@timlub -- What it comes down to is... really good mids with any type of top end extension without cone break up is hard to find in true high sensitivity speakers.
Perceived really good mids and upper range extension (i.e.: "any type of top end extension" leaves room for quite a lot) is readily available with true high sensitivity speakers - without necessarily requiring exotic cone materials. Being so I gather cone break-up, in whatever shape it may present itself (or not), isn't an issue. @unsound -- One will be hard pressed to find high sensitivity speakers that can produce respectable step response or square wave response.
Question is whether it holds significant correlation in regards to perceived sound quality, not least depending on who you're asking. There's hardly consensus here, but transient behavior in (time aligned) all-horn set-ups, representing the best efficiency, are hardly the ones to fault the most in this regard. Even so, relevance/correlation is required. There's a lot more to speakers than sensitivity alone.
Sure, but I'll definitely side with poster @alexberger's above posts on the significance of high sensitivity (and headroom) as an aspect highly overlooked by the audiophile community at large, and that it's an essential ingredient in achieving a live sound imprinting. Those who've heard a well-implemented all-horn system covering most of the audible range will know this kind of sonic ignition, scale, presence and ease simply doesn't exist in low to moderately sensitive speakers; they just sound restrained and malnourished by comparison, not that they can't be highly capable in other areas. Yes, high efficiency and full-range requires BIG size, but you want to eat your cake too that's the pill to swallow. Personally I find it's definitely worth it. |
@timlub -- So you say "Percieved" and that these mid and bass drivers with good extension and little cone break up are readily available.... recently I’ve shopped a few hundred drivers looking for such. Please list the model numbers.
Perhaps we’re addressing this matter differently by now. Initially you wrote "really good mids with any type of top end extension without cone break up is hard to find in true high sensitivity speakers," so I set out to express my impressions from a complete speaker system - not focus on a single driver. Cone break-ups can be more or less challenging depending on your design goal and overall requirements, and nothing yet has been specified into the nature of a given design to illuminate your context. Where "true high sensitivity" goes horns seem to be dictated, and with midrange compression drivers I’d wager their upper range (clean) extension isn’t a bigger issue, if as much as their lower end limitation in a given horn. Knowing what one is dealing with here would dictate what to work around rather than against, and with horns in particular it’s not exceeding the bandwidth of each horn element to main good power response etc., so a full-range all-horn system would typically require a 4 or 5-way approach. With true high sensitivity speakers an excellent midrange can be had via a range of designs, so why would cone break-ups be a particular issue here if the design accommodates inherent challenges? You’re addressing and calls for the existence of specific midrange (and now bass) drivers with good extension, so what’s your context, specific use and related issue? |
@timlub --
Somehow I got around to base my first post only on the quoted passage by you, and not the whole post (I quoted the passage early the day before yesterday to reply, but didn’t get around to actually write it until later on, and so blissfully forgot about the rest of it).
Now taking that into account I better understand where you’re coming from, though I fail to comprehend how you apply a "true high efficiency" design with direct radiators. It appears however that this is what you believe to be the best outset to work from as opposed to horn-loading, and so presents the specific challenges laid out by you - i.e.: if a sealed bass principle is preferred (less efficient compared to a ported alignment, not to mention horn-loading) and you seek to minimize cross-over points as well, then the challenges you find yourself placed in the midst of are certainly present and understandable in the context of aiming at high efficiency.
For what it’s worth: a friend of mine has build a pair of wood replicas of the Western Electric 12a’s (fitted with a Lamar driver), and they in themselves cover from ~100Hz to a few kilohertz (sorry, can’t remember the upper frequency cut-off). Add in a horn tweeter hung down in the midst of the 12a horn and a pair of horn subs beneath them, and you have yourself a very(!) high efficiency all-horn set-up, 3-way at that, with a range potentially from 25Hz on up. Apparently several who’ve heard this setup (though with twin 15" AE units in open baffles per side for the lower range) regard it as the best they’ve ever heard, not doubt in large part due the specific frequency range of the big 12a horn driven from a relatively small and very lightweight diaphragm.
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Hey, @timlub -- Not sure what we’re doing here, but I’ll bite. I assume that you are simply saying that it can be achieved with horns.
A combined effort perhaps of incorporating a horn/waveguide and letting an extra cross-over point come into play (downwards), hereby letting the two "main" driver elements better meet (like better power response at the cross-over point) as well as to achieve higher sensitivity and better control of directivity. Hybrid designs of both a direct radiator and an acoustic impedance transformer have their own set of challenges, but carefully implemented it appears good results can be had. The Lamar driver is very good for sure. Its top end extension lacks, but its nice sounding, fairly linear (plus or minus 5db from 200 to 2500) and can cross as low as 80 hz. Yes, add a tweeter and you’re good to go. So, thank you for posting 1 horn driver that is capable The 12a horn is huge and you are correct, this has not been the target in my designs.Something a little more compact.
