Dipole vs Box speakers

[Neuro]

The perceived sound of the dipole speaker is, as I see it, essentially different from the box speaker.
Exactly what physical facts are related to these perceived differences and exactly how are these physical facts related to best subjective experience?
What are the advantages and disadvantages of dipole speakers compared to box speakers?

 

[Tangband]

The perceived sound of the dipole speaker is, as I see it, essentially different from the box speaker.
Exactly what physical facts are related to these perceived differences and exactly how are these physical facts related to best subjective experience?
What are the advantages and disadvantages of dipole speakers compared to box speakers?

You have to read hundred of pages about dipole speakers and different constructors gonna tell you different advantages. If you have listened to a Magnepan loudspeaker, then you will have a clue how a dipole speaker sounds like in a room.
You can also read about Linkwitz lx521 at his homepage.
This is a good thread:

Is the LXmini by Siegfried Linkwitz the answer for home audio?

So just to get it out there, i'm not an expert or anything close to that. so take whatever I say here with a grain of salt, I'm just discussing what I understood from different speaker building/purchasing trends and processing it all together. This discussion is also for home audio, and i also...

www.audiosciencereview.com

 

[DVDdoug]

The sound waves from the back of the speaker are out-of-phase from the front which means low frequencies (longer wavelengths) tend to get canceled (depending on the size of the baffle).

And the sound from the back is, of course, reflected before it mixes with the direct and other reflected sounds and hits your ear. So the room will have a bigger influence on the sound than a forward-firing speaker.

I assume it's mainly the increase in reflected sound that makes them desirable to some listeners (in some rooms?). If I'm remembering correctly, the old Bose 901 had 1 forward-facing driver and 8 indirect drivers.

 

[Tangband]

The sound waves from the back of the speaker are out-of-phase from the front which means low frequencies (longer wavelengths) tend to get canceled (depending on the size of the baffle).

And the sound from the back is, of course, reflected before it mixes with the direct and other reflected sounds and hits your ear. So the room will have a bigger influence on the sound than a forward-firing speaker.

I assume it's mainly the increase in reflected sound that makes them desirable to some listeners (in some rooms?). If I'm remembering correctly, the old Bose 901 had 1 forward-facing driver and 8 indirect drivers.

One also need a big enough room, because a dipole speaker cant be placed near the front wall, you seems to need about 1 meter of distance from the frontwall to get good sound.

 

[DanielT]

Some like them because they think it creates "sound space" from that sound. Others find that the sound is "smeared" and becomes cloudy.
I know fuzzy concepts. Which are subjective terms and can mean pretty much anything really. Best to add.

It is about how dipoles create reflections of sound in the listening room. What DVDdoug is into.

It depends a lot on the design of the room and the placement of the speakers. The further from the back wall dipoles are placed, the smaller the dipole sound (if you can call it that) you get. Plus that what Tangband say in#4.

You can try with some dipoles and see if you like it.

Speakers with open baffles, dipoles, most likely need box bass modules added to make it sound good.

Electrostatic speakers, advantage often low distortion but they can also have uneven FR. EQ may be needed.

Edit:
The design principle dipole has been known for a long time. The question you can ask yourself is why are there so few such dipole speakers on the commercial market?

 

[DanielT]

As an acoustic experiment, buy some of these and try them yourself. The entire panel they sit on becomes the speaker then. Dipole speakers. A few sheets of suitable material is all you need.

Dayton Audio - DAEX32EP-4 Thruster 32mm Exciter 40W 4 Ohm

DAEX32EP-4 Thruster 32mm Exciter 40W 4 Ohm

www.daytonaudio.com

Edit:
In and of itself, I had bought some curtain rod at, for example, IKEA and some wooden studs and put the curtain rod on. I had hung the panels on the curtain rod. I would have also chosen larger panels, but hey as an experiment just try it out.

 

[Duke]

I assume it's mainly the increase in reflected sound that makes them desirable to some listeners (in some rooms?). If I'm remembering correctly, the old Bose 901 had 1 forward-facing driver and 8 indirect drivers.

Imo two advantages generally accrue from the dipole radiation pattern.

The first is, that the backwave energy of a dipole is (usually) spectrally-correct to a significantly greater extent than is the typically the case for the off-axis energy of conventional speakers, which in turn tends towards natural-sounding timbre and relative freedom from listening fatigue.

The second is, the arrival time of the backwave can be favorably manipulated by increasing the reflection path length. On the other hand, a dipole's clarity is degraded if that reflection path length is too short. Ime one meter distance from the "front" wall (as mentioned by @Tangband) is about where the backwave transitions from being net detrimental to being net beneficial.

