Single full range drivers

[Duke]

Please just acknowledge that an x-over doesn't pose a problem in time domain

No, I don't agree with this. Phase lead and/or phase lag at a given frequency = a time domain aberration. It can be corrected, and sometimes is.

, and that single wide-band drivers exhibit at least as much phase alterations to the original signals as non-pathological multy-way speakers do.

I don't know what you mean by "non-pathological multy-way speakers", so I'm not agreeing with this either.

In case you don't it is your turn to deduce a fully connected chain of arguments for your claim, as my stance is supported by all the literature.

I don't believe that your stance "is supported by all the literature", but if you do, I have zero interest in trying to change your mind.

 

[Tangband]

Greetings,

Has any one measured speakers with single "full range" driver? Is there even a theoretical chance they would measure well?

Thanks

Yes .

Markaudio chn110 , tower speaker, one speaker, inroom , 1 metre , on axis and 15 degrees off axis, Line audio om1 mic, audiotools.

Markaudio CHN 110 building and comparisons with Genelec 8340 SAM monitors

My hypex ncore has come and listening comparisons has begun between this amplifier and one of my Aiyima a04 (tpa3251 now with Opa 1612 ) , using the tunemethod. What amp brings the most enjoyment of the music and the clearest bass pitch ? Talking about timbre, they sound a tiny bit different -...

www.audiosciencereview.com

 

[Matt_Holland]

2” full range by K-array - Tornado KT2

4” full range by KGEAR (K-array sister brand) - GH4

A few years ago I experimented with the BMR drivers by Graham Bank (ex Celestion and NXT) - Cotswold Sound Systems
The 4” driver sounded particularly good and had a very wide directivity. Absolutely no tweeter required.

 

[Frank Dernie]

2” full range by K-array - Tornado KT2

4” full range by KGEAR (K-array sister brand) - GH4

A few years ago I experimented with the BMR drivers by Graham Bank (ex Celestion and NXT) - Cotswold Sound Systems
The 4” driver sounded particularly good and had a very wide directivity. Absolutely no tweeter required.

A friend of mine did much of the computer modeling of modal radiation and prototype design and measurement of NXT and BMR as a consultant.
He has built prototypes which are super impressive but tells me people are waiting for patents to expire...

 

[gnarly]

Please just acknowledge that an x-over doesn't pose a problem in time domain, and that single wide-band drivers exhibit at least as much phase alterations to the original signals as non-pathological multy-way speakers do. In case you don't it is your turn to deduce a fully connected chain of arguments for your claim, as my stance is supported by all the literature.

I'd like to address this in two parts.

First part:
If a single wide-band driver and a multi-way both have the 'same frequency magnitude response', their phase alterations will be the same at the ends of the spectrum.
The same 'frequency magnitude response' means both speakers have the same low-end and high-end frequency response roll-offs.

But those system roll-off regions, are the only frequencies where phase alterations will be the same.
In between, through the main spectrum, their phase alterations will not be the same. (other than special cases where the multi-way uses only first-order IIR or linear phase xovers.

The single wide-band driver will have flat phase, due to not having any xovers.
The multi-way will have phase rotations depending on number of ways/xovers, and crossover orders.

Second:
I agree that a xover doesn't pose a problem in the time domain.
Because my definition of 'time domain' is just that...time. As in seconds, milliseconds, microseconds.

An impulse response shows signal amplitude vs time. Doesn't show either frequency magnitude response or phase.
FFT math derives frequency response from the impulse response...and freq response is defined as complex freq response which includes freq magnitude and freq phase.

My intended point here is that phase is a component of the frequency domain...and not of the time domain.
Time is a constant. Phase is a rotation of frequency's relative cyclical alignments.

They are simply not substitutes ime, one for the other.
The idea that phase can be equated into a unit of time for a given frequency, and then used as a substitute for time alignment....
.....is a very suboptimal but appears oh so commonly used in IIR xover design.

Ok, off soap box and back to topic...
I say xovers pose no time domain problem. They cause a phase rotation problem. (other than first-order IIR or lin phase)

 

[Matt_Holland]

A friend of mine did much of the computer modeling of modal radiation and prototype design and measurement of NXT and BMR as a consultant.
He has built prototypes which are super impressive but tells me people are waiting for patents to expire...

