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Vacuum Tube OTL power amp!!
Vacuum Tube OTL power amp!!
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Old 15th September 2011, 10:18 PM   #151
Alastair E is offline Alastair E  Wales
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Well you could prob calc. it out with the aid of PSUD....

The level of ripple the ripple-filter will tolerate would depend on the voltage drop (Headroom) you set the active device to....
--What nasty effects could occur with a high ripple from smaller caps, and insufficient headroom on the ripple-filter, I cant imagine....
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Old 15th September 2011, 11:23 PM   #152
M Gregg is offline M Gregg  England
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Originally Posted by Alastair E View Post
--What nasty effects could occur with a high ripple from smaller caps, and insufficient headroom on the ripple-filter, I cant imagine....
I can HuMMMMMMMMMMMMMMMMMMMM let me Think...LOL


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Old 16th September 2011, 12:03 AM   #153
Alastair E is offline Alastair E  Wales
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Aye, probably, But it wouldnt be the usual ripple/ramp hum we are used to...

I'm thinking a sorta flat-topped triangle wave...

Description sounds ugly, so guess the noise would be too!
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Old 17th September 2011, 06:52 PM   #154
M Gregg is offline M Gregg  England
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Relay input board connected.
Just for interest.
Cables
PTFE cable silverplated.
Jupiter silk/silver. << built into a screened cable.
Only because its a short run.




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M. Gregg
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Old 20th September 2011, 12:30 PM   #155
Alastair E is offline Alastair E  Wales
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Wow! Thats coming along really nicely!

You should have it working soon! Looking forward to your results!
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Old 20th September 2011, 03:26 PM   #156
gkn202 is offline gkn202  Luxembourg
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Originally Posted by Matthewong View Post
Hi, would like to ask whether the vacuum tube OTL power amp worth to build? How is the sound performance if compare to normal output transformer type?? Does anyone has any good schematic diagram for OTL power amp, can share out, thinking to try to make one.
Hi dear, I just finished a layout for a Totem-Pole OTL with very low Harmonic Distortion levels (0.079% at 20 W rms, 8 Ohm and 1Khz). The design has not been tested in a practical implementation. It is symmetrical and uses that many 6C33C tube stages that you can afford (or have the power supply for).

I've opened a Thread on this this morning, and hope receiving comments and suggestions for further improvements.

Attached you'll find a ZIP with the LTSpice model and the library.

CU Gary
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Old 20th September 2011, 03:38 PM   #157
Alastair E is offline Alastair E  Wales
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Hmm....

That aint much use --Without a Schematic!

All I get is a page of meanigless numbers and another page asking what program it needs to open it!

At least mine WORKS in the real world, with real tubes! Ive never put much faith in simulations, Especially with Tube circuits, Sims never seem to hold up!

Any chance of a scheme we can look at??
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Old 20th September 2011, 03:42 PM   #158
gkn202 is offline gkn202  Luxembourg
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hmmm...

just the schema, here it is... I've also posted a ZIP with the model and its library.

Gary
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Old 2nd October 2011, 06:29 PM   #159
M Gregg is offline M Gregg  England
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Just some more progress,
Just for fun.

Driver/preamp board.

I wanted to compress it into a small area away from the 6c33c's.
So point to point wiring.

Just connections for the IRF710 to do.

Feedback is via PTFE home made screened cables.
Bias supply cap is Rubycon HV.
Coupling cap is Jupiter, Amtranz.
Takman resistors.

Heaters should be DC for the pre/ 6SN7's if all goes well!
and AC for the 6SL7.

Heater cables run across the back of the board to shield them from the pre circuits.
The board only provides screen no signal transfer. star Gnd.

Still on going, lots to do!


Regards
M. Gregg
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Old 2nd October 2011, 07:05 PM   #160
M Gregg is offline M Gregg  England
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Regards the 6SL7,

Neon protection for the DC coupled stage.(grid cathode) has been fitted!

Just for interest the top plate shields the tubes from the Heater cables.

Alastair,

What voltage do you have on the anode of the driver tube?

(6SL7) in my circuit. So I can check the bias point, thank's.

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M. Gregg
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