a tube friendly speaker is one with stable impedance such as 8 ohms nominal and efficiency of 90 or greater. Tube amps do not like speaker loads that dip into the 2 and 4 ohm range since they don't have the high current output of sand amp designs...this is all general information but it's fairly easy to tell from mfg specs if tubes can power the speakers correctly but of course there are exceptions. BTW I'm a SET guy with super high efficiency speakers....and if you go tube then the tubes themselves have different sonic signatures...tubes are great if you like to tinker with your gear and appreciate tonal body and accuracy over hyper detail.
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Coincident... Silverline... Ref3a... to name a few. More names can be found at the wavelength web site with a better depiction of what relates to waht power range of tube amps.
The first poster here said much of what to look for though there are exceptions to manufacturers specs on paper and how some of their loudspeakers will truly react with a given power (wpc) LEVEL.
The room, the amp, and the speakers are all a mix. to wind up with a proper fit for them and yourself, do keep those things in mind.
At or around 50-60wpc and upwards, there will be many speakers which can be driven quite readily. Lots. Probably all of them in fact. to what levels, and with how much bass and so forth is the key question.
80% of the music is made in the first 20wpc.
If you plan on getting into very low powered SET amps this relationship of room, and loudspeaker becomes more important... and can become far more critical as the power diminishes.
What he said...
Speakers that I've heard that sound nice with tubes include Devore, Klipsch Cornwalls (available cheap, but usually need TLC), and Coincident speakers. There are lots out there, but not many that are full-range.
Getting a great match between speakers and amp is critical to success. Many tube amps tend to be weaker as bass drivers, so it gets kinda wooly. And if the impedence really drops (such as with many electrostats), tube amps can be driven to oscillation or other bad behaviors. So if you haven't a starting point (either speakers or amps), then I'd look at experiences of synergistic matches. Buying a great amp separately from great speakers will not guarantee success. Given your software choices, you should have a lot of options.
From my own experience, here's what I've found. I'm fond of planar speakers. Some of the classic combos that have stood the test of time include original Quads with McIntosh 225 amps; Quads with Dynaco Mark III's; Sound Lab A1's with high-power Airtight amps; Magneplanar 3.6's with Wolcott Living Presence amps; Martin-Logan CLS's with VTL 750's, just to name a few.
I'm running a set of Magneplanars bi-amped with solid state on the bass & tubes on the mid/treble drivers. Tubes can often do a nice job of making the music sound "whole" which isn't to say that some solid state amps can't accomplish the same thing. But I love the sound I'm getting.
If you start with the amp, you should seek out owners to see what speakers they have successfully paired. For instance, if you love OTL amps like the Berning or Joule, you may find some of the Coincident speakers to be heavenly matches, but you may not be so happy with PSB speakers.
SET is a whole successful subculture too... You might find that it floats your boat. Read up on what Lynn Olsen says, and give a listen to his Ariels with a set of Art Audio amps.
Dunno if this helps... Good idea to visit with one of your local audio clubs and listen to member's rigs. See what you like.
"More names can be found at the wavelength web site with a better depiction of what relates to waht power range of tube amps."
Anybody know the web address of the wavelength site? www.wavelength.com doesn't seem to be the one. If people are going to recommend various websites and/or articles found in these websites, it might be helpful to include the complete website address that will take you to the recommended article. It's pretty fast and easy to copy the web address and then paste it in "your respond". I know when I have an address I more likely to actually go read the information.
The idea that an amplifier has to double power as the impedance is halved is problematic. I say this because **in general** tubes sound better than transistors and tubes do not double their power. Instead, they will (or they will attempt) to put out constant power (transistors will seek to put out constant voltage; if you do the math this is why they double power as the impedance is halved).
I know that there are many who will object to my statements above, so I want to be clear that while on the face of it, it appears to be the tube/transistor debate, it really isn't, see:
for more information.
If you read the above article, then you know that all you have to do to find a speaker that works with tubes is to look at the speaker designer's intention: is he using tubes in the design of his speakers?
Audiokinesis, Classic Audio Reproductions, Quad, Lowther, nearly all horns except for the Avantgarde Trio, Coincident, High Emotion Audio, PHY, Feasterex, Audio Machina, ZU, Wilson, Vandersteen, Tonian Labs, Reference 3A... the list is extensive!! I would not worry about finding a speaker that will work for you, regardless of the tube amp you ultimately settle on.
I am confused by something. I'm going to use Wilson as the example because I am more familiar with them than some. They are commonly described as s a speaker that seems is "tube friendly". Your previous post recommends one should examine the "speaker designer's intention". Under specs for every model they make the impedence is listed at 4ohms and the sensitivity varies from 89-95dbs depending on the model. My current speakers are Aerial 20t's which are not generally thought of as "tube freindly". They are listed at 4 ohms as well and sensitivity is 90 db. Not really that different from the Wilsons except for maybe the incredibly expensive Alexandrias at 95dbs. Is there something else one needs to consider besides impedence and sensitivity? And if a speaker designer were really designing a speaker to be compatible with lower power tube amps wouldn't they inherently design a higher impedence speaker?