A few years ago Cambridge Audio sold a range of hifi speakers that used the smaller Cotswold BMRs.
Of course there was also the Naim Audio Ovator range from even longer ago that used a BMR designed by Karl Heinz Fink of this Parish. I liked those a lot, but I’m not sure the hifi press did, nor many punters.

 

[kemmler3D]

I know this thread is old AF but I wanted to make a note on beaming, because I didn't understand it myself for a long time:

Beaming is an unavoidable consequence of a large cone-shaped diaphragm putting out high frequencies. When you have wavelengths smaller than the cone coming from the cone, they end up interfering with each other and cancelling out at off-axis angles. So there is basically no such thing as a large full-range cone-shaped driver that doesn't suffer proportionally from beaming.

Someone better at geometry and physics might have something to add here, but I think it's also problem with any shape of diaphragm, not just cone, since the wavefront will emanate hemispherically, right?

 

[fpitas]

I know this thread is old AF but I wanted to make a note on beaming, because I didn't understand it myself for a long time:

Beaming is an unavoidable consequence of a large cone-shaped diaphragm putting out high frequencies. When you have wavelengths smaller than the cone coming from the cone, they end up interfering with each other and cancelling out at off-axis angles. So there is basically no such thing as a large full-range cone-shaped driver that doesn't suffer proportionally from beaming.

Someone better at geometry and physics might have something to add here, but I think it's also problem with any shape of diaphragm, not just cone, since the wavefront will emanate hemispherically, right?

It's complicated. Anything that acts pistonic radiates in a predictable way, narrowing with frequency and eventually lobing. Some softer cone materials do a good job of "shrinking" with frequency, and the beamwidth does not narrow nearly as quickly. Some drivers are designed with concentric break-up rings to encourage an orderly reduction in driving diameter with frequency, too.

 

[kemmler3D]

It's complicated. Anything that acts pistonic radiates in a predictable way, narrowing with frequency and eventually lobing. Some softer cone materials do a good job of "shrinking" with frequency, and the beamwidth does not narrow nearly as quickly. Some drivers are designed with concentric break-up rings to encourage an orderly reduction in driving diameter with frequency, too.

I just landed on this while I was looking for an illustration and it's really interesting. Apparently you can get really even radiation if you maximize breakup? I guess this is the idea behind the NXT / DMR stuff. Strange that it hasn't appeared in high-end stuff and everyone's just waiting for the patents to expire... https://vxm.com/NXT.html

 

[Matt_Holland]

I know this thread is old AF but I wanted to make a note on beaming, because I didn't understand it myself for a long time:

Beaming is an unavoidable consequence of a large cone-shaped diaphragm putting out high frequencies. When you have wavelengths smaller than the cone coming from the cone, they end up interfering with each other and cancelling out at off-axis angles. So there is basically no such thing as a large full-range cone-shaped driver that doesn't suffer proportionally from beaming.

Someone better at geometry and physics might have something to add here, but I think it's also problem with any shape of diaphragm, not just cone, since the wavefront will emanate hemispherically, right?

This is true for drivers that behave close to a theoretical piston. As soon as modal behaviour is involved (normally cone “breakup”) the driver moves always from pure piston behaviour and depending on how the breakup modes behave, can give a wider dispersion compared to the pure piston of the same diameter.

BMR drivers aim to control their modal behaviour such that there is a smooth transition from piston operation into modal operation where a small number of carefully designed bending modes give very wide dispersion of high frequencies.

A distributed mode loudspeaker (e.g. NXT) can be any shape and has entirely modal behaviour. Beaming does occur but in a very different way to pistons and is a function of the stiffness of the driver material. If well designed they can have very wide dispersion at all frequencies albeit with often quite ragged polar response.

 

[617]

This is true for drivers that behave close to a theoretical piston. As soon as modal behaviour is involved (normally cone “breakup”) the driver moves always from pure piston behaviour and depending on how the breakup modes behave, can give a wider dispersion compared to the pure piston of the same diameter.

BMR drivers aim to control their modal behaviour such that there is a smooth transition from piston operation into modal operation where a small number of carefully designed bending modes give very wide dispersion of high frequencies.

A distributed mode loudspeaker (e.g. NXT) can be any shape and has entirely modal behaviour. Beaming does occur but in a very different way to pistons and is a function of the stiffness of the driver material. If well designed they can have very wide dispersion at all frequencies albeit with often quite ragged polar response.

