Coaxials - Reality vs. Experience?

@deep_333 

Clinical sound and i could never get emotionally involved with any tracks no matter what electronics I tried.

I think I know what you mean, but how exactly do we define "clinical"?

Especially when we're talking about some of the most admired and costly loudspeakers out there?

Yet, there is little doubt that far too many designs fall into this category, but is "clinical" even something that can be measured?

I suspect this is a hugely important question to all of us who regard tone as king.

Wasn't it Harry F Olson, one of the acclaimed greats of audio, who first suggested the importance of "good tone"?

Yet here we are some 60 years later, and still without a good means of defining what that exactly means.

@deep_333 The Closer Acoustics OGY + Creek 4240 + Bluesound Node setup is serving me well. I like how responsive the OGY are to amplification. You can make them sound clinical with a budget class D amp or warm with a budget British A/B amplifier or a tube amp. 

I suppose that 2-way speakers (even coaxial) with crossovers are less responsive to amplification. The crossover kind of tunes the sound. That may also explain why the coaxial design doesn't seem to standout compared to having separate drivers. I am just speculating. 

Re: engineering. From what I see on the internet, it seems that engineers focus a lot on measurements and reducing resonances (through measurements). Perhaps engineers have shaped the industry more than they want to admit. We're clearly heading in a specific direction: small narrow enclosures, dead cabinets and many drivers. This direction should result in a very clinical sound. I go to a lot of live shows and it sounds different compared to Hi-Fi. You have a lot more resonances and vibrations. Sounds kind of blend together into a wall of sound (especially in an orchestra of string instruments). Stereo imaging is a fiction. Granted, most if not all rock concerts have terrible sound. Jazz, electronica, folk and orchestral music sound a lot more clear. 

@kokakolia  Focal and Tannoy continue to be rehashed legacy designs. I had the KEF ref 1 bookshelves for about a year before I sold it. Clinical sound and i could never get emotionally involved with any tracks no matter what electronics I tried. I could say the same about Magicos. It is just not my kind os sound (The latter is quite effortless with TADs and the new Technics that i audited). Yamaha is also the biggest manufacturer of musical instruments. It would be safe to say that their engineers understand more about music in addition to core engineering.

Eric, in my case the 3.4 is my first coax

I guess my experiences, limited as they were, also did not convince me that coaxial speakers, or hybrid coaxial (mid + tweet coaxial, with additional woofer) were by themselves a magical new direction that I had to have.

Unlike say ESLs which clearly distinguish themselves, though not everyone loves them or has the space to use them well.

The KEF R3 Meta measures extremely well regardless of price

Except in impedance, this is a very hard to drive speaker which also happens to have a truly odd impedance curve.

@deep_333 Yamaha and Technics are so underrated! However, the low efficiency of Technics speakers in general made me look the other way. 

The story of old manufacturers recycling old designs is best exemplified by Focal. Their drivers have even gotten worse over the years for "economy of scale" reasons. The materials are of cheaper quality these days. The new Focal Vestia line is using tweeters from the Focal car electronics division. 

I am a bit perplexed about your statement regarding KEF. The build quality and engineering of the KEF LS50 is hard to beat for the money (you literally have to go to small boutique manufacturers which underprice their goods or assembled DIY projects with quality parts). The KEF R3 Meta measures extremely well regardless of price. But I'll concede that measurements don't tell the whole story. If it were the case, all amplifier companies would go out of business and everyone would be using class D mini amps from China (forshadowing maybe...). 

The new coax design from Technics (SB-G90M2, ~5k/pair) sounds shockingly good for any speaker under the 10 to 15k price point. I recently got to audit it more seriously at my friend's house, who has it paired with ~40k in electronics. It would be safe to say that the engineers at Technics know how to innovate/design a coax driver better than the guys at KEF and Tannoy (rinse repeat of older driver designs with the same crappy sound).

Ive been ridiculously happy, for a couple years now, with my very efficient Emerald Physics 3.4s. (12" woofer with 1" polyester tweeter) Most of the music I listen to does not go much below 40hz. My amps are LSA Voyager GaN 350 or EVS 1200 based on dual ICEPower AS 1200 modules

It seems that the general consensus is that there is no consensus!

