The Shure V15 V with a Jico SAS/B stylus VS The Soundsmith Hyperion MR and Lyra Atlas SL

@mijostyn "Do you have stadium concerts down under? If you go to one you can hear midrange/bass line sources. The sound is usually awful. I do not bother any more"

Yes, there was a concert last night at Sydney Olympic Park, Main Arena.  Seats over 80,000.  Could hear it from home!  

We went to a Bushfire Aid concert there a couple of years ago.  Queen and Adam Lambert had played the night before, and let every other gig use their sound system.  We arrived early and could hear kd lang practicing hard to get her sound right. The sound during the first session was so bad overall that we found a beer garden outside and listened from a distance.  Later acts must have learned something because the sound became listenable, then good.  kd lang sounded brilliant and Queen finished off in their usual style with superb sound.  All from the same hardware!

Queen's Brian May is an astrophysicist in his spare time.  Fred Hoyle, who coined the phrase 'Big Bang' because he thought that particular origin theory was rubbish, worked out most of the nuclear reactions occurring in stars.  To Fred, a star was a one-dimensional problem.  Work out what happens on one line radiating from the centre and you have solved what happens on every line. 

Brilliant people can sometimes be wrong.  And sometimes conventional wisdom is overthrown by a single visionary, at which point everybody else becomes wrong.  Newton, Einstein, Hawking: each did this/

I am impressed that your subwoofers can do zero Hz.

@lewm Eminent Technology's sub can do DC if the blades are locked In fact a fan is what gave him the idea.

@mijostyn 

ESL in Australia normally means English Second Language, and represents the quarter of the population who don't speak English at home.

I try to use English as a Scientific Language with precise meaning.  Seems we are from two nations divided by a common language.

Anyway, it appears both countries will stop today for important races.  Yours is for a President, our country stops for a horse race!  Australians are the heaviest gamblers in the world, even the Sydney Opera House was paid for by a state lottery ...

@mijostyn 

Can you provide some characteristics of the Hyperion MKII MR? For example, what are things you like about it? Is it balanced and not shouty or overbearing in any of the frequencies? How long did it take to break in? 
 

I have a Hyperion MKIi and am expecting the Hyperion MKII MR in a few days. Will be interesting to hear the differences. I have two SME V arms mounted. One arm has an Air Tight Opus 1, also new, but listening feedback is for another conversation. Thanks. 

@lewm 

So it seems as if the four sub-woofers are spaced in a line with 4 feet between adjacent ones.  The far left and the far right are thus separated by about 3 x 4 = 12 feet..

For the record, Quad ESL speakers, apart from the original, do not beam like crazy.  In fact, quite the opposite.  This is because they have time delays so the entire panel does not behave as a 'moving piston'.  It seems to be a hard concept to grasp, but there are heaps of polar dispersion diagrams in the brochure!

The good thing about 0-Hz is you only have to do it once!

They all do, when no signal is applied.

I am impressed that your subwoofers can do zero Hz.

@richardbrand I know a bunch of very smart people with terrible ideas, my brother, a PhD in aquatic acoustics from MIT being one of them. It is hard to imagine how such a smart guy can be so stupid. Anyway, the Sound Labs ESL is a full range speaker 8 feet tall with a cross section that is 45 degrees of a circle. Dipole ESLs beam like crazy and emulate a line source perfectly. It does not matter where the propagation starts. What is very neat is the image solidifies about 10 feet behind the speaker which people, non audiophiles in particular, are always amazed at. The house is an open concept design, I designed it. The rear of the media room is open to the rest of the house in a very fractured way like a big defuser. The nearest solid wall is 75 feet away. There is no modal behavior in the room at all. You still have barrier effect, the bass gets louder at the side walls.  The subwoofer array ends at the side walls forming a line source from zero to 100 Hz. The side walls are 16 feet apart. The line source behavior ends at about 200 Hz and they turn into one big point source. By then they are 48 dB down and well out of the picture. The subwoofers are perfectly time and phase aligned with the ESLs. This is done by measurement and digital delay and correction. 

@mijostyn According to their website, your so-called ’real’ line source speaker tries to emulate the behaviour of a virtual line source situated about 3 feet behind the panel, just as Quad ESL>63 try to emulate a point source a foot behind the panel. A true point source radiates spherical soundwaves evenly from the point in every direction. A true line source radiates cylindrical soundwaves evenly from the line.

So are your subwoofers actually 12 feet from one end of their line-up to the other?

Does not having a rear wall mean your listening area radiates into free space?

