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

@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

@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.

@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!

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

@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.