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What is the appeal of open baffle?

dc655321

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There is a planar node in ANY dipole,

But, is capitalizing on that not extremely sensitive to source and room geometry, so as to be quite "fussy" in practice (as characterized up-thread)? Or am I misunderstanding?

I suppose what I was really looking for were good measurements of dipole systems, anechoic and in-room.
I feel like monopole/dipole/cardiod choice is maybe a case of "pick your poison"...
 

OWC

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Not according to Linkwitz.

See figure 5 in the linked article.https://www.linkwitzlab.com/H-U woofer2.htm

As mentioned before, I prefer designs with fewer parts, less required equalization and more compact cabinetry.
U- frames and H-frames are both dipoles.

It's only the last picture that shows and describes how it works.
But hey, you're welcome to open up a 8c and look for yourself.
I only worked with Martijn together for just about 10 years or so.........
 

NTK

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Sorry guys, quoting Toole again ...
^^^ Below are from this post
Fortunately the world has decided that omni woofers are to be the norm. Even most "full bandwidth" dipole speakers transition to monopole bass drivers. I think dipole subwoofers have joined the dodo bird, as they should. There are a couple of cardioid woofers out there somewhere I think.
It is a real world problem. Around 1990 I had my first interaction with noted subjectivist Harry Pearson (RIP) when I was to be called to help him with a problem. He had heard a speaker he thought he liked and wanted to review it. When he got the speakers he placed them in his carefully selected "reference" locations and seated in his "reference" seat something was wrong with the bass. The designer of the speaker was called to find out what was wrong. I was invited to join him in what was likely to be an interesting venture. We arrived at Harry's house in the AM, and without listening to a note of music, we got out a tape measure and a calculator. He looked on in stunned amazement. Then we asked if the problem was a deficiency of mid-bass. He said "yes, how did you know?". It turned out that his "reference" location was arrived at while listening to full bandwidth dipoles, and the speaker he was auditioning was a monopole. We moved both the speaker and his chair and all was well. Dipoles couple maximally at a pressure minimum/velocity maximum and monopoles couple maximally at pressure maxima/velocity minima. Dipoles have the additional complication of being vectored sound sources, meaning that the orientation relative to a room-mode null matters. Monopoles are not. There are good reasons to use monopole woofers and subs. He remained in a kind of trance, exclaiming that he had never experienced anything like that. For pure subjectivists science, even really basic science, is a great mystery and/or threat.
Any woofer or subwoofer I have ever encountered does not change its power response "vigorously" - they are minimum-phase systems that are quite well behaved. However, room modes/standing waves do change dramatically with location of the ears or mic. That is the problem to be addressed. Mode cancelling/attenuation using multiple subs greatly simplifies the situation, but only when the budget allows. Good news is that with multiple subs the total system efficiency rises, so they can be smaller subs.
 

Wes

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But, is capitalizing on that not extremely sensitive to source and room geometry, so as to be quite "fussy" in practice (as characterized up-thread)? Or am I misunderstanding?

I suppose what I was really looking for were good measurements of dipole systems, anechoic and in-room.
I feel like monopole/dipole/cardiod choice is maybe a case of "pick your poison"...

Let's go with "interact less with certain aspects of the room"
 

Plcamp

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People do say that a lot. But, without going thoroughly into it, I would assume an OB's baffle would resonate more than most decent cabinets, due to the relatively flimsy restraint. Hence, an OB should be more prone to structural resonance.
This is certainly true in my experience with PAP trio 15’s, where baffle area is about the same as cone area. Especially if the same structure mounts both the lf and hf drivers. I think the baffle should be separately mounted to the drivers. One way to do that is to mount by the magnets through a baffle opening.
 

dc655321

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OWC

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Sorry guys, quoting Toole again ...