Ime with a sufficiently long arrival-time delay for the backwave, corresponding to at least 1.5 meters in front of the wall, a good dipole speaker can achieve a "you are there" presentation, wherein the venue spatial signature on the recording is perceptually dominant. The reasons for this are complicated, and I'm not saying dipoles are the only way to get "there", but ime this approach usually requires a lot less room acoustic treatment than trying to accomplish the same thing with conventional speakers.

 

[zvukofor]

There's also a good hypothesis why dipoles sound so different and often more pleasing, it is about perception and our brain's ability to remove a room acoustics, just like it does with a real acoustic sound sources, like voice or musical instrument. Dipoles "fills" the room better, so we're able to remove room acoustics better. At least it is true for speakers (even closed) with a flat off-axis response. Dipoles radiate less LF in room too, so modes of the room are less disturbed, adding even more naturalness to a picture.

 

[jim1274]

Edit:
The design principle dipole has been known for a long time. The question you can ask yourself is why are there so few such dipole speakers on the commercial market?

The same can be said for other “non-box” speakers like Omnis and bipoles—not even much discussion of all 3 types here on the forum. I found this thread, one of only a handful about dipoles when looking for info. After 50+ years of nothing but unipolar “box speakers”, I got some Omnis and was so taken by the immersive sound and huge soundstage, the next step seemed to be investigate other designs that have potential for a similar effect, bipoles and dipoles specifically. I’m testing some Definitive Technology bipolars now, some dipoles next on deck.

Back to your comment, while there are only a handful of Omni manufacturers, even fewer bipolar ones out there that I’ve found. I understand the potential negatives of all 3 designs, but can hardly listen to box speakers now.

 

[TurtlePaul]

The obvious reason few manufacturers make pure dipoles is that the baffle width needs to be several feet wide to get anything approaching non-anemic bass. While the radiation pattern of dipoles is interesting, most speaker designers and consumers are not willing to make that trade. A ported speaker in a 1.5 cu ft box with a 6.5” woofer can humiliate a two foot wide dipole on bass extension.

 

[jhenderson0107]

The obvious reason few manufacturers make pure dipoles is that the baffle width needs to be several feet wide to get anything approaching non-anemic bass. While the radiation pattern of dipoles is interesting, most speaker designers and consumers are not willing to make that trade. A ported speaker in a 1.5 cu ft box with a 6.5” woofer can humiliate a two foot wide dipole on bass extension.

Many dipoles, such as those designed by Linkwitz, employ W- or H- frames for the woofers to avoid inconveniently-wide baffled widths. The woofer subassembly on the Linkwitz LX-521s are only 13" wide. That design uses two 10" long-throw woofers in an H- frame and the bass performance is exceptional. No subs needed for music playback at any rational SPL.

 

[olieb]

Many dipoles, such as those designed by Linkwitz, employ W- or H- frames for the woofers to avoid inconveniently-wide baffled widths. The woofer subassembly on the Linkwitz LX-521s are only 13" wide. That design uses two 10" long-throw woofers in an H- frame and the bass performance is exceptional. No subs needed for music playback at any rational SPL.

Linkwitz certainly did his best to arrive at an acceptable solution but in the end you need two 10'' drivers to get a bass that an 8'' can produce otherwise. At least in respect to SPL.
And bass is only one problem, it is quite difficult to have a dipole in HF.
In the end dipoles are rather exotic solutions that cater only to few people.
Maybe that would be different if the last question of the OP were answered.

What are the advantages and disadvantages of dipole speakers compared to box speakers?

Disatvantages are obvious and therefore immedioately mentioned (here and elsewhere). But what about the advantages? This is much less clear.

 

[jim1274]

The obvious reason few manufacturers make pure dipoles is that the baffle width needs to be several feet wide to get anything approaching non-anemic bass. While the radiation pattern of dipoles is interesting, most speaker designers and consumers are not willing to make that trade. A ported speaker in a 1.5 cu ft box with a 6.5” woofer can humiliate a two foot wide dipole on bass extension.

Jhenderson beat me to the punch on the Linkwitz comment. What about a “mostly dipole” like the Heil ESS AMT 1b that is dipolar from 700hz and up?
Not “pure”, that is true.

https://www.hifiengine.com/manual_library/ess/amt-1.shtml

Or the “revival”:

AMT-1D Revival (Pair)

The AMT-1D Revival is the spiritual successor to the legendary AMT 1D. Characterized by excellence in every detail, you'll find a build and finish designed to last, equipped with the latest drivers and crossovers. Please note that each AMT-1D Revival is carefully crafted by hand, making each...

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[jim1274]

Maybe that would be different if the last question of the OP were answered.

Disatvantages are obvious and therefore immedioately mentioned (here and elsewhere). But what about the advantages? This is much less clear.