The 12a’s are behemoths for sure, and won’t cater to WAF/spouse factor or interior decoration aspirations, unless one for some reason fancies big horns. Have yet to listen to the Lamar-fitted 12a’s in question, but on my next trip to Brighton will. I’ve been looking for a couple of parts... a 12 to 15 inch that is closer to plus or minus 2 from 40 to 1500. I’ve contacted 3 manufacturers, I’m told that it can be built for me, but as of now is not out there. The AudioTechnology Flex 15 is close but its only 93db. and its only getting 93db because of its very low QTS of .22. Another factor is trying to get a woofer. I’d really like to have more like 97db and I need some xmax. Most every driver that comes close to what I’m try to achieve has a very low xmax. Again, I’m told that I can have it manufactured, we’ll see.
Coming back to my first paragraph I’m wondering why you’re adamant in regards to 40Hz extension from a 12 or 15 inch that extends up high as well, while maintaining a sensitivity goal around 97dB’s - is it to avoid the use of subs and keep simplicity? 1.5kHz extension for this size of driver is a stretch as well (beaming, break-up). My first thought would be to give up extension down low to achieve the desired sensitivity (and then augment with subs), and next I’d think in the direction of a fitting waveguide perhaps (OSWG?) with a compression driver, for a variety of reasons really, but also to lower the cross-over point more comfortably to about 1kHz. I’m sure you’ve heard of Earl Geddes’ Summa and Abbey speakers (now apparently NS15 and NA12 respectively) - just to give an idea of a 2-way design, in the need of subs augmentation, and a sensitivity in the higher 90’s. Actually the first Summa iteration of Geddes used the B&C 15TBX100 - crossed at approx. 900Hz, if I’m not incorrect - the same driver I’m using in my pair of tapped horn subs. EDIT: giving up extension down low from a suitable, say, 15 inch would not only raise sensitivity, but high-passing it at about 80-100Hz (for subs to take over) would make it even more agile/clean sounding up to its cut-off point. |
@gdnrbob
Seeing Almarg's post at the front of this thread brings back fond memories. I hope heaven has a great sound system for him to listen to.
Bob
I wasn't aware of poster @almarg having passed. Sorry to learn of this. |
@atmasphere --
Al was a really nice guy. I miss having him here.
Indeed - a very knowledgeable guy, well-spoken and always with a balanced and to-the-point approach. .. A 'high sensitivity speaker' is really going to be more like 96dB at the lowest; there's something called 'medium sensitivity' which is about 90 to 96dB.
Was going to bring this up as well. I guess it's illuminative into the inertia of hi-fi speakers being by and large rather inefficient, and that anything that hits higher at 90dB's or slightly above this number is then deemed "high efficiency." It certainly is not. @lonemountain --
The thermal compression you speak of is purely a function of the driver's ability to dissipate heat, not the amplifier, as all voice coils get hot when "powered up" by any size amplifier. Its the inability to cool the driver that causes thermal compression and reduces driver performance.
Definitely, and therefore it also goes to show that compensating for low efficiency by simply adding more wattage will, all things being equal, more easily meet the drivers saturation point in regards to thermal compression. Thermal compression happens to high and low sensitivity speakers at all price points.
But at different SPL's, that's the whole point. Listeners will wonder why their speakers "sound different" when played loud for periods of time, this is a voice coil heating up and reducing its dynamic range. Since its impossible to see this in action, its within the driver itself, we cannot assess this externally or by any spec.
Speakers like ATC, certainly the bigger models, use large diameter (though sometimes rather short) voice coils that will more effectively dissipate heat. Large voice coils (+3") generally are not not implemented in low(er) efficiency hi-fi speakers, and so thermally are more challenged. Moreover many ATC speakers - when best, to my ears - are actively configured, and this makes them impervious to the influence and effect of a passive cross-over at higher SPL's, while also having the amplifiers work seeing into an easier load - all of which contributes to a sound that is less "stressed" at higher levels. |
Thanks for linked article, @alexberger. In real-world scenarios with mostly passively configured, inefficient speakers - certainly approaching to some extent live acoustic (or amplified) levels - Thermal Distortion is an inescapable factor. @lonemountain -- Focusing on efficiency as a measure of speaker technology or quality is like judging a passenger car based on miles per gallon.
