[JLM]

Is it the human condition (of never being satisfied, always curious, wanting to be master of it all)?

So many take a nice extended range driver with some sort of cabinet/mounting, and then want to smuck it up with super tweeters, woofers, or worse yet let that nice extended range driver multiply in the same cabinet/mounting. 

Don't they realize the "evils" of crossovers?  Don't they appreciate the precision or lack of phasing errors using a point source?  Can't they hear the advantage of active design (one channel of amplification connected directly to one driver)? Thinking of 2-way, 3-way, dipole, bipole, various arrays, coaxial designs, and any other use of multiple drivers per speaker.

As single driver speaker owner for over 10 years I understand the typical/various limitations (increased IM distortion, limited frequency range, limited deep bass output, high frequency beaming, lack of mid-bass response, thin/forward sound) and the usual limited applications (hard to fill a room, best suited for listening to a little girl with guitar).  But there's the magic of doing the midrange right and the limitations can be largely be overcome with the right driver/speaker design.

BTW, I consider the single driver speaker with a swarm (search AC if you're not familiar) of subwoofers the ideal (and not a violation of the mantra).

So is there no loyalty to the concept?  After experiencing the sonic bliss, how can they turn away?

[MJK]

I have been dabbling in full range drivers for about 15 years.

To answer your central question, maybe it is not good enough for them.

I can understand why people would want to add a woofer and/or a tweeter to some full rnage drivers. Crossovers are perfectly acceptable if done well, designed correctly they can be transparent to the listener.

Depending on the full range driver used, depending on the enclosure design, depending on the room, and depending on the source material I think there are a lot of options that can use a full range driver as the focus of a speaker system. If a modification, like adding additonal drivers or a BSC filter, makes the system sound better to the user it is the right thing to do and to heck with the purist approach.

The purist approach works for some people, I don't think I am not one of them.  In my book it is all about the system performance and not the philosophy.

[Guy 13]

Hi all.
As you know already I now use a Omega 7F extended range driver in a open baffle dipole arrangement.
Of course an extended range driver in an OB arrangement don't produce much bass,
I think, even if it was in a bass reflex enclosure, I would still not find the bass acceptable, for me, that is.
That's why I have a double 12" amplified sub-woofer.
I love bass, that the reason why I supplement the weak bass extended range driver.
Another reason for having an amplifier sub-woofer is that my SET amplifier is only 2wpc and would be penalized running power hungry sub-woofer.
For the highs, well maybe for some young ears a tweeter might be a good idea, but for me 66 years old ears, the extended range driver goes high enough for me.
I find the highs very clear and satisfactory for me.
But that's me.
The mids (And the relatively high highs) are very satisfying.
What will happen later, when I get older, much older, will I want to have something different?
Who knows what the future will bring???
For now, I'm good with what I have and for me the extended range driver from Omega is perfect, well, I mean perfect for the price.

Guy 13

 

[RDavidson]

I don't think it's necessarily a matter of leaving good enough alone as it is a curiosity to try other things and expand one's horizons. I own both single driver and multi driver speakers. I find both have their strengths and weaknesses and I will play one type or the other depending on my mood or music I wish to listen to. At some point I'd also like to have a pair of planars or electrostats as I know they have their inherent qualities also. Why stick to one philosophy if it limits the discovery of other enjoyable things? We're talking about audio systems here, not marriage.

[macrojack]

............ because they do not think it is good enough.

[GT Audio Works]

I whole heartedly agree with the magic of the single full range driver. Its what got me going down the road I am now traveling.
I prefer dipole configuration, for me, putting that driver in a box killed it.
Of course this could be argued to be an even purer form of the full range driver and adding a box and the accompanying increase in LF output, spoils the mix the same way adding more speakers does.
When playing music that does not tax its limitations, they produced a sound that made multi way systems envious.
But listen to more energetic music and the magic falls apart.

