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Edcor Guitar Amp OPT for SE HIFI

Joined 2004
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I have not found a datasheet with EL85 triode-mode operating conditions. Do you have one?

Based on the EL85 SE pentode operations it appears to require higher plate loading than EL84, or EL90. So, the Edcor’s 5k might not be ideal if it is run pentode. Since you plan to use the EL85 in triode-mode 5k might be fine. Let us know after you checked the datasheet.

Also, curious why EL85? Since you already have the 5k OTs perhaps EL84, 6AQ5, 6P1P and 6P15P are plentiful and might be a better fit.
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EL84 in triode wired mode, with 40mA combined plate/screen current has an "rp" of about 1700 Ohms.
Suppose the output transformer has 10 Henrys with 40mA DC current from the triode wired mode.

I did not look up the primary inductance of the Edcor output transformer. Sometimes they list that, sometimes they do not.

Here is an example "different way" to look at the suitability question:
rp = 1700 Ohms
L = 10 Henry (output tranformer primary)
1700 = 2 x pi x L x f
Then f = 1700 / (2 x pi x L)
f = 27 Hz

27 Hz is lower than most peoples loudspeakers go (without reduced amplitude, and without harmonic distortion).

Suppose the Edcor only has 5H inductance.
f = 27 x 2 = 54 Hz

You decide.
I measured the Edcor XSE15-16-5k to have 11H on primary and 39mH on sec. The primary has the tap for ultra linear, and the inductance of the two is 1.8H and 3.9H, taken in series they are 11H in total. The 6AS7 amp using these has great bass but that tube has very low rp so I can't comment how these OPT are on higher rp tubes.
This is my all time favourite flea power amp which keeps getting put back in my rack after other designs have had their chance... (I probably enjoy the harmonics it produces - yeah I know I just aint no audiohysteric. Not sure it's the tubes, or the OPT, or the combo)
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