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How to accurately gauge speaker sensitivity to match with tube amp?

I'm in the process of matching speakers to my amplifier and need a bit of advice. Most recently, I'm trying Focal 936 towers with my Quicksilver Mono 60w amp. They were sounding pretty decent until I experimented by hooking up my old Adcom 535L amp. All of a sudden, there was a giant jump in control, tautness in the bass, quickness in transients. The QS stuff was doing quite decently, but the Adcom really snapped these towers to attention. The mids and high ends, not to mention the soundstage, were worse with the Adcom — no question. But there was quite a difference with the other qualities just mentioned.

My question becomes one of sensitivity. The Focals self-rated as 92 db. Stereophile rated them as 89.5db. I realize that these are average measurements and a much bigger picture is told by the impedance graph (and other factors).

As I continue to search for the right match of speaker (I have a couple contenders), I'm sure one piece of advice is to look for speakers with higher sensitivity averages. But what else should I look for to help make a guesstimate about whether the amp will drive the speakers with the kind of control they are capable of? [Specs for this amp are here: http://quicksilveraudio.com/products/sixty-watt-mono-amp/ ]

I realize I need to hear speakers, in my house, with my gear, etc. to get a sense of them. I’m working in exactly this way. Your advice can help me eliminate candidate speakers that would pose similar challenges to my amp as these Focals have.

And I just bought the amp, so I don't want to change it.

Thank you for any thoughts. 

P.S. Anyone who has has had great success with this amp or similar, please shout it out.


128x128hilde45
clhs04
62 posts
 
Legacy‘s are large cabinet big multi-driver speakers that demand a lot of current..despite what their persuasive specs regarding sensitivity may imply.
if you were to do a generalized perusal online of Legacy speaker systems I would bet that > 50% of the guys are using high current muscle amps to run them. In fact Legacy has or had their own line of amps... I suspect that Coda was in some way involved. In fact Coda amplifiers are ideal in that they are high current designs and highly biased in class A as well.

im not saying the QuickSilvers are “bad” in fact they are good in the context of their application. That said I think wrong tool for the job with Legacy speakers.

60 WPC is ideal / great for your highly efficient speakers such as those that were discussed prior.  However with Legacy anything I think I would want to start with no less than 100 wpc (or more).  Too little power = not good.  There is no such thing as too much power..it will give you gobs of headroom even at the lowest listening levels.!
decooney
2,098 posts
 
@clhs04
Legacy‘s are large cabinet big multi-driver speakers that demand a lot of current..despite what their persuasive specs regarding sensitivity may imply. if you were to do a generalized perusal online of Legacy speaker systems I would bet that > 50% of the guys are using high current muscle amps to run them.

Fact check for the other 50%, various tube amps used successfully with Legacy speakers. It doesn't take an overpriced Coda to run them. Not all tube amps are created equal, it all starts with the transformers. As suggested, a quick five second search:


clhs04
62 posts
 
help!!
  @decooney has me on the ropes here....somebody bail me out!  just kidding folks I agree and actually I’m all for tube gear myself...my Viva has some of the largest transformer iron I’ve ever encountered in my life.
 Not to totally derail this thread but did @hilde45 ever mention what preamp he is using.?  That’s a whole nother rabbit hole to go down in.
ieales's avatar
ieales
1,201 posts
 
a look at Legacy impedance curves  https://www.stereophile.com/content/legacy-audio-focus-2020-loudspeaker-measurements and  https://www.stereophile.com/content/legacy-audio-studio-hd-loudspeaker-measurements clearly show they could be some transformer, AND a good many SS, unfriendly.


decooney
2,098 posts
 
@clhs04

Not to totally derail this thread but did @hilde45 ever mention what preamp he is using.? That’s a whole nother rabbit hole to go down in.


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heheh, ah just having some fun here with ya, it’s all good. He’s running a Quicksilver Linestage, non-remote control version preamp. They sound pretty nice with good vintage tubes and drive QS Mono 60 amps just fine.

To your point, and others, you cannot simply throw just any amplifier at these types of loudspeakers, agree 100%. I grew up here in the land of PASS, Coda, ESS where it all started with AMTs too and it truly does take a better amplifier to help these types of speakers sound their best. Even AMTs sound "right" with a ballsy amp. You are correct sir. I would not throw a dinky integrated tube amp at any of these Legacy speakers, but perhaps some small monos with really good transformers, maybe.
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