I only mentioned Duntech Sovereigns because they were a D’Appolito configuration with careful time alignment that exhibits dreadful interference, despite being engineered to sound like a Quad ESL-63. John Dunlavy was a US physicist specialising in radar and wave propagation. Duntech speakers are still being built in Sydney, I suspect mainly for the Asian market.

@richardbrand A line source does not have to be thin like a ribbon. The most impressive characteristic of a liner source aside from higher acoustic power is that they do not send any sound up toward the ceiling or down towards the floor. You can make a line source tweeter only 9 inches tall. The problem is the vertical beaming is so bad you can only hear it if your ears are exactly at the same level. Now take an 8 foot ESL dipole speaker system and put it in a room with an 8 foot ceiling and you get a REAL line source that will maintain line source behavior over the entire audio band and have minimal interaction with the room. They only throw sound at the front and rear walls. My listening area has no rear wall, so I only have to deal with the front wall. When dealt with correctly the image produced is better than anything you have ever heard. Honest,

@richardbrand Not only do I have a REAL line source speaker, I have a real line source subwoofer array. Perhaps what you are talking about is the fact that most "line sources" lose their line source behavior at some low frequency depending on the height of the speaker. My system acts as a line source over more than the entire audio band from ZERO hertz to 20 kHz. There is absolutely nothing pseudo about it. Again, you need to read more about line source behavior. It is why my subwoofers are 4 feet apart and by the way there was nothing all that special about Duntech speakers. I installed a pair in a very rich person's home on Miami Beach in the late 70's when real Duntechs were still being made. They were OK for dynamic speakers. They fit the clients decor nicely. Their image was mediocre. The real company folded in the 90s I believe. 

@mijostyn "What is a pseudo line source?"

A true line source speaker does not exist, any more than a true point source speaker can actually exist.  If they could, the energy they emit would have to be crammed into an infinitely small volume, a singularity.  Singularities are hated in physics theory.  If you can get an ounce or two of matter and cram it into a very small volume, you pretty much have the preconditions for the creation of another big-bang and a new universe.

Ribbon speakers probably come closest to a line source, but big electrostatic panels have to use geometry and / or smarts to give the illusion they behave like a point, or a line, somewhere outside the plane of the panel.

Countries with small populations like Australia, New Zealand, Norway, Denmark, Slovenia can all make really good equipment.  Australia even invented WiFi.  But there is little government support or venture capital for start-ups.  The volumes are low, so prices have to be high.

The flip side is that there are very few import duties anymore.  The car industry is wide open to imports.  Ford, General Motors, Chrysler, Toyota have all stopped local manufacture quite recently.  Chinese cars will dominate very soon!

In general I can import stuff and save about 25% compared with buying the same item locally, after allowing for transport costs.

I made reference to the HD-3P Tweeter when being in discussion about the ESL 57, and my intention to attempt to tidy up one of it's obvious shortcomings with the Tweeter. Under the guise of "Hearing is Believing", I made more known about my experiences with Speakers using this Tweeter. 

Referencing the Driver was not a prompt to encourage the use of it, even though that is a consideration I do recommend.

To see that the Tweeters Data is now sought out and added as a further information was not expected to be seen within this Thread. Maybe in a Thread dedicated to the Tweeter as can be discovered on other forums. 

To the on-looker who has an interest in Self Produced Speakers, the added info might be enough to convince the Tweeter is worth a further investigation and worthy of such  contemplation. 

@mijostyn 

I do know and understand that stuff, pretty much like the back of my hand.  Absolutely right, subwoofers should be put to work on long wavelengths, which often will be longer than the listening room.  They will excite room resonances and one benefit of having multiple subs is that they average out these resonances a bit.

Now are you saying that the longest distance between any two of your subs is four feet?  I am particularly familiar with the Duntech Sovereign where the blurb says it is "acknowledged by experts as the finest speaker in the world, certainly the most accurate".  Each speaker has seven drivers in a floor to ceiling D'Appolito arrangement, which puts 12" bass drivers near the floor and ceiling.  Base is quoted as down to 27-Hz within 2-dB.  A huge amount of effort was put into time aligning the seven drivers so if you sat at the right ear height, phase differences were less than 25 degrees.

Because time alignment is so important, vertical listening position was crucial.  Slowly lower yourself and suddenly a huge image came into focus.  A few inches more and it was gone.  That was in a very large demonstration room where wall reflections mattered less than usual.  I've mentioned before that the reference used when designing these speakers was the Quad ESL-63.

