Output power

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Wakarusa, Mar 20, 2005.


  1. Wakarusa

    Wakarusa Member

    Messages:
    1,477
    Joined:
    May 7, 2004
    Location:
    Newnan, GA
    Doing final measurements on an amp and thought this might be of interest.

    This is one way to answer the question "How do you know the output power of an amp?".
    Note: thermal dissipation in the power tubes (plate current * plate voltage) is not the right answer ;)


    [​IMG]
    [​IMG]


    FWIW, the C50-RT ("Bob") into an 8 ohm load with a 440Hz (low A) input starts to compress at about 25W with max clipped power at about 43W when running a pair of 6L6GC :cool:

    And yes, I need to clean up my bench.
     
  2. John Phillips

    John Phillips Member

    Messages:
    13,080
    Joined:
    Mar 17, 2002
    Location:
    Scotland
    NICE meter, Todd!

    :)

    Here are mine:

    [​IMG]

    AVO Model 7 & Model 9 MkII

    Nothing like vintage analog Bakelite, is there? ;)


    (They still make one today, AFAIK - they cost a fortune too. I got both these from yard sales for next to nothing :).)
     
  3. Wakarusa

    Wakarusa Member

    Messages:
    1,477
    Joined:
    May 7, 2004
    Location:
    Newnan, GA
    Thanks John :)

    Digital stuff is nice, but an old analog (with the mirror for parallax) is really tough to beat. This one goes to 200W and claims 1/4% accuracy up to 1KHz, 1/2% accurate to 2.5KHz.
     
  4. Reeek

    Reeek Member

    Messages:
    1,208
    Joined:
    Feb 1, 2005
    Location:
    Reno, NV
    Even though I need and want one, it still reminds me of Mayberry RFD :p :cool:

    I need a Variac much more right now and should just go and pull the trigger. . .
     
  5. Wakarusa

    Wakarusa Member

    Messages:
    1,477
    Joined:
    May 7, 2004
    Location:
    Newnan, GA
    Autotransformers are easy to come by, keep an eye on Fleabay. But for test meters (excepting general purpose DMM, in which case it's Fluke, Fluke, and Fluke) the old high quality analog meters from Weston, Avo, Simpson, etc. make current stuff look like garbage. The meter movements for current production stuff tend to be pretty sloppy. I can only assume because most folks want digital -- but on an analog device you just get a better feel for what's going on in some cases.
     
  6. Reeek

    Reeek Member

    Messages:
    1,208
    Joined:
    Feb 1, 2005
    Location:
    Reno, NV
    That's good to know. Thanks! That's how I bought my tube tester. It's not the best device in the world but it's a flawless working vintage device and works very well and is accurate since I'd had my readings confirmed on better gear.

    Thanks again,

    Rick
     

Share This Page