What I mean is that co-axial speaker technology has not, by itself, won anyone over. Specific implementations though have.

Another way to put this is, if you own a Tannoy for instance, and you could not buy Tannoy again, you would not focus on buying co-axial speakers.

I don't know. Maybe the benefits of coaxial speakers are overstated. I liked the KEF LS50 Meta, but I also enjoyed many other 2-way speakers from the likes of Castle or Atohm. I'm talking about the $2k price bracket. I'm saying that if you try a dozen speakers around the same price, then the coaxial speakers won't necessarily stand out. 

I'll just be a weirdo and enjoy my single-driver speakers for now. I think that they sound fantastic.

The only guy i know who has perfected coaxial designs is Andrew Jones. Try one of his higher end coaxial designs  (TAD, Mofi, etc).  Many other coaxial designs i've tried (Tannoy, KEF. etc) sound like sht.

@mulveling

I traded Rockport Atria ii’s for Tannoy Kensington GRs. Bought Autograph Minis for my bedroom and was so smitten I searched out the larger Tannoys. Listened to GRFs which were not quite to my taste, and Canterburys which were to big for my room and my wallet. (Previously had Harbeth and Focal - so you see my tastes swing a bit.)

Also swapped D’Agostino Progression integrated for Pathos InPol Heritage integrated Endgame for the present

@audiotroy 

 Not true Vandersteens are exclusively time and phase correct at the listening position for those who can hear it and appreciate how this offers a realism connection to the music , not a priority for everyone.

Again, I was speaking specifically of listening above the tweeter axis, to make a point about how distance changes the time alignment. 

I have been using Altec 604Cs since 1978. 
I have never been unhappy enough to make a switch. 
or rather, I’ve yet to come across something that would incline me to do so, at almost any price point. 
For me, they ain’t broke and I’m not fixin’ ‘em. 

Erik,

Not being sensitive, just from a reader standpoint clarifying its not a concern at the listing position and will perform as the measurements indicate.

((((same limitations of other multi-way speakers in this particular sense))))

 Not true Vandersteens are exclusively time and phase correct at the listening position for those who can hear it and appreciate how this offers a realism connection to the music , not a priority for everyone.

 Cheers JohnnyR

 Vandersteen dealer

We have sold hundreds of these and this hasn't really been a problem because very few of our customers critically listen while standing up.

@audioconnection 

Johnny, don't be so sensitive. 😁 I was merely pointing out that Vandersteens have the same limitations of other multi-way speakers in this particular sense.

Erik

((((Your typical 2 or 3 way speaker is neither a point nor a line source. Vandersteen may be time and phase aligned but it’s not a point source.That perfect step response in the Stereophile measurements goes out the window when you stand up. A true point source maintains it's time alignment no matter where you measure it from.))))

Erik

We have sold hundreds of these and this hasn't really been a problem because

very few of our customers critically listen while standing up.

 We simply adjust the vertical tilt for their favorite listening location

  Cheers JohnnyR

 Vandersteen dealer

Love the Kef concentric speakers been using and loving my Blades and Reference 1's. There is something nice about a point source speaker that does it for me.

tomcy6  +1

herb, if Andrew Jones couldn't explain it to you while setting up a pair of coaxial speakers, I doubt that anyone here can.

hello closenplay,

I promise I am not being modest. I really and truly do not understand. I asked these exact same questions of Andrew Jones when he was setting up the SourcePoint 10s in Steve Guttenberg's listening room, and his answers plus all your answers and I still don't know what is and WHERE ARE the 'acoustic centers' of the cone and either a dome or a horn-loaded-compression driver tweeter? To the best of my understanding it is a time-domain thing that is not a physical alignment of of the voice coils; but something that must be determined experimentally using some type of wide-band pulses.

As for point sources, I have never encountered one.

As for my Heretic AD614 experiences: they seem extremely coherent and musical.  

They are notable because they use a series-connected Linkwitz-Rielly crossover that is very low-power SET-friendly.  John Atkinson told me that in all his years he had only tested three speakers with series crossovers. 

