Single driver speakers. Are they worth considering ?


I don't mean electrostatic. How close to a full range speaker can you come with single driver ?
inna
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How about a pair of Omegas with a pair of monster subs?

I had the Omega Compact Hemp, Alnico Super 6 Monitors and Alnico XRS 8 all with dual Omega subs. Could never get proper integration until I used a Dspeaker Dual Core. The Dual Core helped to blend and manage the bass well but not perfect. I never used the X4 but have been told by others who own one, that it does a fantastic job. 
The best bass and sound top to bottom has been with my Charney Audio Companion Horns with Omega RS7 drivers. Charney doesn’t make the Companion with RS7s anymore. The Voxativ and AER drivers are so superior in every way. Hoping to unload my Companions soon and step up to the Voxativs. 
Unless your budget is infinite, there will be compromises.   So the question becomes, what are you willing to give up ?

A single driver can deliver deep bass, lifelike midrange, extended treble, but not at the same time.  It is physically impossible to create a single driver that can deliver 90db of distortion free 30hz bass, AND deliver 90db of non directional, undistorted 15khz treble at the same time.   So what are your preferences ?

The majority of musical content lies in the upper bass to low treble region....about 100hz to about 5khz.    That range should be achievable using a single driver system.  One can add loading to extend bass response another 25-30hz, and an outboard tweeter for anything above 5khz.  This would technically become a 2 way system, but the vast majority of sound, including the human voice and almost the full range of a piano, will come from a single driver.   

The famed Western Electric / Altec 755a excels in this application, and many say that modern drivers still do not come close.    Caveats are the fragility of the driver....15w is too much power.  That said, the driver is very efficient and can deliver room filling sound powered by a SET amp. 

Single driver systems sound different than mulit driver systems.  There is merit in point source reproduction.   (This is one of the reasons why people like small monitors also).   Some have gravitated to coaxial drivers as a way to get past inherent limitations.  Vintage Altec, Jensen, Tannoy drivers  are valuable and held in great esteem because of the clarity of their sound.  But to get the best sound one has to invest in a precise outboard crossover, careful amplifier selection, and construction of a cabinet well matched to the characteristics of the speaker.

Be prepared to experiment, and think seriously about what you want to accomplish.
As mentioned before, it is so easy and cheap to find out, why not try it. Pencil, or Frugalhorn, or Woden - these designs give a pretty flat response from around 40 to 14,000Hz, are really easy to drive, easy to adjust to your room and tastes - and if you don’t like them there is a market for them if your DIY skills are halfway decent. The money you save can be spent on music, or fancy cables, or whatever. 
Horn loaded 7.9" Field Coil Driver.
14.4" wide x 39.4" high x 17.7" deep cabinet with a rectangular front facing port.
8 ohm impedance.
96 dB Sensitivity.
20 Hz to 20 kHz Frequency range.
$20k (in 2018), standard finish and $21k, upgraded finish.

The Shindo Lafite.

I love how easily the Lafites disappear and the wonderfully musical image they produce. They sound good at low volumes and at elevated volumes that easily pegs my iWatch’s SPL meter. I’ve had a pair of Lafites for several years. Most of the time, I drive them with a 10 watt/channel Shindo Cortese SET F2a power amp and Shindo Giscours preamp.  Using analog or digital source material, the Lafites do not go as high nor go as deep as a very nice sounding pair of 25 year old Vandersteen 3A Signatures driven by a VTL ST-150 power amp in triode mode with KT88 output tubes and with an old faithful Conrad Johnson PV-11 preamp.
@sheldonbsmith, at the risk of appearing petty, though without electrical cross-overs, the Ohm Wash driver does have mechanical cross-overs, unlike the similar German Physiks DDD driver, though the DDD is not full range.

@realworldaudio, with proper application, time aligned drivers coupled with first order cross-overs can resolve the time and phase issues that typically plague other multi-driver configurations, and lend themselves to full range capabilities while doing so.
dht4me,

I have not heard the AER BD5 driver, but I would bet that it sounds terrific.  I've heard the BD2 utilized full range (no other drivers) in a couple of systems.  One just had a large horn on the front, and was completely open in the back. This system had a very pure sound, but no deep bass.  The other was a Charney speaker that had substantially more bass because of its use of a backloaded horn on that driver.  The Charney speaker is fantastic.  I've been somewhat interested in the BD5 in a backloaded horn system.  AER sells a very expensive system that utilizes that driver in with a front horn/waveguide and a backloaded horn for bass.  It is an interesting looking system, but, it is quite expensive.