Yep, the wavelengths tweeters should handle make it unwise to use more than one (why does Infinity spring to mind here?).  Tweeters can be made coincident (concentric) with mid-range drivers, as was done by Tannoy and is now brilliantly executed by KEF.  I have not heard the Tannoy re-incarnation by Fyne.

@lewm Vermont also has great riding, but New Hampshire rules with the Harley crowd because you do not have to wear a helmet here. They think that putting along at 30 MPH means you can't get your head squished by a run away truck or a WOMAN in an SUV on her f-ing cell phone. I emphasized the female gender to make sure everyone knew I was talking about an XX, not an XY masquerading as an XX.  This is particularly true of XXs driving Jeeps. My helmet is fluorescent yellow and it scares the h-ll out of many drivers. They move over even if they are not in my lane, Brilliant. We now have airbag vests. When the vest detects an unusual acceleration in the wrong direction it fires off the airbags and you go bouncing down the road or off other vehicles until the bags deflate. I don't use them too uncomfortable. I would use them for racing, but I do not do that any more in the strictest sense. 

I do own a Ducati, but in this case I was referring to my Triumph Thruxton RS. There are times when the British hit the nail squarely on the head like the Jag XKE and the Thruxton RS. The Ducati is raucous and in your face, but the Thruxton is just a beautiful thing, visually and mechanically. 

@richardbrand What is a pseudo line source? Do you have stadium concerts down under? If you go to one you can hear midrange/bass line sources. The sound is usually awful. I do not bother any more. 

The problem with most "line source" speakers is that the line source behavior is limited to certain frequencies depending on the design of the speaker. Very few people have a line source system capable of maintaining that behavior below 200 Hz. This is the big reason these speakers tend to lack really punching bass. Point source speakers lose acoustic power by the cube of the distance away from the speaker, but line sources only at the square of the distance. As you move away from the speaker bass frequencies fall off much faster leaving an anemic sound. Full range line source systems have advantages. The sound stage you get is right up from within the first 10 rows. Point source systems are back in the 25th row. Bass and percussion are much more life like in terms of power and dynamics. The problem for most people is the size of the system, it owns the room.

You do not need a distributor. Sound Labs will ship anywhere in the world that allows it. God knows what the duties are like down there. The Aussies make some great equipment. My DEQX preamp is Australian. There are many speaker manufacturers. Nobody makes ESLs? 

I have zapped myself on numerous occasions usually from forgetting to ground out the diaphragm before working on the speaker. That is a bigger zap than what you get from the bias supply directly. It is not capable of much current. The stators are referenced to ground, they discharge immediately when the music stops. 

You listen to "modern electronic music"? Just kidding.

If I lived in rural New Hampshire, I would have a Ducati for sure.

@richardbrand Sorry if you got that impression, but this is pretty basic stuff. The book is really good and would make a good read for any one who wants to discuss speaker design. You bring up useful issues, but they all have boundaries. You can use multiple drivers without comb filtering as long as they are not too far apart. As an example all really great dynamic speakers rely on one tweeter and that is usually the limit on output capability. The reason is that you can not get any good high power tweeter close enough to a neighbor to function as one driver. The motor is too big. This is not the case for midrange drivers and woofers resulting in designs like and extensions of the D'Appolito Array. Even though the midrange drivers are separated by the tweeter they are still close enough to each other to function as one driver acoustically as long as you do not set the crossover too high. My 4 subwoofers have four feet between them. The cross at 100 Hz the wavelength being about 10 feet. Since they are closer than 1/2 the wavelength they function acoustically as one driver and there is no interference between them, also because the line of subwoofers ends at fixed barriers, the side walls, they are functioning as a line source dove to 1 Hz which has further advantages in terms of room interaction. Not to mention it is a gas to hear eight 12" drivers powered by a total of 10,000 watts put out those low synthesizer notes you hear in modern electronic music. It's like twisting the throttle of your Thruxton wide open and shooting off towards the horizon, front wheel in the air. Some people never grow up. 

Here they give the specs for the DH-3P, showing a frequency response pretty flat between 4500 and down -6db at 37kHz. Drops off pretty fast below 4500Hz. For me, the term "midrange" makes me think 500 to 2000Hz. But the definition is plastic.

@mijostyn The HD - 3P is not a Super Tweeter in the usual description.

To me from my experiences had of a large range of Cabinet Speakers that can be models that extend toward the £20K+ purchase area and a handful of £40Kish Speakers.

The HD-3P used in the way I am quite familiar with is a Tweeter that produces Mid - Upper Frequency that is extremely attractive and wanted to be readily available to experience. 

That is more than enough for my needs. 