@kemmler3D A cone entering a breakup region can be thought of as an array of smaller radiators - and each of these radiators, being smaller, will radiate more widely than the pistonic cone they are part of. However, it is the nature of breakup that some of these regions will be moving out as others are moving in, and as a result, they will interfere with each other, and the patterns of interference will change dramatically with frequency. When the cone is reproducing many frequencies, as is the case of a midwoofer, it is safe to assume that the breakup region is too chaotic to satisfy the demands of any radiation pattern you want from the system. So, traditionally, speaker designers only accept breakup at the top end of a tweeter, where it is hopefully ultrasonic.

BMR drivers use small weights added to the cone to shape the first breakup modes so that they are annular in shape and have relatively predictable radiation. BMRs are a miracle technology, especially considering the cost, only diminished by the fact that these masses, and the small diaphragm size, reduce efficiency enormously. However, they do create a region of 'controlled breakup' which really is controlled, and things only get 'uncontrolled' at frequencies where it starts to matter less; they really can be used without tweeters.

If we go back to first principles of audibility, the problems with full range drivers are that they lack bass and lack treble dispersion. To a large extent, these deficiencies can be mitigated by a subwoofer and accepting a slightly chaotic upper treble response; which is fine, but why bother?

If you really want an amazing wideband midrange, SB Satori probably makes the best ones at the moment that I am aware of. Scanspeak has traditionally optimized their paper midwoofers for greater bass dynamics, which is a sensible design direction, but I am happy that SB decided on the wideband driver as a design goal for their driver. Scanspeak does make a nod towards wideband midrange with the ellipticor drivers, with an 18cm/7" unit which radiates simply up to 4.5khz. Quite good for the size, but you pay for it.

 

[Matt_Holland]

BMR drivers use small weights added to the cone to shape the first breakup modes so that they are annular in shape and have relatively predictable radiation. BMRs are a miracle technology, especially considering the cost, only diminished by the fact that these masses, and the small diaphragm size, reduce efficiency enormously. However, they do create a region of 'controlled breakup' which really is controlled, and things only get 'uncontrolled' at frequencies where it starts to matter less; they really can be used without tweeters.

So, assuming we accept we can solve beaming with a technology such as BMR, the remaining problems are IMD, and power handling. To get good HF from the any driver we need low voice coil inductance and a very short voice coil former, which precludes the use of thick gauge wire and lots of wire. So we really need to focus on making a BMR a mid/tweeter, which at the same times goes some way to addressing the IMD issue as we need to limit the driver to about 250-400Hz. This keeps excursion to a minimum and our SPL is thermally limited.

BMRs from Cotswold are reasonably efficient. I believe typically in the region of 87-90dB/2.83V. So very useable.

Hardly anyone has adopted them, and I think the reasons are:
at the high-end of the market they don’t look expensive enough, in fact they look low-end.
At the pro end of the market they don’t play loud enough and wide dispersion is not desired.
At the low end of the market they are too expensive and everyone is happy with normal mid-bass plus tweeter designs.

 

[gnarly]

Hardly anyone has adopted them, and I think the reasons are:
at the high-end of the market they don’t look expensive enough, in fact they look low-end.
At the pro end of the market they don’t play loud enough and wide dispersion is not desired.
At the low end of the market they are too expensive and everyone is happy with normal mid-bass plus tweeter designs.

My take is that they simply don't sound so good.
They rely on destructive interference for their wide dispersion patterning...and can't really convey clean HF/VHF, from anything approaching a more singular HF/VHF source..

 

[Matt_Holland]

My take is that they simply don't sound so good.
They rely on destructive interference for their wide dispersion patterning...and can't really convey clean HF/VHF, from anything approaching a more singular HF/VHF source..

Which examples have you heard?
In my experience they compete well against dome tweeters, even their measured response.
Agree their off axis can get a little lumpy, so possible quite room dependent?

 

[norman bates]

8" full range driver basically has the listening area of about a head at 7' distance.
2 person wide (shoulder to shoulder) at 12'.

However, you can have a driver with a climbing response and get lucky enough to sit off axis so the HF doesn't climb nearly as much.

