Cayin tube amp

Discussion in 'Audio Hardware' started by Stephane Quiniou, Feb 11, 2019.

  1. Stephane Quiniou

    Stephane Quiniou New Member Thread Starter

    Location:
    Montreal
    Hello everybody,

    I am pretty new to tube amps. I bought a Cayin CS-55A a couple of years ago and I love the sound.
    However I have a big problem, the tubes have burned out twice in the last couple of years.
    I have used Gold lions KT88 tubes and they are not cheap.
    I am trying to find out what is the problem, why they burn out so fast.
    Like i said I am new to tubes and I have been told that this is not normal.
    Tubes "should" last around 3000 hours.
    I listen to my amp a couple of hours per day and close it after.
    Now I have a choice of 4-ohm or 8-ohm on my amp but my Dali Ikon 6 speakers are 6-ohm.
    I always put the connectors at 8-ohm on my amp.
    Could this be the cause of my tubes burning too fast?
    If I switch to 4-ohm on my amp will I lose some benefits in the sounds?

    Thank you in advance for your help.

     
  2. mjcmt

    mjcmt Forum Resident

    Location:
    NC, USA
    I'm sure you checked the bias. Maybe manufacturers specs are too high for long tube life.
    If it has auto bias, maybe it's off what it should be.
     
  3. tubesandvinyl

    tubesandvinyl Forum Resident

    Depends how hard the amp runs the tubes. Some amps run tubes near their max plate voltage and bias current.

    Power tubes in my amps are still going strong after 3,000 hours because I don't run the tubes hard.
     
  4. allied333

    allied333 TUBE AMPLIFIER REBUILDER - inquire

    Location:
    MI
    Likely the bias is too low causing maximum plate current on the tubes. I do not know if your amp is fixed or cathode bias. If adjustable fixed bias, turn up the bias. It will change the sound at some point. So, adjust bias upwards (higher tube bias voltage) just below when the sound changes a little. Tubes should last 5000 hours if manufactured correctly. I think the speakers would sound better connected to the 4 ohm taps. This unloads the plate to plate impedance and that usually sounds better. Either speaker tap will not effect tube life.
     
    Stephane Quiniou and DrZhivago like this.
  5. Drew769

    Drew769 Forum Resident

    Location:
    NJ
    You should call Steve Leung, who is the exclusive importer of the Cayin amps in the USA. He’s a true engineer/audio geek, and I’m sure he’ll help.
    +1-732-888-3288
     
    jpelg, David M. and Helom like this.
  6. Helom

    Helom I'll take the monkey coffins

    Location:
    U.S.
    Your tubes should be biased between 350mV and 400mV. 385 is the sweet spot for my Cayin.

    If your amp doesn't have test points on top for inserting meter leads, it likely requires opening the amp for biasing - not recommended for newbies as there are fatal voltages in there.

    Run your 6 ohm speakers from the 4 ohm taps.
     
    SandAndGlass and DrZhivago like this.
  7. Guitarded

    Guitarded Forum Resident

    Location:
    Montana
    Which Model and Tubes are you running?
     
  8. Helom

    Helom I'll take the monkey coffins

    Location:
    U.S.
    These tubes from this vendor:
    Ruby KT88V-STR
     
    Guitarded likes this.
  9. TheVinylAddict

    TheVinylAddict ___The Enforcer___

    Yeah, cuz there's nobody like that around here..... :)
     
  10. Stephane Quiniou

    Stephane Quiniou New Member Thread Starter

    Location:
    Montreal
    Cayin 55A With Genalex Gold lions KT88
    First quand was Cayin stock coming witht he amp.
    Cayin
     
  11. Stephane Quiniou

    Stephane Quiniou New Member Thread Starter

    Location:
    Montreal
    thank you, will do
     
  12. Stephane Quiniou

    Stephane Quiniou New Member Thread Starter

    Location:
    Montreal
    thank you for your help
     
  13. SandAndGlass

    SandAndGlass Twilight Forum Resident

    Tubes will last longer in some amps than others, depending on how hard they are run.

    I think that 3,000 hours (or more) is overly optimistic for most large power tubes of new manufacture.

    I think that an average of 2,000 for modern large power tubes like KT88's is more realistic.
     

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