So - why DON'T people go with open baffle?

[Paul Carmody]

Re: So - why DON'T people go with open baffle?

Give me a design and specify what/how to implement the XO. If we can't do that, if every OB is essentially "I have to specifically design for my room, etc, etc", then you answered the question why people don't go OB. We haven't even touched on size and SAF.

I understand and can build a design from Paul or Wolf, or Lou, or Chris, etc, but I don't find OB designs here. Lot's of talk in this thread, but nothing more concrete than Orion. If Orion is the solution, just say so.

Well, that is a very interesting point you raise. There are very few plug-and-play open-baffle designs (I didn't say, "None," so hang on there Martin and DIY Guy).

Back before I even got into DIY I wanted to own a pair of dipoles; my dad's Martin Logans always intrigued me. Once I got into the hobby, I found OB/dipoles to be a pretty enigmatic arena... bits of information scattered here and there... nothing well-documented like sealed or bass reflex speakers. The only people who have really been documenting this are Linkwitz, John K, and Martin King. And for better or worse, they don't necessarily agree on best practices.

So what we end up with are people on various forums doing random experimentations, always tweaking and swapping in new baffles--or non-baffles--and drivers. (Which leads one to believe "are they really happy with it?")

[johnk...]

Re: So - why DON'T people go with open baffle?

There are a number of examples of "dipole done right", ORION, of course, topping the list. .

If by done right you mean betwwn 50 and 1k Hz.

[Deward Hastings]

Re: So - why DON'T people go with open baffle?

Not insufficient at all, since it only goes down to 60 hz it'll go pretty loud

It's easier to design a partial-range dipole . . . but then you've compromised (crippled) the design right from the beginning.

The drivers are fairly high quality for what they are and they don't sound bad

And all the *other* considerations of speaker design (like driver quality) don't just "go away" when designing dipoles. Dipoles just impose *additional* considerations.

I have no way to know what Orion sounds like

I'm pretty sure there's at least one in "Canada" that you could find to listen to.

I'll share my OB designs when I get around to them but it won't be anytime soon

No worry . . . there's no hurry . . .

I've still got a couple cases each of the 3x5 JVC "closeout" drivers and the $10/case "closeout" mylar tweeters from a couple years ago (bought for a dipole line array experiment) . . . I'll let you know how they sound when I get around to it . . .

[fastbike1]

Re: So - why DON'T people go with open baffle?

Thanks Paul, you get what I'm talking about. As for Martin-Logan, I have yet to hear a pair that I like for more than a couple of minutes, or until I stand up and/or move off axis.

Well, that is a very interesting point you raise. There are very few plug-and-play open-baffle designs (I didn't say, "None," so hang on there Martin and DIY Guy).

Back before I even got into DIY I wanted to own a pair of dipoles; my dad's Martin Logans always intrigued me. Once I got into the hobby, I found OB/dipoles to be a pretty enigmatic arena... bits of information scattered here and there... nothing well-documented like sealed or bass reflex speakers. The only people who have really been documenting this are Linkwitz, John K, and Martin King. And for better or worse, they don't necessarily agree on best practices.

So what we end up with are people on various forums doing random experimentations, always tweaking and swapping in new baffles--or non-baffles--and drivers. (Which leads one to believe "are they really happy with it?")

[Paul Carmody]

Re: So - why DON'T people go with open baffle?

Thanks Paul, you get what I'm talking about. As for Martin-Logan, I have yet to hear a pair that I like for more than a couple of minutes, or until I stand up and/or move off axis.

Well, yeah, that's true. I never could quite "hear" the greatness of Martin-Logans--it was the concept behind them that intrigued me. Mid and high-frequencies playing in free-air, just like real instruments. (Oh, if only transducers were that simple!)
Never heard a pair of Mangepans, though that's on my to-do list.

[ocdSCHACK]

Re: So - why DON'T people go with open baffle?

Well, that is a very interesting point you raise. There are very few plug-and-play open-baffle designs (I didn't say, "None," so hang on there Martin and DIY Guy).

Back before I even got into DIY I wanted to own a pair of dipoles; my dad's Martin Logans always intrigued me. Once I got into the hobby, I found OB/dipoles to be a pretty enigmatic arena... bits of information scattered here and there... nothing well-documented like sealed or bass reflex speakers. The only people who have really been documenting this are Linkwitz, John K, and Martin King. And for better or worse, they don't necessarily agree on best practices.

So what we end up with are people on various forums doing random experimentations, always tweaking and swapping in new baffles--or non-baffles--and drivers. (Which leads one to believe "are they really happy with it?")

Amen,brotha! I'd also like to add... the further below 80hz you go dipole, the further you waste your money. Again, to Spastic, 4 twelves is just fine, but this post turned into a battle of the titans. I'm not one, but I can pick sides...."anyone who's claiming (dipole under 100hz is the bomb) is a PU$$Y!!!!" Not really, but lets not waste others money here. Isn't the beauty of this sport, I mean hobby, wasting your own money and having something impressive to show for it. I appreciate dipole, but at low frequencies....come on.

[benchtester]

Re: So - why DON'T people go with open baffle?

I have an inquisitive question (not a flame, no really): what advantage is it to have sound coming from the back of the speaker that is out of phase with the sound from the front?

