Triode Trick

jkeny · 20th February 2007, 12:32 AM

Has anybody tried this trick to convert pentode to triode operation ala Bill Perkins from Pearl Inc and shown here: http://t-linespeakers.org/tubes/triode-trick.html

This seems to be an alternative to ultralinear operation - am i right?

Any impressions?

John

Tweeker · 20th February 2007, 02:12 AM

Only insofar as triode connection is an alternative to UL operation. Its an alternative to a ~100 ohm resistor.

Jaap · 20th February 2007, 07:42 AM

the reports are that this solution sounds better than a resistor.

ray_moth · 20th February 2007, 07:50 AM

An alternative to UL connection is not what is intended here. All he is saying is, if you want to connect a pentode/tetrode as a triode, it's better to do it his way. The arguments make sense to me, but how much better it will sound I wouldn't know.

Geek · 20th February 2007, 08:25 AM

That's also known as "boosted triode".

You'll also see that used on some Lafayette and Hallicrafter tubed CB radios on the RF final.

jkeny · 20th February 2007, 09:22 AM

Ah! now that I know the name for it I can find past refernces to it in here.

I had a quick search and found refs but nobody seems to have tried it and reported on the sonics. I'm only new to tubes & seem to be ploughing the same furrow many have before - Have I missed something?

Thanks
John

Luanak · 27th February 2007, 10:27 AM

I have tried a similar aproach. But I do it with a programable tl431
shunt regulator at around 25V , with a Elna 450uf cap across it.
The power is a little bit smaller, but the sound is bit better to me, more relaxed or open.

Regards

Cosme

Klimon · 27th February 2007, 11:51 AM

Hi,

I've incorporated this 'trick' in my el84 se and must say that it makes an excellent improvement. My grievances before the mod were a somewhat slow, romantic but also muddled sound lacking attack; after the mod the amp sounds much more detailed and tighter. I wouldn't consider building another triode-strapped amp without using the trick. BTW the schematic contains a few small errors, ask me if you're really interested than I'll take a peek into my amp and see how I did it. fwiw Eddie Vaughn made a few suggestions for optimising the circuit (he uses something similar in his carina), namely using 5,6V zeners IIRC (same number would do the job) + one 1000µF electrolytic instead of the two 470µ and resistors. He also explains the benefits on his website (think he calls it black box).

Simon

pescalune · 27th February 2007, 01:23 PM

Hi,

Simon,

What are the few small errors in the schematic ?

Bien à vous .

Robert

jkeny · 27th February 2007, 02:08 PM

Hey Cosme,
I would be interested in a schematic for the tl431 version if that was possible?

Simon,
Ditto with your corrected schematic - would love to hear more.

John

20th February 2007, 12:32 AM	#1
jkeny Banned Join Date: Feb 2007 Location: Dublin	Triode Trick Has anybody tried this trick to convert pentode to triode operation ala Bill Perkins from Pearl Inc and shown here: http://t-linespeakers.org/tubes/triode-trick.html This seems to be an alternative to ultralinear operation - am i right? Any impressions? John

20th February 2007, 02:12 AM	#2
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	Only insofar as triode connection is an alternative to UL operation. Its an alternative to a ~100 ohm resistor. __________________ Be sure your foil hat has a good low impedance ground.

20th February 2007, 07:42 AM	#3
Jaap diyAudio Member Join Date: Dec 2002 Location: Netherlands	yes the reports are that this solution sounds better than a resistor.

27th February 2007, 01:23 PM	#9
pescalune diyAudio Member Join Date: Jan 2007 Location: hautes-alpes	TRIODE TRICK Hi, Simon, What are the few small errors in the schematic ? Bien à vous . Robert

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20th February 2007, 07:50 AM	#4
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	An alternative to UL connection is not what is intended here. All he is saying is, if you want to connect a pentode/tetrode as a triode, it's better to do it his way. The arguments make sense to me, but how much better it will sound I wouldn't know.

20th February 2007, 08:25 AM	#5
Geek diyAudio Member Join Date: Sep 2004	That's also known as "boosted triode". You'll also see that used on some Lafayette and Hallicrafter tubed CB radios on the RF final.

20th February 2007, 09:22 AM	#6
jkeny Banned Join Date: Feb 2007 Location: Dublin	Ah! now that I know the name for it I can find past refernces to it in here. I had a quick search and found refs but nobody seems to have tried it and reported on the sonics. I'm only new to tubes & seem to be ploughing the same furrow many have before - Have I missed something? Thanks John

27th February 2007, 10:27 AM	#7
Luanak diyAudio Member Join Date: Jan 2005 Location: Basque country	I have tried a similar aproach. But I do it with a programable tl431 shunt regulator at around 25V , with a Elna 450uf cap across it. The power is a little bit smaller, but the sound is bit better to me, more relaxed or open. Regards Cosme

27th February 2007, 11:51 AM	#8
Klimon diyAudio Member Join Date: Apr 2005 Location: Leuven	Hi, I've incorporated this 'trick' in my el84 se and must say that it makes an excellent improvement. My grievances before the mod were a somewhat slow, romantic but also muddled sound lacking attack; after the mod the amp sounds much more detailed and tighter. I wouldn't consider building another triode-strapped amp without using the trick. BTW the schematic contains a few small errors, ask me if you're really interested than I'll take a peek into my amp and see how I did it. fwiw Eddie Vaughn made a few suggestions for optimising the circuit (he uses something similar in his carina), namely using 5,6V zeners IIRC (same number would do the job) + one 1000µF electrolytic instead of the two 470µ and resistors. He also explains the benefits on his website (think he calls it black box). Simon

27th February 2007, 02:08 PM	#10
jkeny Banned Join Date: Feb 2007 Location: Dublin	Hey Cosme, I would be interested in a schematic for the tl431 version if that was possible? Simon, Ditto with your corrected schematic - would love to hear more. John

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