Different speaker concepts

[JiiPee]

Putting aside the active vs passive discussion, What's the deal with atypical speaker concepts like:
- Full range drivers
- Open baffle / dipole concept
- Horn loaded drivers / transmission line speakers
- Electrostatic / Magnetostatic speakers
- Sealed cabin
- etc....

As we know the market is dominated by 2-way and 3-way bass reflex speakers. Why is is it so ?

Regarding sound quality and measured performance, do You think some of these atypical speakers have a potential to match / exceed the sq of a well executed bass reflex speaker?

 

[puppet]

Ever wonder why ice cream comes in different flavors?

 

[sergeauckland]

Putting aside the active vs passive discussion, What's the deal with atypical speaker concepts like:
- Full range drivers
- Open baffle / dipole concept
- Horn loaded drivers / transmission line speakers
- Electrostatic / Magnetostatic speakers
- Sealed cabin
- etc....

As we know the market is dominated by 2-way and 3-way bass reflex speakers. Why is is it so ?

Regarding sound quality and measured performance, do You think some of these atypical speakers have a potential to match / exceed the sq of a well executed bass reflex speaker?

It's an easy and inexpensive way of achieving a commercially acceptable result.

Full-range drivers have audible problems with coloration due to resonances, beaming at anything approaching high frequencies, and either a lack of bass due to small cone size, or excessive beaming on larger cones.
Open Baffles are physically large, and likely to be cosmetically unacceptable.
Horn loaded drivers are physically very large if LF is to be acceptably extended, and/or if folded into something domestically acceptable, can be quite coloured.
Transmission lines are necessarily physically large, and cabinet construction complex, so more expensive. Small 'Transmission Lines' are nothing of the sort, just a somewhat more complex reflex.
Electrostatic/magnetostatic loudspeakers are physically large if LF is to be adequately extended, and are more expensive to manufacture
Sealed box loudspeakers are probably the better alternative to reflex, but again the box size is larger than reflex for the same LF extension, albeit it decays slower, but extended LF requires a big box.

Darwinian evolution of the market has resulted in lots of adequate two or three way reflex loudspeakers of modest size and acceptable cosmetics.

S.

 

[tuga]

To the best of my knowlege:

- Full range drivers –> generally no crossover (electronic components) in the signal path, time-coherent, high levels of IMD, cone breakup in audio band, limited badwidth

- Open baffle / dipole concept –> narrow constant directivity for reduced side-wall interference above Schroeder, potentially delayed reflections from rear for potential increased envelopment/spaciousness

- Horn loaded drivers / –> narrow constant directivity for reduced side-wall interference above Schroeder, potentially lower distortion

- / transmission line speakers –> hardly ever, except for the Nautilus and maybe large Vivids?

- Electrostatic / Magnetostatic speakers –> ...

- Sealed cabin –> better transient response

 

[ppataki]

- Full range drivers

- Sealed cabin

This is my personal favorite combination
I have ditched all my bass-reflex multi-way systems and moved to sealed one-way solutions. This is highly subjective obviously but when I first heard how a full range driver sounds it was a no-brainer for me to switch (again, this is highly subjective; there are many people who do not prefer that for various reasons)
If you check my threads in the DIY section of this forum you will see many examples

Regarding sealed vs reflex:
Sealed design can leverage your room much better for the low-end since the low frequency decay is only 12dB/octave for sealed designs vs 48dB/octave for reflex designs --> you can boost the lows with EQ for sealed designs to have much better LF extension (at the expense of max SPL obviously). But all this can be simulated upfront so you would know exactly your figures.
The drawback is that you need DSP to do this - so off-the-shelf loudspeakers are easier to manufacture being bass-reflex since they will not need DSP for LF extension (hence commercially available sealed boxes are extremely rare)
Sealed design has a better transient response (=much lower group delay) exactly for the above mentioned reason - again when you simulate sealed vs ported designs these will all be totally obvious differences

 

[JiiPee]

This is my personal favorite combination
I have ditched all my bass-reflex multi-way systems and moved to sealed one-way solutions. This is highly subjective obviously but when I first heard how a full range driver sounds it was a no-brainer for me to switch (again, this is highly subjective; there are many people who do not prefer that for various reasons)
If you check my threads in the DIY section of this forum you will see many examples

Regarding sealed vs reflex:
Sealed design can leverage your room much better for the low-end since the low frequency decay is only 12dB/octave for sealed designs vs 48dB/octave for reflex designs --> you can boost the lows with EQ for sealed designs to have much better LF extension (at the expense of max SPL obviously). But all this can be simulated upfront so you would know exactly your figures.
The drawback is that you need DSP to do this - so off-the-shelf loudspeakers are easier to manufacture being bass-reflex since they will not need DSP for LF extension (hence commercially available sealed boxes are extremely rare)
Sealed design has a better transient response (=much lower group delay) exactly for the above mentioned reason - again when you simulate sealed vs ported designs these will all be totally obvious differences

Thanks. So, if I've understood correctly, a relatively small full range driver (to avoid cone breakup and high freq beaming) in a sealed cabin aided with DSP could be a good solution as long as the required sound levels are reasonably modest.

