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Parallel Triode amps vs Triode wired pentode amps

Specifically a JJ 322 using parallel 300B output tubes ... do parallel triode present the same matching difficulties of SE triodes in that they are (generally speaking) optimized for single driver speakers or speaker with very simple crossovers??? Or, with the increased power output, do they work well with "average" sensitivity speakers??

In my case, I am considering the purchase of a used JJ 322. Not from a dealer so there is now way to audition at home. I am willing to take the chance on used gear, mainly because it can usually be sold at little or no loss.

My system consists of North Star 192 DAC and transport and Alon Exotica speakers (88db 7 ohm min, 10ohm max), Cardas cables througout. I have used push-pull tube amps (6L6GC, 28w/ch) with very good success but am looking for some of the "SET magic" (knowing a true SET amp besdies an 845 based model).

Have also been considering a Cary SLI-80 F1 triode as an alternative ... any comments on this amp appreciated as well.

Jeff
jrinkerptdnet
4 responses Add your response
jrinkerptdnet OP
430 posts
 
Paul,

thanks for your response ... that is what I was wondering though I may not have worded it well. I saw and responded to your post on AC withdrawing your Viva amp for sale ... I think you made the right decision :)

any opinion on a triode wired pentode amp such as the Cary SLI-80 F1 in triode???

I have never used a pentode amp in triode configuration

Jeff
paulfolbrecht
603 posts
 
Jeff,

Paralleled 300Bs do not drive speakers like a 211 or 845 SET despite the similar wattage ratings. A 211 or 845 will drive fairly easily a three-way speaker with mid-sized bass driver(s) as long as the impedance & phase are fairly benign while IME the parallel 300B simply will not. It will be non-optimal.

Parallel 300Bs or even a single 300B can work quite well on many mid-sensitivity two-way speakers that are an easy load (DeVore, Audio Note, etc).
jrinkerptdnet OP
430 posts
 
Atmasphere ... thanks for your response. I am well aware that pentodes wired as triodes are NOT the same as a true triode tube but how close do they come?? seems MANY listeners with amps that have the ability to switch from ultra-linear operation to triode operation PREFER triode mode. This is actually oppposed to what I would THINK would happen - that a tube designed for ultra-linear operation would sound its best in that configuration.

The main focus of my question I guess is whether a paralleled triode amp has any limitations when driving multi-way speakers or those speakers with a less than simple cross-over network. Rare that a true SET amp will do this REALLY well.

Also how would a paralleled 300B amp compare to an 845 based SET??? These amp would have similar power ratings but does the paralleled amp have any theoretical advantage with the more complicated type of speaker discussed above.

thanks again!
atmasphere's avatar
atmasphere
11,793 posts
 
Jeff, pentodes wired as triodes are not the same thing as actual triodes. It is not that hard to put triodes in parallel; there are techniques for that and the linearity you get is still well ahead of that of a pentode wired as a triode.

This only addresses that question- there are other things that affect the sound of an amplifier such as transformer or power supply design, so audition is still the best bet.
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