Single full range drivers

[KSTR]

Physics speaks against single driver speakers. It it wasn't due to many other problems, intermodulation cannot be avoided. I'm not referring to motor generated IM, but to phase modulation aka Doppler effect. There is nothing one could do about it, because it is inherent to the dynamic driver, and only mitigated with strict bandwith limiting for the individual driver..

Well, Doppler distortion can be handled. Two makers of active speakers have implemented it, one in the analog domain (Backes&Müller) and one in the digital domain (Schanks Audio). Both use motional feedback on the mid-woofer drivers to keep the regular motor/suspension distortion low enough at large excursions so that Doppler distortion actually becomes dominant.

A scientific paper on Doppler distortion correction: https://acta-acustica.edpsciences.org/articles/aacus/pdf/2020/01/aacus200002s.pdf

 

[fineMen]

Well, Doppler distortion can be handled. Two makers of active speakers have implemented it, one in the analog domain (Backes&Müller) and one in the digital domain (Schanks Audio). Both use motional feedback on the mid-woofer drivers to keep the regular motor/suspension distortion low enough at large excursions so that Doppler distortion actually becomes dominant.

A scientific paper on Doppler distortion correction: https://acta-acustica.edpsciences.org/articles/aacus/pdf/2020/01/aacus200002s.pdf

Thanks for sharing! Well, of course the Doppler can be corrected. To continuously measure the cone's position helps a lot ;-) But is that practical for an otherwise relatively limited device?

The literature proves the effect to be relevant. Why is each speaker you mention a multi-way design? Why don't I know of a single driver speaker using the correction?

 

[KSTR]

Thanks for sharing! Well, of course the Doppler can be corrected. To continuously measure the cone's position helps a lot ;-) But is that practical for an otherwise relatively limited device?

The literature proves the effect to be relevant. Why is each speaker you mention a multi-way design? Why don't I know of a single driver speaker using the correction?

Well, as you say (and I completely agree), wideband single driver is a compromise to begin with and I would assume that regular distortion is already dominant at excursions that are large enough for significant Doppler distortion, so not much benefit in sight.
If we could have a true widebander based on "distortion-free" motors like the Purifi things might change, though. Wobbling +-10mm at 60Hz will have impact, for sure
IMHO widerbanders can be truly excellent for low-volume desktop monitors with reasonable bass cut, and for horn-loading, obviously.

 

[Frank Dernie]

Well, as you say (and I completely agree), wideband single driver is a compromise to begin with and I would assume that regular distortion is already dominant at excursions that are large enough for significant Doppler distortion, so not much benefit in sight.
If we could have a true widebander based on "distortion-free" motors like the Purifi things might change, though. Wobbling +-10mm at 60Hz will have impact, for sure
IMHO widerbanders can be truly excellent for low-volume desktop monitors with reasonable bass cut, and for horn-loading, obviously.

IMO the big problem of full range drivers is sudden changes in frequency output and phase and directivity due to the multitude of resonant modes in various parts of the diaphragm at higher frequencies.
A bit of doppler distortion on top of that is a drop in the ocean.

The only possible long term is if a maker learns to exploit the resonant modes by getting them to radiate evenly, like in a BMR.

 

[thewas]

I agree, in my experience the two biggest problems of full range drivers are a rapidly changing directivity (BMRs usually cannot go low enough) and very high multitone distortions, like Frank writes above doppler distortion is minor in comparison.

 

[holdingpants01]

there's this weird argument of a crossover distortion in multiway speakers and single driver speakers are often presented as a remedy. This makes me wonder, are there some multiway constructions that doesn't use crossover? It's technically possible to use drivers with matching roll offs, doesn't mean it would sound good or even acceptable, but is there something like this?

