I have used the Dayton RS52s, they are very detailed and handle lots of power but I do LPad them down by about 4dB, which helps at 85dB+ volumes. The cone break-up occurs about 10-11 kHz so crossing them to a tweeter lower down (say 3,000 Hz) is advisable IMO. Right now I have used a standard Dayton second order which crosses at 4,500 Hz, too high I think.
Are you refering to me? Weird. I used to own ProAc Studio3s and loved them. They are very similar to ATC SCM50s - the passive ones. I loved them, and regretted letting them go when I had graduated and moved to London, renting. They were too big and heavy. I should have asked my parents to store them, instead of selling them at cost (I bought them second hand) to a friend from Uni. His son still has them. No sign of him letting them go, despite my yearly hints. Those speakers are 40 years old and I suspect that ATC would still renovate the drivers.
For a long time I wanted to replace them and that got me interested in DIY and kits - at the time Wilmslow sold the drivers AND the ATC power amps.
But that was decades ago and now we have different tools and capabilities, not least easy access to DSP and powerful and inexpensive amps. Those drivers became insanely expensive and hard to source and for some years now ATC don't sell them any more through distributors. What's more - on paper they don't look so great except maybe in robustness, servicing, and power handling - which as a home user rather than pro is not really an issue.
So rather than replicate what I'd had, I became more open minded about midrange, though for a long time it seemed that the game was the 12M Scan and the 135M Seas. I think things are better now - we have (as well) the small Purifi and Kartesian drivers, for a start, and some rather inexpensive SBAcoustics drivers that look good on paper - I actually have some to play with, they are so cheap.
I wish there was an affordable dome that would go 350 to 3.5k without insane EQ - I don't need to go very very loud. The open back Bliesmas look like they will but they are expensive next to anything except the Scan ellipticals (which don't seem that great on paper).
There is an issue to discuss I think about the bandwidth we expect to be handled by 'midrange' and why. I don't see anyone saying that a small point source full range driver with no phase changes etc etc wouldn't be ideal and there are well regarded speakers that use small efficient full range drivers. I can see that we may be quite sensitive to phase changes within the human evolved audio band which seems most sensitive relating to sounds from hunting/not being hunted and also baby cries. So that does lead me to buy into the idea tha a 3-way speaker can be superior if the midrange handles all of that with somewhat coherent phase. That requires a wide bandwidth driver, and some of the midrange domes we have on offer now are just too small (unless they have a great deal of xmax - which they don't). I don't feel this is an unreasonable position to evaluate. The unobtanium ATCs seem to have gone signififcantly lower than many.
You appear to be calling 'troll' simply because I might question whether the best midranges we can buy now (all of which have compromises) might not necessarily be domes -and yes I know this was a dome thread but I think 'why?' is a legitimate question. I'm not trying to hijack it really and I've tried to see whether I can get the domes in the recent Yamahas or Revivals, at least to understand how much it would cost to do some measurements. I didn't try wiith Wharfedale, to be fair. It certainly was the case that, even 20 years ago, I thought 'go dome or go home'. More recently, I'm not so sure. If domes have become niche, and consequently expensive, and Mr Putzys has made a nice midrange and its cheaper, then I'm changing my tune, extra effort to have a midrange enclosure notwithstanding.
In practice it seems that the domes we can buy at reasonable prices have limitations and compromises unless you plan to use the humped response as 'filler driver' rather than covering a 8x or 10x frequency range as one might want in a conventional quality midrange. I don't really see the point of a filler driver system compared to a small 2-way with a 19mm or ribbon tweeter with decent subwoofer support. I'm not wedded to using low power amps so inefficiency doesn't really bother me - I'm not going to hit thermal limits and excursion limits are what they are however efficient your driver is.
If I was doing
Now, we have no amp power limitations for class D and if you like measurements the best class D wipe the floor with everything and are not expensive. So efficiency is yesterday's problem. As is the timing delay between mid and tweeter if you use DSP. I can't imagine trying to make a complex 3 way analogue crossover and I might try for fun when I've retired but its so easy with DSP that I CBA at present. Maybe line level where changing components isn't ruinously expensive but not passive, and efficiency in a passive 3 way seems a bit elusive if you want deep bass anyway.
I'm sorry if dome affcionados take umbrage that I should even question whether they are the best option. This seemed at least somewhere that doesn't regard a 5.25" driver as a midrange, or a pro-audio 8" driver as a midrange. Actually - no I'm not: I've been there, done that, and recently wondered if its the most effective choice, if you don't like that, well......
Look at a Dynavox LW5004... it is essentially a 3" dome with a surround (makes it a midwoofer) that can go down to 100 Hz and up to 4,000 Hz or so before break-up. Best to cross at 2,000 - 2,500. It allows all of the vocal range to be reproduced by one driver, advantage vs. crossing typical mids at 300 - 500 to a woofer. A key question is how high into the midrange do you want your woofer to go?
I gave a brief summary in post #502 of how the 75mm came to establish itself as the accepted "standard" in professional audio engineering. In short, it provided a horn-free, high power, highly reliable driver that covered the most of the midband from 350Hz to 3.5kHz without "insane EQ", and at the time it was needed. (FYI I believe ATC actually operate their drivers from 380Hz to 3.8kHz?).
It was long-known that the limited low frequency output of the 75mm dome was a compromise - just it was the best compromise available. I referenced elsewhere the 100mm ATC dome that was capable of operating from 250Hz-2.5kHz, but this only produced a greater power demand on the tweeter that was/is already the limiting factor with a 3" dome-based loudspeaker.
