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E80CC - 12AU7 in Mcintosh mc-225

Discussion in 'Tube Audio' started by apachef1, Oct 8, 2018.

  1. apachef1

    apachef1 Well-Known Member

    Messages:
    881
    Location:
    Southbury CT
    Can Someone advise if using an E80CC in a Mcintosh Mc-225 PI section V2 & V4 12AU7 position will work safely in the circuit.

    I rolled a pair of E80CC's in place of the 12AU7's and they do make a difference. I like the sound but the higher heater current has me concerned if the the circuit will handle the higher current safely over time. The E80CC is recommended for PI circuits that use the !2AU7, but some place it in the driver and cathode sections with varied results.

    I placed a post in the Mcintosh thread just asking if anyone tried this move and no bites.

    Ed
     
    Last edited: Oct 8, 2018

     

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  2. primosounds

    primosounds Powered with pure tube sounds. Subscriber

    Messages:
    2,808
    Location:
    Terra, 21st century CE
    If you are going to worry about the extra filament current, then you would not be enjoying the music while that nagging suspicion that the amp will fail from the extra current demand. Designers always over engineer parts to give a safety margin. For the 2 e80cc that would be an addition .6A of current. That would be about 5% more total filament current. You could take temp measurements of the PT with the 12au7 and then the e80cc after the temps have stabilised. It may not be very much difference and if its a lot then it maybe a bad idea.
     
  3. apachef1

    apachef1 Well-Known Member

    Messages:
    881
    Location:
    Southbury CT
    I think the E80CC is a better fit in the 12BH7 driver section, not perfect but the heater amp current is the same as the 12BH7. Would like to hear more about this if anyone has tried them as the driver tubes?
     
  4. Lavane

    Lavane AK Subscriber Subscriber

    Messages:
    7,576
    Location:
    northern cal.
    I like the E80CC. The 12BH7 didn't do it for me. I just lost one half of my E80CC. I payed less than $20 for a NOS two years ago. It developed an intermittent short in one side recently. I got sticker shock when I saw what they go for now. Back to my RCA clear tops for now.
     
  5. apachef1

    apachef1 Well-Known Member

    Messages:
    881
    Location:
    Southbury CT
    It was never recommended for the driver position and only for the PI. Back to the heater current issue on this one. They do sound fantastic substituting the 12AU7's in the mc-225. I need to have a tech bench test the amp for distortion, also current draw at the PS and PT with the E80CC tubes installed. I just dont want a slow melt down using the E80CC's as my everyday tube for the Mc-225.
     

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