The bigger soundstage created by a dipole seems like the biggest potential advantage? If one wants to trade-off that for other speaker attributes, then it seems a conventional box speaker is the a lot less expensive way to achieve “good sound”. After going from 50 years of “box” speakers, as much as I’ve enjoyed them, the recent omni experience changed my view on “good sound”, the deep soundstage and immersion having added another dimension I find compelling.

 

[Blumlein 88]

The bigger soundstage created by a dipole seems like the biggest potential advantage? If one wants to trade-off that for other speaker attributes, then it seems a conventional box speaker is the a lot less expensive way to achieve “good sound”. After going from 50 years of “box” speakers, as much as I’ve enjoyed them, the recent omni experience changed my view on “good sound”, the deep soundstage and immersion having added another dimension I find compelling.

You have unravel the dipole from how it makes sound. ESL's have lower distortion, run full range, are driven over the entire surface, are inefficient and require lots of power. The dipole part is only part of why people like them. Maggies do something like the same thing, but with flat magnetic panels and ribbons, and the single diaphragm is not driven full range. Then you have dipoles that are made with conventional speakers. So some of it is being cross-over-less, others are not cross over less. Others are regular speakers.

If you have 4 of any speaker, you could experiment a little. Put them back to back and in phase for bipole use, or out of phase for dipole use or just one for the normal unipolar use. By the way the old Mirage M1 and M3 speakers were pretty good bipoles.

I've had lots of dipole speakers. Quad ESL57, ESL 63, Acoustat 2 (and friends with most of the other models), Soundlabs. All ESL in that group. Then I've had both the older Maggies, and some newer Maggies with ribbon tweeters. All of these are large, difficult to ship, inefficient making them peculiar about amps, and all capable of being very enjoyable. Oh, and any decent dipole requires more space behind it to work well. So all contribute to them being expensive to work well, and you need an expensive amp, and you need the space for them to work. Some are beamy and pretty much a one person speaker.

I'm not discouraging you, just giving you an honest accounting. Jim Thiele when he started his speaker company considered doing dipoles, panels ESLs, but decided they had some advantages, but some physically unsolvable disadvantages. But then so do regular speakers. My opinion is panels driven full range have some advantages and some disadvantages. You'll have to cater to those needs which are more difficult to make work vs other good box speakers. But not that difficult. In my opinion panels with regular woofers is a no go (unless that woofer stays below 100 hz). Panels with different parts covering the different frequencies is sort of giving you back all the problems with a 2 or 3 way box speaker.

 

[jim1274]

You have unravel the dipole from how it makes sound. ESL's have lower distortion, run full range, are driven over the entire surface, are inefficient and require lots of power. The dipole part is only part of why people like them. Maggies do something like the same thing, but with flat magnetic panels and ribbons, and the single diaphragm is not driven full range. Then you have dipoles that are made with conventional speakers. So some of it is being cross-over-less, others are not cross over less. Others are regular speakers.

Some of this might be more appropriate over on the Omni thread, but briefly: I have a pair of Heil ESS AMT 1B dipoles that I put in the system just about an hour or so ago, mainly just as a soundstage comparison vs the Omnis. I found it deeper and wider than the Definitve Technology bipolars that were being tried after the Duevels. The AMTs were much closer to the Omni, but expected that with a wide horizontal dispersion bipole tweeter crossed over pretty low.

If you have 4 of any speaker, you could experiment a little. Put them back to back and in phase for bipole use, or out of phase for dipole use or just one for the normal unipolar use. By the way the old Mirage M1 and M3 speakers were pretty good bipoles.

I've had lots of dipole speakers. Quad ESL57, ESL 63, Acoustat 2 (and friends with most of the other models), Soundlabs. All ESL in that group. Then I've had both the older Maggies, and some newer Maggies with ribbon tweeters. All of these are large, difficult to ship, inefficient making them peculiar about amps, and all capable of being very enjoyable. Oh, and any decent dipole requires more space behind it to work well. So all contribute to them being expensive to work well, and you need an expensive amp, and you need the space for them to work. Some are beamy and pretty much a one person speaker.

ESL is the next piece of the puzzle here, still working on shipping 2/3 across the country without original crates. I Have a Benchmark DAC3 and AHB2 amp acquired specifically from recommendation by Roger at Soundlabs. I’ll probably need a second AHB2 to run dual mono, but cross that bridge when I come to it.

I'm not discouraging you, just giving you an honest accounting. Jim Thiele when he started his speaker company considered doing dipoles, panels ESLs, but decided they had some advantages, but some physically unsolvable disadvantages. But then so do regular speakers. My opinion is panels driven full range have some advantages and some disadvantages. You'll have to cater to those needs which are more difficult to make work vs other good box speakers. But not that difficult. In my opinion panels with regular woofers is a no go (unless that woofer stays below 100 hz). Panels with different parts covering the different frequencies is sort of giving you back all the problems with a 2 or 3 way box speaker.