 

[Mr. Widget]

This is my personal favorite combination
I have ditched all my bass-reflex multi-way systems and moved to sealed one-way solutions. This is highly subjective obviously but when I first heard how a full range driver sounds it was a no-brainer for me to switch (again, this is highly subjective; there are many people who do not prefer that for various reasons)
If you check my threads in the DIY section of this forum you will see many examples

I think this relates to our individual sensitivities.

What I mean is, I appreciate that there is a simple "cleanness" to the sound of a single driver system with no crossover and all sound coming from a single source. However for me and apparently most listeners, the characteristic frequency nonlinearities are a deal breaker.

I am of the horn camp. These speakers definitely have their own issues and most vintage horns exhibit all manner of frequency nonlinearities and phase/time issues with arrival times from different parts of the frequency spectrum etc. Modern horn based systems have corrected most of these issues, but they are still far from perfect.

Large planar speakers have their strengths and weaknesses as well... have owned a few, ultimately not for me.

Dome tweeter with a mid and woofer is the safe bet and can sound really, really good. Properly aligned bass reflex (4th order) or sealed box (2nd order) can be equally good. The current fashion is ported, but arguments can be made for each.

 

[ppataki]

Thanks. So, if I've understood correctly, a relatively small full range driver (to avoid cone breakup and high freq beaming) in a sealed cabin aided with DSP could be a good solution as long as the required sound levels are reasonably modest.

Yes, correct, if you are willing to fiddle around with DSP (not just for the low end but for the full spectrum) and if you like the sound of these kind of loudspeakers.
If you don't mind beaming (again this is up to personal taste) you can definitely go for larger drivers too (those can move more air so will be more effortless)

 

[Zapper]

Regarding sealed vs reflex:
Sealed design can leverage your room much better for the low-end since the low frequency decay is only 12dB/octave for sealed designs vs 48dB/octave for reflex designs --> you can boost the lows with EQ for sealed designs to have much better LF extension (at the expense of max SPL obviously). But all this can be simulated upfront so you would know exactly your figures.
The drawback is that you need DSP to do this - so off-the-shelf loudspeakers are easier to manufacture being bass-reflex since they will not need DSP for LF extension (hence commercially available sealed boxes are extremely rare)
Sealed design has a better transient response (=much lower group delay) exactly for the above mentioned reason - again when you simulate sealed vs ported designs these will all be totally obvious differences

One quibble: you don't need DSP per se, you need active equalization. Analog active filters have long been used to extend bass (and treble) response in both sealed and ported cabinets. The Bose 901 is the best known commercial application. Many mini stereo systems and all-in-one players had analog "bass boost" tailored for their intended speakers. An early 1960's KLH compact stereo (turntable/FM/amplifier with two 2-way acoustic suspension bookshelf speakers) I once worked on also introduced a bit of analog bass boost in the amplifier feedback network.

A bit more history: sealed "acoustic suspension" designs dominated the HiFi speaker market in the 1960's and 1970's because they were just much better than the poorly designed ported "bass reflex" designs of the time. By the standards of the day, acoustic suspension speakers offered a lot of bass in a relatively small box, leading to the popularity of bookshelf sized speakers for full range HiFi systems. After the engineering theory for accurate ported speakers reached maturity in the 1970's, ported speakers slowly but steadily gained dominance over acoustic suspension as they offered the same bass in a smaller, cheaper box, to the point where today the latter are almost extinct.

 

[Zapper]

Open Baffles are physically large, and likely to be cosmetically unacceptable.

To elaborate, the open baffle design suffers from poor bass response due to the inverted back wave canceling the front wave, as any bass player who's tried to play through an open backed guitar amp can testify. The bigger the baffle, the lower the bass cutoff, so the baffles have to be physically large to have acceptable bass response.

 

[jhaider]

What I mean is, I appreciate that there is a simple "cleanness" to the sound of a single driver system with no crossover and all sound coming from a single source.

Personally speaking, I’ve never heard that. I think the “magic” of a 1 single driver is only uncovered with the eyes. I’ve come around maybe 80% to think that about coaxes as well, despite a long history of favoring them.

