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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Converting from UL to Triode: Is this correct?

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jhstewart9

jhstewart9

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Joined 2013
M Gregg said:
I use 1K with EL34 and switch,

You could try diode enhanced U/L (slipstream) sound is close to triode with more power.. remember to watch the bias current when you change connection types.

The mod is simply a 1K to the tube and a diode from the U/L tap on the output Tx pointing towards the tube something like 1n4007 would do it.

Its mentioned here..however I fit a 1K on the tube side of the diode..
Hiend Audio, DIY, Hi-Fi, Stereo, Electronics site, for lovers of high-fidelity music reproduction. High-End Vacuum Tubes. Silicon. Do-It-Yourself Audio Systems. Schematics: amplifiers, speakers, horns, CD, DAC. Circuits, Topologies, Acoustics, Cables

I switch between RH/U,L slipstream/triode on SE you can use diode enhanced triode as well but I'm not a fan..:)

NB important don't just replace the resistor with the diode the diode is in series with the resistor.

Regards
M. Gregg
Click to expand...


I carefully read the article on this Diode/UL modification. But there is no measured experimental proof offered. It simply 'Sounds' better, but better than what? Would it pass a double blind test, with & without the diodes?


Listening tests are subjective observations, subject to the listeners own judgement. Others may not agree. And to a very large degree the transducers (speakers), the room & so on. Difficult for others to reproduce at a distance.
That is why measurement data is important, something others can do as a comparison. On the other side of the World.:)
 
jhstewart9

jhstewart9

Member
Joined 2013
Common Sense

A diode usually allows current in one direction. Never heard of a pentode or tetrode where the screen current ran backwards. That only happened with some noise, light & smoke. The diode won't do much.:eek:


The author is laying track, a Fog of BS. Is he selling something.:rolleyes:
 
jhstewart9

jhstewart9

Member
Joined 2013
Well you tell us. You're the one that bumped this old thread.:confused:

jeff



Sure beats me, what do you think? What are your thoughts on the diode mod, I stated mine for all to see. That item was referenced in the thread I was following just yesterday, complete with a link to that circuit.


I see you are a vinyl fan, I've about a thousand in my pile. Including a few very early 10 inch disks, Bill Halley, Ray Anthony, Billy May, Errol Garner & Others. But a very wide variety, I like both Rock & Classic. Many of these are now on Cassette.



All play thru a Sony PS-S6 (1978), don't recall what pickup is in it today. The Amp is a Sansui AU717 with the matching TU717 on top. My ears are shot now. So in my office I've a pair of wide range 6X9's in unported boxes, driven thru Hammond distribution transformers to limit power. The Hammonds are switched so three levels are possible. In the rec room twin RSC speakers. Don't recall the model tho.


And four bass reflex on the back deck, the first neighbors on that direction are an Imperial Mile away. Lucky for them. But looks like no parties this year!:D


All my toob amps are on the shelf in the workshop, all my own design & build. Some are working, some not, they are for the most part experimental.
I've authored several papers on them, published primarily in AudioXpress Mag.:)
 

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