@mijostyn ya the physics of TRYING to fill holes is tough on amplifiers… 

Yes of course music lovers are not always audiophiles…and same for converse. A nice jab that didn’t land with any tympanic solidity with me… Of course, i’ve heard at some length the larger Quad you mentioned… when they work… Displaced by Apogee Caliper - Signature driven by a sweet sounding and quite modest Accuphase… in a lovely acoustic space chock a block full of Core Audio Design acoustical treatments… Fun

Enjoy the music

@mijostyn 

"I cannot imagine owning a speaker that could be so easily blown. In my hands it would not last 5 minutes. There is no excuse for a speaker to be so fragile. The materials exist today that can be used to make a totally bullet proof ESL panel. They existed back in 1978! Jim Strickland made a bullet proof panel back then. I can rap the diaphragms against the stators without any damage. The transformers are the elements that are potentially fragile particularly with amps that are clipping. I have blown amps and transformers but never the speaker itself"

No, in your hands they probably would not last 5 minutes, but you would really have to try hard to beat the protection circuits.  My two pairs of Quads have lasted about 20 years each before needing repair, which is much better than my bullet-proof Krell amplifier.

Yes, you can rap the mylar against the stators, but be aware that when powered, and for some time after switching off, the mylar carries 5.25-kV.  The stators carry no voltage until a signal is applied, but then can be fatal.  I always keep one hand in a pocket when near the high tension bits!

Unfortunately there is no Aussie distributor for Sound Labs.

@lewm 

No, not if it emulates a point source!  But it is a problem for pseudo line sources.  I am not stupid enough to believe that any claimed line source really is one!

Not a problem with a single full range driver.

@mijostyn 

"Do you realize that you have just noted that every great speaker designer is absurd, that the laws of acoustics are flawed. Don't listen to me. Get The Loudspeaker Handbook by John Eargle. It is written in terms most lay people can understand. Learn what you are talking about before you spew out ridiculous concepts. The British don't like music? I think you need to listen to V.W.'s The Lark Ascending"

Sir Thomas Beecham is a far greater authority than me, and I suspect, even you!  It was his quote.  If it were mine, I might substitute audiophile for British!

I have many copies of The Lark Ascending, and one of my favourite flicks is the Australian "The Year My Voice Broke" which uses it poignantly, and has just been reissued.  Vaughan Williams could write almost anything, from his Fantasy on a Theme of Thomas Tallis to his sixth symphony, which is exactly my age.  The latter opens with shattering intensity, swerves into jazz rhythms, and ends like Holtz' The Planets.

I note with some disappointment that you choose to criticise the person, rather than debate the specific technical points I raised.  For example, what is your answer to the complete cancellation of two drivers half a wavelength apart, which you claim act as one drive?  This is pure physics, simple to understand by anybody who knows what a sine wave is.

Of course, this really is a problem with almost all speaker designs, so not too many want to talk about it.

Dear @bdp24   : As you low coloration is too apririty for  me but even live MUSIC has natural colorations and it can't avoid it.

But that was not my point why I posted about " horns " ( and there are horns and horns not all are Klpish or the like ) but something that is near to the Live MUSIC:

Immediacy and things are that horn has it as no other type of speaker driver. Colorations culprit ( if any ) comes by manufacturer design. Audio is not perfect but you needs to have the Acapella experience.

R.

Dear @mijostyn :I listened the Triolon Excalibur in a home system in Houston and as you posted the Acapella are something to listen it yes very expensive:

@dogberry It is the timing of the reflections that is important, early reflections being the worst. Late reflections dictate the sound of the room. Early reflections should be eliminated as much as is possible. The best way to do this is with speakers that do not send sound in the wrong directions. Eliminating early reflections improves image specificity. 

@lewm I am not looking for a flat response. I am looking for a specific response which is far from being flat. I measure everything at the listening position. The microphone is comfortable at 85 dB.  Sine wave sweeps on a CD are used in conjunction with a computer program. The channels are measured independently and adjusted so that their response is as close to identical as possible. 

You are always welcome Lew. Anytime you are on your way up or back. 