I've also heard, and liked, a full range Feastrix field coil driver.  The system was a bit deficient in bass, but, the driver was in a fairly small Jensen Onken cabinet, so I don't know if bass response was optimized.


I am still running a pair of Cain&Cain Abby's that use a Fostex single driver and a Voigt pipe design. They have kept pace with my other upgrades, and I love them. 

Although their bass is surprisingly good, there's nothing to stop one from adding subwoofers; I also recently added rear-firing horns with exactly the aim that Ralph described in his post: "The solution is [... to] add a rear firing tweeter (and not cross over the main driver) to correct the tonality and help with soundstage palpability" (both products I purchased from Audiokinesis).

These two additions solve many of the issues with extension while preserving the coherence and liveness of single main driver. I am sure many members here have superior set-ups, but OP, you'd be surprised how full and immersive these speakers can sound.

Bache audio and Tri-Art both pursue designs built around a full-range driver supplemented by super tweeters and woofers.
My experience with Omega loudspeakers was not good. Sound was too shouty, very aggressive regardless of material and tubes or ss equipment.
Dan
Personally, I am not willing to compromise. Everything that has been mentioned in this thread that I have heard has been hopelessly colored.
Some people like the sound of these speakers. So I suppose what colored loudspeaker you like is a matter of taste. 
The only type of loudspeaker that can approach full range performance and avoid coloration is an ESL which the OP did not want to hear about.
Sorry. Just the way it is. Dynamic drivers are flawed in so many ways it is remarkable that some systems can sound as good as they do. Full Range? This is an illusion.  
Absolutely not. Why would you even consider? There’s a really good reason that the large majority of audiphiles buy speakers with more than one driver. It’s not dumb luck or brainwashing. It’s that multidriver speakers sound better. I know there’s a few guys that speak about a single driver that’s “full spectrum” in the hearing wavelengths that make listening to music so enjoyable. Well maybe their ears are satisfied with a single driver, but at almost 70 y/o, a musician, and a man with numerous friends in the music industry, mine are not and neither are theirs.
I have a set of Markaudio Alpair 12P set in a "pencil style" cabinet with appropriate internal organs and ports of 1" B grade Baltic birch on 3 sides.  The front baffle is 1 that's right 1 solid piece" of 1 !/2" of FAS bookend bird's eye maple.  Near field they are fantastic.  They are not for everyone, more of an extra to your systems.  The speakers are extremely complex, fragile, difficult to make, it's pretty neat to read how they are made.
One particular factor is a very difficult to accept reality. The range of heard frequencies declines with age. Modern noisy life certainly has exacerbated that too. By age 60 everyone has lost some significant degree of high frequencies. If you can connect a computer or other internet enabled device to your system, google for a frequency generator and sweep your system. If you are over 50 you will certainly hear a point in the low teens where sound disappears. 
Once I had done that, despite all my resistance to it, I realized that at least when it came to frequencies above about 12 or 13 kHz, I simply could no longer hear them. That made the idea of a single driver wide band or full range speaker system much more acceptable. One of it's flaws is matched by my own.

One designer builder not yet mentioned but renowned for exceptional full range drivers is Oleg Rullit. His designs deliver superb sound. His 9" and 12" Super Aero field coil drivers when properly mounted in front loaded or open baffle designs really lack nothing with most music. Supremely musical with surprising bass and smooth response right up through my hearing limits. 


The Rethm speakers I’m referring to are the current version that does not use the Lowther drivers as mentioned in the post above. I do not know the brand of driver that is being used, but there were none of the issues that jdal mentioned in his post. But the model speakers I’ve heard were the Saadhanaa’s.  Very clean, strong and full bass.  
I once owned a pair of Rethm speakers with Lowther drivers. The problem was a thin sound with no bass. Adding a Rel subwoofer didn't help much. There was always a dip between where the driver left off and where the subwoofer picked up. 
Check out Bache Audio. I have the Tribeca speakers.  These are based on a modified wide band driver that covers the range from 700-10K, augmented by a super tweeter and 2 woofers. The wide band driver is directly connected to the amp (no crossover). It's like a single driver but with better top and bottom end.
I have a friend here in Vegas with the AER BD5. It is an insanely expensive driver ($45K/pr) but the sound is incredible. I need to add that is is augmented in the bass as it is on a 200hz LeCleach horn but absolutely stunning regardless. I have never heard a single FR driver sound that good. Everything else has some issue somewhere. If you do not have the budget or equipment then you have to accept some compromise somewhere.
I have an 8 watt 300B system (Wavelength Duetto), and single driver Stein Music SP 1.1 speakers.  I have very much enjoyed the Steins for going on five years (a record for me).  I cycled through many traditional speakers prior to them, and even during this period have scratched the itch to buy and try Devore 3XL, 0/93, Daedalus, and Audio Note AN/J. 

