Horn vs Open baffle bass

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Konnichiwa,

jeff mai said:
I'd argue that "similar" is being rather kind to the dipole

Based on a friends fairly large (24" Cube) 2 X 18" per side W Dipole Woofers and based on what I am familar with from large horns, but not "architectural" ones I would say it is kind to the horn, not the dipole... ;-)

I will agree that the big Horns of Mr. Roggero are likely > 108db/1m/1W at 50Hz, probably also at 30Hz.... But they are exreme cases, with, for starter 6 pcs 15" Altec Woofers per side AND then around 3 X 2m+ Mouth Surface in 1/8 space, being "corner" types, which sugests a very low cutoff for the horn. And yes, this is "horns done right".

Now hands up all those whose significant others will allow speaker like this in the living room:

vue-en-long-rugi.jpg


:wave:

Sayonara
 
"Please correct me if I'm wrong, but this is my understanding of the difference between dipole and others when it come to room interaction. Dipoles radiate sound primarily in 2 directions front and rear because the sideways and vertical energies cancel each other out since they are out of phase. This results in reflections primarily on the front and back walls. Other speakers radiate sound in all directions and making the early reflections more complex and numerous so where reflecting surfaces meet (a corner) the pressure builds much more than with a dipole."

A dipole becomes a monopole as soon as the baffle gets to be too small! == a poor one at that -- it's also where front to back cancellations occur- there is no free lunch!

:att'n:
 
Magnetar said:
"Please correct me if I'm wrong, but this is my understanding of the difference between dipole and others when it come to room interaction. Dipoles radiate sound primarily in 2 directions front and rear because the sideways and vertical energies cancel each other out since they are out of phase. This results in reflections primarily on the front and back walls. Other speakers radiate sound in all directions and making the early reflections more complex and numerous so where reflecting surfaces meet (a corner) the pressure builds much more than with a dipole."

A dipole becomes a monopole as soon as the baffle gets to be too small! == a poor one at that -- it's also where front to back cancellations occur- there is no free lunch!

:att'n:
How does a dipole speaker stop radiating sound in both directions when the baffle is too small?
 
Kuei Yang Wang said:
Konnichiwa,

So, for the palatial mansions of the elite in imperial america clearly horns, for the small rooms found in Europe........
Sayonara

Thorsten - if you would indulge a question, please _grin_

My listening room is larger than some in the US but not as large as others _grin_

13.5 ft x 23.5 ft x 8.7 ft

or in meters

4.11 x 7.16 x 2.65

What do you think would likely be best in a room that size? I am crossing to Azurahorns at 134 hz.

Regards

Ken L
 
454Casull said:

How does a dipole speaker stop radiating sound in both directions when the baffle is too small?

It still radiating but you can't hear it. The front and back waves cancel due to being 180 degress out of phase. Here the dipole becomes the least efficient way and highest distortion method of coupling bass to your room. The extreme opposite of what I want..!

:cannotbe:
 
Konnichiwa,

Ken L said:
My listening room is larger than some in the US but not as large as others _grin_

in meters

4.11 x 7.16 x 2.65

What do you think would likely be best in a room that size? I am crossing to Azurahorns at 134 hz.

Dipole & Monopole combo with a crossover in the 35-40Hz region, one per channel. So perhaps 2pcs reasonable 15" Dipole Woofers per channel with a natural rolloff (after EQ?) around 40Hz and a single large sealed box woofer somewhere in the room?

Sayonara
 
Magnetar said:
A dipole becomes a monopole as soon as the baffle gets to be too small! == a poor one at that -- it's also where front to back cancellations occur- there is no free lunch!

I can't see any basis for that statement. Surely whether a speaker is a monopole or dipole is indicated by the polar response. The figure of 8 polar response of dipoles continues below the point where the baffle is small. The cancellations which you seem to describe as a negative point are a big part of the main advantages of dipoles bass. The result is near constant directivity, which means that the direct and reflected field are more closely matched, resulting in less coloration from the room. This is starting to go outside the current discussion of bass ...

I applaud your committment to creating your own horn-based sound system, clearly you know horns better than most.
 
Kuei Yang Wang said:
Konnichiwa,



Dipole & Monopole combo with a crossover in the 35-40Hz region, one per channel. So perhaps 2pcs reasonable 15" Dipole Woofers per channel with a natural rolloff (after EQ?) around 40Hz and a single large sealed box woofer somewhere in the room?

