Do you prefer pentode or triode?

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fastonebazfastonebaz Frets: 151
 Which sound do you prefer on your Marshall amp pentode or triode?  Can you describe the difference in how it sounds to you?

I realised mine's always been in triode, I forgot about it tbh.  Penny for your thoughts....
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  • revsorgrevsorg Frets: 361
    I know it's not a Marshall so I don't know if this will help at all but my Rivera M60 runs on a pair of EL34 valves and has a triode/pentode switch round the back.  Triode is dull, pentode makes me feel like a guitar god - harsher, louder and more alive.
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  • Guitar_SlingerGuitar_Slinger Frets: 1145
    edited July 6
    When you ask "prefer"... I've got a JCM900 combo which is run in low power (triode) mode at 25w.

     I hadn't thought of it as pentiode and triode, but as not wanting to play in a "you're OK but your guitarist's too loud" pub band.
    “Supposing a tree fell down, Pooh, when we were underneath it?' 'Supposing it didn't,' said Pooh after careful thought. Piglet was comforted by this.”
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  • timmysofttimmysoft Frets: 1638
    I prefer pentagrams 
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  • ICBMICBM Frets: 31118
    Pentode, always. Triode sounds crap - muddy and lifeless. (It can also increase hum.)

    If it’s too loud in pentode, just turn the master volume down slightly.
    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."
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  • jpfampsjpfamps Frets: 1324

    Pentode.


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  • Guitar_SlingerGuitar_Slinger Frets: 1145
    ICBM said:
    Pentode, always. Triode sounds crap - muddy and lifeless. (It can also increase hum.)

    If it’s too loud in pentode, just turn the master volume down slightly.
    Like, dur, why didn't I think of that?  Seriously, I turned up at a rehearsal room years ago, put it at 25W, rocked out and have left the amp in triode ever since without thinking about trying it the other way.

    Next outing, I'll switch to pentode after a few songs and compare the difference.  Thanks for the (stating the obvious) tip.
    “Supposing a tree fell down, Pooh, when we were underneath it?' 'Supposing it didn't,' said Pooh after careful thought. Piglet was comforted by this.”
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  • RiftAmpsRiftAmps Frets: 1158
    'Triode' sounds crap in a circuit designed for pentodes - which is where you'd most likely hear it. Design a circuit around triodes properly though and they sound just as good
    Rift Amplification
    Handwired Guitar Amplifiers
    Brackley, Northamptonshire
    www.riftamps.co.uk
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  • ChuckManualChuckManual Frets: 401
    RiftAmps said:
    'Triode' sounds crap in a circuit designed for pentodes - which is where you'd most likely hear it. Design a circuit around triodes properly though and they sound just as good
    Out of interest; What are the best examples of this?
    Not much of the gear, even less idea.
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  • fastonebazfastonebaz Frets: 151
    ICBM said:
    Pentode, always. Triode sounds crap - muddy and lifeless. (It can also increase hum.)

    If it’s too loud in pentode, just turn the master volume down slightly.
    Like, dur, why didn't I think of that?  Seriously, I turned up at a rehearsal room years ago, put it at 25W, rocked out and have left the amp in triode ever since without thinking about trying it the other way.

    Next outing, I'll switch to pentode after a few songs and compare the difference.  Thanks for the (stating the obvious) tip.
    Doh. That's exactly what I did
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  • RiftAmpsRiftAmps Frets: 1158
    RiftAmps said:
    'Triode' sounds crap in a circuit designed for pentodes - which is where you'd most likely hear it. Design a circuit around triodes properly though and they sound just as good
    Out of interest; What are the best examples of this?
    Many, many old radio and HiFi circuits. Most valve datasheets for power pentodes show suggested operating conditions for triode mode, yet modern designers seem to ignore them (admittedly because the Pentode/Triode switch is usually an afterthought).

    My PR6 uses a pair of 6V6s configured as triodes running in push-pull, with optimised conditions to do so. You get 6w without SE hum and no perceivable loss in tone (other than that associated with lower volumes).

    Rift Amplification
    Handwired Guitar Amplifiers
    Brackley, Northamptonshire
    www.riftamps.co.uk
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  • ChuckManualChuckManual Frets: 401
    RiftAmps said:

    My PR6 uses a pair of 6V6s configured as triodes running in push-pull, with optimised conditions to do so. You get 6w without SE hum and no perceivable loss in tone (other than that associated with lower volumes).

