Tubes Asylum

• Some clarification here just to be clear ;-) - AbeCollins 15:15:51 03/04/23 (2)
  In Reply to: RE: Nice Abe! Maybe we can share impressions soon. posted by JoshT on March 03, 2023 at 16:56:16

  Yes, it will be interesting to compare notes on these tubes in the CM. I look forward to it.

  I've been running my more efficient Tannoy Definition D500 towers lately (91dB 6 Ohm nom.) and have the power hungry Thiel CS2.4 speakers stored in the closet.

  When I ran the Cronus Magnum on my Thiels I really needed every once of extra power so I was pretty much limited to using the KT120 power tubes. The EL34 / 6CA7 were noticeably compressed sounding vs the KT120. But this is no longer the case with the Tannoys which allows me a broader choice in power tubes for the CM.
  

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  As an aside I emailed Rogue a couple days ago. Here' my email exchange with Nick:

  Hi Abe,

  We have never used he 6CA7 in production for any of our products, so I don't know how their longevity will compare to the EL34 tubes. The GL KT77 is a nice sounding tube which is very similar to the EL34 but should provide longer tube life. The recommended bias setting for KT120's is 35mA and it would be 30mA for EL34, KT77, and 6CA7 tube types. Of the 3 tubes you have listed, I would expect the KT120's to provide the best tube life in the Cronus.

  Best Regards,
  Nick Fitzsimmons
  Rogue Audio Inc.
  545 Jenna Drive
  Brodheadsville, PA, 18322

  - - - - - - - - - - - - - - - - - - -

  From: Abe Collins
  Sent: Friday, March 3, 2023 11:49 AM
  To: info rogueaudio.com
  Subject: EL34 / 6CA7 / KT120 Bias for Cronus Magnum ?

  Hello -

  I have an older Cronus Magnum (not the II or III) and have been happy running it with a quad of EH 6CA7 tubes or Tungsol KT120. I have a few quick questions I was hoping you could answer.

  Is the 6CA7 considered to be a more "rugged" EL34? I heard something to that effect many years ago. Will the 6CA7 have a longer tube life in the Cronus Magnum vs the EL34?

  Your BIAS recommendations for:

  - EH 6CA7
  - JJ EL34
  - Tungsol KT120

  I've been biasing them all at 35ma but this may not be quite right. Which of the above tubes should last the longest in my Cronus Magnum?

  - - - - - - - - - - - - - - - - - - -

  Cronus Magnum / Benchmark - Polar Opposites? Sort of:
  

  
  
  
  

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  Edits: 03/04/23

  • Good news - JoshT 08:01:22 03/05/23 (1)
    In Reply to: RE: Some clarification here just to be clear ;-) posted by AbeCollins on March 04, 2023 at 15:15:51

    I run Heresy IIs with the CMII and am running Devore Fidelity Super Nines with my new ST-70, which are 8 ohm nominal and around 91 db efficient. Both systems have great dynamics and solid bass with those amps and the tubes in them. Still, I might go for some JJ KT88s for the CMII at some point given the tube life caution from Nick.
    
    Your email exchange is consistent with my call with Nick last week, though I'd not specifically asked about the KT77.
    ___
    "If you are the owner of a new stereophonic system, this record will play with even more brilliant true-to-life fidelity. In short, you can purchase this record with no fear of its becoming obsolete in the future."
    
    

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    • RE: Good news - AbeCollins 12:35:27 03/05/23 (0)
      In Reply to: RE: Good news posted by JoshT on March 05, 2023 at 08:01:22

      
      I didn't mention the KT77 to Nick but he offered it up as a nice sounding tube that's more rugged than the EL34. I've never heard one.
      
      News Flash!
      
      I ordered my JJ 6CA7 from the TubeDepot on Friday and they arrived Sunday afternoon. I specified FedEx 2-days [which is 2 business days] but I suspect they got here so quick because the main FedEx hub is in Memphis TN and TubeDepot is in Memphis.
      
      Time to play.
      
      
      
      
      

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