Sayonara

I can use my digital crossover for EQ and have a couple of Crown Com-tech 410's that I could use to make that active - Say maybe H-frames for the dipoles?

I had seriously considered dipoles at one point, but figured I would leave the bass till last.

your suggested approach has major benefits to me also in that I can easily implement it and easily build it -

Thanks for your response, I will be giving your suggested approach most serious consideration and thought.

Best regards

Ken L
 
paulspencer said:


I can't see any basis for that statement. Surely whether a speaker is a monopole or dipole is indicated by the polar response. The figure of 8 polar response of dipoles continues below the point where the baffle is small. The cancellations which you seem to describe as a negative point are a big part of the main advantages of dipoles bass. The result is near constant directivity, which means that the direct and reflected field are more closely matched, resulting in less coloration from the room. This is starting to go outside the current discussion of bass ....

I have built around 20 dipole systems and owned some commercial ones ie Magnepan, Soundlab, Inner Sound, Quad, Acoustat, Infinity, Martin Logan ----- ;)

Let me say it another way -- once the baffle is undersized (as in almost all open baffle bass systems) the panel/driver acts like a monopole as it becomes omni-directional in the low frequencies ACCEPT there is no linear, quality, low distortion bass to speak of because the front and back waves cancel. I don't think I can explain it much simplier than that.
 
Magnetar said:


Let me say it another way -- once the baffle is undersized (as in almost all open baffle bass systems) the panel/driver acts like a monopole as it becomes omni-directional in the low frequencies ACCEPT there is no linear, quality, low distortion bass to speak of because the front and back waves cancel. I don't think I can explain it much simplier than that.

Omni directional in terms of our perception, yes, but that's the way our ears and brain work for the low frequncies.

Wave cancellation in the plain of the front baffle is a desireable aspect of a bass dipole, so fewer room modes are excited. Yes you lose efficiency and if the baffle is too small, the cancellation reaches too far around to the front.

I have a 15"x15"x19" dipole with a pair of 12's in a W baffle. It works great for bass fill for my dipole speakers with a flat in room response down into the 30's without EQ. I do plan to build a dipole bass array though to get lower extention and higher SPL for HT use and music for occasional extreme volume.
 
Magnetar said:


It still radiating but you can't hear it. The front and back waves cancel due to being 180 degress out of phase. Here the dipole becomes the least efficient way and highest distortion method of coupling bass to your room. The extreme opposite of what I want..!

:cannotbe:

Why do you keep mentioning distortion? Distortion comes into play only if you push the drivers too hard, but that is true with any speaker. Once I make dipole speakers the size of a bass horn, they will be quite efficient and have plenty of SPL.

To me the edge the horn would have would be in chest pounding, in your face, dynamics of a good horn system. I like that sometimes too, but it's not the sound I want in my home system.
 
johninCR said:


Why do you keep mentioning distortion? Distortion comes into play only if you push the drivers too hard, but that is true with any speaker. Once I make dipole speakers the size of a bass horn, they will be quite efficient and have plenty of SPL.

To me the edge the horn would have would be in chest pounding, in your face, dynamics of a good horn system. I like that sometimes too, but it's not the sound I want in my home system.
Distortion comes with heating up voice coils, low efficiency , lack of linear excursion, and exceeding Xmax -- this is what happens when attempting to reproduce realistic bass response from a dynamic coned open baffle. Sure, you can spend eight times the amount on drivers and use eight woofers a side with a wall sized baffle - why bother when you can better that with some horns?

I horn system is NOT all about what you say - it is about reproduction of music with no peer. That's at all volume levels and with all types of music.
 
johninCR said:


Omni directional in terms of our perception, yes, but that's the way our ears and brain work for the low frequncies.

Wave cancellation in the plain of the front baffle is a desireable aspect of a bass dipole, so fewer room modes are excited. Yes you lose efficiency and if the baffle is too small, the cancellation reaches too far around to the front.

I have a 15"x15"x19" dipole with a pair of 12's in a W baffle. It works great for bass fill for my dipole speakers with a flat in room response down into the 30's without EQ. I do plan to build a dipole bass array though to get lower extention and higher SPL for HT use and music for occasional extreme volume.

