Matching Power and Speakers -- Much Ado about Not-that-Much? (Tube amps and speakers)

Interesting conversation at the Part Time Audiophile's The Occasional Podcast.
There, tube amp maker Justin Weber of Amps And Sound makes these comments:

At about 24:03 in, they have an interesting conversation about power in tube amps and speakers' needs.

Justin makes an interesting comment about power and speaker efficiency. He's careful to caveat that room size might be an important differentiating factor, but for many (most?) audiophiles (with small-medium size rooms), there is just not that much to worry about regarding amplifier power and speaker matching. He is not touching on "synergy" in some larger sense -- he's just addressing the "power needed to drive speakers" question.

If I'm understanding the upshot of what he's saying, it's that lower-power tube amps made with quality transformers (and well made generally) have a very good shot at doing an excellent job for a much wider range of speakers than is typically assumed in conversations audiophiles have.

The whole interview is interesting, but here's the interesting bit -- I did my best to transcribe it, but go listen for yourself!

"Almost always, you need vastly less power than you realize....I've seen 1 watt power whole rooms and big rooms with moderately efficient speakers....What's a practical standard? 30 watts should do 99% of everything for everyone, and 15 watts should do 95% of everything for 99.9% of everyone....

Most audiophiles have small listening rooms.... [A more powerful tube amp may sound better, but] I think that’s a matter of it having a better output transformer and [that] output's transformer's core actually having a flatter frequency response and going lower.

So [in those cases where a more powerful amplifier is used] I don't know that it's a question of producing more power -- that you need more power -- as much as the transformer [in] the more powerful amplifier is [instead just] a better transformer."

Not sure what folks here think about these claims. Perhaps they seem so obvious as to almost not need repeating. But there are so many conversations about speaker sensitivity and watts that do not mention the quality of the transformers or which seem to overstate the importance of how powerful an amp is.

If Justin is right, then many, many pieces of advice related to "how many watts do you need" are basically wrong.


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There is a caveat here.  Originally, the magic of tube amps was produced by SETs that made up to about 6 wpc.  Thus, the need for moderately sensitive speakers, say 94 dB and up.  

Then people who had already invested lots in less sensitive speakers wanted the tube magic, so much more powerful push pull amps were made.  Some of them are very very good (I have one) but many of us agree that the paragon of tube amp performance happens with just a couple of watts produced by a direct heated triode SET.  

So yes, you can power an 89 dB speaker with a Primaluna, but I'm aiming higher.


But keep in mind that no amp works at its best when pushed near to or at its limits, so just because you maybe CAN drive a less-efficient pair of speakers with a tube amp doesn’t mean you’ll be getting the best out of the amp — or the speakers.  As always, proper matching is key. 

It also depends on what type of music you listen to. Folk/Vocal Jazz/Pop don’t require the kind of dynamics you need to reproduce a concert piano or a symphonic orchestra. Also, if you’re very fond of rock/blues/pop, which feature a lot of bass where most modern speakers have a low impedance mode with high phase angle, no 15W amp out there can do anything. The instantenous current draw that a modern 4ohm speaker with EDPR of 1.5/2 ohms can be met by very few 100/150w tube amps, let alone a 15W amp. Keep in mind that a speaker that is 89 db sensitive does require usually much more than 1W to reproduce sound at 89 dB under realistic conditions. 

Tube amps are excellent at providing voltage not current, no matter what some random guy claims. That’s why a 83db sensitivity LS3/5a can be driven easily by a 30W tube amp, because of its high impedance (11 or 15 ohms depending on versions). Also, tube amps are very linear and noise free amplification devices, but at low levels, whereas most SS amps are more noisy with signals and behave more linearly with higher output.

pta is a fringe publication, I have read a lot of uninformed opinions there. But there may be something to power being overrated. 

Someone should by the new Schiit amp for a few hundred dollars and give it a try compared to what they have - I’d love to hear opinions on that. The GJALLARHORN is 10 watts of fun.