30 W from 6c33b?

protos · 31st March 2005, 03:49 PM

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 · 31st March 2005, 04:33 PM

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 · 31st March 2005, 04:59 PM

Quote:

Originally posted by analog_sa
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 · 31st March 2005, 06:40 PM

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 · 1st April 2005, 07:22 AM

Hi!

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

G.M.

Sch3mat1c · 1st April 2005, 07:33 AM

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

31st March 2005, 03:49 PM	#1
protos diyAudio Member Join Date: Mar 2002 Location: Athens+Addis Ababa	30 W from 6c33b? 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

1st April 2005, 07:33 AM	#6
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	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 __________________ Seven Transistor Labs Projects and Resources

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31st March 2005, 04:33 PM	#2
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	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

31st March 2005, 06:40 PM	#4
analog_sa diyAudio Member Join Date: Aug 2002 Location: Sofia	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.

1st April 2005, 07:22 AM	#5
gianmaria diyAudio Member Join Date: Dec 2004 Location: Roma	Hi! I think the secret is A2 class (low power dissipation) and Harmonic Cancellation from the EL34..... G.M.