SET amplifier recommendation
@cygnus_859 If you're curious how much power your speakers are using and have (or are willing to buy) a multimeter, you can use the technique at this link to actually measure how much power you'll need.. https://www.diyaudio.com/forums/multi-way/204857-test-voltage-power-speakers.html |
And since some of the information is buried in the thread, here's a quick rundown: all you do is set your volume at the max listening level you use, then play the provided -12db 120hz test tone while measuring voltage at the speaker terminals. Square that value and you’ve got the maximum watts needed. Plenty to read at the link...
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The B&W speakers are voiced for SS amplification and are never going to sound their best with tube amplification; possibly with the exception of a pair of Atma-Sphere OTL monoblocks. Sorry, but I disagree with this statement. I own 804S and when searching for amps I listened to them in the same room and setup with McIntosh MC252 (250W SS) vs MC275 (75W tubes), and preferred the 275. My system has evolved quite a bit since and now the 804S run as active speakers with 400W class D driving their woofers, subs under them, but the MC275 still drives mids/tweeters. In my journey I veered towards building my own active speakers and looking to drive mids and tweeters with SETs, but doesn't mean good PP powerful tubes can't drive 805 well. OTLs could very well be it. BTW, thanks Ralph and Almarg for the informative exchange! |
@lewinskih01 Thanks for the mention! Regarding your experience with the MC275, it’s worth noting that it has a considerably lower output impedance (and correspondingly a considerably higher damping factor) than most other high quality tube amps. So the likelihood of adverse impedance interactions with the speaker’s impedance variations over the frequency range, that I referred to for the 805 in an earlier post, would be minimized with that amp compared to most other tube amps. For example, Stereophile measured the output impedance of the MC275 version 5 at most frequencies as being only 0.33 ohms for the 4 ohm tap and 0.57 ohms for the 8 ohm tap. And version 6 is specified at the McIntosh website as having a damping factor of 22, which theoretically corresponds to an output impedance of 4/22 = 0.18 ohms for the 4 ohm tap, and 8/22 = 0.36 ohms for the 8 ohm tap. In contrast, the damping factors of the majority of high quality tube amps are in the single digits, and some SETs have damping factors in the vicinity of 1 or even less. With the corresponding output impedances being much higher than those of the MC275. So in terms of the tonal effects resulting from impedance interactions with the speaker those numbers suggest that the MC275’s behavior will approach solid state territory, rather than being representative of the behavior of most high quality tube amps. All of that is not to say, though, that no tube amp having a relatively low damping factor/high output impedance can work well with these speakers. For example Ralph’s amps fall into that category, but I don’t doubt for a second that the reports of good customer experiences he has cited involving pairings of his amps with these speakers are accurate. But generally speaking, obtaining good results pairing a tube amp with these speakers figures to be less predictable and a good deal more doubtful than with a solid state amp. Best regards, -- Al |
