Advice on amplifier and B&W speaker pairing


I know this topic has been covered before, but I’m looking for recommendations on two specific amplifiers and what the optimal pairing would be for B&W 800D3 speakers. The speakers have not arrived yet, but I already own the amplifiers: Nagra Classic Amp and the Audio Research Reference 150SE. I’m guessing most people will suggest that I listen to each configuration, and make a decision myself as to what option sounds best. I’m looking for more technical guidance though. The idea is to keep the better matched amplifier and sell the other. The preamp being used is the Audio Reference GSPre

My dilemma: I adore the 150SE and generally prefer tubes over to SS. However, even though the ARC can push out 150 watts on the 4ohm tap, and the B&W has a sensitivity of 90db - this speaker has a wild impedance curve (3 ohm-20 ohm) and has some pretty significant phase angles. I’m wondering if ANY tube amplifier can deal with these types of loads. Because one must choose the correct tap, it seems the amplifier will never be running in it’s comfort zone. I think my biggest concern is how the frequencies could possibly be skewed at the upper frequencies.

The Nagra wouldn’t have these issues, but only outputs 100W into 8ohms and approx 175W into 4ohm. Considering the 90dB sensitivity of the B&W... perhaps this is the better option?

Setting aside sonic preferences. What do people recommend in this situation? Thank you!
rtilbury
You know you are making a nearly impossible request.  Sonic preferences IS the right answer, and you haven't even gotten the speakers yet.

Here's what I suggest though, when you listen listen in the area of music you are most worried about.  Looking at the impedance curve, the area of concern is a depressed mid-bass to treble, but!!!!

There's always a but .... ;-)

Technically, yes, lower impedance can depress the output of an amp with a high output impedance (i.e. tubes) ... BUT! ... you might like that. Depressing the output here may make these speakers easier to listen to at lower volume.

So, when you compare listen for this effect and ask if you like it and if that works at your normal listeningi levels.  Louder, the missing mids could be more pronounced.

If you hear none of this, then pick your fave otherwise.
Thank you Erik - I appreciate the feedback and do realize this is a difficult question to answer based on the information I've provided. As you say, listening is the best test, but I'm not terribly familiar with how electrical components (tubes/transistors) work and what the negative impacts could be with using tube amplifiers with such a speaker.

My understanding is this: Since the 800D3 dips to 3 ohms, I should probably use the 4 ohm tap on the ARC. But... the speaker also rises up to 18 ohms in the 1Khz-10Khz region. I'm not sure how this effects the amplifier and frequency response. I would think the amp would struggle with this type of impedance shift. Best case this would probably reduce the amount of watts the ARC could produce. But could it also damage the speaker/amp? 

Thanks again


I’m wondering if ANY tube amplifier can deal with these types of loads. Because one must choose the correct tap, it seems the amplifier will never be running in it’s comfort zone. I think my biggest concern is how the frequencies could possibly be skewed at the upper frequencies.

Sometimes reading threads like this I wonder, do these guys even care what it sounds like? Or is it all about the tech talk and what the tech talk might sound like. If it ever was tried. Which it seldom is. Because imagining is so much better than listening.

Then another thing I wonder, if they did somehow hook the stuff up and listen, would they be content to let their ears do the talking? Or would they be so wrapped up in the tech talk they interpret everything through that lens and force their experience to match their theory? When it should be the other way around.

There are amps that tend to sound really good with speakers. They're called tube amps. You might want to try listening to some of them. Raven. Prima Luna. Etc. 
I know you don't want this advice but... To get full pleasure from the magnificent B&Ws, Get monoblocks.
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If you like tube amps, why choose B&Ws?  Just asking for trouble IMHO.  At least you’ve got tubes in your preamp, so I’d go with Class A solid state for amps that might be a nice compromise from tubes and have plenty of juice to let your 800s fully open up.  A Clayton S100 should do it as would a Plinius SA103, Pass Labs, etc.  Best of luck. 
Thanks for the feedback everyone. The speakers will arrive tomorrow and I'll be testing both the Nagra and ARC with them.

I'm not really sure what to expect, but based on a few of the comments here, it sounds like the 150SE may work perfectly fine. The flipside is that neither amplifier will work adequately and these speakers require more power than the Nagra and ARC can output. If that's the case, I guess I can always add another Nagra and use them in bridged-mono mode. 

Considering the 800D3 is rated at 90dB/1W - I'd think that both amplifiers have enough watts to play loud, it seems the real question is regarding current. 

It's a hobby for me and I enjoy testing new components/configurations. It will be interesting to see how this one turns out. 
Audio Research Reference 150SE will be a bit “underdamping” solution, which will not give you the best of bass/lows tones out of BWs. You may look into decent output current amps, like PASS/Accus/etc. BWs in many occasions are “amp” limited beast. 
Sorry but you won’t be able to realize full potential of 800D3’s with any tube amps. I used to own B&W 800D2’s, went through quite a few amps including class A/B and Tube (ARC GS150). They did not start rocking until I paired them with Bel Canto Ref600M monoblocks. B&W’s especially the 800 loves brute power :-)