Therein lies the rub...As Albert Einstein was quoted to have said...."Everything should be made as simple as possible, but not simpler"
Its easy to design a machine for a job where you know it must perform well within a fixed and narrow set of parameters.
But design a machine for a continuously varying set of inputs within a wider envelope of parameters, such as the complex reproduction of sound waves with wide variations of frequency and amplitude all happening at once, and simple is not so simple anymore.
As the complexity of the musical input goes up, so needs to be the complexity of the machine to reproduce it.
Of course as the machine gets more complex, it becomes too complex to reproduce the simple input accurately.

Yes there are speaker designers out there myself included that try to focus on the sweet spot and design a product that will perform well with a variety of music.
But what we really need is a chameleon of a speaker that has the ability to track the musical input and continuously change and correct the driver configuration in a time frame undetectable to our ear/brain, to favorably reproduce the simple to the complex.

Peter Walker was on the right track with the ESL 63, his delay line allowed the width of the panel to be less of a concern for dispersion by energizing the center of the esl panel first and energizing concentric rings moving outward later in time, creating the approximation of a spherical wave front.
This simple application along with the resource of modern or yet to be computing power may be the building block to create a speaker that will have the ability to not only manipulate the signal as needed but to use only the amount of driver surface needed to reproduce a particular frequency.
Allowing the simple as it needs to be theory to come into practice.

I envision a large planar driver,, driving force yet to be determined that could be controlled in a way to actuate only as much of  the surface as needed at that moment in time along with the ability to vary the driving force on that particular part of the driver.
Add input collected by other microphones to map the room at the time of the recording. This info could recreate a more realistic experience for the listener.   Greg

[Danny Richie]

As I am sure you know I am involved in loudspeaker design across the board from drivers themselves, line sources, open baffles, single drivers, etc. So I see just about everything including good and bad implementations of wide band drivers.

I am totally with you on this one.

So many take a nice extended range driver with some sort of cabinet/mounting, and then want to smuck it up with super tweeters, woofers, or worse yet let that nice extended range driver multiply in the same cabinet/mounting. 

Many full range drivers lack energy in the top octave and the larger ones beam pretty badly in the upper ranges so the room isn't filled with the upper harmonics that allow spacial ques to develop. This is why many wide band driver designs have poor imaging and sound stage layering qualities.

So people try to add a super tweeter to gain back the loss. Front firing tweeters though always have issues especially with low order filters on them. They will be in phase with the main driver in some areas and out of phase in others. So the upper ranges will have 6db peaks and 15db dips every time. It usually is a disaster and typically has negative effects on the response even down into the 3kHz range.

A solution is to face the tweeter to the rear (unless the full range driver is in an open baffle) or face it upward. Facing it upward works every time. It will allow the air and spacial ques to come to life without a negative effect on the response. And it can improve imaging and sound stage layering.

Don't they realize the "evils" of crossovers?  Don't they appreciate the precision or lack of phasing errors using a point source?

Crossovers or parts used as a filter are not evil and are almost always necessary to some degree even with wide band drivers. And a lot of wide band drivers have enough inductive reactance to cause a significant rise in the impedance. This causes a shift in phase. A filter can be used to reduce the impedance rise and minimize any shift in phase.

Can't they hear the advantage of active design (one channel of amplification connected directly to one driver)? Thinking of 2-way, 3-way, dipole, bipole, various arrays, coaxial designs, and any other use of multiple drivers per speaker.

They all have advantages and disadvantages.

But there's the magic of doing the midrange right and the limitations can be largely be overcome with the right driver/speaker design.

Yes, but often in order for the mid-range to be "right" a filter is required.

More often than not I see wide band drivers used in an application where they have significant baffle step loss. Check out the red line. It's a wide band driver in a transmission line box. It was a customers speaker that I tested for them.



That mid-range that you want to be right is in the 300 to 500Hz range. Note that from 300Hz to 700Hz there is a 5db swing. This makes vocals really thin. So a simple filter is used to compensate for the baffle step loss and now the mid-range is "right". It is more balanced and beautiful to listen to.