Alternatives are available, but each with different compromises...
A cone, for example has an edge that requires terminating.
And if we adopt a larger cone size too, then we have either increased beam forming at high frequencies, or a requirement for the cone to "decouple" and have its effective diaphragm size effectively reduced as frequency increases: Hard diaphragms are not best suited to this task.
And if we have a 75mm cone, we will have a smaller voice coil diameter, and a reduced power handling capacity. The 75mm dome was intended for professional monitoring applications that tend to operate at higher SPLs than in a domestic setting and often for longer periods of time. A smaller voice coil diameter would undoubtedly compromise reliability and performance.
Multiple driver arrays are expensive, although the 75mm dome is otherwise exceptionally well-suited to such configurations.
Some other factors to keep in mind too...
The dome requires no enclosure (although the ATC's feature a "breathing" hole that controls the suspension compliance).
The major advance in ATC's dome was the introduction of a non-conducting motor system that gave a significant reduction in current dependent non-linearities (just you cannot buy them since this upgrade). The audible compromises due to its size/geometry are/were less important.
Actually the Volt 75mm dome used latterly by PMC sacrificed the underhung coil in order to provide greater displacement, and therefore a lower frequency cut-off. Another trade-off, but one that might warrant your investigation?
A well-controlled dome does that well already. Properly engineered low frequency crossovers can substantially ameliorate any problems where bandwidth is limited.
Efficiency was not a significant problem in the 1980s when the 75mm dome was developed. The barrier with power remains the capacity of the 25 or 34mm tweeters that are used in conjunction with the 75mm domes.
I certainly don't! I advocate questioning everything. Just I hope to have conveyed that three-way systems based around a 75mm dome represent an engineering compromise, where the design has been optimised over many years within the constraints of physics to minimise the audible defects.
Will technological advances improve matters? Material advances, such as employed in non-conducting motor systems have brought significant performance gains. New dome materials too, although history shows well this is not always the case. But the basic geometry remains.
Are there better solutions? Maybe in lower power systems we might find a different paradigm - a small two-way bookshelf design, for example, or a large panel electrostatic design for another. But each comes with different compromises - compromises that often limit the usefulness of such loudspeakers in professional audio environments, and likely the performance in domestic settings too.
The 75mm dome (and loudspeakers based around it) is perhaps most remarkable for its longevity in its intended environment. It was/is a significant product in audio engineering and will IMHO likely remain so for a while yet. But that is certainly no reason to accept the paradigm...
The Volt has a higher resonance frequency as the ATC. And lower sensitivity - no wonder with that coil.
I believe it also lacks the ATC's double suspension too? If true, that might well cause problems with the higher displacement. But it might also require a larger gap size and so further lower its sensitivity. Hopefully someone here can correct me if I am wrong?
No, both versions of the Volt 3" dome (VM752 and VM753) have double suspension, according to their datasheets. The 2" version, VM527, has single suspension, however.
Thank you for your clarification. I duly retract most of my prior statement therefore, although the manufacturing tolerances and gap sizes remain unknown to me.
In my directivity study, it's clear the 3" dome has some advantages:
https://www.htguide.com/forum/forum...l-small-and-large-baffles?p=951255#post951255
https://www.htguide.com/forum/forum...l-small-and-large-baffles?p=951255#post951255
This huge chancellation at 2,4kHz ... sorry but I would not accept that in one of my designs. I had a chancellation at 7kHz with a faceplate design and worked on it to make it less so it doesn't influence filter slope and phase ... I cross over at about 2kHz.
Directivity at 200Hz looks also too much ... sure the distance to the mic didn't change at his measurements? Influence of the wide baffle should be less at 200Hz?
But nice work on checking these cabinet forms!
It's curious to me where it comes from though, as it wasn't present in Vance's review on Audioxpress.
As you can see from my modelling, if one can accept a mild loss in sensitivity, there's a workable solution around it.
With the OSMC having only a single woofer, I think it's acceptable trade-off.
I can see now why a 3" dome may be favored in some settings- it certainly does something that a 5" cone cannot- which is the consistently wide directivity in the passband.
At some stage I will see what a 4" high sensitivity cone with full copper sleeve does in term of distortion and directivity. (Faital 4FE42)
As you can see from my modelling, if one can accept a mild loss in sensitivity, there's a workable solution around it.
With the OSMC having only a single woofer, I think it's acceptable trade-off.
I can see now why a 3" dome may be favored in some settings- it certainly does something that a 5" cone cannot- which is the consistently wide directivity in the passband.
At some stage I will see what a 4" high sensitivity cone with full copper sleeve does in term of distortion and directivity. (Faital 4FE42)
Post 66 and 67, containing comparative measurements of 4" cone and 3" domes by Dcibel tell us otherwise
You chopped off the other half of my quote! To quote myself: "we have either increased beam forming at high frequencies, or a requirement for the cone to "decouple" and have its effective diaphragm size effectively reduced as frequency increases". As I also tried to reflect, the 75mm resulted from more than one consideration too. It was the best compromise at the time for its intended use.
The 75 mm dome is i.m.o. not so much a deliberate compromise. but rather the result of extreme lucky trial and error at Kurt Muller. As is mentioned the ATC and its KM made 75 mm dome is basically an upscaled version of the SEL/ITT 50 mm dome. But I admit, this is nit picking, so I will stop here.
I think the version depends on the time period of manufacture, most recently I believe is Taiwan. I have bought these through Newark Audio, better price than P-E.