Fortunately the world has decided that omni woofers are to be the norm. Even most "full bandwidth" dipole speakers transition to monopole bass drivers. I think dipole subwoofers have joined the dodo bird, as they should. There are a couple of cardioid woofers out there somewhere I think.
It is a real world problem. Around 1990 I had my first interaction with noted subjectivist Harry Pearson (RIP) when I was to be called to help him with a problem. He had heard a speaker he thought he liked and wanted to review it. When he got the speakers he placed them in his carefully selected "reference" locations and seated in his "reference" seat something was wrong with the bass. The designer of the speaker was called to find out what was wrong. I was invited to join him in what was likely to be an interesting venture. We arrived at Harry's house in the AM, and without listening to a note of music, we got out a tape measure and a calculator. He looked on in stunned amazement. Then we asked if the problem was a deficiency of mid-bass. He said "yes, how did you know?". It turned out that his "reference" location was arrived at while listening to full bandwidth dipoles, and the speaker he was auditioning was a monopole. We moved both the speaker and his chair and all was well. Dipoles couple maximally at a pressure minimum/velocity maximum and monopoles couple maximally at pressure maxima/velocity minima. Dipoles have the additional complication of being vectored sound sources, meaning that the orientation relative to a room-mode null matters. Monopoles are not. There are good reasons to use monopole woofers and subs. He remained in a kind of trance, exclaiming that he had never experienced anything like that. For pure subjectivists science, even really basic science, is a great mystery and/or threat.
Any woofer or subwoofer I have ever encountered does not change its power response "vigorously" - they are minimum-phase systems that are quite well behaved. However, room modes/standing waves do change dramatically with location of the ears or mic. That is the problem to be addressed. Mode cancelling/attenuation using multiple subs greatly simplifies the situation, but only when the budget allows. Good news is that with multiple subs the total system efficiency rises, so they can be smaller subs.
Yes, that is exactly what I also said before.

For everything below 100-150Hz, it just doesn't make a lot of sense.

Btw, don't forget that there is/was also quite some critique on Toole's vision.
Moreover because he has a tendency to over simply certain things a lot.
Especially when it's about just the technical details of a system.
Some of them are very noticeable and a reasonable experienced listener will pick them up in a double blind test.
The tech side also was never Toole's strong side (he even admits that)

And in general what most people seem to forget, is that there is not an ideal system, for the simple reason that there is no ideal room.
In fact, there is not one single situation with the same constrains let alone the same budget.
 

q3cpma

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and by the market you mean five or six digit price boutique speakers?
For the "boutique" stuff, you get the GGNTKT M1 at 6000€ everything included, the D&D 8c for 10000€ (I think) and the Kii for even more. For established pro brands, Genelec does it in a partial manner with the Ones (only in one place and only the 8361A has it "in full", unless you get the W371A) and ME Geithain does it for 10~12k€ with its K models. So yes, it's expensive and quite rare, but it's not only boutique stuff.

PS: all of these prices include the disgustingly high central europe VAT of 20% for most countries.
 

abdo123

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For the "boutique" stuff, you get the GGNTKT M1 at 6000€ everything included, the D&D 8c for 10000€ (I think) and the Kii for even more. For established pro brands, Genelec does it in a partial manner with the Ones (only in one place and only the 8361A has it "in full", unless you get the W371A) and ME Geithain does it for 10~12k€ with its K models. So yes, it's expensive and quite rare, but it's not only boutique stuff.

PS: all of these prices include the disgustingly high central europe VAT of 20% for most countries.

No Genelec speaker has any sort of directivity control at low frequency, they’re not even directive lol.
 

Burning Sounds

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People do say that a lot. But, without going thoroughly into it, I would assume an OB's baffle would resonate more than most decent cabinets, due to the relatively flimsy restraint. Hence, an OB should be more prone to structural resonance.

Yes, that's true, but only if you have a large, wide unsupported baffle, which some dipoles have. But look at the baffle of a LX521 or an LXMini (not a dipole throughout its frequency range, true) - it is quite small or almost non-existent in the case of the LXmini. So, although there is some very slight vibration from the baffle of the LX521 at high SPL it is minimal and not audible. Same with the bass unit (hence the bridge to isolate the upper baffle) - it's a very stiff box with no front or back with the sides reinforced by the woofer mounts.