Our brains and ears can also hear (or should I say not hear) 180 degree phase cancellations that you get with your open baffles. It's like driving your car on the highway with your foot on the brake -- ;)
 
Magnetar,

I don't quite get your line of reasoning. Low xmax, low dynamics, and polar problems, are found more commonly in ESL's and the like, and much less so in dynamic driver dipoles.

Dynamic dipoles can be very competently engineered, with all the calculations and distortions measurements right up there to back up the theoretical feasibility. Siegfried Linkwitz for once has shown an impressive amount of theoretical background, actual measurements including driver distortion and off axis response, limitations by necessary EQ vs. xmax AND amp power levels, vs. obtainable SPL in ordinary sized rooms, vs. room reflections, reverberation time etc etc. - it's all right there. You may not like the sound, but it sure looks like it is perfectly feasible. Besides, I have dipoles myself and they work.
 
MBK said:
Magnetar,

I don't quite get your line of reasoning. Low xmax, low dynamics, and polar problems, are found more commonly in ESL's and the like, and much less so in dynamic driver dipoles.

Dynamic dipoles can be very competently engineered, with all the calculations and distortions measurements right up there to back up the theoretical feasibility. Siegfried Linkwitz for once has shown an impressive amount of theoretical background, actual measurements including driver distortion and off axis response, limitations by necessary EQ vs. xmax AND amp power levels, vs. obtainable SPL in ordinary sized rooms, vs. room reflections, reverberation time etc etc. - it's all right there. You may not like the sound, but it sure looks like it is perfectly feasible. Besides, I have dipoles myself and they work.

I've heard the Beethoven and although it was somewhat pleasant to look at and OK to listen to it was severely limited in realistic bass reproduction as in power, weight, pitch and definition also overall in dynamics and imaging. My reference is the Cleveland Orchestra at Blossom and Severance Hall and local blues bands in small clubs
 
Magnetar,

Well, I have heard the Orions, and I have a system with Diatone fullranges (now with a tweeter as well but it's not properly integrated yet), and two 10" woofers sub-300Hz. I have been very happy with my bass since, although my woofers' xmax leaves to be desired, and my baffle dimensions could be better to allow for less EQ. Nothing that some cash for 4 Peerless XLS 10" per side couldn't fix ;-)

Imaging: I have to say that my diatones were better in that regard than the Orions. But the Orions had more resolution and subjectively more accurate sound. Very involving too, I felt myself drawn to keep listening, which is always a good sign. OTOH I have often seen comments about the poor imagoing of horns. And Imaging in the bass is quite a non issue as far as the bass horn discussion is concerned.

Limited bass of the Beethovens: this surprises me a lot. Could it be that you prefer the fatter, more resonant (=more distorted) bass of other speakers? I am not being cynical, I am trying to find out what's going on. Dipole fans (and SL himself) would say that people get accostumed to overblown bass and may be put off by realistic bass, although SL concedes less "gut slam" from dipole bass. One could similarly argue that dipole bass has a "sterile" quality to it, or that in some way it's not "natural". Me, I like it, but it may just be that there is an issue here. I don't believe that it lies in the measured frequency response, which I believe the Beethoven's designers were perfectly capabe of achieveing flat through EQ, and of measuring. So the SPL output likely is there, it's just that you didn't like the subjective quality of it, and that I take as a valid argument.

I have noticed in my system that when I EQ'd the room resonance out (there was a 6 dB peak at 90-100 Hz), the bass became "leaner", but the midrange much clearer, and the whole presentation much more realistic. I suspect the argument about getting too used to resonant bass has something to go for it, and that the lean dipole bass *is* the real bass.

Your references: a concert hall and blues bands in clubs: well, the blues bands are likely using ported PA woofers in highly resonant rooms. So, yes, the dipole will sound much different. The concert hall - well, again... if you are used to that one concert hall, you may well be used to its specific acoustics. And, a speaker is not the real thing, that's for sure.
 
Maybe I should reword my last comments.

The blues band scenario poses a real headache, because the "live" sound depends heavily on the sound coloration (likeely huge) of the speakers the band uses. So in a home system it won't sound "right" unless you use similar speakers, because the "true" sound of the instrument depends on a speaker, by nature.