As for my lifetime of coaxial experiments, I believe coaxial drivers project voices into the room with greater presence. 

That really is all I know.

herb

I’ve been building/listening to Coax speakers for just over two years? 5 different drivers in 9 or 10 unique enclosures? (Tannoy, SB Acoustics, Seas and Dayton)

Currently listening to a pair of Seas C16N001/F in enclosures I built following Seas exact recommended build. They are a fantastic match to my Hiraga Super 30 watt amp.

I tend to switch out speakers/amps with a certain regularity. These have been in my listening room, hooked up for several months now, and I feel no need to swap then out. Love the sound of these! My Quads, Cornwalls, full range voigt pipes, coax voigt pipes and some other units I’ve built as well, are waiting in the other room to be revisited.

These particular speakers are quite special. I have built a lot of full range speakers, and I like a point source, but felt I wanted more “sparkle” than a full range driver could supply. Coax drivers fit that bill perfectly.

As I’m using the Acoustic Reality Series Crossover with these (and several of the others I’ve built) the time/phase alignment of the speakers is amazing. A ridiculous amount of detail, while at the same time staying true to the tone of the original driver.

Im hoping to buy a pair of the Great Plains Audio 604’s, and build something with them. But they are costly…

The Heretics look interesting, and as the FaitalPro drivers they use are fairly cost effective, might be something I look into also.

Unless you couldn’t tell, I’m a fan of these types of drivers :)

Pluses and minuses in all designs; pick the flavor that suits.

I was lucky to meet and spend an evening with John Dunlavy in the mid 90s when he was in Colorado Springs (thanks to a local dealer) and have heard all models from small to huge. They could be magic, but only ever for one listener at a time.

For good or bad, those configurations were the largest one-person speakers I ever heard. They were off-the-charts fabulous sounding when you were exactly in the sweet spot. Move an inch right or left and it was gone. Not kidding, gone.

I have Tannoy Churchill’s with 15 in dual concentrics. Let me tell you they are nothing, I mean nothing like the coaxial and triaxial speakers of yesteryear! 

I’m an Ohm and KEF fan these days. I heard the new Mobile Fidelity Sourcepoints and those caught my ear. In a larger room from further away the inherent coherency of this kind of design matters less.

OOPS. After reading the previous few posts. I should make a correction. I know you are a pretty sharp guy!

I managed to wrestle the keyboard from my wife😅. @herbreichert C'mon, Herb none of this false modesty! You know we know you're a pretty sharp guy! I Know old wisdom says not to let on how smart one really is 😉.

Can we get some initial impressions of the Heretic? We can keep a secret until the review. 

You must be totally confused by one of the bullet points on their site:

                   POINT SOURCE CO-AXIAL TRANSDUCERS

"All sounds originate from a single point in space. No transducers all over the place, yielding fuzzy, phasy music reproduction. Excellent soundstage, precise location of instruments and coherency."

Love this hobby.

Truly appreciate you, Herb!

@herbreichert PS - Your typical 2 or 3 way speaker is neither a point nor a line source. Vandersteen may be time and phase aligned but it’s not a point source.

That perfect step response in the Stereophile measurements goes out the window when you stand up. :)

A true point source maintains it's time alignment no matter where you measure it from.

what is the definition of "acoustic center" ?

@herbreichert The point in space from which sound appears to originate in terms of time.  Think of a woofer and tweeter mounted on a flat baffle.  Look at it from the side.  The tweeter's acoustic center is practically at the baffle, but the woofer's may be 1" or more behind the baffle.  Speaker designers have to take this into consideration for either phase or time alignment.

how do we know when they are aligned? A tone burst?

Kind of depends how you mean "alignment." Phase aligned you can tell by an smooth transition from one driver to the other. Time aligned you can see using a step response. See figure 9 in these measurements for time aligned speaker step response.

what is the definition of a point source?

A theoretical "ideal" (one of many ideals) in which the full range of sound appears to come from a single point in space. A single, full-range driver is by definition a point source. Some multi-way speakers may attempt to mimic this behavior in time and space. The Duntech Sovereign is a famous, early-ish example.

Contrast to a line-source, like the famous Infinity RS.

