SET vs OTL

Thanks Atmasphere for clearing up the issue of safety/reliability of direct coupled. A friend has direct coupled OTLs hooked up to Sonus Faber Stradivari speakers. When asked about what might happen if a tube shorted, he just shrugged his shoulder and said: "I guess you just buy another speaker."

On the which-low-powered-triode-is-my-favorite debate, I like 45s, they are sort of in between: not as dry and lean as the 2a3, not as warm, and lumpish as the 300B. 45s have a big low end, but that low end is also tight. The other nice thing is that a lot of decent older 45s can be had without spending crazy dollars. The PX25 is a nice tube too. I am not a big fan of 300Bs, but some amps using them can be quite nice, particularly when equipped with Kron 300Bs.

A question for the 45, 50 2A3 crowd:

What's a good speaker choice to evaluate the bottom end capability of a low powered SET like the 45/50/2A3.

Given that

A) every 300B SET amp I've heard (granted, I haven't heard all of them) lacks power & control < app 50hz when paired with a speaker with sufficient bottom end to reveal that shortcoming,

and

B) the way I reached the above conclusion is by pairing said speaker with a solid state amp and comparing the delta in bass response

It raises the question as to which low power SET friendly speakers go low enough in frequency to allow such a comparison.

In particular, if there's anything in reasonably wide distribution that not crazy expensive and fits this description, it would be great to know of. Similarly, if there's a particular low power SET amp that's specifically recommended for that speaker, such info would also be appreciated.

Thanks in advance.

Marty

Martykl, one thing about SETs that makes them quite different from OTLs is the way their distortion signature interacts with the human ear/brain system. SETs tend to have very low distortion at low power, but on transients, where the power occurs, the distortion can be quite a lot higher (10% at full power is quite common).

Thus there is high distortion on transients, and while normally the odd-ordered harmonics are kept at vanishingly low levels, at high power they have an effect. Of course, they are masked by the presence of even-ordered harmonics, but despite that the brain reacts to their presence anyway.

That reaction is a sense that the amplifier somehow is a lot more dynamic and can play louder than it should be able to given its actual power output. You commented about that quality in describing your amplifier above.

OTOH if the amplifier actually has the power to make real spls, and if the distortion is kept low, then the result is that the system is can be more relaxed- that the volume you pick is not based on perceived 'loudness'. IMO, a good system will not have a sense of volume or loudness- it should act that way real music does in that regard.

Atma,

I know what you mean. I also wonder if the steep impedence spike of the VSMs (@ app 1Khz) is audible via SET and contributes to the sense of dynamics from the SET/VSM combo. Nevertheless, the cumulative effect of pairing this speaker with these amps was very, very satisfying in many (not every) way(s).

While I wouldn't particularly agree with your description of the dynamic behavior of a "good" system, I will acknowledge your point. There were times when the dynamics felt a bit more "juiced" than strictly natural, but with most of my recordings, I'd call this quality more realistic sounding. There were recordings, however, which would substantiate your view.

When I described OTLs as more "revealing" earlier in this post, that's partly what I was getting at. Shortcomings in speakers and source material was usually more evident via OTL. I know some folks find this the holy grail of this hobby, but I don't.

Marty

Marty, I understand what you are saying. I want the amp to play what is good in a recording, and with the poor recordings, not get upset by artifacts in the recordings. In other words, forgiving? -but without giving up anything to resolution. Its a fine line to tread.

Bobby P. has been making certain over the years that Merlins are tube and particularly OTL friendly. OTLs and Merlins are a very common and successful combination!