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Quartet vs Pair of EL84 - Tone benefits?
Posted: Mon 08/17/20 3:27 pm
by Tommy_D
Hi all
Have you seen in practice a sonic benefits of 4xEL84 vs “only” 2?
Hopefully not opening a can of worms!!
What made me think about it is Dumbles and Two-Rock seem to advocate for higher watts = better tone both a high and low volumes
Here Jim Kelley seems to argue quartets have a little extra something
https://www.tdpri.com/threads/4x6v6-vs-2x6l6.456146/
Is that consistent with the group’s experience?
I’m actually pretty inclined to try it, unless there is really no benefit beyond making the amp 3dB louder.
Thanks!
Re: Quartet vs Pair of EL84 - Tone benefits?
Posted: Mon 08/17/20 5:05 pm
by crgfrench
4 is louder. In my 36W I have a half power switch that cuts out the outer pair. Tone completely unaffected, just volume. I think some people perceive more Decibels as "better tone".
Re: Quartet vs Pair of EL84 - Tone benefits?
Posted: Mon 08/17/20 5:24 pm
by Tommy_D
Thanks Craig
So no perceived “additional complexity of tone” or increased articulation at lower volumes? Interesting
Has anyone tried running 2 pairs of tubes matched differently? I’ve read somewhere that in blind tests people tend to prefer slightly mismatched tubes (conscious that it’s not perfect for hum cancelling)
Re: Quartet vs Pair of EL84 - Tone benefits?
Posted: Mon 08/17/20 6:08 pm
by crgfrench
I'm running a matched quad of new production Mullards and it's just been running for a few days so I don't have any color on mismatching...
Re: Quartet vs Pair of EL84 - Tone benefits?
Posted: Tue 08/18/20 2:13 am
by Daviedawg
Interesting question. I have an Orange TH30 on my bench just now. It has behavioural issues I am trying to trace. The voltages at the plates/screens are strange and the cathode voltages for the pairs are different for no apparent reason. Hunting for resistor issues.
But the perceived volume difference between the two valve setting and the four valve is not as much as you would think, within my small space at least. But tonally they are quite different. Four valves sound fatter and beefier.
Dd
Edit. four matched JJs with very little use (I am told) are in it.
Re: Quartet vs Pair of EL84 - Tone benefits?
Posted: Tue 08/18/20 2:26 am
by Bieworm
Daviedawg wrote: ↑Tue 08/18/20 2:13 am
Interesting question. I have an Orange TH30 on my bench just now. It has behavioural issues I am trying to trace. The voltages at the plates/screens are strange and the cathode voltages for the pairs are different for no apparent reason. Hunting for resistor issues.
But the perceived volume difference between the two valve setting and the four valve is not as much as you would think, within my small space at least. But tonally they are quite different. Four valves sound fatter and beefier.
Dd
Edit. four matched JJs with very little use (I am told) are in it.
Dd... JJ EL84s are about the worst of their kind. The spread on them is huge. I changed mine for 6p14p NOS russians. They are unmatched, but spot on. I would try other EL84s before you bring on the soldering Iron.
Re: Quartet vs Pair of EL84 - Tone benefits?
Posted: Tue 08/18/20 1:11 pm
by Daviedawg
Indeed the JJs can be unreliable. I did fit another set of mismatched valves from my box just to see what that did. The issue is with the screen voltages being equal to or higher by a volt or so than the plate voltages. The cause is the circuit board I am sure as the voltages correct themselves if I press it down close to one of the screen resistors. So I need to take a deep breath and pull the board. All those sockets and pots to undo.
But on the bright side if the board is duff then I can build a hand wired version using all the expensive parts already here.
Dd