Also note that many wide band drivers have some break up in the top end. Another filter was used to notch out the peak at 9 to 10kHz. Without that filter (or crossover parts) the top end was so hot that it made the speaker hard to listen to. With the filter it was much better. See the green line. See, crossover parts aren't evil.

And check this out. This is the spectral decay without the filters. Lots of stored energy and ringing...



Now here it is with the filter. Much less ringing....



See filters are good. 

And only a very few times have I ever measured a wide band driver in an application where it did not need a compensation filter of some kind.

BTW, I consider the single driver speaker with a swarm (search AC if you're not familiar) of subwoofers the ideal (and not a violation of the mantra).

I am with you on that too. This set up can be awesome. They are my second favorite configuration for low bass.

[DaveC113]

JLM, I'd agree with others that say they aren't good enough... although I currently own a set of Omega Super 3 XRS and have for many years, about as long as you've had your Fostex speakers. The new RS5 drivers are great, but I have a few issues:

- Maximum SPL abilities are not enough to realistically recreate some kinds of music before distortion becomes an issue. Excursion caused by low bass effects the other frequencies too much at higher SPL levels.

- Dynamics are challenged as well, when you have a system without high SPL abilities and very little driver surface area, the result is you cannot feel the impact of instruments, highly dynamic music, especially drums with low-frequency content, cannot be accurately portrayed.

These issues are largely the result of using a smaller diameter driver, but I'd argue the driver would need to become large to the point high frequency reproduction then becomes a problem, creating other issues such as the highs rolling off early, beaming, and issues associated with whizzer cones, which is a mechanical crossover with it's own set of compromises, and I'd argue they are worse than an electrical crossover in some cases.

So, I choose a smaller diameter driver that can play up to 20 kHz without a whizzer, and without beaming to the point it becomes a problem, in fact the opposite, you get controlled directivity which is the hot topic these days it seems.

And there IS a solution to the above issues, one that I feel is well worth the extra complexity and expense... augment the low frequencies with another larger driver up to around 3-400 Hz. There's nothing that beats the dynamics and impact of a large woofer, and that's exactly what a smaller wide-band driver needs. I also think it's possible to control the directivity of the small full-range driver as well, producing a speaker with controlled directivity down to the crossover point, which will be much lower than most speakers manage.

This kind of augmentation can be implemented without destroying the single driver "magic"... and the tradeoffs are mostly financial imo.

[Danny Richie]

I agree with Dave on the adding of a low frequency driver.

I like to let a more capable woofer or woofers handle at least from 200Hz and down. This keeps them just out of the mid-range and doesn't have any negative effect at all. And relieving the full range driver from seeing those lower wavelengths can also improve the sound of it across the board. I prefer a single small cap value used in the RCA input to the amp to roll off the lows. This tends to increase the headroom of the amp as well since it sees much less current demand not having to produce the lower range.

[RDavidson]

I agree with Dave on the adding of a low frequency driver.

I like to let a more capable woofer or woofers handle at least from 200Hz and down. This keeps them just out of the mid-range and doesn't have any negative effect at all. And relieving the full range driver from seeing those lower wavelengths can also improve the sound of it across the board. I prefer a single small cap value used in the RCA input to the amp to roll off the lows. This tends to increase the headroom of the amp as well since it sees much less current demand not having to produce the lower range.

Interesting, Danny. I might have to look into this. Harrison Labs makes a variety of exactly what you're talking about, if one is not inclined to make their own. At 200hz, subwoofer placement would be pretty critical, right? For such, would you maybe recommend something like 100hz?

[Danny Richie]

Interesting, Danny. I might have to look into this. Harrison Labs makes a variety of exactly what you're talking about, if one is not inclined to make their own. At 200hz, subwoofer placement would be pretty critical, right? For such, would you maybe recommend something like 100hz?