IMO all that an unfiltered wideband driver gives you is what’s been stereotyped as “Bose sound” - no highs, no lows. Thought I would take the most basic powered Bose system over, say, a Lowther based system, any day of the week! An EQed full ranger just sounds either dull and closed in or piercing and closed in, depending on how the treble is voiced, because of the collapsing dispersion.

As for the other things in the OP:

- Open baffle / dipole concept

Open baffles excite room modes differently from monopoles, so they will sound different than box speakers: maybe better, maybe worse! They cannot pressurize a room very well, which depending on musical preferences may degrade realism.

In the midrange and treble they add much stronger reflections. Some like the effect and some find it adds a discomfiting stamp atop the imaging baked into a recording. That is a matter of program and taste. They also radiate less to their sides than box speakers.

- Horn loaded drivers / transmission line speakers

“Transmission line” is mostly marketing…. So is calling bass “horn loaded.” Either a system shifts the energy under the curve by using the back wave to add radiated energy above a given passband, and subtract radiated energy below, or it does not.

Horn midrange/treble can be the best or can be the worst! Benefits are higher efficiency and fine control over dispersion pattern. But much depends on the quality of the design as well as the suitability of the resultant dispersion pattern to one’s room configuration and sonic preferences. Also most horns throughout history have been terrible sounding!

Note that most (not all!) speakers that perform properly (flattish and smooth on axis response, smooth off axis response) use sculpted waveguides to control the tweeter’s dispersion at the bottom of its range. All horns are also waveguides.

- Electrostatic / Magnetostatic speakers

Different radiation pattern, generally narrower horiztonally, much narrower vertically.

- Sealed cabin

Less efficient in key areas of the passband by up to 6dB, but more efficient down low. Closed boxes make a lot of sense for main speakers designed to be used for subwoofers, powered speakers with decent sized woofers, and powered subs. They’re harder sells as unpowered speakers, because people like bass and they have less.

You think some of these atypical speakers have a potential to match / exceed the sq of a well executed bass reflex speaker?

With the exception of closed boxes, which I find generally better in well-optimized modern systems because they’re smaller and the benefits of bass reflex are addressed with multiple subwoofers, it depends on the rigor of the design as well as program and personal taste.

 

[fineMen]

- Horn loaded drivers ...

No so much a horn, but a waveguide from as low as possible for maybe even narrower directivity.

Why is narrow directivity even acceptable? Because stereo commands you to sit at a very specific position anyway. The direct sound field counts. The indirect, or reveberant sound field is secondary. Caveats? But wait: because of narrow directivity the reveberant sound field can be filled up with a third, forth loudspeaker independently, which of those have wide directivity, or even diffuse phase ... mono ... without interferring too much with the direct and indirect sound field from the main speakers. Add-on benefit would be that when sitting, lying outside of the stereo triangle the irritating remainders of the stereo e/g switch of sound impression to the nearest speaker as 'real' origin, are vastly suppressed.

What do you think of this concept? The idea of a center speaker is not new, I know.

 

[617]

Every fringe speaker idea seeks to resolve an imagined technical problem, at the expense of things which matter more. People like them because when they are well executed, they offer something which other speakers do not, while hopefully minimizing other problems.

Full Range Drivers
Imagined Technical Problem
Crossovers are bad and hard to implement, big amplifiers are bad
What you get
Not much. Simplicity of construction I guess, unless you're building a back loaded horn. Efficiency can be high.
Problems
Most have mechanical crossovers, where different parts of the cone vibrate, no bass, chaotic mid dispersion, huge directivity problems.

Horns
Imagined Technical Problem
Big amplifiers are bad (mostly) and directivity should be narrow
What you get
High efficiency, very focused sound
Problems
No bass unless you use direct radiators, incredibly chaotic dispersion from large horn arrays and immense expense. Can work well but very hard to implement and not many commercial offerings available.

Open Baffles
Imagined Technical Problem
Near reflections and cabinet resonances are bad
What you get
Reduced near reflections from side walls and no cabinet resonances.
Problems
No bass, directivity can be pretty smooth, high expense. Overexcursion distortion can be an issue due to the load put on bass/mid drivers, but distortion is not a psychoacoustic metric. These can work pretty well.

Transmission Lines
Imagined Technical Problem
Sealed enclosures don't have enough bass but bass reflex has high group delay
What you get
More bass than a sealed enclosure and less than a bass reflex
Problems
None really, just a bit bigger and trickier to design but very much achievable. In reality all bass alignments are on a continuum with most of their operating principles exhibited in most of them.

