2. amps-preamps
  3. 130671-3105

Sonic qualities of SET output tubes?

Can you readily identify a 300B, 2A3, 805, 211, etc., amp’s sound with your eyes closed most of the time?


If so, I’sure would like to hear from you.


Amplifier design and the technology utilized within its confines decides the ‘voice’ or influence it will yield as much or more so than merely the output tubes the designer has chosen to use.


I get that part emphatically. One must hear the amp regardless the type of output tube technology on hand.


And yes, some Pentodes and Tetrodes are used as Triodes but are not indeed triodes by their specific architecture. That’s OK, just focus on their use as Triodes herein, please.


There are however certain tube types, irrespective of vintage which have basic undeniable sonic colors or characteristics, apart from their electrical aspects which keep attracting people to amps which use this or that tube in its output stage.


Some love 211s. some adore 300Bs. Some love EL34s configured to run as Triodes. I have an affinity for the latter. So far anyway. This topic could change my mind.


Has your own experience informed you what this or that output tube’s natural flavor regularly announces itself to be so you can have a reasonable expectation of its general presentation?


What sonic attribute continually attracts you to a particular SET tube design, 300B or some others?


Or, conversely, what is it about the sound that would bring you to covet a 211 amp over a 2A3, for example.


Why as another example, would you pick a 2A3 amp over one using 805s or 300B, 211, etc. or vice versa?


Removing ‘vintages’ and electronic or electrical qualities from the argument, what sonic attributes for the more popular S.E.T. amp output tubes have you determined seem to persist in their particular DNA?


I’m asking for input from those SET tube devotees to lend their experiences and knowledge on the subject of what tube sounds like what irrespective of the SET application, generally speaking.


My goal is to try getting a better feel for which SET Tube amp design, if any, I’d want to pursue and possibly invest heavily into going forward as the soul of a new system.


Tremendous thanks to all!

blindjim
swampwalker's avatar
Ag insider logo xs@2x
swampwalker
5,132 posts
 
@grannyring- I forgot about the 300b monos. 
@blindjim  - Grannyring and I went the same route; from 8-9 wpc 300b to 12 wpc EL-34 SETs with the same results.  My speakers were quite a bit more efficient than his (92-95 dB/w/m, 8 ohm nominal, flat impedence) but we both found that Atmasphere was right; when you are down in 10 wpc range, you need +/- 100 dB speakers and/or high impedance speakers if you want more than moderate volume levels in a mid size room.  I know Charlesldad (and others) have had great luck w 300b SETs driving somewhat lower eff speakers, but IIRC, his speakers are 16 ohm. 

Of course, you COULD opt for the WAVAC HE-133 150 wpc SETs @ $77K.  That would maximize your choices for speakers, if in fact you had any $ left over to buy speakers ;-)
grannyring's avatar
grannyring
4,637 posts
 
Well great question. Since the OTL amp does not carry the 20% of rated power caution that Ralph has been talking about, and I have experienced, then the Crescendos can use all the watts available in the M60. Better said, most of the power available.

Also, adding the Zero autoformers actually increases the power output of the M60s by some 50%. So the speakers would be utalizing, in effect, 90 watts.  Yes indeed this would work great.

Just have to decide if I want that many output tubes. I suppose it would be better to get a 12-16 ohm, 95db or better sensitive set of speakers😬

However, I did love the sound of Ralph’s amps. Uncanny resolution and sense of being right there in the midst of the performance.
inna
5,245 posts
 
No need for Wavac. LAMM ML2.2 would do for many situations. Only $20k or so used.
stfoth
435 posts
 
Great thread.

As an SET/SEP noob, and likely convert, I hedged and blew out the initial budget on the first dip--going with a pair of Wall PSETs with about 35 watts off two 6c33s each.  They are probably the best sounding amps I've had in the house, and provide more flexibility than low-powered SET/SEP.  I only mention it to maybe followup swampwalker and to suggest a PSET as a possible "hedge" for you, as well.

Something similar to CAD805s with 50 watts off an 845 or 211 with humongous transformers might be something to consider.

Maybe neither hold the full magic of a great 2a3 or 300b, but they probably get you most of the way with extra beef and provide more speaker options.

Also picked up an Inspire SEP HO with something like 17 watts off KT88s, and I mostly agree with Wolf.  Really nice amp for, imo, a really good price, especially slightly used.  SEP could be another option, too.
grannyring's avatar
grannyring
4,637 posts
 
Good points @stfoth,

We have to remember 50 watts with an 805 tube etc, is still a SET amp and the 20% rule comes into play. Speaker matching is still critical. Will it work with a 4-8 ohm, 90db effecient speaker? It depends. Big room, like to listen at 85-90db levels at times, sit 10-12 feet back, then it won’t.

Small to moderate sized room, 70-80db listening, 8-10 feet back from the speakers, then it may work wonderfully indeed. Once the room gets bigger and you want to turn it up more often, then you enter a real risky area. Sometimes your happy, sometimes not with that system. Can be a frustrating place to be.  




More to discover