@mulveling I have no problem with the assist. I respect your thoughtful/experience based opinions. I am referencing the majority of coaxials on the market (home hifi not the old Jensen co/tri-axials of yore). Examples, as have been mentioned by others/myself, Tannoy, Kef, TAD, MOFI's new two way (Sourcepoint 10), diy drivers (Eminence, Seas, SB acoucoustcs, B&C, BMS.........). Of course, some of these models are not exclusively concentric (mid/hi, low-mid/hi), but are aumented with low frequency drivers. 

@herbreichert You communicate/resonate fabulously with the inner artist in all of us that think we have an inner artist! Appreciate your style. As Mulveling mentioned, looking directly at the driver in question (as JA would perform an on axis measurement of MOFI's Sourcepoint 10); the attempt by most of these (passive) designs is to time align the acoustic centers (dual concentric) of these coaxials to best approximate a point source How accurate each designer is at this is up to measurements. If the sound/presentation is "good" is up to personal preference. Of course, the drivers don't have to be concentric, but still coaxial and the time alignment adjusted via dsp (fully active in speaker solution or external with a DEQX, for example........each with its own pros and cons).

Be happy to try and clear any waters I may have muddied.

Herb, you're the pro, I am just a guy with some electronics and a room full of drivers.

@erik_squires You speak in generalities or specifics when each suits you, not when it suits the details of the discussion. Tell me about the real world D'Appolito arrays you have deigned/built/tested and formed opinions on through listening to at your home. Or for that matter, listened to out in the wild. Your experiential observations of point source style speakers vs any two way D'Appolito array speaker? Crickets?

You LITERALY can't have a point source! A point source is an abstraction, it doesn't exist in reality. We use the idea of a point source to model and make calculations that can help guide a particular design. The theoretical pros and cons (and the relative importance of each) of any particular design will play out once you select drivers, select crossover type (active/passive), create a pile of sawdust, twist a screwdriver, skin some knuckles, measure, listen, adjust, rinse and repeat. The devil is in the details (apology for the hackneyed phrase).

Erik, thank you for the reading suggestions, but the design literature I read pre internet has served me and my ears quite well. There are as many opinions as keyboards out there, each telling you which benefit they champion on whatever design. There is no inherently "good" thing about narrow vertical dispersion unless your use case for some reason necessitates it. (Also, I believe you interchanged vertical/horizontal in your two previous posts). One doesn't go into a store and the audio clerk says " this speaker has narrow vertical dispersion, so it's the BEST you can buy!"

For gigs....If you had a two-way MT bookshelf (with its unique dispersion pattern) and create a quick and dirty D'Appolito array lengthening the baffle and symmetrically placing a matching M above the T creating a MTM (appropriately altering the crossover) your main gains you put your benjamins down for are: Mimicking point source for that perceived presentation, Higher power handling (louder, but at the expense of lower impedance), Lower midrange/woofer distortion due to less cone movement, lesser impact of ceiling/floor interaction (in my experience....meh)

Erik, disagree as vociferously as you like..........now go make some sawdust and enjoy some righteous tunes!

Well wait.......... you still haven't explained "off-plane axis listening". (Tasty geometry salad)😋.

I listen only in the "sweet" spot.....where all the magic happens! 

(There are probably numerous errors above, not having typed this much since my last term paper. Retractions, denials, apologies to follow. Good night gentlemen/gentlewomen/gentlefluids, my wife is yelling at me to get my fingers the frick away from the keyboard.

That being said I've heard the SourcePoint 10s and am listening to the Heretic AD614s right now.

hr

more dumb, not rhetorical, questions:

what is the definition of "acoustic center" ?

how do we know when they are aligned? A tone burst? 

what is the definition of a point source? 

I am completely confused. 