I do of course notice less bass response as well as a loss of some treble.  That is why I thought I might be able to improve upon them.  And for a week or so every one of those trials convinced me that I made a good choice.  Then, I put the Steins back into the system and very quickly decided that the Stein's presentation is more organic, realistic etc.  The immediacy of single driver speakers is very addicting.  For me they give me a "band is in the room" vibe better than the other designs I've tried.  Holger Stein is known for effective, natural and physics-based tweaks and his SP 1.1 design considerably tames any downsides to the design. Your mileage and ears may vary.

I just recently found a set of Musical Affairs speakers with natural wood cabinets and PHY Sag drivers, and am looking forward to my 2nd pair of single drivers!
Feel the most famous single driver speakers would be the Bose 901. Yes they had multiple drivers but all to form a single driver in basic delivery. What was the quote “ no highs no lows must be Bose”. I did and still have a pair. Need an amp that had a power supply that could double as an arc welder to drive them properly. Sansui 9090 Them run through a eq to shape the sound by bending the wave form to an extreme level. Yes set up right and playing loud to an over served crowd they sounded good. Set up with a quality system in a listing room you keep struggling to try and hear what is in the music you know is there but you can’t hear it. I have never heard ZU speakers but they do have a good reputation and following——
It’s all about where you’re willing to compromise. I have a diy 6.5-inch ported bookshelf speaker that I think sounds great — for what it is. The mid-range is just very sweet and the highs are good. But I added a subwoofer soon after. Looking at my speaker measurement w/o the sub, I’ve got a nice 100Hz to about 8 kHz spectrum. That used drivers costing $100 each, so not cheap-o but not fancy either, with neodymium magnet and a cast basket, so good construction. And I tuned them pretty carefully with acoustic stuffing and port size. Put on girl-with-a-guitar music, or “unplugged” Clapton or Nils Lofgren, or moderate-level jazz or combo, or chamber music or piano solo, and they do great, a real pure sound. And think about it — that’s a lot of great music! It’s probably about the time domain and point source and other stuff I’m not competent to address. Ask Atmasphere. And they were 95 dB sensitivity for the 15-watt class A amps, so a good team. But not as a do-it-all speaker, I’d say.
Currently running Fostex Fe208ESigma in free air with a NAD D3020 and sub. Also running Audio Nirvana 8" alnicos in free air, with a class D icepower ASX125 and sub. I listen at around 58-60db. Krall, Jones, Fagen, Lofgren, Davis, Clapton and similar music. Sold a Primare I30 to finance most of the above pieces. Best decision so far on my personal music journey. Cheers, gotta love this hobby
@ kenjit1 " KEF likes to do single driver point source speakers. It depends what you want. Single drivers have less highs but perfect dispersion. A 3way speaker has clearer sound but horrible dispersion.

Nonsense.

1. KEF offers zero "single driver" products. At minimum KEF hi-fi speaker systems are coaxial, with two distinct though concentrically mounted drivers.
2. There are numerous products on the market with excellent dispersion properties. Is it your contention that Magico's published assertion that the M3 has "ultra-wide dispersion characteristics" and ultra-low distortion measurements" is false advertising or exaggeration? 
3. Allow me to disabuse you of the notion that single drivers exhibit better dispersion properties than a proper multi-driver system incorporating a high grade tweeter: https://www.soundandvision.com/content/dispersion-show-and-tell 

@vinylbrother, 
If the occasion arises for further listening to the Cube Audio speakers (Especially the 10" Nenuphars) please share your impressions if you do not mind. 
Charles 
@inna,
Ocellia and Tonian Labs are two brands that have used various size  PHY drivers. There were probably a few more. 
Charles 
Hi. I have done some short term  listening to the Cube Audio Bliss, Magus and Nenuphar at a local retailer in my area. I have never been attracted to single driver technologies as my past experience with a few designs indicated a very thin, one dimensional sound that I simply was not interested in. Unfortunately, I only had approx. 30 minutes of time to spend, but I will say this, I will come back for another  audition when time permits. There was something very different about this brands general sonic delivery. 
I can't remember the name of speaker brand that uses 10" PHY driver and optional super tweeter. Or maybe there are a few brands.
Cal,
Agree .
The PHY-HP is a legendary paper cone driver created by the late Frenchman Bernard Salabert. The 12" version in particular is held in high esteem for superb sound8 quality. The Cube Audio Nenuphar is a very different design and approach which by all accounts extends deeper and goes higher than the classic PHY.
Charles
According to their published specifications, Cube Audio’s 10" driver is flat to 30hz: https://www.cubeaudio.eu/cube-audio-f10-neo (but does drop off at the top end above 10k)
I thought PHY had 10" drivers as well, there are other brands of 8" and 10" drivers used in single driver speakers. They go much lower than 60HZ.
No full range driver is really full range.


