?

Where can I buy the stock tubes?  Could someone post the make/model number of the stock tubes?

Update (Solved): I replaced the 6080 tube [Sylvania Gold Brand 6080] that came with the kit with a fresh tube that I ordered online.  The background is now silent and black.  Would bottlehead.com replace the faulty tube?

 

[fullheadofnothing]

Could be cell phone / wifi interference, examine this first.

Tube noise could be dirt on the pins; try cleaning them thoroughly with a contact cleaner.

Tubes included in a kit will be random, there is no "stock" model.

 

[starflyer77]

Could be cell phone / wifi interference, examine this first.

Tube noise could be dirt on the pins; try cleaning them thoroughly with a contact cleaner.

Tubes included in a kit will be random, there is no "stock" model.

Thank you for the response.  I noticed RFI initially and the noise was kind of different: mild static noise.  When I surrounded the input tube with my hand and cleaned the pins of both tubes, it went away.  However, the buzzing/humming noise on the RIGHT phone still remains, and comes and goes intermittently.  The noise is present even if I remove the RCA jacks.  The noise is unaffected by the volume control knob.  The noise remains even if I move the amp to a different room in my house.  I do not hear any noise from my Vali 2 under similar operating conditions (same locations, same source, same headphone).  I have reflowed all solder joints and I have used my ohmmeter to check that the resistance between any two components connected to the same connector is 0 ohm.

 

[starflyer77]

I replaced the 6080 tube (Sylvania Gold Brand 6080) that came with the kit with a fresh tube (GE 6080) that I ordered online.  The background is now silent and black.  Would bottlehead.com replace the faulty tube?

 

[Paul Birkeland]

It's quite likely that the 6080 that you have will settle down after 50-100 hours of use.  Often times we get tubes returned to us that are noisy, and letting them run idle in a Crack for 2-3 days usually cooks them in enough that they are no longer problematic.

-PB

 

[starflyer77]

I left my bottlehead crack on for 4 days.  Note that my OA and OB voltages came out as 106 V each which is higher than 100 V.  I learned from a forum that this happens if the 6080 tube is weak.  This is why I ordered a new 6080 tube online.

 

[Paul Birkeland]

Being 5V over on those voltages is not an indicator of a worn 6080. In fact, a highly emissive 6080 could show 120V on those terminals with other factors in the amp coming into play.