The concert scenario goes the other way round. I have read figures of about 60 W acoustic power developed by a full size orchestra. Even with 10% efficiency from horns you'd need a 600 W horn to achieve the same output, the same dynamics (not to speak of an uncompressed recording, unlikely to find). In addition to that, the concert hall likely has dimensions that put the room modes at 20-30 Hz. That will develop a true full bass for sure. So, to correctly reproduce that same feeling, you'd need a similar size room.

And more: all speakers can only be compromises. Studio recordings will sound bland without some room effects, so wide dispersion speakers are better for those. Live recordings already have a lot of the venue's ambience on the recording, so they benefit from minimal room interaction.

In my opinion, dipoles represent a good compromise, with well controlled room interaction, and especially, with a more accurate power spectrum: dipole bass is not omnidirectional, which is a good thing, because the higher frequencies aren't either, because all conventional (non esoteric) tweeters start to beam around 4-6 kHz. With omnidirectional bass and directional tweeters you necessarily distort the power spectrum towards the bass. Dipoles are a clever way out of that.
 
Regarding the "driving with your foot on the brake" comment, don't forget that for a front horn half of the speaker's output is lost in the box. We dipole fans put the rear wave in play and give it up on the sides where it's a detrimental influence in coupling with the room anyway. We're driving using the brake how we choose while you're driving with the emergency brake on. You've just got a big V8 and we have a 6 cylinder turbo.

The increased cost of the extra drivers can easily be offset by the fact that cheaper drivers can be used with great results and any incremental cost is easily offset by the cost of wood and construction time it takes to build a proper horn.

I agree with the start of the thread, horns and dipoles are the best and they are very different. In terms of room interaction and accuracy I'd have to give the edge to dipole.

Magnetar, I think you should hear a high output dipole rig before you throw stones. Your musical tastes are obviously different from SL's, so you'd need a different rig. I think a dipole line array combined with a multi-driver high output dipole sub (huge baffles are not required) would give you the kind of dynamic presence you prefer.
 
Konnichiwa,

Magnetar said:
I have built around 20 dipole systems and owned some commercial ones ie Magnepan, Soundlab, Inner Sound, Quad, Acoustat, Infinity, Martin Logan ----- ;)

You have owned PLANAR speakers, all of which invariably are saddled with enough designed in problems, never mind their stupid retention of dipolar radiation where it actually becomes a liability (in the diffuse range of the room.

Magnetar said:
Let me say it another way -- once the baffle is undersized (as in almost all open baffle bass systems) the panel/driver acts like a monopole as it becomes omni-directional in the low frequencies

As there is invariably a delay between the front and rear radiation the cancellation of the front radiation by the rear one is not complete and equally, the cancellation of the rear radiation by the front one is not complete. The only point where the cancellation is complete is where the delay is equal, in other words for a plan baffle along the edge. So the dipolar radiation pattern is retained.

Yes, the output at low frequencies is reduced by cancellation and the dipole speakers design needs to account for that, however it does NOT become omnidirectional. Any such claims show a rather deplorable lack of understanding acoustics or a deliberate simplification of the subject below the point where presented model is still adequate to represent reality.

Magnetar said:
ACCEPT there is no linear, quality, low distortion bass to speak of because the front and back waves cancel.

Having actually measured quite a few dipoles by now, your statement is proven ad absurdum, as reality refuses to comply with your view of what it should be like.

Of course, with the kind of transducers you mention further up as dipoles ("ie Magnepan, Soundlab, Inner Sound, Quad, Acoustat, Infinity, Martin Logan") LF problems are unavoidable, because while the driven surface is large the actual linear excursion is miniscule, resulting in by far insufficient displacement capability, in other words, poor design.

I also cannot fail to not that at least two of the quoted manufacturers do not employ dipolar systems for the low frequencies.

Please note I am not arguing that "Dipoles are better than horns", I am arguing that it depends upon the specific application and personal taste as to which is preferable.

In my current living conditions the dice clearly fall for Dipoles, maybe if I ever move into a barn conversion I will be going for the kind of system used by Mr. Roggero, all Horn with architectural solutions (and huge cone surfaces), if this is what is called for.

However, there is one speaker that by all right has no place whatsoever in domestic settings, that is conventiuonal Box with a Dome tweeter, cone midrange and reflex/sealed box.

Sayonara
 
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