Sure, you can make your own high pass filter. The value you need also depends on the input impedance of your amp. So be sure to look at that. Here is one with a by-pass for the amp driving the lower range woofers.



And at 200Hz or so you are dealing with wavelengths that are about 5.5' long. So you want your acoustic centers to be less than that distance apart. And the closer the better.

If your crossover point is double that (100Hz) then you need to keep the woofers to within (less than is better) 11 feet of the mains (center to center).

[Don_S]

Having worked for the federal government and two state governments where "rocking the boat" was frowned upon  , I applaud the creative genius I see in the audio industry.  As I walked the halls at CES I was impressed by the enthusiasm and energy I felt from equipment designers. Although I frequently wished they would apply a little more practicality to their designs with regard to price, size, and user friendliness.

I salute those who never think "it is good enough". They are creative forces and push the envelope. How would we have what we have now if everyone arbitrarily decided to "leave good enough alone"? Here is to the restless spirits that jump out of bed at 3am to test another design idea in their workshop. 

I further submit that each of us has only reached the point we are at now with our systems by being somewhat curious if not compulsive/obsessive.  We have not reached our destination. We are still on the journey.

[RDavidson]

Sure, you can make your own high pass filter. The value you need also depends on the input impedance of your amp. So be sure to look at that. Here is one with a by-pass for the amp driving the lower range woofers.



And at 200Hz or so you are dealing with wavelengths that are about 5.5' long. So you want your acoustic centers to be less than that distance apart. And the closer the better.

If your crossover point is double that (100Hz) then you need to keep the woofers to within (less than is better) 11 feet of the mains (center to center).

Thank you very much, Danny. I'm very new to single driver speakers, and this is the kind of info that will help me get the best from my setup, especially as I'm currently looking at low power SET/SEP amps.....and possibly adding a subwoofer later.

[rjbond3rd]

Personally, I've seen the "purist" single driver (no circuits) approach work many times, with the trade-off that you have to choose the music to avoid the speaker's weak spots.  With no circuit, the single-driver designs need a whole lot of help from the boundaries (walls, floors, corners, ceiling) which can only partially flatten the response.

At that point, though, the "point source" is often degraded (e.g., too many reflections from boundaries, furniture, shelves etc.)  It seems much better to use a .5 driver and get the speakers further from boundaries, which improves imaging (at the small cost of a cap or coil).

One exception I've noticed is a back-loaded (or tapped) horn which extends directly into the (floor or ceiling) corner, but the rest of the box extends out into the room. This gives good imaging if (and only if) you sit in just the right spot. 

But as good as that can be, a .5 driver (pulled out into the room) seems to get better imaging more easily (because you can pull it away from boundaries and furniture), with the trade-off that you obviously need twice the drivers (not always an option, e.g., when using vintage or expensive drivers).

[DaveC113]

Personally, I've seen the "purist" single driver (no circuits) approach work many times, with the trade-off that you have to choose the music to avoid the speaker's weak spots.  With no circuit, the single-driver designs need a whole lot of help from the boundaries (walls, floors, corners, ceiling) which can only partially flatten the response.

At that point, though, the "point source" is often degraded (e.g., too many reflections from boundaries, furniture, shelves etc.)  It seems much better to use a .5 driver and get the speakers further from boundaries, which improves imaging (at the small cost of a cap or coil).

One exception I've noticed is a back-loaded (or tapped) horn which extends directly into the (floor or ceiling) corner, but the rest of the box extends out into the room. This gives good imaging if (and only if) you sit in just the right spot. 

But as good as that can be, a .5 driver (pulled out into the room) seems to get better imaging more easily (because you can pull it away from boundaries and furniture), with the trade-off that you obviously need twice the drivers (not always an option, e.g., when using vintage or expensive drivers).