Is there a book on this stuff?

herb

Coaxials with acoustic centers which are not coincicent does kind of beg for an active, DSP crossover doesn't it? :)

@herbreichert wrote:

I know what "coaxial" means but how are you defining "concentric"? Are you suggesting that two coaxial drivers (i.e. their voice coils) may me mounted at an angle to each other? That they are centered but not perpendicular? Or?

sincerely

herb

Pragmatically speaking it would seem mostly to be a terminological twist; Tannoy calls it ’Dual Concentric,’ whereas others typically refer to it as ’Coaxial.’ Whatever differences there are between different iterations/designs of these point source transducers, not that they're irrelevant, should have no practical impact on whether they’re called one or the other.

closenplay stated,

"To add clarity, concentric is a subset of coaxial. In other words, all concentric drivers are coaxial but not all coaxial drivers are concentric. @erik_squires Pardon the presumption; you are probably referencing most designs intended for the hifi home user, of which most (if not all) are concentric."

I know what "coaxial" means but how are you defining "concentric"? Are you suggesting that two coaxial drivers (i.e. their voice coils) may me mounted at an angle to each other? That they are centered but not perpendicular? Or?

@herbreichert - Not to speak for @closenplay but my interpretation was that he’s focusing on the z-axis (forwards / backwards) alignment. An egregious example of z-axis non-alignment would be in some car stereo drivers, where they (sometimes) clumsily suspended & mount a tweeter in front of a woofer. That’s what I think he was calling out.

But the reality is that none of the coaxials really seem to have perfect z-axis alignment (relative to the 2 drivers’ acoustic centers). Certainly not Tannoys, which mount the tweeters well behind the back of the woofer, coupled through a relatively long waveguide. Tannoy’s brief attempts to time-align the drivers via electrical means were generally regarded a failure. Their pepperpot waveguide drivers at least have phase alignment at the crossover point; not sure about the tulip drivers.

Tannoy chose to call theirs "dual concentric" early on, probably to help distinguish their approach from far less refined coaxial arrangements of the time.

Hello everybody, please help me with a dumb question that I do not know the answer to.

closenplay stated, 

"To add clarity, concentric is a subset of coaxial. In other words, all concentric drivers are coaxial but not all coaxial drivers are concentric. @erik_squires Pardon the presumption; you are probably referencing most designs intended for the hifi home user, of which most (if not all) are concentric."

I know what "coaxial" means but how are you defining "concentric"? Are you suggesting that two coaxial drivers (i.e. their voice coils) may me mounted  at an angle to each other? That they are centered but not perpendicular? Or? 

sincerely

herb

One sound quality I rarely see mentioned is how a speaker sounds all around the room. While the "listening" position is important, I also demand that speakers sound good as I walk around the room, and also around the house. I’ve had multi-way speakers whose sound falls apart as soon as you stand up.

My 15" Tannoy’s fill the room, and sound natural all around the room, and while I’m working in the kitchen. This is very important to me. I also use an 8" Tannoy driver as a center channel (in a DIY cab). It makes an ideal center, with no off-axis "phaseyness". No my Tannoys are not perfect, but this is a quality that they excel at, over non-concentric speakers.

I had Tannoy 10" Red's and Altec 604-8G's in refrigerators.  I couldn't cotton to either.  Then I landed a pair of JBL Hartsfields 15 years ago.  They are my forever speakers.  I love the 375 compression driver through a horn!  I also love my Quad 57's and LS3/5a's~

I came full circle back to kef and i'm not sure if it's because of my familiarity with the house sound or because they just due midrange better. I had the r105/3 and consistently listened at 104db peaks and the louder they played the more realistic they sounded. I was always let down by the bass which measured good in room but just didn't sound full bodied. I would say the benefits of the kef design is fairly easy placement to get most of what the speakers are capable of, most will be under powered, but many speakers that design for a flat in room response sound bass shy and take time to adjust to. Kef Blades have ironed out the midrange driver reflections making for a softer and more detailed treble play back than earlier designs and bass has been addressed.

which you are calling "narrow vertical dispersion" and as a "benefit" It is not a benefit, but a downside.

I absolutely disagree.  In a brief reading of articles online you'll see that the horizontal dispersion control of D'Appolitos is in fact a good thing, as it is for tall ESL's.

Generally speaking, the more controlled dispersion of a speaker the less acoustic treatments a room will require. 

Further, you literally can't have a point source if you are deliberately changing the dispersion on one or the other axis.

