Triode or Pentode tube configuration

haimoc
haimoc Posts: 1,031
edited March 2008 in 2 Channel Audio
Could someone please educate me what Triode or Pentode tube configuration is? Thanks.
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  • Gretsch6136
    Gretsch6136 Posts: 80
    edited March 2008
    I'm not an expert and this won't be the full story but here's a start.....

    Valves basically have 3 elements, an anode, a cathode and a grid. Electrons flow from the anode (+) to the cathode (-). The grid is between these two points and regulates the current flow of electrons. How much effect the grid has is determined by the amount of bias current supplied to it. Simple! This setup is called a triode valve.

    A pentode valve has two anodes, two cathodes and the grid. This design allows a greater flow of electrons without overloading the valve and therefore allows the development of more power or amplification.

    Many amp designs allow a pentode valve to be used either as a pentode or a triode by simply turning off one anode and cathode pair. The triode mode delivers less power but tends to be more sensitive to voltage changes and therefore more transparent sounding.

    In practice with my amp, I find both triode and pentode modes to be about as loud as each other but triode is more dynamic and resolves detail better. If you want to rock out to Metallica, pentode is the way to go, but if you want to chill out to Miles Davis or Chris Isaak, triode is your friend.

    I hope that helps a bit.

    Cheers,

    Mark
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  • haimoc
    haimoc Posts: 1,031
    edited March 2008
    Thanks, Mark. I am not an expert, neither, so this gives just a perfect definition or concept that I need to know. I read a product brochure of Synthesistube amps/preamps and want to understand these terms. :)
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  • mhardy6647
    mhardy6647 Posts: 33,802
    edited March 2008
    More on triodes, tetrodes, beam power tubes, and pentodes...

    http://www.anthemav.com/OldSitev1/pdf/taste.pdf

    EDIT: Even better (if a bit technical):
    http://www.pmillett.com/Books/crowhurst_basic_2.pdf (see Section 2)
    A pentode valve has two anodes, two cathodes and the grid.
    Nope, sorry. One anode ("plate"), one cathode, and three grids in a pentode.

    pentode.gif
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  • haimoc
    haimoc Posts: 1,031
    edited March 2008
    Don't know that I have more homeworks for this weekend.. :D Thanks.. :cool:
    Download them all..
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  • Gretsch6136
    Gretsch6136 Posts: 80
    edited March 2008
    Sorry dude....I thought my understanding was close to the mark. That link MRH supplied is gold!

    Cheers,

    Mark
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  • organ
    organ Posts: 4,969
    edited March 2008
    Don't forget that just about all pentode amp could be converted to triode with a resistor between pins 3 and 4 on each output tube.
    I first experienced this when I converted my vintage Dynaco amp (EL34 output tubes). The sound is so much better in triode.
    The downside is your output power being reduced by half after the conversion. I find that the sound keeps improving as you go down in power. IMO, triode is all about tone. It's quite different than the others.
    The 2A3 and 300B tubes are the most incredible sounding tubes I've heard so far. The 2A3 is 3w and 300B 8w.
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  • mhardy6647
    mhardy6647 Posts: 33,802
    edited March 2008
    The 2A3 and 300B tubes are the most incredible sounding tubes I've heard so far. The 2A3 is 3w and 300B 8w.

    Guess you haven't heard a 45 yet :-)
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