Dear Mijo, You don’t need to teach me about the electronics, and no, I did not own the Parasound amplifiers any longer by the time I upgraded my 845PXs. In fact, my experience with the Parasound JC1s was entirely driving my M1s, which were completely stock in terms of the backplate components. With all respect to you and your quest for Nirvana, I perceive that the difference between you and several of us is that you want a perfectly flat in room response, regardless of the necessary interposition of the electronics (digital or other) necessary to achieve that. Whereas, I prefer the purest pathway with the least possible processing of the signal, come what may, with the exception that I do treat room reflections in my listening room with various wall panels and tube traps, etc, but that sort of thing is after the fact. You are operating on the signal in the digital domain before the fact. That (digitally correcting for droops and peaks in your listening room) has to be why you are stressing the MA2s, because there is no way they should be stressed purely by driving the Sound Lab speakers in the manner that you espouse. I tried equalization by signal processing once and hated it, but I admit the methods have come a long way since then. So I am curious to hear your system. Perhaps next time we go to northern Vermont I can stop by.

As to your response regarding how you measure in room response, "using a very expensive Earthworks microphone", etc, that is not a complete answer.  Where do you place the microphone? At what SPL do you map the response deviations from flat?

Elsewhere I believe you have said the soundstage should be entirely between the speakers, and anything else is because wall reflections have not been eliminated.

Well, we know what music with no reflections sounds like: play it outdoors. It sounds 'dead.'

But too many reflections muddies things and getting it just right is a dark art that a few concert hall designers have achieved largely by luck.

@lewm With a very expensive Earthworks microphone. It is perfectly flat from 10 Hz to 30 kHz. They send each mic with it's own curve. If you had already modified your speakers the JC 1s would not have liked it at all. I blew mine up. Both died within 30 seconds of each other. Live and learn. Fortunately, I got them open box, but it was still the most expensive mistake I ever made. I was going to use them on subwoofers having already gotten the MA 2s. One of the MA2s got into trouble. After a driver tube shorted out two resisters and a voltage regulator burn out. While I was waiting for parts from Ralph I pressed the JC 1s back into service after I modified the backplates. Live and learn. Where your system rolls off is entirely dependent on the output impedance of your amps. My MA 2s have an output impedance of 1.75 ohms. 

@pindac I believe that is a super tweeter. Must of us would not be able to tell if it was present. It would also be a mistake to put it into a system based on dipole line source speakers as it's contribution would change with distance. I once experimented with  Magnepan Ribbon tweeters on my Acoustat 2+2s. Eventually I reverted to the plain loudspeaker. ESLs have a characteristic no other speaker can emulate. Having one driver than handles everything from 100 Hz to 20 kHz without any interference between the amp and the speaker is special. The image is spectacular. I do love estate sales. You can waltz into some incredible deals. 

@richardbrand I cannot imagine owning a speaker that could be so easily blown. In my hands it would not last 5 minutes. There is no excuse for a speaker to be so fragile. The materials exist today that can be used to make a totally bullet proof ESL panel. They existed back in 1978! Jim Strickland made a bullet proof panel back then. I can rap the diaphragms against the stators without any damage. The transformers are the elements that are potentially fragile particularly with amps that are clipping. I have blown amps and transformers but never the speaker itself. 

@rauliruegas Their Sharon Excalibur is quite the loudspeaker. I would love to hear them. The price is listed "on request" 

@richardbrand Do you realize that you have just noted that every great speaker designer is absurd, that the laws of acoustics are flawed. Don't listen to me. Get The Loudspeaker Handbook by John Eargle. It is written in terms most lay people can understand. Learn what you are talking about before you spew out ridiculous concepts. The British don't like music? I think you need to listen to V.W.'s The Lark Ascending. 

@lewm There was a Branded Speaker back in the day using the HD-3P Tweeter. The Cabinet Volume and Matching Drivers even though Audax as well did not get the best from the set up.

A Build Your Own design become available as a Kit using a similar array of Audax Drivers

The more savvy builders of Speakers who adopted this design, were quick to produce much improved Xovers not constrained by a Commercial entities budget.

The next substantial changes for the Standard Kiit and more importantly the Commercial Design was the designs selected for the Casing/cabinets and External Xovers. Housing

Cabinets for the Build Your Own designs, were known to be produced from Board Material of a Thickness between 11/2 inch to 2 Inch. with all internal edges Chamferred.

Substantial Bracing with Chamferred Edges was adopted and independent chambers produced for all drivers.

These types of designs for a Cabinet were not known of in Commercial Speakers at a certain pricing, I suggest Speaker Cabinets were not produced to this Substance full stop.

My Speakers are With ext Xovers and a Cabinet using Board Material as sides up to a Thickness of 2 Inches, they are 5 Sided Cabinets with Chamferring Internally - Substantial Bracing and Chambers for the Drivers.

My Friends are Four Sided Cabinet produced from 11/2 Inch Board with ext’ Xovers in their own substantial housing.