It would be neat if there were some recordings (right in front of the speaker) where they compared (flattened freq response) very transient sounds (striking a wood block, jingling keys, rain, voice, a snare drum), comparing a full range driver to a 6db time phase slanted acoustic centered (think thiel/vandersteen/dunlavy) and say a 18db/18db crossed speaker.

I think stereophile mentions people like (on a speaker's step response) where the tweeter fires first then hands off to the midrange or mid/woofer.

Using headphones, we can hear the distortion/frequency response much easier than the phase thing.
Honestly, I found it sounds different, not necessarily superior.

I think Dunlavy would have a live violin playing in an anechoic chamber versus his speakers and others. Without a live instrument, I'm sure we can hear a difference, but qualifying which is better, well, up to the buyer I guess.

Music, let alone in a room sitting 10' away, it would be harder to detect the differences in phase/time/etc (assuming dispersion pattern are the same).

granted, there would be zero bass from the little guys sitting 10' away, lol.

 

[617]

They will never sound like a dome tweeter simply because they have wider dispersion than even a small dome tweeter. Look at the graphs.

https://www.parts-express.com/pedocs/specs/297-216--tectonic-tebm35c10-4-spec-sheet.pdf

Dispersion is actually wider at 20k than 9k. The projection of high frequencies is totally unlike pistonic radiators and interacts with the room differently. Might be good, might be bad, might be a matter of taste. I think we need to appreciate that our entire experience of 'good sounding speakers' are speakers which are omni in the bass and gradually laser beams at HF, and this is literally the only transducer that works in the reverse.

 

[nowonas]

I'd like to address this in two parts.

First part:
If a single wide-band driver and a multi-way both have the 'same frequency magnitude response', their phase alterations will be the same at the ends of the spectrum.
The same 'frequency magnitude response' means both speakers have the same low-end and high-end frequency response roll-offs.

But those system roll-off regions, are the only frequencies where phase alterations will be the same.
In between, through the main spectrum, their phase alterations will not be the same. (other than special cases where the multi-way uses only first-order IIR or linear phase xovers.

The single wide-band driver will have flat phase, due to not having any xovers.
The multi-way will have phase rotations depending on number of ways/xovers, and crossover orders.

Second:
I agree that a xover doesn't pose a problem in the time domain.
Because my definition of 'time domain' is just that...time. As in seconds, milliseconds, microseconds.

An impulse response shows signal amplitude vs time. Doesn't show either frequency magnitude response or phase.
FFT math derives frequency response from the impulse response...and freq response is defined as complex freq response which includes freq magnitude and freq phase.

My intended point here is that phase is a component of the frequency domain...and not of the time domain.
Time is a constant. Phase is a rotation of frequency's relative cyclical alignments.

They are simply not substitutes ime, one for the other.
The idea that phase can be equated into a unit of time for a given frequency, and then used as a substitute for time alignment....
.....is a very suboptimal but appears oh so commonly used in IIR xover design.

Ok, off soap box and back to topic...
I say xovers pose no time domain problem. They cause a phase rotation problem. (other than first-order IIR or lin phase

You are right that phase is a component of frequency, but it is also a component of time. Since phase shift is increasing with time, it is impossible to only have a phase rotation problem (as you state) and not a time problem as well.

 

[dasdoing]

phase is a component of the frequency domain...and not of the time domain.

that's like saying light-year is a component of the time domain....and not of the distance domain

 

[gnarly]

Which examples have you heard?
In my experience they compete well against dome tweeters, even their measured response.
Agree their off axis can get a little lumpy, so possible quite room dependent?

Sure. I owe a better explanation re my preferences..

The single driver speakers are great imo, in comparison to conventional full-range cones.
BMR's ability to go low, and in my opinion sound about the same up high, as small cones...makes then a great small single-driver speaker choice.

When I've heard arrays of them, they sound dull in comparison to more point-source like speakers.
But in fairness, any type multiple-driver HF/VHF array sounds comparatively dull I think. (I've built large line arrays and CBT's with small cone drivers.)

My overall feeling about single full-range drivers, is that they are excellent when used singly and only used for applications they fit...
when low SPL, breakup mode highs, and usually severely truncated bass extension....all are OK.
It's really cool though, how BMR's help mitigate the bass extension part.

 

[Middle Earth]

My hearing is degraded at the high-end so it is more realistic for older folk like me.
I agree with what @daftcombo stated, I.e. “… a single full range speaker can sound good”