I'm just looking for the most realistic sounding system I can get. While my current system is pretty awesome, I can't help but wonder if something else is better. Unfortunately (or perhaps fortunately) the only way to be sure is to try them. I guess that's what makes this a hobby? In this instance I think I'll be doing more than tweaking my DAC. Thanks for the suggestion though!
Maybe I can put on my speaker designer hat and comment on Ralph aka Atma-Sphere's statement that you need to find out the intention of the speaker designer.
Let's say we have an "8-ohm" speaker whose impedance dips to 4 ohms in the upper bass region, and rises to 32 ohms at 3 kHz, where the crossover is (I'm picking exaggerated impedance swings here to make the math easier). If this speaker is voiced on a solid state amp, which puts out constant voltage, it will be voiced with the expectation that a 2.83 volt volt input into that 4 ohm dip will result in 2 watts into the speaker in that region, while a 2.83 volt input into that 32 ohm peak will result in 1/4 watt input in that region.
So, what happens when you hook this speaker up to a tube amp, which in many cases puts out approximately the same wattage into 4 ohms, 8 ohms, or 32 ohms? Well, now your speaker is getting only half as much wattage as it should get in that upper bass region, and it's getting 4 times as much wattage as it should get at 3 kHz! So we end up with a 3 dB dip in the upper bass, and a 6 dB peak at 3 kHz. Yuck! If we didn't know better, we'd conclude that tube amps generally suck.
But, what if this speaker was designed ("voiced") to be used with tube amps? Then it would sound fine on a tube amp, but with a solid state amp it would be 3 dB hot in the upper bass region and have a 6 dB dip at 3 kHz. Now, if we didn't know better, we'd conclude that solid state amps generally suck.
BUT if we knew the speaker designer's intention to begin with, we could have picked the right type of amp for the job.
Is there a way to build a speaker that works well regardless of the amplifier type? Yes, I think so. Briefly, the designer would shoot for as smooth an impedance curve as possible so that the tonal balance would stay pretty much the same when going from one amplifier type to another.
I've done some over-simplifying in this post, and left some issues unaddressed, but can come back and go into more detail if anyone wants.
Mike, as Swampwalker suggests, you can ask. Or if you want to do some legwork (or keyboardwork), you can see whose amplifiers they have shown with at audio shows.
When I first became a SoundLab dealer, I was quite frustrated that the factory wouldn't tell me what amplifiers work well with their speakers. They gave me generic answers that were of no help. So I tried a different approach: "What manufacturers have you shown with at audio shows?" Well immediately their tongues loosened and soon I had a list of amplifier manufacturers to look at.
So, you might try asking that question if the more straightforward one doesn't work.
Duke said it better than I can. FWIW Wilson has shown with Audio Research a good deal in the past and ARC has Wilson speakers in house. So despite the dips in impedance, Wilson's are 'tube friendly'.
The Wilson Watt has long been an example of the phenomena that Duke presented above. The speaker had a reputation some years back for being bright- around 2KHz. There was a tweeter resonance at that frequency, which anyone with a transistor amp would tell you was uncontrolled. The tweeter did in fact have a resonance, but Wilson controlled it with a 'band reject' filter, tuned to 2KHz, which caused the speaker to have a 2 ohm impedance at that frequency. The rest of the speaker was about 8 ohms; transistor amps would dump power into that filter, and tube amps would not make any power due to the filter. As a result the speaker sounded great with good tube amps, bright with transistor amps.
I would second the horn recommendation in general, and the Klipsch Cornwall recommendation in particular, unless you have a small room, then maybe something smaller in the Klipsch Heritage line. I have Cornwall II's that have 101dB efficiency. The very high efficiency is especially important if you want to experiment with SET amps. If you get speakers with this high efficiency, it almost won't matter what you drive them with, though, and the Cornwall's sound fantastic.
Thanks Ralph, and thank you too, Dev.
Blindjim, in my opinion the "order" of the crossover doesn't reveal whether or not a speaker is tube-friendly. I can think of examples with filters ranging from first through fourth order, and don't really see any reliable pattern there.
In general high-efficiency speakers are more likely to be tube friendly, but there are exceptions to that as well.
IMHO, I would look at a speaker's "impedance curve" in determing where or not it's "tube-friendly". If the impedance is relatively flat throughout the speaker's frequency range, with whatever deviations represented by smooth curves, than those speakers are likely to work well with tube amplifiers. If the "impedance curve" shows some sharp peaks and dips where the impedance is changing quickly, then a tube amplifier will probably have some problems dealing with those changes. I know Duke said the same thing I just said, but hopefully I said it in a way that some of us who are less "technically oriented" than others can understand.
Cleaneduphippy, you can also have the case where the impedance goes high and the tube amp will put out constant power. This is OK if the designer expects that. Impedance dips are usually not a problem too, as you have to sometimes shut down the output of the amp right at the area of the dip, as in the case of the older Wilson Watts.
Electrostatics can have low impedance at high frequencies and very high impedance in the bass- tube amps will often play that with constant power at all frequencies and actually get the speaker to play bass, where a transistor amp will make way too much power in the highs (so it will be bright), and not be able to make any power at all in the lows.
Really, the best way to find out is to look at the designer's intent- what he uses for reference, what manufacturers are using his product, who he shows with at shows.