The correction method adopted for the HD-3P Tweeter is a long term correction. It is now proven to have remained usable for a much longer extended period than the Audax Design.

As a Speaker it is another Bespoke Design, not typically encountered and not usually heard in use, which makes it one Speaker that is needed to be experienced to form an assessment.

I have recently been introduced to Troel Gravesend Design Speakers where Drivers and Xovers are approx’ £4K. The Cabinets and Speaker assembly were produced by Troel’s and exported to a UK Customer.

It is strongly suggested this design from Troel’s will be in the realm of £20K - £30K Commercial Speakers if a Speaker was to be searched out as a fair comparison. .

My gut feels, my friends or my own Speakers with carefully selected Upto date Electronics used on the Xover and PC Triple C Wire used as Internal / External Speaker Wire, will be a very very interesting Comparison, especially in the Upper Frequencies, where Troel’s is happy to allocate a £1000+ for Tweeters.

My own speakers were bought from an estate sale where the Widow told me her Husband’s System which was sold to a dealer was approx £100 K in total purchase value.

The Speakers weren’t Branded and not taken by the Dealer.

When picking up the Speakers, I gave the Seller very valuable advice on learning the Value of the Substantial Vinyl Album collection, where much of the collection was Classical.

She was now with new info to use and was to delegate the Grandchildren to getting an initial value using the Albums EAN No..

Classical Albums can acquire quite a sum as a purchase price, I hope some Gems were extracted for selling on.

Or, as Sir Thomas Beecham said "The British don't like music, they just like the sound it makes"

@tomic601 "imo the 63, of which i’ve sold ( new ) and rebuilt 4 ( several times over… the troubleshooting flow diagram is necessary but not, NOT sufficient, certainly has virtues but is hardly full range for various musical tastes…"

At least the ESL-63 Service Manual has a very comprehensive fault-finding flowchart! The 2905 does not, so I use the 63 as a guide. The 2905 improves the bass by doubling the bass panel area, going down to 32-Hz -6bB and less than 1% distortion above 50-Hz at 100-dB and 1-metre.

Quad made systems for music lovers, not audiophiles. Hence the infrasonic filters reducing bass output in the 405 amplifiers, and the extensive and subtle controls in the 34 pre-amp designed to allow music lovers to tame flaws in their records. A music lover will tolerate poor sound, an audiophile would prefer silence!

@mijostyn "you need to learn more about speaker design. The foot comes from the wavelength at the crossover point. ... What you are succumbing to is lay assumption and as we all know assumptions are the mother of all f-ups"   

So now I know that the "foot" comes from your assumption about the cross-over frequency - some mother of an assumption, especially with 3-way speakers which have two crossover frequencies! 

Your next statement is equally flawed "If two drivers are closer together than 1/2 the wavelength at the crossover frequency they function acoustically as one drive".

This proposition fails when reduced to absurdity.  Imagine the two drivers are omnidirectional and 1/2 wavelength apart..  Then along the line of the drivers, there is complete cancellation!  And on any other position, except equidistance, there is some cancellation.  Hardly functioning as one driver.

From memory you have made equally odd claims.  One is that only the sound from the closest point of your Sound Labs reaches your ear.  Well, if that were true, you could just keep an horizontal inch or so of the panel, and ditch the rest.  (See the reciprocity principle below).  The idea behind your assertion probably comes from that White Peper which describes the radiation pattern like the bristles from a bottle brush, entirely in the horizontal plane.

But that is not true either.  If it was, there would be no radiation to reflect from the ceiling and floor, and no need for the speaker to reach either!

The White Paper makes a big thing of an "acoustical principle that we refer to as microphone/speaker reciprocity".  I would not dignify it by calling it a principle, but it makes the case that speakers should be positioned as far apart as the (two!) microphones were, and the incoming (microphone) and outgoing (speaker) radiation patterns should match. The aim is that walking around the listening room should give the same experience as walking round the recording venue.

Why then, does this principle not also dictate that the speaker should be positioned at the same height as the recording microphone, and approximate it in vertical dimension?  I don't like so-called principles where you pick and choose what applies.

Walk round a concert hall (unpopular with the rest of the audience) and you will find sound coming from every direction.  Elsewhere I believe you have said the soundstage should be entirely between the speakers, and anything else is because wall reflections have not been eliminated.  Get real, decent systems can, and should, throw a soundstage extending far beyond the speakers, because that mimics the original venue.

"Quad was trying to improve dispersion. Stick with your KEFs"

Seems as if you are unfamiliar with the ESL-63 and later Quads?  Quad deliberately reduced the treble dispersion to "improve" it.

