Tubes Asylum

Tube Rush and Tube Hiss Different Channels

76.253.186.185

Berrell88

A

I have a somewhat exotic preamp with DHT 71a tubes as power tubes and a duo of C3G Siemens driver tubes plus rectification and regulation tubes. Made in Japan. I'm getting normal tube rush in the left channel and an odd, shrill tizzy noise in the right channel. The noise in the right channel isn't audible except when I use my tuner. All other line sources are fine. There is a hum adjustment on the preamp but that isn't corrective. Any ideas why this is happening or should I just forget about it? I have rolled different 71a tubes but that makes no difference. The Siemens tubes are very expensive and long lasting.

Follow Ups:

RE: Tube Rush and Tube Hiss Different Channels - Palustris 07:12:27 02/22/23 (2)
Did you swap the R&L input from the tuner to see if the noise is coming from the tuner?
- RE: Tube Rush and Tube Hiss Different Channels - Berrell88 16:09:07 02/22/23 (1)
  I did not swap the ic's on the tuner. I will, thanks. There is a problem with one particular station, a classical music station and my favorite station, that is close by and presents noise in that one channel. That problem persists to a lesser degree using another tubed pre. Other stations further away with equivalent wattage come in much clearer. Go figure.
  
  But let me return to my main point. When you turn on the DHT preamp regardless of the line stage employed, there is normal rush in the left channel and a shrill hiss in the right channel.
  - RE: Tube Rush and Tube Hiss Different Channels - 6bq5 12:07:13 02/27/23 (0)
    Tubes can generate extra noise, a rushing or hissing, Microphonics, and other sounds deemed 'extra' and not desirable -
    This is what started the Tube Testing practice.
    Unfortunately, some of the sounds are 'normal' others are a result of age, and others still are the result of the circuit-
    and Interconnect cables
    
    Assuming that the unit was once quiet, and the interconnects have a ground shield that IS connected at each end, then we are down to tube age -
    (Sounds like you have a Shindo Preamp - so I will presume that the circuit is good)
    
    Do you have a spare set of tubes?
    If yes, try them out if it regains its quiet condition - then that is the issue...
    
    Happy Listening

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