Triode mode.

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pre65
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Triode mode.

Post by pre65 » Tue Apr 21, 2015 12:58 pm

I was going to ask some questions regarding triode mode on a pentode, but this article answered them for me.

http://www.kaponk.com/~yanyong/ETF06TS.pdf
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IslandPink
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Post by IslandPink » Tue Apr 21, 2015 6:23 pm

Very good ! I need to look through that in more detail soon . He could do with getting his > and < signs the right way round on slide 7, though .
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jack
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Post by jack » Tue Apr 21, 2015 9:17 pm

Oddly, I was reading this only last week - Its a good article but there are several small mistakes in it. e.g. as mentioned above (and a missing "=").

FWIW, I always thought that "KT" was "Kinkless Tetrode".

I would have loved to have gone to the lecture at 14:00 in the library room :)

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rowuk
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Re: Triode mode.

Post by rowuk » Sat Jun 20, 2015 9:59 pm

I read the article, but he gave no real reasons for not using the pentode mode. I am getting such wonderful performance with a 307A super and EL84 in the RH pentode circuits that I wonder why someone feels the urge to "waste" so much power.
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Re: Triode mode.

Post by Cressy Snr » Sun Jun 21, 2015 11:24 am

rowuk wrote: I am getting such wonderful performance with a 307A super and EL84 in the RH pentode circuits that I wonder why someone feels the urge to "waste" so much power.
Well I feel the same, but each to his own I say. We can't all like the same things.
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rowuk
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Re: Triode mode.

Post by rowuk » Sun Jun 21, 2015 12:28 pm

I don't think that we need to all like the same things, but being here is a chance to develop "vocabulary" for what we hear as differences and that would help put things into perspective. What I do know is that a triode amplifier without feedback is VERY sensitive to load. If someones journey lead them to a speaker/amp combination made in heaven, then great. My experience has been different. I see little posting about the effects of amp loading - does that mean that no one is trying? That they can't hear it? That it doesn't matter? That they are missing something important? I don't know. Mostly I read bogus arguments and none of the real life issues. It does make me wonder.
SteveTheShadow wrote:
rowuk wrote: I am getting such wonderful performance with a 307A super and EL84 in the RH pentode circuits that I wonder why someone feels the urge to "waste" so much power.
Well I feel the same, but each to his own I say. We can't all like the same things.
Whenever I feel blue, I start breathing again.

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Re: Triode mode.

Post by Cressy Snr » Sun Jun 21, 2015 1:15 pm

I think that the difficulty with developing a vocabulary around differences is that it's next to impossible, which is why no-one except magazine reviewers bothers trying. I wish it was easy.
In terms of single-ended pentode amps and even worse, pentode push-pull amps, 99.9999% of tube loving audiophiles simply don't want to know. The mainstream goes for powerful push-pull ultralinear, the discerning enthusiast goes for SETs.

That's fine by me as the popularity in the guitar amp world, of output tubes such as EL34, KT88 etc keeps prices reasonable and the small signal pentodes I like to use as drivers for pentode output stages are cheap and plentiful NOS, as nobody wants them.
The exceptions to this rule are the fashionable German small signal pentodes that DIY'ers use to drive SET output stages. True to form, these have become expensive over the years.

I think we have to accept that outside of the guitar world, proper pentode power amps are a niche interest in a niche section of the audio industry and as such, there's probably only yourself, Gary Pimm, Lynn Olson, Steve Deckert, Bob Carver, Alex Kitic, a few Japanese enthusiasts and me, on the whole planet, that give a monkeys :wink:
If that's not an exclusive club, then I don't know what is! :D :lol:
Last edited by Cressy Snr on Sun Jun 21, 2015 7:21 pm, edited 2 times in total.
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Paul Barker
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Re: Triode mode.

Post by Paul Barker » Sun Jun 21, 2015 2:25 pm

Of course Rosenblit is a prominent influence. He states in one of his articles if not more, that the whole it must be band A held views is not right. Whatever the words he used thats what I understood from them.

I was reminded of this when you Steve admitted you had been listening to class B at a time when you thought your system sounded better than ever (following the driver mod).

I have to harken back to the time I built the Rosenblit Glass Audio 6080 OTL amp. Unbeaten in many respects. It is the sort of sound I just know you would love Steve. But you did try going down that road and got yourself into a headspin over it. But I think where you are now is as far as you need to go.

Hoping you have it back up and running for Thursday but if not we can postpone.
I can do it right or I can do it now, but I can't do it right now.

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Re: Triode mode.

Post by Cressy Snr » Sun Jun 21, 2015 2:56 pm

Paul Barker wrote:
Hoping you have it back up and running for Thursday but if not we can postpone.
It's fine now Paul; up, running and kicking ass again. No need for any postponements.
Got some jaaaaaahz (Stan Getz with Cal Tjader) wafting around the room at the moment :)
As you say, I think I have now gone as far as I need to go. I have spent 18 months with the current amplifier
and have been using and loving various flavours of pp pentodes since 2012.

Oh yes OTLs. These are my ultmate dream amps.
The likelihood of my ever being able to build one without some major disaster occuring, is less than zero. :D :D
Happiness is not good for the economy Matt Haig.

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