@richardbrand: While it appears the tweeter of the DIPTYQUE could be a little closer to the midrange/bass driver next to it, the distance between the two is not too bad. The crossover point is 1600Hz, the wavelength of which is 21.45 centimeters. Most loudspeakers are worse than that in terms of the two drivers creating comb filtering issues.

The distance between the ribbon tweeter and p-m driver in the Eminent Technology LFT-8b/c is even greater, AND the crossover point is at the very high frequency of 10kHz, the wavelength of which is only 3.4 centimeters! I’m seriously considering having a new filter built with a more sensible crossover frequency, in the neighborhood of 1500-2000, assuming the tweeter will play that low without distortion. I would love to hear why on Earth Bruce Thigpen chose such a high x/o frequency in the LFT-8.

On the other hand, the p-m driver in the LFT-8b reproduces 180Hz up to 10kHz, with no crossover in that range. And it has a relatively high modulus of impedance of around 8 ohms, the panel itself 11 ohms (the woofer and panel each have their own pair of binding posts, making bi-amping simple enough). Far better than Maggies for use with tube amps.

@rauliruegas: In the video below Danny Richie examines the Klipsch Forte 1, and in that examination the reason most horn loudspeakers are extremely colored (imo) becomes obvious. Low coloration is a high priority for me.

https://youtu.be/QlVG0Qx5Ds8?si=PamEu5u61kkTlXSl

The real wisdom is “ everything has tradeoffs “…. but knowledge and acknowledgment  of that is rarely demonstrated by those preaching a singular one true path answer….. 

imo the 63, of which i’ve sold ( new ) and rebuilt 4 ( several times over… the troubleshooting flow diagram is necessary but not, NOT sufficient, certainly has virtues but is hardly full range for various musical tastes….

Dear @mijostyn  : I really like ELS and especially Sounlabs and Eminet Technologies even that the faster transients where MUSIC comes developed is through horns, yes as everything has trde-offs at both frequency extremes but in its specific frequency range ( depend of manufaturers and models. ) ESL just can't beats it and yes : as always seated at near field position..

Why I don't own horns yet? because its agresivity that many times surpass the liove MUSIC natural agresivity.

Acapella top of the line is a ery good blend of different speaker drivers and really good and expensive ones.

R.

@bdp24 

A couple of obvious issues apart from those @mijostyn has pointed out.

1.  They have two drivers offset spatially by a considerable horizontal distance, which will give rise to comb interference with frequencies in the crossover region

2.  They have a crossover!

The result according to the video is that they are very hard to position.  Coincident source speakers tend to be very tolerant of room positions, and have much larger listening sweet areas ...

@dogberry 

"Not really a problem if you obey the instruction manual that says to use (an) amp(s) of 40-100W power and no more. As you may recall, I have replaced all the panels in my 2905s, and while the older panels were short on glue, it was the case that one would fail and start to arc after playing too loudly."

I still have four out of twelve panels in their original condition.  The rest have been reglued (really much more than that as it involves new mylar and new slightly conductive coating, plus proper tensioning).  Panel failures have been revealed by a slight murmuring noise, or popping as a spark flies!  I have also had a high voltage failure in one speaker - the high voltage is on the same circuit board as audio.  In the end, I made up a piggyback board to produce 5.25-kV.

Initially I used a Quad 405-2 100-Watt amp, basically designed for the speaker.  Later I switched to a lower power amp, the Krell KSA-80.  Well, lower power when measured into 8-Ohms, at just 80-Watts RMS.  The Krell is about 9 times larger, but only 4 times heavier, than the Quad, which made 100,000 405-2 amplifiers, on top of 64,000 405 ones.

In my experience, transients tend to be faster on SACD, BluRay audio and 4K disks, for example West Side Story, Spielberg fashion. Any instantaneous input voltage over 56-V triggers the protection, regardless of amplifier power.  The Krell has an impressive slew rate!

What speaker is being augmented by the piezoelectric tweeter?

It looks like my Prompts over the past year+ to a friend, encouraging them to revisit experiencing their owned Audax HD-3P Gold Dome Piezo Tweeter, has paid off, as when I went to the friends today to Drop off my Technics SP10 MK II Kaneta Design TT as a Long Term Loan. I was informed in advance there was a little surprise experience for myself to encounter.

It wasn't the Multi Tonearm Mountable P'holz Plinth for the SP10 MK II, which I am eagerly awaiting to experience, which will have enabled the experience using all the TA's that have been lined up to compare to each other, to be pencilled in as a date to occur.

