Low SET versus High SET


Low powered SET tubes:
2a3, 300b, 45 and 50.

High powered SET tubes:
32b, 52b, gm70, 845 and 211

Are there any generalities about the frequency output ranges and sonic characteristics (not power output or consumption) that can be made about low and high powered SET tubes?

What is your favorite high powered SET output tube?

(I'm assuming all are used in SET topologies into a speaker load appropriate to their power output). The question was inspired by the spirited debate about low power tubes in the SET v OTL thread.

Let me know your opinion. Thanks, Jeff
jj2468
The 211 is my favorite- love the big power triodes!
Presuming I have a sympathetic pair of loudspeakers to mate the amplifier with, and admitting to being willing to live with the inherent tradeoffs of the marriage, I prefer the lower power SET amps. There is a certain magic there that I feel the larger tubes cannot match.

Of course, in most real world scenarios, where people use more conventional loudspeakers, if one is going to choose the SET route, you would need the higher power variants.

However, as opposed to going the 211 or 845 route, I've personally found more happiness in either using the smaller tubes in either parallel single-ended (preferred) or push-pull operation, or even (heaven forbid!) a good Class A push-pull EL34 amp.
The 300b is my favorite tube but I really like the extension of the 2a3/45. My wish came true (I didn't know I had one) when I got a high eff/easy load speaker with an active x/o. I run a 300b on the mid/woofer and a 2a3 on the tweeter. I initially ran a 300bxls on the low and 300b on top and it was nice but the 2a3 on top is noticably better.

The 845 is my fav high power SET tube.
agree with Onemug.The best is to bi-,tri- amp and then you use the low power SET on top and the big p SET on the woofers.That said, I think the 2a3 or 45 is a magic, when used in no-crossover systems.
Do the 845 and 211 have the frequency extension of the 2a3 and 45 tubes?
Presuming I have a sympathetic pair of loudspeakers to mate the amplifier with, and admitting to being willing to live with the inherent tradeoffs of the marriage, I prefer the lower power SET amps. There is a certain magic there that I feel the larger tubes cannot match.

Totally agree. For me, the secret is the "sympathetic speaker" plus a good circuit design of the SET amp using 2A3/45 or a 71A.

Personally, my understanding is that the magic happens because distortions are avoided. Distortion is directly proportional to the amount of power use. Why go SET and then go high power? I really think that its beating the purpose already. When you go above 100 dB sensitivity drivers, you will find out that you do not need more than a2A3/45/300B tubes to drive it. My honest opinion base on my system only..