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EL84 parameters

Discussion in 'Shock Brother's DIY Amps' started by Tom Kamphuys, Sep 18, 2018.

  1. Tom Kamphuys

    Tom Kamphuys Tele-Holic

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    Hi all,

    I'm planning to build an 18W clone. Instead of simply building what the manual says, I'm trying to understand the circuit. I've read the book 'Designing Tube Preamps for Guitar and Bass' by M. Blencowe and currently I'm reading/learning 'Guitar Amplifier Power Amps' by R. Kuehnel.
    I've been able to reproduce the numbers in 'Chapter 18. A Class AB Parallel Push-Pull Design Example' using the Norman Koren models and parameters as given in https://hal.archives-ouvertes.fr/hal-00631752/document for the 6L6 tube used in the example using (mostly) Octave/Matlab.
    However, the parameters for the EL84 don't result in a good match with the datasheet (see attachement). As the match is quite good for the 6L6 tube, I suspect the parameters used for the EL84:

    u = 16
    Kg1 = 570
    Kg2 = 4200
    Kp = 50
    Kvb = 24
    Ex = 1.35

    Can anyone provide me with the correct parameter values? Or even better, give me an alternative source for more Koren parameters for several types of tube?
     

    Attached Files:

  2. Tom Kamphuys

    Tom Kamphuys Tele-Holic

    Age:
    41
    Posts:
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    Somehow just the mere fact of posting helps me find the answer. It might force me to organize my thoughts....

    I tried a search for 6BQ5, an equivalent tube. It gave me these values:
    % source: http://af6ea.blogspot.com/2016/04/6bq5-spice-model-calculations.html
    u = 18.894;
    Kg1 = 1004.346;
    Kg2 = 2200;
    Kp = 100.421;
    Kvb = 20.288;
    Ex = 1.548;

    Judging from the plots, they seem OK.
     

    Attached Files:

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