BLHs used to be a trend some years ago. Feastrex built a bunch or them as did other companies to try to get the most from the driver. But none of them sound right, the bass is always "wooly" and lags behind, destroying PRAT. They have all disappeared, replaced with simple vented cabinets.  I think the BLH is more of a compromise than augmenting the single driver with another driver, in trying to maintain a "purist" approach more damage is done than giving up preconceptions and considering all the alternatives.

The only possible exception is the Voxativ BLH, but it's $40k and TBH, Omega's Alnico XRS is just as good for under 10% of the price.

One positive of smaller single drivers without a whizzer is they are small enough to not beam too badly at high frequencies and you get a gently collapsing directivity that mitigates room effects. They are also capable of playing up to 20kHz or very close. This is why I feel like a smaller diameter single driver combined with a large woofer will work really well. If the woofer is crossed over low it shouldn't be an issue to match directivity with the woofer, but I am also considering a 15" woofer crossed over at 800 Hz with a 90 degree waveguide to match directivity at the crossover point and have the midwoofer completely cover the delicate midrange region. Geddes considers 800 Hz ideal and Louis has mentioned he thought it was a sweet spot as well, so I'll have to test 3-400 Hz vs 800 Hz and see what ends up sounding best...

In the end we need to remember there is no right or wrong, good implementation of a chosen design is more important than anything and the design should be selected to match your personal listening preferences. Pure single drivers are only one option and they have their own set of compromises. If they match your preferences then great, but I see no value in considering them any more or less ideal than any other design, nor do I see any value in maintaining "purist" ideals. I have heard excellent speakers of every conceivable design, which leads me to believe it's more about implementation... like most things. My favorite speaker ever is average efficiency and looks a lot like a cookie-cutter tower with 2 smaller woofers, mid and tweeter. But Alex Jones' implementation of the TAD line is very well done, if out of my financial reach right now... 

[rjbond3rd]

BLHs used to be a trend some years ago...But none of them sound right, the bass is always "wooly" and lags behind, destroying PRAT. They have all disappeared...The only possible exception is the Voxativ BLH, but it's $40k

How many have you heard, though?  It sounds like not that many (because the Voxative is at best average compared to the better computer-modeled designs). The "wooly" part is not inherent, it's a common misalignment, usually trying to get more bass out of them (most ported boxes are also mis-aligned, as are most multi-ways). There are good and bad examples, and 99% of everything is junk.

[DaveC113]

How many have you heard, though?  It sounds like not that many (because the Voxative is at best average compared to the better computer-modeled designs). The "wooly" part is not inherent, it's a common misalignment, usually trying to get more bass out of them (most ported boxes are also mis-aligned, as are most multi-ways). There are good and bad examples, and 99% of everything is junk.

At least 6, probably more... a few made by Feastrex or Lotus Audio, a few made by other companies. I'm sure not all of them were poorly implemented and I've heard enough of them to know it's not a design I care for. I prefer a simple vented box.

[rjbond3rd]

At least 6, probably more... a few made by Feastrex or Lotus Audio, a few made by other companies.

The good BLH examples are all DIY, or at least started that way.

[JLM]

Most horns I've heard suffer from insufficiently rigidity (horn wall vibration) or excessive compression (trying too hard to boost efficiency).  With the dynamic presentation of horns its almost impossible to find bass fast enough to keep up.  And of course bass horns to cover the full musical range would have to be the size of a garage and made of concrete.   

If reaching 30 Hz is the goal, consider the Fostex F200A driver (its rated F3 is 30 Hz).  Quality AlNiCo magnet (huge), machined aluminum frame, very heavy, 90 dB/w/m, 8 ohms, and just $576 each currently at Madisound.  Expensive yes, but no other drivers, crossover needed, just a baffle if you're happy with 30 Hz and dipole presentation (many do just that).  Or build a cabinet and go deeper.  Bud Purvine, inventor of the EnABL treatment, calls the treated F200A the best extended range driver in the world.

[FullRangeMan]

Maybe Purvine unknow the Omega 7 Alnico which is 93sB SPL and was $190 each.
Too bad this driver is no more avaliable.