 

[nowonas]

I know that the thread is about single drivers, but for me, the biggest advantage for single drivers is that it allows for really low crossover points (200-300hz) where the ear is not sensitive. You can then have a two-way system where the single driver play from 200-20.000hz, this is known as a FAST design. By removing the areas of the speaker which have most energy (bass), you reduce the IMD and doppler effects drastically. I see that a lot of people here mention that single drivers are a flawed design, in my opinion the same argument can be used for speakers that are crossed in the most sensitive areas of the ear. ( 500-4000hz). With speakers with higher crossover points it is physically impossible to have a good vertical dispersion, in addition to the other challenges with analog crossovers

 

[computer-audiophile]

there's this weird argument of a crossover distortion in multiway speakers and single driver speakers are often presented as a remedy. This makes me wonder, are there some multiway constructions that doesn't use crossover? It's technically possible to use drivers with matching roll offs, doesn't mean it would sound good or even acceptable, but is there something like this?

Yes there is. My first prototype with Greencone speakers was something like this. The full range driver ran completely free of external circuitry and did virtually all the work. It was just a super tweeter high coupled via a capacitor for some sparkle in the highs. The speaker was then measured and the experts were amazed to see the well-balanced frequency response and good bass response. Nobody had expected that. Nor do I. I had only gone by ear.

Audio experts interpreting the frequency response.
Dietmar Hampel (Germany), Kari Nevalainen (Finland), Jean-Michel Le Cléac'h (France).

I am very grateful to these gentlemen for giving my speakers their attention.

 

[holdingpants01]

Yes there is. My first prototype with Greencone speakers was something like this. The full range driver ran completely free of external circuitry and did virtually all the work. It was just a super tweeter high coupled via a capacitor for some sparkle in the highs. The speaker was then measured and the experts were amazed to see the well-balanced frequency response and good bass response. Nobody had expected that. Nor do I. I had only gone by ear.

View attachment 289528

Audio experts interpreting the frequency response.
Dietmar Hampel (Germany), Kari Nevalainen (Finland), Jean-Michel Le Cléac'h (France).

I am very grateful to these gentlemen for giving my speakers their attention.

View attachment 289529

Man I remember those, I don't know if they were presented in some hifi magazine back then or local hifi board, but they are imprinted in my memory, what a surprise to cross the roads after all! Was the box open on the bottom or I remember it wrong?

 

[computer-audiophile]

Man I remember those, I don't know if they were presented in some hifi magazine back then or local hifi board, but they are imprinted in my memory, what a surprise to cross the roads after all!

At that time I had a highly frequented audio homepage where I presented such projects in detail. Much of it served as inspiration for other DIY colleagues. Later I developed these loudspeakers further and it was also reported in audio magazines. I also presented my stuff at international scene meetings - with some success. I do this only as an amateur, I must say. I am not in the audio business.

Was the box open on the bottom and top?

Open on the bottom and slots on the back. My later designs which I called Reso|Beta, I did describe as 'distributed port enclosure'.

 

[holdingpants01]

At that time I had a highly frequented audio homepage where I presented such projects in detail. Much of it served as inspiration for rebuilding. Later I developed these loudspeakers further and it was also reported in audio magazines. I also presented my stuff at international scene meetings - with some success. I do this only as an amateur, I must say. I am not in the audio business.


Open on the bottom ans Slots on the back. My later designs hich I called Reso|Beta i did describe as: Distributed port enclousure.

Awesome, I loved that this was almost complete opposite of how the loudspeakers suppose to be made, yet it worked well enough to be widely appreciated

 

[computer-audiophile]

Awesome, I loved that this was almost complete opposite of how the loudspeakers suppose to be made, yet it worked well enough to be widely appreciated

Yes, thank you, it did. I was pleased that artists, musicians and composers also used and valued my speakers and amplifiers for their purposes. This is exactly in my mind, because I love music and art above all.

 

[Waxx]

Physics speaks against single driver speakers. It it wasn't due to many other problems, intermodulation cannot be avoided. I'm not referring to motor generated IM, but to phase modulation aka Doppler effect. There is nothing one could do about it, because it is inherent to the dynamic driver, and only mitigated with strict bandwith limiting for the individual driver..

The single driver thing has its followers for reasons that are clearly understood. I see it as an educational toy, so why not? But the real thing, namely to produce sound with bearable distortion, wide bandwith and reasonable dispersion at comfortable levels is something else.

