Single way or multiway

Thinking "I want my cake and eat it too" can be good practice, and so what on the surface of things are mutually exclusive design features or properties can occasionally be overcome or partially alleviated with smart engineering or a sound, pragmatic approach to acoustic design. Simplicity and maintaining a single point source per channel has its merits and is a core element to strive for, and yet a widebander will be frequency extreme challenged for obvious reasons, among other things. However Tom Danley came up with the synergy horn that sums the output of several, closely mounted drivers from tweeter to woofer within a single horn flare, thereby acting as a single point source over a fairly wide frequency range while, practically speaking, not being SPL limited. There's a degree of complexity, yes, but it all serves a purpose to what sums into a single point source - which in itself is a very desirable trait.

More typically spaced drivers in a multi-way design (i.e.: that therefore don't emulate a point single source) can be made to behave less acoustically divided when also paying attention to dispersive behavior and matching directivity patterns over crossover points between driver sections and maintaining good power response. My own speaker setup is a 4-way design, but there's only a single crossover point between ~80 to 11.5kHz and so, essentially, it's an augmented 2-way design (that's capable of +125dB SPL). Being also the speakers maintain uniformity of dispersion pattern at the vital crossover frequency at just over 600Hz, it helps to aid the impression of listening to what's a "widebander on steroids." 

The aspect of simplicity, or at least that of maintaining a single point (or line) source per channel should, ultimately, be approximated with every speaker design, I find. Oftentimes I think of a smaller, simple quality 2-way speaker setup with an integrated amp and a turntable to be the core qualities I seek to achieve and f*ck up as little as possible in my current setup, but "beefed up" to have the combination of a coherent, full-range, resolved, tonally accurate, analogue sounding and dynamically uninhibited presentation with, in my case, a digital source only.

So, to me it's about merging one and the other, simplicity/purity of approach with complexity, and achieving (or trying to maintain) in a sense the former via the means of the latter, and built upon it. Sort of like having your cake and eat it too..

@bache wrote:

@Phusis     Respect you opinion , but looks like you disagree  with Dr. Gauder or did not read above post, you can see more at https://gauderakustik.com/

Basically I'm not in a disagreement with Mr. Gauder - certainly not what he points to about the essentials behind going multiway, which is fairly straightforward and common knowledge in speaker design btw., and something that shouldn't need his doctoriel status to get through. 

What I attempted to elucidate was that of seeing the strengths from using a crossover-less widebander, mainly that it's a single point source per channel (but also and not least, which I didn't get into earlier, that there's no passive XO parts between the amp and driver), as an inspiration or important reminder in designing a multi-way speaker. Using multiple drivers dedicated to different frequency bands is typically a design necessity, but by its nature also a design challenge; you don't, or rather you shouldn't want a multiway speaker to sound like distinct, different driver elements nor that it is spatially inhibited compared to what a widebander/single point source is capable of. By the same token using what's usually a passive crossover is a design necessity to facilitate the frequency divisions, but it's far from desirably placed between the amp and drivers where it messes with the interfacing between them, not to mention its inherent sonic "contributions" and limitations. Then there's the choice of crossover points and where to place them, the choice of driver type (dynamic, ESL, direct radiating, acoustic transformer/horn, etc.) and what it affords in crossover point positioning (if any with ESL's), the size of the speaker design, etc.

I'm not as much interested in a wideband driver as the fact that it's a single point source, with all that entails. I'm not as much interested in a crossover-less speaker design as the fact that there's no passive crossover between the amp and driver. I'm not as much interested in large, multiway high efficiency horns than the fact they provide better, effortless dynamics, dispersion control, etc. And so on. Get it? Take a fittingly large Synergy Horn design with multiple, frequency divided drivers loading their shared horn flare actively configured, and now you have a single point source per channel that isn't frequency nor SPL limited and that has no crossover - between the amp and drivers, that is. Take a 4-way horn-loaded speaker design like the one I use that only has a single crossover point in a some 7 octave span and that has a uniform dispersion pattern at this crossover point - actively configured. There are ways to minimize the negative impact of going multiway, while conversely taking advantage of what it can provide with different, frequency divided driver elements. That's what I was trying to get across. 

@sns wrote:

I suppose most don’t fret about their passive crossovers since the loudspeakers they’ve chosen provide contentment. The importance of knowing the specs of one’s speakers and providing sympathetic amplification mitigates most issues.

I’ve not seen empirical evidence that provides universal superiority of minimalist passive or active crossovers vs more complex crossovers. Speaker designers  are pretty sophisticated these days, have many drivers, crossover components to choose from, based on listeners experience I trust they know what they’re doing. If what you propose is clearly superior don’t you think they’d go down this path?

Issues that to some are deemed mostly "mitigated" with a passively configured speaker scenario and its amplifier partnering, to others - like knowing the difference active configuration can make - is a potentially flawed approach. Of course to compare the active vs. passive speaker scenario in any way meaningful one should ideally use the same speakers in the same listening environment and overall gear; typically passively configured speakers to begin with that are stripped of their crossovers, extra outboard amp channels added to feed each driver section of the speakers (preferably the same amps as the one already used in the passive context, as an outset simply to serve the purpose and experiment to get a clearer bearing on the sonic differences between the two types of configuration to more effectively isolate the one thing that’s investigated here), a quality DSP/digital crossover or analogue electronic ditto, and then a filter preset ideally made by the original designer of the speakers (in, ideally, the specific listening room and at the listening position) that draws on the opportunities and advantages that an active crossover offers. Speaker re-positioning and acoustics tweaking may be needed to best accommodate filter setting changes compared to the passive version.

