Matchless Clubman Question

[jackplug1]

I have built a Matchless clubman clone which appears to have excessive plate dissipation using this calculator:

https://robrobinette.com/Tube_Bias_Calculator.htm

Plate to cathode voltage: 402v

Tubes that share a cathode resistor: 1
Voltage across cathode: 28v
Cathode resistor: 330R

= Plate current 80.1Ma
= Dissipation per tube 32.2watts

It appears that the safe limit should be 67.2Ma

Should I increase the cathode resistor to about 600R?

The amplifier appears to run hot and is very loud for a 35watt amplifier although it sounds quiet bright and lively.
Running at these levels will the life of the output tubes be short but very gay?

[Latole]

Wich tubes ? EL34  ?

Schematic here ;
https://www.thetubestore.com/lib/thetubestore/schematics/Matchless/Matchless-Clubman-Schematic.pdf

80 ma is for resistor dissipation, not for tube dissipation ?????

I may be wrong too 

[jackplug1]

The Matchless Clubman output tubes are EL34

[Latole]

In class A EL34 can hold 56 ma for 400 volts /plate
Class AB 43 ma

[Latole]

I'll increase the resistor for each tube, your calculation look right.

Do you use one resistor for each tube or one resistor for both tubes ?
__________________

"It appears that the safe limit should be 67.2Ma"

This wrong. Not more than 56 ma. You make a mistake in calculation

[pdf64]

Why build a clone and then change a key aspect of what made the original what is was? eg super hot idle.

"It appears that the safe limit should be 67.2Ma"

This wrong. Not more than 56 ma. You make a mistake in calculation

For a cathode biased amp, the anode voltage is somewhat greater than the anode to cathode voltage.
And cathode current equals anode current plus screen grid current.

[PRR]

Allowing for screen current, it may be 27 Watts in the plate. The book says 25W. Every EL34 I ever abused would take 30 Watts for days. And that seems to have been standard practice with amp designers for decades. Any current tube-maker knows that, and must allow for it or be drowning in warranty claims.

600r is surely too much. 380-420 may be worth a try. But as said: don't be timid and accept boring tone. EL34 is about the cheapest big tube around, the 5-cent cigar of the tube world.

[pdf64]

If we accept that the 6L6GC has an anode dissipation limit of 30W, then under that same design max rating system, the EL34 limit would probably be about 29W.

[jackplug1]

I'll increase the resistor for each tube, your calculation look right.

Do you use one resistor for each tube or one resistor for both tubes ?
__________________

"It appears that the safe limit should be 67.2Ma"

This wrong. Not more than 56 ma. You make a mistake in calculation

One resistor per tube:

If you click on the link the calculation is done for you.  You just fill in the values

[jackplug1]

The output tubes do not share a cathode resistor, there is a separate resistor or for each tube
I had another look at it, I think I have misinterpreted the results on reflection
The total plate current is 80.1ma divided by 2, so it's 40.05ma per tube.
Plate current per tube is plate current PER TUBE minus plate voltage is 17.4watts per tube
err .. I think, Is that right?
The calculator does not have an input for how many tubes there are.
Maybe sombody could have a look at that tube bias calculator to clarify things

[pdf64]

...using this calculator:

https://robrobinette.com/Tube_Bias_Calculator.htm
...

A significant oversight / failing of such calculators in my view is that they make no distinction between the various rating systems used to determine anode dissipation limits, ignoring the expectation / intention of the rating system designers that limits provided under the design max and absolute max systems should have a suitable de-rating applied before being used in such calculations.

[sluckey]

I think, Is that right?

Wrong. You had it right to begin with.

[shooter]

the math is faster than web pages loading 
Vk (cathode) / Rk = tube current
Vp EDIT: - Vk * tube current = watts dissipated
(built in fudge factor because I didn't subtract G2:)

[pdf64]

...
Vk (cathode) / Rk = tube current
Vp* tube current = watts dissipated
(built in fudge factor because I didn't subtract G2:)

Need to subtract Vk from Vp 

[Latole]

"
If you click on the link the calculation is done for you.  You just fill in the values

That is what I do.