Some can do alright in the highs, like the Tangband 1772 and 1808.

Whizzer cones can be problematic due to breakups and a bit of discontinuity with the main cone. PHY gets around this by eliminating the whizzer cone on their 6" driver and having otherwise low mass. It has surprisingly smooth highs.


The big problem you run into is beaminess. The solution is either to crossover the driver into a tweeter, or add a rear firing tweeter (and not cross over the main driver) to correct the tonality and help with soundstage palpability.


If you have that sorted, then the other issue is bass. The trick here is to get the driver to go down to something well less than 80Hz. If you can do that, then a sub can be used that has no output (including distortion) above 80Hz. If this is done the sub will not attract attention to itself. I prefer the Swarm subwoofer system from Audiokinesis, as in addition to being a worthy sub (goes to 20Hz) but also solves standing wave issues in the room so bass is evenly distributed, especially at the listening chair.

The other limitation most 'full range' drivers have is power is they are also efficient (+95dB) - most don't handle a lot of power, the ZU being one of the exceptions. That little 6" PHY I mentioned would be toast by the time it sees 20watts, and its rated at 96dB. In most rooms 10 watts works with it, as long as a sub is also involved. If you plan to use an amp that has more power than the driver has, its a really good idea to place a fuse in series with the driver! Some of these drivers are quite pricey owing to the level of precision needed to make them work. Frying a voice coil can be really disappointing.


If you don't cross the bass out of the driver, you can expect Doppler Effect distortion and unnecessary heating of the voice coil.


Getting a full range driver to go to about 50-60 Hz is doable (more like 65Hz if you're thinking about that 6" PHY...). Adding rear firing tweeters while otherwise not crossing over the main driver is also doable. If you sort this out properly, you can get excellent results.


Musical Affairs Grand Crescendo with 10 watts of SET is very nice.  Of course its not going to sound anything like Magico M with Soulution monoblocks.  Both are perfectly valid for enjoying music.
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The OP asked a question, without specifics as to what is meant by "single driver" and "fullrange speaker". Seems like most responses discuss a dynamic speaker as a "single driver", and full-range speaker as s comparative well-known or accepted model that reproduces a wide enough audio frequency range to be called "fullrange".

My take on the question is a single radiating surface unit (speaker) that can come closest to reproducing the full range of audio frequencies (20 Hz to 20 kHz). Nowhere in the question is the required levels of distortion, power handling, efficiency, waveform accuracy, dynamic compression, linearity, sound coverage (dispersion), etc. 
With one driver we do not have any phase, timing and tonal discrepancy issues that plague multi-driver systems. There are no obscured bands in the midrange, hence there is a possibility to integrate the most sensitive midrange better to the room acoustics. When the integration to room acoustics is perfect, the jump is significant. With a well integrated multi-driver system the improvement is not as drastic, as the midrange is still plagued by issues from the multi-driver solution. The question is: do we want pure midrange (single driver) or extended extremes (multi driver)? Given that over 90% of our brain's sound processing power is in the midrange, we benefit most from improved midrange. We have a culture that obsesses with extremes, so most people go for that automatically. It's ultimately a personal choice. Just an observation: my friends who settled on a single driver solution have stuck to it, and rave about the music they are playing, and have no thought about speaker upgrades.... single driver sound has a rightness to it that multi driver cannot match. If you look for "submarine crashing to the iceberg" then they are not the right choice.
This is another coaxial speaker; there is an add on tweeter ("super-tweeter" per Zu). The main driver functions to slightly above 10KHz.

No crossover (though filters). Still not a true full range single driver speaker.

Zu make full range single driver speakers.