@erik_squires The main design objective/benefit of a D'Appolito array is to mimic a point source. Benefits that inherently follow are higher power handling (plays louder) and lessening of the potential impact of floor and ceiling reflections due to two drivers producing the same frequency range. The design doesn't actually reduce vertical dispersion, just potentially helps alleviate some negative interaction of the floor and ceiling. Before the D'Appolito array the only way to mimic a point source was to use a dual concentric driver (with its attendant pros and cons).

One downside of the D'Appolito array is the tighter vertical listening window created by the three drivers (five drivers in my fully active 3-way design)(seven drivers in the Duntech Sovereign). It just so happens that the symmetrical drivers couple optimally at a certain distance........which you are calling "narrow vertical dispersion" and as a "benefit" It is not a benefit, but a downside. There is no free lunch, each design has its pros and cons. You get the benefits of that narrow window of optimal coupling when in the sweet spot, and the downside of potentially less coherent sound outside of the sweet spot (in reality...not so terrible).

Unfortunately, we can't give full respect to the details in this short response form. 

Please explain "off plane axis listening".

This is an interesting thread on coaxial speakers. It was nice to read the comments on the HSU CCB-8’s.

I upgrade my speakers every 15 years or so and this summer I replaced my L/C/R speakers with the HSU CCB-8’s. They sound great, providing exceptional detail with a very full soundstage.

Of course, I also wanted to replace the rear surrounds and originally thought about two more CCB-8’s but that seemed like overkill for surrounds. Instead, I purchased KEF Q-150’s for the rear surrounds. They are also a coaxial speaker and blend very well with the HSU’s. Picked them up at Crutchfield at $254 for the pair, which was a great price (they retail for $599 a pair, but they go on sale frequently now).

Our home theater, with new speakers in the 5.1 setup, has never sounded this good before. Very pleased. And while I’m sure that upgrading to any speakers in this general price range would have made a difference, I like to think that the coaxial speakers are punching above their weight class!

@jacksky I think the prime benefit of the D'Appolito configuration is narrow vertical dispersion.  with wide horizontal, so it is very different than a coaxial with equal dispersion in either direction.

Because of the changing time alignments in a D'Appolito, he's gone away from low order filters and now recommends 4th order (combined electrical + acoustical) crossovers for best off-plane axis listening.

@prof “:The other thing with the Thiels is the insane imaging prowess.  There is a focus and precision and density to the imaging I have rarely heard before.”

I had the Thiel CS5 monsters, had to work at placement really hard to get imaging and even then it was finicky relative to slight changes in sitting position. Granted that model didn’t have coax drivers. Eventually gave up on them, too much work.

Regarding coaxial drivers, as a general statement to OP with my take, slanted baffle speakers get the time domain right in the vertical plane. coax drivers get them right In both horizontal and vertical. So my question is this : a stereo setup offers a center image as if there was a center channel. So with D’appolito driver setups sandwiching a tweeter between 2 equally spaced midranges, do you get a phantom centered midrange that seems to come from where the tweeter is? Is that faking a coaxial presentation?

Altec Model 18, 604-8h alnico coaxial, mantaray horn, 9cu.ft. Cabinet.  By far the best of all the speakers I have owned.  Just amazing with good tube amp.  But very hard to find.  I’ve only see one other pair for sale in the last 10 years.

A coaxial application done right can give the best coherence and power dispersion in all directions.  You have the potential for the biggest sweet spot and sound stage with proper supporting equipment, positioning and amplification.  

Unfortunately getting coincident drivers right is only part of the recipe.  It has been ruined for me overall with the following errors-

1) Voicing.  Coax drivers will not make up for a voicing and frequency balance you do not like.

2) Driver size step.  using too big of a step between drivers (e.g. 8 or 10 inch woofer to a 1" tweeter) can cause issues that a coax setup will not make up for. 

3) House sound.  Some coax speakers sound artificial and metallic to my ears.  Again, a coax design cannot make up for a bad house sound. 

@mulveling Main stream very succesfull co like Wilson,Paradigm, JBL ets dont follow you suggestion LOL,   I am not participate in forum only . 

I think I'll buy those new Steinway Lyngdorf Model A's and end this game for good 🤔😎 Enjoy the music 😃