    I can't find any videos of the PR6 on YouTube - but, from your description, I'm imagining a pleasantly warm and easily naturally compressed tone from two 6V6's only putting out six watts...? Or is my understanding of these things woefully poor?
    Not much of the gear, even less idea.
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  • DJH83004DJH83004 Frets: 166
    +1 for RiftAmp's comments, the characteristics of the valve change significantly when switching to triode operation and have to be taken into account in the design, e.g. output impedance, open loop gain (hence amount of NFB), input sensitivity, lower distortion etc.have to be catered for, so simply putting in a switch to connect the screen grid to anode, results in the woolly sound that you actually hear.
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  • SporkySporky Frets: 12905
    Pentodes are harder to push over. 
    Be your own evil twin. 
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  • fastonebazfastonebaz Frets: 151
    Had a brief experiment at home levels between triode and pentode and I think I'm starting to hear the slight woolliness in the triode that has been mentioned above.  Will give it a thorough blasting at rehearsal next week! 
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  • Phil_aka_PipPhil_aka_Pip Frets: 8592
    Don't know about guitar amps, but some triode hifi amps can sound pretty lush.
    "Working" software has only unobserved bugs. (Parroty Error: Pieces of Nine! Pieces of Nine!)
    Seriously: If you value it, take/fetch it yourself
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  • TA22GTTA22GT Frets: 221
    I've never played any guitar amp that sounds good in triode.
    My amp can do it but I can't understand why they would want to make a crap sound a feature!
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  • PhilKingPhilKing Frets: 212
    I always find that triode mode loses the attack and softens the response of the amp.  Not a sound that I really want.
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  • ecc83ecc83 Frets: 807
    edited July 7

    Funny story. The first Artisan 15s and 30s switched to SE for the lower power option i.e. still pentode but it transpired that someone (in the states?) claimed they had a patent on the circuit. Since B's were then just getting started and an international legal battle was not on,  the circuit was modified to triode operation.

    Not ideal as many above have said but what can yer do with yer nuts in a vice?

    The HT-5/HT-1 is of course triode from the go-get.

    Dave.

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  • pintspillerpintspiller Frets: 484
    @ICBM does the sensitivity switch on the back of my Sound City 50+ chance between pentode/triode? I know theres a difference in volume but can't remember why (I tell people who ask that it's an attenuator). 

    I used to frequent PlexiPalace and a Sound City fan site years ago, but have forgotten much of what I've read. I blame old age.
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  • ICBMICBM Frets: 31118
    @ICBM does the sensitivity switch on the back of my Sound City 50+ chance between pentode/triode? I know theres a difference in volume but can't remember why (I tell people who ask that it's an attenuator).
    No, it's just a basic volume cut before the power amp. Technically it *is* an attenuator - of the signal level - but not what most people would call an attenuator now .
    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."
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  • DJH83004DJH83004 Frets: 166
    edited July 8
    @ICBM does the sensitivity switch on the back of my Sound City 50+ chance between pentode/triode? I know theres a difference in volume but can't remember why (I tell people who ask that it's an attenuator). 

    I used to frequent PlexiPalace and a Sound City fan site years ago, but have forgotten much of what I've read. I blame old age.
    No, it changes the gain of preamp valve V3b (the last stage before the PI) by altering the resistance in the cathode leg - actually switching an internal trim pot in and out of circuit.  
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  • WazmeisterWazmeister Frets: 3620
    I can only speak for a Carr Rambler, which is a Fender flavoured amp.... for home use, I prefer the Triode... Pent for live 
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  • pintspillerpintspiller Frets: 484
    @icbm and @DJH83004 thanks for the heads up as I was wondering about the difference in tone mentioned earlier in the thread as I didn't believe I heard anything when I switched.

    There is a noticeable volume drop when the switch is engaged. Perhaps equal to two or three notches on the volume knob.
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  • DJH83004DJH83004 Frets: 166
    @icbm and @DJH83004 thanks for the heads up as I was wondering about the difference in tone mentioned earlier in the thread as I didn't believe I heard anything when I switched.

    There is a noticeable volume drop when the switch is engaged. Perhaps equal to two or three notches on the volume knob.
    The gain is actually adjustable with an an internal trimmer, but it does mean taking the chassis out of the cab unfortunately  :s
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