Looking at an article form Sublime Acoustic they noted that "the capacitor and inductor values drift with temperature. When you turn up the volume the values will begin to drift, which causes the effective crossover frequency and other characteristics to drift, which  can lead to distortion of the sound."
Before purchasing my speakers, I probably spent 6 months reading about speaker performance and concluded that if all possible it would profit me to eliminate crossovers as much as it is possible to do so. 
Zu make full range single driver speakers.
I have a pair of the Soul Superflys and they sound really good to me. They can be a bit finicky to set up properly as mentioned above but that’s part of the fun, right?

Their high efficiency means a lot of low powered tube amps become a viable option to audition.Zu also suggests some SS amps that pair well with their speakers.


A Miniwatt N3 for example, has more than enough power to make the Zu's sing and go to ear-splitting sound levels. Pretty much any vintage receiver works great too.
Single drivers are great....
....70+ years ago.

Things have changed quite awhile ago....it's harder to pull off the 'hat trick' to make things blend properly, but....

'One trick pony's' still only do one trick.
Long game is fine if it is not too long and frustrating. Why are they more sensitive to room acoustics than other designs ?
Sound purity, that's worth pursuing.
Indeed, single driver sound is highly subjective, and it's also extremely dependent on the actual build. Among my audio friends' circles we have several single driver speakers which are phenomenal speakers. Bruce Edgar's Lowther horn comes to my mind (RIP Bruce Edgar! He just passed away...), 100+dB/Wm efficiency, and had enough bass and high frequency extension to create the most memorable Cantata Domino experience I ever had. (It has full size chorus and church organ.) My Fostex Voigt pipe could reach down to 30s, and surprised me with the most lifelike timpani reproduction I ever heard, from any speaker. Although Bruce Edgars legendary designs are well known, but not sure whether you can buy any... my Voigt pipe is certainly one of a kind... the commercial Rethms comes to my mind, but that, in comparison completely lacks bass. 
The most important consideration is that single driver speakers have NO CROSSOVER, and will give you the purest sound ever. That is, they will allow system weaknesses to pop up their heads that you had no idea there were. Generally, solid state amps are a terrible match for single driver speakers (although there are exceptions - Michael Yee amps sound great with them.) Also, they are EXTREMELY sensitive to you room acoustics and speakers placement, and it can easily take a year until you find their optimal position. However, if everything jives, you have an endgame situation. My Voigt pipe gave virtually identical experience with recorded jazz as a live jazz event - I listened to my friend's concert at the Dragon Upstairs (in critical listeners mode), and right afterwards put on the Jazz at the Pawnshop, and with closed eyes I did not get any hints which was the live, and which was playback... But that was after 15 years of playing around with them, and when I moved to my new place, I could never set them up so they image like that, and their midbass is not coming to life either. So, YMMV tremendously. They have almost infinite potential, but everything has to line up. If you want plug & play, look elsewhere, they are very long game speakers... provided you find the right one. If you can get an Edgar horn, go for it, although to my knowledge he designed that Lowther horn for my friend, and that might have been the only one he built. I have heard extremely disappointing reports from my friends when they ran into commercial single driver designs.  Good luck!  
There is also a YouTube guy, Erin's Audio Corner,  I bet he would like to put one on his new Klippel. 

https://www.erinsaudiocorner.com/
They would happily measure them  if anyone wanted to send them or if the company did. They are interesting looking. 
“I don't suppose there are any third party measurements anywhere?”

You’re unlikely to find third party measurements cause speakers like Charney are outside the scope of CFO (Chief Fun Officer) at ASR 😂
Erik,

I've heard a lot of wide-band/full range drivers used very successfully in multiway systems.  Some were, as you discuss, assisted by a woofer, others were assisted by a tweeter (most commonly with large diameter full range drivers) and some with both a woofer and tweeter.  Most of these were custom-built systems.  An example of use of extended range drivers in multi-way systems includes the SoundKaos Model 42.  By using simple, first order crossovers and allowing the crossover points to be away from the critical midrange, fullrange drivers minimize the negative aspects of multi-way designs. 


I see Charney claims 20hz-20khz with no roll off on the top of the line speaker. Some of the others in the 30's to 20khz . I see no measurements on their site to substantiate this. I don't suppose there are any third party measurements anywhere? 
I recall hearing a very well implemented single driver speaker based on an 8 " Fostex driver at RMAF a few years ago. I was really taken with the sound quality. One of the better rooms of the entire show.

There are some inevitable tradeoffs but this applies to "any" type of speaker. Multi driver/Multi crossover speakers have their own set of tradeoffs. It is always a choice of what compromises can you willingly tolerate long term and be happy.
Charles