Midrange dome drivers banned ?

[mhardy6647]

The venerable Peerless KO10DT tweeter used a silk dome.

 

[Audionaut]

With the BMS et al, there is one voice coil, and a special shape diaphragm. This drives 2 different horn flares at the same time. I understand why they call it coaxial, but to me it is less so than your average coincident driver.

You have not understood how the BMS coaxial drivers work.
There are two diaphragms and also two different connections for the mid-range driver and for the high-frequency driver, which of course are also assigned different crossover frequencies via the crossover.

Here, for example, for the BMS 4590, which I have already installed several times.

HF
https://en.toutlehautparleur.com/br...aphragm-for-hf-section-of-bms-4590-8-ohm.html

MF

https://en.toutlehautparleur.com/repair-diaphragm-for-mid-section-of-bms-4590-and-4591-16-ohm-including-phase-plug.html

If you want to know how the BMS drivers work, take a look at the patents.

The Celestion AXI 2050 actually only has one diaphragm and one voice coil

 

[Penelinfi]

So I did some research and the only 3" dome I could find that is underhung is the ATC SM75-150, and guess what? Not only is it pretty high sensitivity, it's also the only one that can acceptably be crossed below about 500hz (ATC crosses them at 380hz). It's also completely unavailable outside of their speakers. K&H did use it on the O500, but that is long since discontinued - though I hear it's an absolutely badass speaker.

I guess your post came before these were released :

BlieSMa M74A-6, M74B-6, M74P-6 and M74S-6 | HiFiCompass

What is on the test bench? In the end of 2021, the German company BlieSMa pleased the loudspeaker designers community with the release of a line of four 3" dome midranges at once, the development of which had been rumored for a long time.

hificompass.com

Modern, underhung, single winding, copper sleeve etc and you get to choose from paper, silk, aluminium, beryllium

 

[dfuller]

I guess your post came before these were released :

BlieSMa M74A-6, M74B-6, M74P-6 and M74S-6 | HiFiCompass

What is on the test bench? In the end of 2021, the German company BlieSMa pleased the loudspeaker designers community with the release of a line of four 3" dome midranges at once, the development of which had been rumored for a long time.

hificompass.com

Modern, underhung, single winding, copper sleeve etc and you get to choose from paper, silk, aluminium, beryllium

Considering it was 4 years ago, yes!

Also - these probably can, with enough waveguide loading (think KH420, for example), be crossed with the acoustic slope starting below 500hz. That's pretty neat.

 

[JRT256]

Even if properly designed, a metal cone/dome will behave like a piston only up to its first structural resonance frequency. There isn't much inherent material damping in metals, so any resonances are going to have a very high Q. This is clearly apparent in the audio passband when bass-midrange drivers make use of metal cones (and usually a bit above 20 kHz for tweeters). Even though the crossover may heavily attenuate those resonances, is it wise to have them present in the first place as a result of a poor choice of material, when better approaches are available?

What is meant by the characteristic sound of the cone material when it is breaking up? Doesn't a cone material simply possess properties of density, stiffness and loss factor (damping)? Aren't those the fundamental material characteristics that are needed to be identified when engineering a new cone design? How do any of these engineering properties translate to a "characteristic sound" if the frequency response of the driver is ostensibly flat? Isn't the audio performance simply a result of the structural resonances, damping and piston-range behaviour of the cone, and not the "material" per se?

The following might provide some guidance. In terms of audibility of different materials, back in 2010, Rotter and Lindau published a paper titled "Audibility of tweeter performance beyond spectrum and phase" (PDF). They concluded that (emphasis added):

"When eliminating frequency and phase response irregularities, baffle and room interaction, non-linear behavior, and distance effects, a blind-comparison listening test could not reveal audible differences between different types of tweeters. Neither the material nor the actuator principle, neither the tweeters geometry nor the specific form of wave fronts in the far field could be shown to be distinctive features of different tweeter types. Divergent results of previous studies can only be explained by aforementioned shortcomings of the test designs. Furthermore, when excluding room and baffle interaction, FIR equalization seems to be capable to compensate for the behavior of different loudspeakers at the sweet spot within a typical range of horizontal head movements."

Then perhaps it makes a difference with a mid-range dome. ADS L speakers sound different and it has been presumed to be that strange 50mm dome mid-range with the huge magnet.

 

[Arindal]

I'm not sure how that plays in to its use in soft domes.

It does play an important role for sure, as soft domes are usually excited solely in a circular area where the voice coil former is attached, leaving a significant fraction of the diaphragm, particularly the dome center, dependent on the parameters of the material.

 

[thewas]

I have the German version as Braun L710 in my vintage collection as well as the smaller Braun SM 1002 which both with some EQ still sound good today and have the timeless Bauhaus design from Dieter Rams which was later copied also from Apple:

View attachment 76429 View attachment 76430 View attachment 76431

After many months of search I finally got the larger and in Germany rather rare (especially in wood veneer instead of white coloured) Braun L810 for a very good price which are very popular in the USA (they are called ADS 810 there):

They seem to measure as neutral as the L710 but have deeper bass response, their bass and mid distortion is impressively low, even more considering their age

and give also a very smooth response at my listening position, so I needed only one PEQ per channel for the bass region and nothing above which is very rare for my weird room, left and right loudspeaker vs. a -1dB/oct line:

Nice to see also the data (including a representation of directivity) given by the manufacturer back then:

Must say I really love their sound which reminds me how great Hifi existed already more than 50 years ago, as those models were released in 1969!

 

[MAB]

After many months of search I finally got the larger and in Germany rather rare (especially in wood veneer instead of white coloured) Braun L810 for a very good price which are very popular in the USA (they are called ADS 810 there):

View attachment 461173

They seem to measure as neutral as the L710 but have deeper bass response, their bass and mid distortion is impressively low, even more considering their age

View attachment 461174

and give also a very smooth response at my listening position, so I needed only one PEQ per channel for the bass region and nothing above which is very rare for my weird room, left and right loudspeaker vs. a -1dB/oct line:

View attachment 461175
View attachment 461176

Nice to see also the data (including a representation of directivity) given by the manufacturer back then:

View attachment 461177
Must say I really love their sound which reminds me how great Hifi existed already more than 50 years ago, as those models were released in 1969!

Absolutely gorgeous. I have a good friend with a pair of ADS 910 (picture below is not his pair).

Thanks for the post and the measurements. I personally love the style. Does the Grundig versions use a perforated metal grille? Many of the A/D/S models available in the USA used press fit grille in a groove, like these:

 

[thewas]

You are welcome and yes, perforated metal grille with MDF frame behind:

Source of the photo: https://braunaudio.de/