Now we’ll be able to better assess the difference active configuration can make, and in each of these instances and under the conditions just described above (except from setting the filter values actively that weren’t done by the speaker designers themselves, though in the specific listening room at the LP) where I’ve heard this conversion from passive to active the latter has won - hands down. Truly, to me and the other attendees it was no contest. 

Some may balk at the need for more amplifier channels, like tripling the amp count for a 3-way setup, but that’s simply what active configuration necessitates; one dedicated amplifier channel directly connected to each driver section with no passive crossover parts in between, meddling with the interface. Of course you don’t need to multiply the number of the same amp(s) you’re using already for an active setup, but could instead apply a power differentiated approach from top to bottom with less individually powerful amps that accumulates into a power capacity that’s suitable. It’s worth noting though that an amp’s power capacity and overall performance is much better utilized actively, and so overall you may need less power (and even general quality) overall.  

Bundled, active speakers don’t always appeal to audiophiles, who like to make their own choices with amplifiers, DAC’s and cables, not to mention that many don’t feel built-in amps and DAC’s comply with their quality standards - be it conjecture or not, and irrespective of the advantages an active package may offer. Outboard actively you can do whatever you please with the choice of components and even filter settings, but in most such cases you’re left to dealing with setting filter values by yourself or with the help of others, which to many if not most is a deal breaker. Few speaker manufacturers offer outboard active solutions with preset filter values, and from their chair demand is likely(?) still limited.

Paradoxically it seems many feel amp matching with speakers outboard actively is a problematic and/or complex issue, but from a certain perspective it’s actually the other way ’round; passively amp matching is much more critical, whereas actively you are offered many more options and opportunities to specifically tailor your amp to driver choices. Potentially more complex, yes, but you’re always better off pairing an amplifier to a speaker actively with the negation of the passive crossover between the amp and speakers.

The actual frame of reference of active speaker configuration to go by for the consumer and how to assess its potential vs. a passive speaker scenario from a more practical/pragmatic perspective is fairly diffuse, to put it mildly, and in light of that it’s understandable why many may not feel convinced about the merits of active, if they even care to navigate in this field to make a proper assessment (and so, and this is important: it falls back on the audiophile him or herself to be willing to investigate and put some effort into active configuration and its intricacies to realize its potential). If people are happy with their passively configured speakers, then that’s all that matters. If however curiosity into an outboard active speaker scenario gets the better of you, go explore and find out what it can offer. Indeed: from my chair it appears quite a few audiophiles have an entrepreneurial spirit, so why not invest some energy into this area?

@toddalin wrote:

You can have an active crossover and still use passive components between the amp and speaker to "meddle with the interface" to improve the results by "fixing" flaws in the original.

Lovely vintage setup. I imagine it produces stellar sonics. 

Sure you can apply a both/and approach with, in this case, an active, analogue electronic crossover as well as passive components between the amp and drivers, but from a more puritanical perspective it also slightly defeats the purpose of active qua active. On the other hand another puritanical approach, to some, would be avoiding a digital step with a DSP altogether and keeping it all analogue, so there’s that. Whatever works and suits a specific context of equipment and taste. With a quality, transparent pro DSP unit the likes of Xilica/ACX, XTA or Lake I really appreciate the intricate crossover settings they offer and which is especially suited for horn-loaded speaker setups. 

@ditusa wrote:

A well executed two way speaker can deliver excellent sound reproduction. 😎

Mike

+1

With a low sensitivity speaker segment however you can only go so far macro dynamically with a 2-way design, and they’re typically LF-restricted due to the need for a smaller woofer/midrange to "meet" with a direct radiating dome tweeter above that can only be crossed so low (used as a direct radiator not much lower than 2kHz).

As an exception to this "rule" the now sadly discontinued speaker brand, S.P. Technology, made an interesting 2-way design based on a ~10" waveguide loading a low fs 1" dome tweeter, and a 8" Seas Excel woofer/midrange (arguably mostly a woofer). Their largest model, the some 6’ tall floor standing Revelation, sported two of the 8" Seas woofers flanking the waveguide in a d’Appolito configuration and a kind of quasi horn-loading of the woofers. The crossover frequency sat in the 700-800Hz region, very low for a dome tweeter, but aided by the waveguide that "relieves" the dome tweeter in its lower spectrum in a progressive, nonlinear fashion. These speakers were essentially and honestly full-range and played down to 20Hz clean - a very impressive feat for at 2-way, lower sensitivity design - and they sounded wonderful to boot, though presented a hideously difficult load to the amp in their passively configured form (they were developed with the Crown Studio Reference 1 amps). 

It’s very different of course with the high sensitivity segment of speakers, like your JBL 4435’s, that allows the use of large woofer/mids in conjunction with a horn + compression driver combo that can cross over lower than 1kHz. Different challenges design-wise, but a potentially much more capable package overall as a 2-way (or 2 1/2-way with your JBL's) design - not least actively configured :)