What was in use as the surprise, is the individuals Speaker Design using the Audax HD-3P Gold Dome Piezo Tweeter.

After about an Hour of Listening to a selection of known to me tracks and a few new encounter tracks, I can say the HD-P3 is as impressive in this system as it has proven to be in my own.

For a reason I care not to try and understand, I'm just very happy to be present.  The Speaker using this Tweeter has the ability to immerse a listener into the music, the sound being produced has the capability to captivate ones full attention for the music being produced.   

I remain content with my assessment this Tweeter might be one the Best Produced Tweeters and it is a shame the design issue it developed was not sorted and it was kept in production.

The owner of the Speakers listened to today has made it known modern Parts used on the electronics will enable a much more expansive Soundstage, and the Xover is to be modified to a up to date design, using PC Triple C Wire within the Cabinet. It is hard to believe more is suspected to be able to be extracted in relation to the sound already being so impressive.    

I have learnt today the intent of the friend as a result of their impression oof the HD-3P, is to produce a OB with a Driver Array that will fully compliment the HD-3P, it has also been voiced that as there is a collection of the HD-3P Tweeters, a Dipole Array could be used for these.

The friend has also made it known that they are now seeing the time to take on the Kaneta Design SP10 MK II, with a much more dedicated commitment.

Hopefully something might happen with the TA Comparisons across the Xmas Hol's, where a Kaneta Design TT is the TT design selected for the comparisons?     

Re Mijostyn’s observation on driving the Sound Labs speakers that he and I own: The JC1+ may "work" fine but doesn’t sound nearly as good as my much modified MA240s. I once owned a pair that I purchased only because my Atmasphere amps were going to be out of commission for a few months. I sold the Parasound amps immediately after doing a comparison on the SL speakers.

How did you measure speaker frequency response? Like you inferred, anything above 12kHz is for a dog so far as I am concerned. Many years ago, our youngest son came down from doing his homework one evening to complain about a high frequency whistle he perceived to be coming from my M1s (speakers that preceded the 845PX). I had no idea what he was talking about; nor did my wife hear it. But I did find and fix the problem. (It was coming from the CDP.) Plus, he now lives in Tokyo. If he can hear it from there, we got a problem. Anyway, that incident also did prove there was some response from the speaker at very high audio frequencies well beyond my hearing, with my OTLs driving the M1s.

Modern recordings seem to have more high-level transients, which trip the Quad protection circuits!

Not really a problem if you obey the instruction manual that says to use (an) amp(s) of 40-100W power and no more. As you may recall, I have replaced all the panels in my 2905s, and while the older panels were short on glue, it was the case that one would fail and start to arc after playing too loudly. I'm cautious with the volume control, and I expect my remaining half ear is grateful to be spared the acoustic barotrauma!

I'm glad we never had to experience Soviet-Russian cars.

lucky you, in so many ways. Those were my dream cars until my late 20s

@lewm Actually, I think they are $45 K now. I can say definitively that bi amping the transformers does not work. It is impossible to keep the amps from interfering with each other. I tried every permutation.

Our OTLs do a fine job of driving these speakers particularly in the midbass and midrange. They are not so hot in the treble. Because of the high output impedance the treble starts rolling off at best at 12 kHz. I know because I have measured it. On the bright side most older guys can't hear up there anyway. Solid state amps are more prone to having difficulty in the very low bass due to the high impedance of the speakers down there, but they go easily up to 20 kHz. The solution to this problem is to use a VERY big solid state amp. The JC 1+ does a fine job of driving these speakers as long as you keep the impedance of the interface up above 2 ohms. The Bricasti M28s also do a fine job. It is entirely possible that I might be selling my MA 2s. I have not made up my mind yet. 

@bdp24 Interesting speaker with a few obvious problems. The tweeter is too wide which will cut down on it's horizontal dispersion at very high frequencies, the space in the middle is also a problem and the tweeter is not long enough, it will beam vertically. The Magnepan tweeter is a much better design. Like you I would like to hear them. 

@richardbrand you need to learn more about speaker design. The foot comes from the wavelength at the crossover point. If two drivers are closer together than 1/2 the wavelength at the crossover frequency they function acoustically as one driver. Woofers can be farther apart than midrange drivers and midrange drivers can be farther apart than tweeters. Tweeters have to be very close together which is the major problem for speakers trying to make line sources with stacked drivers. What you are succumbing to is lay assumption and as we all know assumptions are the mother of all f-ups.   Quad was trying to improve dispersion. Stick with your KEFs