The Sibelius guy--I didn't watch the whole interview, though, presumably doesn't know about the difference between a microphone and a human ear, and what recording technology really is for. Quite a narrow bandwith ;-)

The actual design of the Sibelius (the engineering part) is done by Scott Lindgren, not by the owner of the company Harley Lovegrove. And Scott Lindgren is a scientist (PhD in history and a reputed speaker designer by diy study) working for decades on single driver fullrange TL and horn type speakers designs as consultant based on measurments and science. He works especially with and for Mark Audio where he is first critic of the driver designer Mark Fenlon but also take other consultant jobs, also for multiway designs.

The Sibelius is a TQWT with a OEM Mark Audio Alpair 10 driver (somewhere between a 10.2 and a 10.3 says Scott on DIYAudio where he is known as Scottmoose). The way it's build (from massive french oak) and the final visual design are done by Harley Lovegrove, the owner of the company, and the build quality of the one i saw and heared is exception good. Sound is very similar to my own MLTL fullrange design with the CHN110 (menstion elsewhere). It's very good, broader in dispertion than most would expect and relative flat in response. The bad sides is that it's limited in volume (you want to sit no further than 3m (+/- 10ft) from the speaker and keep the volume reasonable. A bit like my CHN110 MLTL. It's a good design for the smaller European living rooms, maybe less for the cliché big houses of the Americans.

The biggest difference between my diy build and this Sibelius is the build quality of the enclosure (cheap mdf build by amateur vs expensive high quality solid wood french oak build by experienced carpenters) and the very detailed finish of the build. That is what you pay for mostly i think (and the fact that it's handbuild in France).

 

[fineMen]

The actual design of the Sibelius (the engineering part) is done by ...
It's very good, broader in dispertion than most would expect and relative flat in response. The bad sides is that it's limited in volume ...

I don't see any, not even thought-of virtue with a single driver speaker box as we have exceptionally well designed coaxials at hand (KEF, GENELEC). To use those with substantial support by a bass/lower midrange driver finishes any comparision off. I understand the charms of a single diver speaker box at least remotely, but that would be about the speaker box, no about the music, right?

 

[efnord]

I've got 5 of these in progress: https://projectgallery.parts-express.com/uncategorized/smoke-and-fire-full-range/ - https://www.madisoundspeakerstore.c...uvia-seven-hd-4-metal-cone-full-range-chrome/ is the driver. They're going into a bedroom home theater setup.

 

[sarumbear]

The Fane 12-250TC is not bad as a single driver.
45-17000Hz.
It will beam of course but sounds pretty damn good.

 

[Waxx]

You (and Fane actually also on their website) should give full info on their graphs:

and their measurements are different than mine actually (speaker in box). I'll have to find those back in my archive. But in reality it's dispertion is fairly controlled untill 30° off axis. The blue line is 45* off axis. That is not as good as a dome or horn tweeter can do, but quiet good for a fullrange driver of this size. Especially if you know that this driver is actually ment for floormonitors for stages, not for hifi. I did use it for an garden system, that is good enough to use inside also (i did for a while) but i do use some passive eq on it.

 

[Bach]

When built in a device like a hair dryer of a barber then directivity is no problem nor is max. spl.
It is then more like a big headphone but without any direct contect with your head. So wearing comfort is no issue.

 

[sarumbear]

You (and Fane actually also on their website) should give full info on their graphs:

As you said, the manufacturer doesn’t give any extra information. I simply copied their chart. How am I supposed to give more information? Care to explain?

However, what matters is that high frequency step. Check that unlike @amirm’s charts they are in 10dB increments; the step would like twice worse otherwise.

 

[Waxx]

As you said, the manufacturer doesn’t give any extra information. I simply copied their chart. How am I supposed to give more information? Care to explain?

However, what matters is that high frequency step. Check that unlike @amirm’s charts they are in 10dB increments; the step would like twice worse otherwise.

That's why you use eq, be it passive or active (analog or dsp). And this is easy to tame in any way. I used a small cap, a small inductor and 2 small resistors for a passive eq to tame that. With dsp it's probally even easier to do (but i wanted a all in one that i can connect with every system so passive).

And what i showed comes from the spec sheet at their site. Always check the pdf spec sheet of a driver, it often contains more info than the webpage itself.