SET vs OTL

Martykl, if there is one maker of SETs that could be called LUSH, it's Cary. Even their 2A3s are lush, which I'd have thought impossible to do.

You're description of SET bass is especially off in regards to the 45, by the way: very, very tight low end, NO exaggerated mid-bass at all. In fact, they're rather like Ralph's OTLs in that aspect.

No triode is as clear and direct as the 45 IME. I may have mentioned the 211 in the same breath - it's still not nearly as see-through - not in amps I have experience with anyway. (Ongaku? Maybe. Cary? Even less than the Consonance 211s I owned.)

Like you said, 'lush' is not necessarily bad.

Ralph, I didn't realize your OTLs have only one gain stage. I learned something. I may need to try one again.

Paul, I like the type 45 tube a lot too. Not many speakers that will work with a 45 SET though. I am using a set of Coral Betas, which are fine as long as you don't expect any volume.

Larryi, We've been doing this over 30 years now and all our amps have had a direct coupled output. We've seen many tubes fail in that time. So far, we can still count the number of times that a power tube failure damaged a driver on one hand. In all the cases but one, alternative power tubes had been installed in the amp. So it appears that the amp is quite safe. All of our amps except the big 500-watt unit do not use a servo circuit (we installed one in the big amp, but for convenience only). They are quite stable, and simply don't need a servo. The key is controlling the power tubes, something that you would **think** would be common sense, but it is an issue in a lot of designs. That is one of the reasons why our amps have been so reliable over the years (the other being that the amp does not need negative feedback to work).

Martykl:

Gotta side with Paul on this one. My Wyetech Sapphire monoblocks use two 300Bs in parallel per side (18 wpc) and sound exactly like Paul describes: "crystal-clear, just right, completely natural", and certainly not lush. And these are 300Bs! And they drive monitors with a wild impedance swing as well.

Agree with Paul. The 45 is the triode gold standard.

Followed closely by 50, 2A3, and PX-25.

The 300B is a distant fourth and IMO, highly overrated.

I agree with Bill's ordering of the triodes except that I've never heard a 50.

300B can be done well (I learned recently I really like the JE Labs 76/6SN7/300B circuit) but bad implementations outnumber the good, it seems! The thickened midbass and blunted transients is a show-stopping for me.

I'd also throw the PX-4 in there either before or after the the -25. I had a Kurashima PX-4 - amazing amp.

People always talk about how much difference the circuit, driver, power supply, and output tranny make, yes the various tubes almost always retain their basic sonic character no matter what the amp IME.

However, I've heard those Wyetechs really break the 300B mold. I've also heard that about the Welborne DRD circuit.

As for volume and dynamics, yes, for a 45, you need a back horn, front horn setup, or highly efficient widebander on OB. But it's amazing how dynamic the good SETs are within their capabilities.

Any decent 300B SET will drive 90 dB/W dynamic speakers that are a fairly easy load very well. I'm thinking DeVore, Green Mountain.. lots of others.