Not discouraging me at all. This has been an adventure and journey after 50 years of “box” speakers (some enjoyed immensely), if nothing else better developing my listening skills as well as learneing a lot from generous folks like you. I know I’m in the minority, but the box speakers lack the immersion and soundstage of the Duevel and even this AMT one. Maybe I’ll feel differently after more critical listening, but I want to explore all the options. I can see where others would find what conventional speakers do better of more value.

 

[jim1274]

Imo two advantages generally accrue from the dipole radiation pattern.

The first is, that the backwave energy of a dipole is (usually) spectrally-correct to a significantly greater extent than is the typically the case for the off-axis energy of conventional speakers, which in turn tends towards natural-sounding timbre and relative freedom from listening fatigue.

The second is, the arrival time of the backwave can be favorably manipulated by increasing the reflection path length. On the other hand, a dipole's clarity is degraded if that reflection path length is too short. Ime one meter distance from the "front" wall (as mentioned by @Tangband) is about where the backwave transitions from being net detrimental to being net beneficial.

Just measured and I my HEIL ESS AMT 1b dipoles are a little over 4’ from the front wall, remembering your suggestion of 1M minimum when reading this post earlier.

Ime with a sufficiently long arrival-time delay for the backwave, corresponding to at least 1.5 meters in front of the wall, a good dipole speaker can achieve a "you are there" presentation, wherein the venue spatial signature on the recording is perceptually dominant. The reasons for this are complicated, and I'm not saying dipoles are the only way to get "there", but ime this approach usually requires a lot less room acoustic treatment than trying to accomplish the same thing with conventional speakers.

I’ll move it to 1.5M next, but sounds pretty good at 4’, maybe even better still out a bit further from the wall.

 

[StigErik]

The obvious reason few manufacturers make pure dipoles is that the baffle width needs to be several feet wide to get anything approaching non-anemic bass. While the radiation pattern of dipoles is interesting, most speaker designers and consumers are not willing to make that trade. A ported speaker in a 1.5 cu ft box with a 6.5” woofer can humiliate a two foot wide dipole on bass extension.

Most big dipoles like Quad ESL, Soundlab, Magnepan etc. fail on radiation pattern, bass extension and SPL since they try to cope with all of it at the same time, and those requirements are contradictory. They are typically wide to get some low end, but then the baffle gets way too wide for a good dipole radiation pattern. The Linkwitz LX521 is a good example of the opposite, where the radiation pattern is very good, and the low end kind of OK by using high excursion woofers.

 

[DanielT]

The same can be said for other “non-box” speakers like Omnis and bipoles—not even much discussion of all 3 types here on the forum. I found this thread, one of only a handful about dipoles when looking for info. After 50+ years of nothing but unipolar “box speakers”, I got some Omnis and was so taken by the immersive sound and huge soundstage, the next step seemed to be investigate other designs that have potential for a similar effect, bipoles and dipoles specifically. I’m testing some Definitive Technology bipolars now, some dipoles next on deck.

Back to your comment, while there are only a handful of Omni manufacturers, even fewer bipolar ones out there that I’ve found. I understand the potential negatives of all 3 designs, but can hardly listen to box speakers now.

Then you will like this tip. Starting on page 26, #504, Floyd Tools enters the discussion. He then answers and discusses various questions in the following pages.

omnidirectional loudspeakers = best design available

Happy to be shown examples and discuss. I think you missed the point that I was responding to someone saying Toole’s cartoon was “too smug”, so the teacher’s conundrum is about what style to use, eg humour “too smug”, math “too specialised/unintelligible to many”, short and pithy “lacking...

audiosciencereview.com

 

[jhenderson0107]

...and the low end kind of OK by using high excursion woofers.

In my experience, none who actually listen to the LX-521's describe their low-end as "kind of OK". A more typical response is "that's the most realistic bass I've ever heard". Of course, that's anecdotal and subjective.

When listening in the far field, for my musical preferences (mostly chamber music, solo instrumentals, occasional electronic, ambient and rock), the sound stage, impact and and tonality produced by the LX-521 4.0 system rivals my 7.3.6 home theater. The LX-521 experience is better for some recordings, worse for others but always fun and engaging. Only specific Atmos-mastered music can provide a superior experience on the 7.3.6 system.

When listening to music at my audio workstation in the near field (< 1m), I am very satisfied with a 2.1 system and desire no artificial sound-stage augmentation. The ambience within recordings is less contaminated by room effects and a simple full-range system is sufficient. Another identical 2.1 system in my den doesn't sound nearly as good for far-field listening due to room acoustics.

Surely, my equipment preferences are linked to my music preferences. Other musical preferences likely influence alternate gear selection. To each their own.