30 W from 6c33b?

[protos]

I would appreciate some comments on how this is possible as the author claims and how this circuit is different from others.
The designer was not forthcoming about its functioning.
http://www.audiodesignguide.com/ba/msb_aloia.jpg

 

[analog_sa]

As the transformer impedance is not shown i wouldn't make any comments upon the max power. As both the anode and grid voltages are shown max power should be easy to calculate with a known load. It can't be much different than any other SE circuit using the same tube.

What else? It's parafeed and there is some cathode NFB through the speaker. Call me paranoid but i wouldn't do this to my speakers 🙂

 

[protos]

Call me paranoid but i wouldn't do this to my speakers 🙂

I don´t understand your point.Is cathode nfb so objectionable?
Is it possible that the grid is being driven positive and extra power is derived from there?I don´t know if a 6c33b can handle this grid current.

 

[analog_sa]

No, the grid is not driven positive in this design. I have no probs with cathode feedback and assuming that a faulty tube can fry your speakers is probably far-fetched but then again i am not into OTLs either. After all one principal advantage of transformer coupled tube amps is the galvanic isolation of the speaker.

 

[gianmaria]

Hi!


I think the secret is A2 class (low power dissipation) and Harmonic Cancellation from the EL34.....

G.M.

 

[Sch3mat1c]

No grid current. RC coupling.

Maybe he measured it with a square wave. It "takes up more space", making RMS = peak power. 😀 Which of course means about 1.5 good watts with a 20:1 peak/average ratio of music. 😉

Tim