That’s only assuming high efficiency has main priority regardless of other aspects and ultimately sonic outcome - a convenient position trying to make your own point, but hardly the bigger picture. Low efficiency is a hindrance; never a trait, and as such has that to fight as well in addition to all other areas in speaker design. They’re the product initially of a desire and need for smaller size to cater to a commercial market, NOT because they were deemed better sounding (but of course marketing efforts made their best to sell the acoustic suspension principle as such). High efficiency and large size as a foundation is giving acoustics their more proper due, but also moves the design, at least partially, into the realm of acoustic transformation. The most predominant enemy of horns it seems, except when they’re bad designs and too small, is passive cross-overs and too shallow slopes. Horns generally don’t like working outside of their "comfort zone" or design specifics here, something active configuration can more readily accommodate with steeper cut-offs compared to (the side effects of) complex passive filters. So, a high efficiency design properly (and actively) configured is a win-win scenario from my chair, the only real drawback being - to whom it may concern - large size. |
@lonemountain --
This efficiency issue is one "spec" out of many that a designer must balance. All these performance parameters are evidence of the enormous number of trade offs in creating a complete driver/box/electronics design. So designers make their own choice ("I want a horn, that’s what I like") and balance everything to favor their choice ( it will have limited dispersion, HF narrowing, but that’s okay I’ll try and minimize it, etc). This is the way speaker design is, balancing hundreds of issues that represent hundreds of choices and all of them have resulting tradeoffs. You may want a low distortion driver but its too expensive, or the OEM manufacturer can’t build it till next year and you’ll be out of business by then. Or, the horn you want to use wont fit the box you already bought or built, or you don’t care about efficiency as amps are cheap so you want the widest bandwidth possible, ..on and on.
Here's a different perspective: don't mind the reasoning behind and outcome from a manufacturer who's business model is sought kept afloat, but simply choose with an open mind - without blindly converging with consensus - what you as a user/buyer prefer. I'm aware manufacturers usually cater to the majority of buyers, hence why smaller and inefficient speakers became popular in the first place, but small(er) size and inefficiency is something that dictates a whole darn lot design-wise, just like the ripples created from a high efficiency design has implications that go far beyond efficiency alone. It's two quite different segments of speakers in many regards, as you know, and it's why efficiency isn't just efficiency - or "one spec," as you so put it. And the thing about not caring about efficiency isn't something that can be freely compensated for by simply adding power; wattage is wattage, and "innovation" in heat dissipation is only so prevalent that it's a major issue still, and likely always will be.
There is a practical science at play here, with product development controlled by economics, engineering principles, sales, marketing and a whole bunch of other factors we’ll never know about at the factory that drive those choices. In the end, the company "sells what they have" as ALL speakers are a sum of trade offs. Many of the issues debated are really arguments over someone’s clever marketing points and we as consumers take these marketing issues as gospel, as facts. Since everything is choices, it may be these performance features are important only in THIS type of design. To another design, they don’t matter. Like wide dispersion is not desirable when you are trying to throw sound over a long distance (think football stadium). But to home audio, and wide dispersion means I get to sit on both ends of the couch and hear it properly, that matters a whole lot to me.
Just to narrow this down to dispersion, I mainly think of (and hear) the dispersion characteristics of many horns as something that limits the influence of the acoustics at play, and not (necessarily) a head-in-a-vice outcome or what's otherwise sonically unwanted in a home environment. My actively configured main EV speakers are intended to fill up to large cinema auditoriums with loud movie sound, but they work wonders in a moderately sized living room, at any SPL, and that at a listening distance of 11-12 feet. I WAS afraid their large midrange/HF horn wouldn't gel with the twin 15" woofers below it, but as a 2-way design (in addition to subs) that's not a problem. Go figure. I'm not trying to convince anyone that this is the only viable way to enjoy music (and movies) in your home, but that contrary to what many believe here it's actually an extremely capable option, not least actively configured, and one not overly expensive at that. Dynamics, ease, scale, resolution, presence, coherency - audiophile speakers struggle here by comparison.
The company I work with makes perhaps the best cone and dome drivers on the planet but their speaker cabinets are plain rectangular boxes. Some say the box is everything but in this design 2 of the 3 drivers have their own chamber and the box is not involved in the driver at all. The baffle is more or less "a holder" for position and improves output as there is acoustic gain by sealing drivers to a surface. Some say the box looks old fashioned- so to balance that we use some exotic woods and make them look like beautiful furniture. The best you can do is find a way to make some happy and others will just not see it/hear it the way you do.
What I love about ATC speakers (my assumption of what you're referring to above) is their consistent, some may even say conservative approach to making speakers, them being made for the pro market - which is not excluding the domestic ditto, and the lack of marketing BS. Rock solid drive units that stand the test of time; honest, coherent and rather authentic/natural sound, and active configuration (as a main trait of theirs). I couldn't care less about the look of the cabinets; they do what they're supposed to do - no more, no less. ... There IS more than one way to do it and many good sounding speakers out there. Each has its own application set that it excels at and other applications that it doesn’t do well with. We have not arrived at a universal solution.
Agreed, but speaking of diversity high efficiency is very often disregarded by audiophiles and the associated industry. The latter, figures. The former I'd say mostly buys into the sentiment of the latter, simply because it's gotten the norm, and not least because it's convenient one way and the other. There ARE many accepted ways in the range of low efficiency speakers, but for this to really be diverse high efficiency is definitely to be more readily accepted in audiophilia - or so I find.
Does your comment Sounds_Real_ Audio mean you think a passive crossover is different in a horn vs a direct radiator?
Different challenges, I'd say; complex passive cross-overs not least suck the life out of already relatively stale-sounding low eff. speakers, whereas passive XO's often do horns a disservice by having them work outside of their safer bandwidth range. Once again: active configuration to the rescue. |