..... I appreciate dipole, but at low frequencies....come on.

Curiously, my first dipole will be a subwoofer. But it will be a compromise: trying to deliver a moderate amount of bass to the listener with the least amount transmitted through the walls and floor. It will be a coffee table (near field monitor to the listener) with the woofers and baffles forming the legs. I even have a name: the coffee tabla.;)

[killersoundz]

Re: So - why DON'T people go with open baffle?

I have an inquisitive question (not a flame, no really): what advantage is it to have sound coming from the back of the speaker that is out of phase with the sound from the front?

It's in phase once it bounces off the wall Sort of.

[benchtester]

Re: So - why DON'T people go with open baffle?

It's in phase once it bounces off the wall Sort of.

I can imagine that the extra distance traveled would bring some of the frequencies back in phase. The reflection itself doesn't cause a phase shift to the sound in the air.

(I had to check my memory with the internet. Since the air is less dense than the wall there is not phase reversal; sound in a more dense medium does get a phase reversal when it reflects from an lower density interface.)

[tktran]

Re: So - why DON'T people go with open baffle?

A colleague of mine has the Martin Logan Purity.

His acoustic treatment is made of treated cedar strips on the ceiling, and costed some US$80,000. Architecturally, it was stunning.
He carefully explained to us that this was to counteract the overall noise levels caused by the marble floors and predominant glass & stainless steel fittings in the home.

Probably a fine speaker, but we would never know because the speakers were spaced about 6' apart (in room some 40+' wide) and pushed right up against the front wall.

Another reason why you shouldn't go dipole. They sound best well away from walls (= or > boxed speaker)

[Sydney]

Re: So - why DON'T people go with open baffle?

As a guideline for LF: a 1/4 wavelength distance from a boundary results in a 1/2 wave cancellation. The destructive interference extends +/- .5 octave.
Pro Sound people cognizant of the effects of boundary cancellation: place LF cabs <2.5' or > 10' from a boundary to avoid cancellation in the LF passband.
The effect is very noticeable as a cab spacing is varied from boundaries
Room integration issues often make some designs impractical.
Klipschorns are another example of a design that requires a large room.

[fastbike1]

Re: So - why DON'T people go with open baffle?

Maggies are a different matter. I haven't heard the new 1.7's, but I can say that the 1.6s put Stevie Ray in the room with you.
Close your eyes and you can clearly place the band members in space. The most convincing "image" I have ever heard. The only other commercial design I've heard that could convince you the musicians were in the room was one of the large Harbeths (don't remember the specific model). For commercial speakers, the Maggie 1.7s are worth the money. They're a bit large for my physical space, otherwise I'd have them.
You owe it to yourself to hear them.

Well, yeah, that's true. I never could quite "hear" the greatness of Martin-Logans--it was the concept behind them that intrigued me. Mid and high-frequencies playing in free-air, just like real instruments. (Oh, if only transducers were that simple!)
Never heard a pair of Mangepans, though that's on my to-do list.

[Sydney]

Re: So - why DON'T people go with open baffle?

RE: Magnepans
A friend who purchased a set was convinced that he had the "perfect speakers".
They are very clear and detailed; in the same vein as Electrostatics I've heard. Their compromise was in their dynamic range and limited LF extension.
When recordings with extended dynamic range were played - they clipped and compressed badly.
With their low to average eff. ( 82 - 89db depending on model ) program material hit peaks that exceeded 200 watts and the maggies complained badly. Fine for low to moderate SPL.

[ocdSCHACK]

Re: So - why DON'T people go with open baffle?

I have an inquisitive question (not a flame, no really): what advantage is it to have sound coming from the back of the speaker that is out of phase with the sound from the front?




Curiously, my first dipole will be a subwoofer. But it will be a compromise: trying to deliver a moderate amount of bass to the listener with the least amount transmitted through the walls and floor. It will be a coffee table (near field monitor to the listener) with the woofers and baffles forming the legs. I even have a name: the coffee tabla.;)

Dipole works off reflections...and phase can change off axis...so I assume a lot of the sound reflected back to the listener isn't out of phase. On another note, I have found that dipole bass does travel though walls. Many with more knowledge may disagree, but in my experience, low frequencies travel wherever they want regardless of their enclosure. I may be totally wrong, but it seems like the weakness in the low end that dipoles have could be more of the reason.

[dlr]

Re: So - why DON'T people go with open baffle?

Amen,brotha! I'd also like to add... the further below 80hz you go dipole, the further you waste your money. Again, to Spastic, 4 twelves is just fine, but this post turned into a battle of the titans. I'm not one, but I can pick sides...."anyone who's claiming (dipole under 100hz is the bomb) is a PU$$Y!!!!" Not really, but lets not waste others money here. Isn't the beauty of this sport, I mean hobby, wasting your own money and having something impressive to show for it. I appreciate dipole, but at low frequencies....come on.

While this may be true for flat OB, you apparently haven't heard John K's active U-Frame subwoofers. They provided possibly the best in-room bass I've heard.

NaO-II U-frame
U-frame

Effectively down -3db at 30Hz:



I've got two Peerless subwoofers on the shelf. I may do a version of a U-frame sub for my next dipole.

dlr

Edit: John doesn't refer to them as a subwoofer, but I doubt I'd have need of more than this for most any music application.