As Toole has been mentioned, here's what he had to say in another thread:

"There is absolutely nothing wrong with conventional - true - dipole loudspeakers. They are free-standing full-range speakers radiating identical sound fields forwards and backwards, but in opposite polarity. An ideal dipole has a figure-of-eight polar pattern over most of the frequency range, with cancellation dips at +/- 90 deg. As might be expected there are both good and less-good dipoles, as with any other configuration."

Bold is my emphasis.
 

q3cpma

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No Genelec speaker has any sort of directivity control at low frequency, they’re not even directive lol.
Read their whitepaper, LF directivity control in one plane (along the slots) was one of the goals.
For example, the 8361A:
8361-ver.png

down to ~200 Hz, which is a lot more than what the baffle alone could do.
 

Newman

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...As Toole has been mentioned, here's what he had to say in another thread:

"There is absolutely nothing wrong with conventional - true - dipole loudspeakers. They are free-standing full-range speakers radiating identical sound fields forwards and backwards, but in opposite polarity. An ideal dipole has a figure-of-eight polar pattern over most of the frequency range, with cancellation dips at +/- 90 deg. As might be expected there are both good and less-good dipoles, as with any other configuration."

Bold is my emphasis.

Notice he is not saying there is any reason to prefer them. Also, he has recently said, "people allude to panel speakers having a more "open" sound, lacking "boxiness". This is fantasy." OB speakers are not superior to panel speakers on that front, hence not superior to box speakers either.
 

drplinker

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Novice question: What are musical instruments - dipole or monopole? Does it vary by instrument type? (wind / string / percussion)
 

Newman

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Varies not just by instrument type, but by the notes being played. Which, logically, means the harmonics of some instruments have different dispersion than the fundamentals.

From what I have seen, I would conclude that, in broad and general terms, if you wanted to pick a loudspeaker type that had dispersion most similar to most instruments of the most common variety, including voice, it would (oh how disappointing) be..... the forward-firing monopole speaker.

cheers
 
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drplinker

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My Quad 2805s reproduce the music in the room rather than from the speaker. They also produce fewer room modes, for a cleaner bass. Their size is the only disadvantage.
I thought room modes were properties of "room", unrelated to speaker.
 

Jim Matthews

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But, is capitalizing on that not extremely sensitive to source and room geometry, so as to be quite "fussy" in practice (as characterized up-thread)? Or am I misunderstanding?

That was precisely my experience. The nadir of my nonsense was when shopping for apartments I considered expensive larger spaces to give my long departed Apogee duettas room to "breathe".

I'm much recovered, now.

My name is Jim and I'm an audiophile.
 

Jim Matthews

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U- frames and H-frames are both dipoles.

It's only the last picture that shows and describes how it works.
But hey, you're welcome to open up a 8c and look for yourself.
I only worked with Martijn together for just about 10 years or so.........
The diagram presented by Linkwitz illustrates the resultant pattern in figure 6 of the link above.
 

abdo123

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Read their whitepaper, LF directivity control in one plane (along the slots) was one of the goals.
For example, the 8361A:
8361-ver.png

down to ~200 Hz, which is a lot more than what the baffle alone could do.

Genelec’s directivity plots are only up to -/+ 90 degrees, I guess that’s why i was confused.

1629789059767.png
 

Burning Sounds

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Notice he is not saying there is any reason to prefer them. Also, he has recently said, "people allude to panel speakers having a more "open" sound, lacking "boxiness". This is fantasy." OB speakers are not superior to panel speakers on that front, hence not superior to box speakers either.

Toole is speaking about panel speakers, not properly designed dipoles using dynamic drivers that are made specifically for that project eg LX521. Properly designed OBs like the LX521 are far superior to panel speakers - I have both.

For some reason when the discussion gets to OBs they are all lumped together. When it's about closed boxes it become more nuanced. Strange that.
 
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