Electrostatic / Magneto-Planar
Imagined Technical Problem
Heavy diaphragms and cabinet resonances are bad
What you get
You get the advantages of a dipole
Problems
No bass (noticing a pattern here?) fragile, incredibly chaotic and overly directive treble due to the huge diaphragm size. Can work well though. Also, expensive.

The thing they all have in common? They are motivated not my psychoacoustic evidence but by engineering problems. A heavy diaphragm 'must' be bad, so make it lighter. Cabinet resonances 'must' be bad, so get rid of them. Crossovers 'must' be bad, group delay 'must' be bad.

Good speaker design comes from a psychoacoustic understanding of speakersin small rooms and works back from there, it doesn't start with an imagined 'perfect transducer'.

 

[LightninBoy]

Every fringe speaker idea seeks to resolve an imagined technical problem, at the expense of things which matter more.

Bingo.

 

[Mr. Widget]

Every fringe speaker idea seeks to resolve an imagined technical problem...

I generally agree with your entire post, but I have issues with two words, "fringe" and "imagined".

Every speaker built to date has had a host of as yet unsolved issues. You don't need to look solely at the "fringe" designs, and while the tech speak used by some designers or marketers may use imaginative verbiage and thinking, the problems are real.

 

[OldHvyMec]

I've never heard a good full range coned driver. Small planars can range from 250hz to 20khz.

OB is hard to get right. It is so room and speaker placement dependant I usually settle for good sound effect vs imaging and soundstage.

There are two boxes you have to deal with. The one least looked at (the room) is 50% of the sound. The actual speaker enclosures are pretty
easy to work with when you treat the room first. You can pick almost any speaker if you understand what your room is like. Lively, dead, cluttered,
open, tall ceilings, no carpeting, curtains, trees, etc.

Check your hearing. Get a baseline and take care of your ears. When you think you can hear and you are DEAF it is a problem. You can fix things,
you can hear. I've argued with a lot of mechanics behind their BAD hearing and not taking care of what they had left. Iron workers, welders, fabricators
are the worst for making noise and NOT taking care of their ears.

Tune the room then use DSP for the bass region. If you have to use HEAVY DSP/PEQ/GEQ look backwards chances are 50% of the plan was left out.

I suggest you pick the type of driver/speaker you like and stick with it. If you like stereo sound then learn how it sounds the best without DSP.

Treat the room and take care of the built in receivers you have. YOUR EARS.

I chose small planars/ribbon driver a long time ago. The names have changed but the quality has just gotten better.

I like a 4 way system. Sub cabinets (servo), Bass columns (direct coupled SS) Monitor Cabinets (mids highs) valve driven.
The room treated with heavy curtains and Helmholtz resonators. The best investment I ever made.

Swapping wives every 10 years seemed to be most of my buddies problems. Speaker selection seemed to follow a close pattern. LOL
Alway looking for the pot of gold at the end of the rainbow. The rainbow is the reward, there is no pot of gold.

Time to feed my chickens.

Regards

 

[Mr. Widget]

Swapping wives every 10 years seemed to be most of my buddies problems. Speaker selection seemed to follow a close pattern. LOL

Not that it is any of my business, but swapping or changing?
Sorry... couldn't help myself.

 

[fineMen]

Good speaker design comes from ..., it doesn't start with an imagined 'perfect transducer'.

I like a 4 way system.

The BBC paradigm of a 2-way with a sufficiently controlled bass/mid was, in the 1960s, the final nail to the coffin. Even JBL fell for it with the 4435 and still today their flagship speaker, the M2, celebrates the wisdom from the past.

But let's assume for a moment that a perfect speaker was available. What about the actual listening experience in-room at home, significant other besides? Is the listener assumed to be a virtual clone of the sound engineer, listening 'critically' all the time, I mean, for fun?! He might tell his compagnion how good the sound is, but is just that the essence of the stereo? He might end up listenng alone, discussion with himself the merits of different cable brands, urging for a change, once in a while taking costly actions.

So, you don't like the idea of a center speaker for stereo? (see post #12)

 

[Deleted member 58722]

 

[OldHvyMec]

What do you think of this concept? The idea of a center speaker is not new, I know.

Trinaural Processors are a neat concept. SST (analog), Mac, Krell and a few others have a nice ability to use three (3) speakers.
I used it on "Long wall" setups. I tried two sets of stereo speakers one set wide and set side by side too. That was interesting.

I used 8-12 neo 8 planars in pairs side by side for a center and Elixirs for the Mains. There was a lot of sound.

The idea was the center channel worked better if the speaker was larger than the mains. It was a pretty amazing coupled with
a servo bass system. I still have the lattice neo 8 towers and Elixirs. 410lbs each. Not as mobile as they once were or is that me. LOL