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

[skatz]

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

Madison, WI. Ten miles from Madisound. Who doesn't have a demo system.

Bummer, thats a long drive. I know there are people in the Chicago area who have systems, if I think for a while I may recall a name. I believe the guy who's ribbon system was on the cover of Speaker Builder --a name I've forgotten for now -- was from Chicago. I may be able to find the name. He built an open baffle almost identical to mine.

Steve

[ocdSCHACK]

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

It does not have to be expensive.

It does not have to be complex.

You can get bass into the 20 to 30 Hz range with a woofer costing less than $80.

I'm not arguing, but what's the F3 at 30hz and what's the driver you have in mind? With my setup of four 10's for the low end, I could only get to 40Hz at relatively decent spl's. Sure they could hit 20, but they couldn't play flat to 20 or 30Hz at decent SPL's. Crossed to a sub at around 60Hz, I can get to almost concert levels playing to 30Hz. I'm just wondering if you're being overly optimistic or if I'm totally missing out and wasting money on the wrong stuff.

To Spastic:
That setup should be perfect for OB. In a small apartment, you'll have plenty-o-bass with 4 decent 12's. I don't even enjoy bass below about 30Hz, but at louder levels you might want a sub...if your the bass heavy type. I'm jealous of your setup, so post more pictures. Unless you wire something wrong, four 12's should be enough for your situation.

[Deward Hastings]

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

At least four reasons:

Unfamiliarity.

For the same drivers/$ dipoles don't play as loud.

Size. ORION is about as small as it gets (with acceptable performance).

Complexity. Done right they require "electronics" (wiring a passive crossover is closer to plumbing than to electronics), and dipole design is more complicated than just plugging numbers into a spreadsheet.

If you can get past those it's totally worth it. The incredible clarity of full-range dipole bass is amazing. In the mids the better the driver the better it sounds . . . there's no "box sound" to mess things up.

[diy speaker guy]

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

At least four reasons:

Unfamiliarity.

I agree with this but disagree with the rest.

For the same drivers/$ dipoles don't play as loud.

It's not so simple to make direct comparisons since OB bass drivers have totally different specs than monopole bass drivers. (Unless you wish to use active eq, which is fine but by no means necessary.) Also, OB bass drivers are typically high q and therefore generally less expensive.

Size. ORION is about as small as it gets (with acceptable performance).

That depends on what you mean by acceptable. But this would require a long conversation. The short version is that I disagree (assuming a sub is used for 60 hz or so and down, and there's not much benefit to using OB too far below that and no benefit at all below the lowest room mode).

Complexity. Done right they require "electronics" (wiring a passive crossover is closer to plumbing than to electronics), and dipole design is more complicated than just plugging numbers into a spreadsheet.

If you choose your drivers and baffle size properly there is no need for active electronics and passive OB xo design is no more complex than monopole xo design. Bagby's software (for example) is more than adequate to nail down a complete multi-way design and while it might need a small amount of tweaking to perfect that's hardly out of the ordinary for any alignment.

If you can get past those it's totally worth it. The incredible clarity of full-range dipole bass is amazing. In the mids the better the driver the better it sounds . . . there's no "box sound" to mess things up.

This last part I agree with completely.

[Deward Hastings]

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

It's not so simple to make direct comparisons since OB bass drivers have totally different specs than monopole bass drivers.

The Peerless woofers in ORION were designed for use in boxes (monopole), and I'd guess that *far* more of them are installed that way than in dipoles.

That depends on what you mean by acceptable.

For me "acceptable" is capable of reproducing symphonic (or other live acoustic) music at realistic levels in a 3,000 cubic foot room without a subwoofer. "Rock and roll" at "club" levels is more difficult, dinosaurs and Martian boom-booms more difficult still. Both require sub-woofer assistance for any reasonable sized dipole, and the loss of quality doesn't matter. But . . . if you want the (acoustic) string bass to sound right you want it entirely handled by the dipole woofer.

If you choose your drivers and baffle size properly there is no need for active electronics and passive OB xo design is no more complex than monopole xo design.

Without equalization drivers and baffles must be significantly larger to get full-range dipole bass, to the point of being unwieldy. I have yet to see this allegedly "simple" passive dipole design that is not significantly larger than ORION but which matches it's dipole bass in SPL, let alone in overall quality.

There's a nice challenge for you . . . not as easy, I think, as you think. Design a fully passive full range dipole loudspeaker that is no bigger than ORION but can match it's available SPL down to 30Hz (at least, but that satisfies the requirements of the symphonic repertoire). For extra points . . . make it cheap . . .

[diy speaker guy]

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

The Peerless woofers in ORION were designed for use in boxes (monopole), and I'd guess that *far* more of them are installed that way than in dipoles.

You cut my quote too soon. I said "(Unless you wish to use active eq, which is fine but by no means necessary.)"

For me "acceptable" is capable of reproducing symphonic (or other live acoustic) music at realistic levels in a 3,000 cubic foot room without a subwoofer. "Rock and roll" at "club" levels is more difficult, dinosaurs and Martian boom-booms more difficult still. Both require sub-woofer assistance for any reasonable sized dipole, and the loss of quality doesn't matter. But . . . if you want the (acoustic) string bass to sound right you want it entirely handled by the dipole woofer.

Without equalization drivers and baffles must be significantly larger to get full-range dipole bass, to the point of being unwieldy. I have yet to see this allegedly "simple" passive dipole design that is not significantly larger than ORION but which matches it's dipole bass in SPL, let alone in overall quality.

I think you already know it's going to be somewhere between extremely difficult to impossible to match the Orion in specs but in a smaller package. I wasn't claiming I could do that. But if you are willing to give up the bottom octave I can make an "acceptable" dipole 1/4 of Orion's size. With a passive crossover.

There's a nice challenge for you . . . not as easy, I think, as you think. Design a fully passive full range dipole loudspeaker that is no bigger than ORION but can match it's available SPL down to 30Hz (at least, but that satisfies the requirements of the symphonic repertoire). For extra points . . . make it cheap . . .

Again, I'm not claiming I can beat Linkwitz's life's work. The only thing I was disputing was your original claim that "ORION is about as small as it gets (with acceptable performance)."

But if your definition of "acceptable" means 30 hz or lower, then I agree with you. My point is that "acceptable" doesn't have to go down to 30 hz, that last octave requires massive displacement requirements for limited benefit. There's no benefit to dipole bass below the room's modal region, and while 60 hz is still in the modal region, there's only likely to be one room mode below 60 hz so the benefit of hitting 30 hz with the dipole is extremely limited and IMO not worth the extra cost and size.

This is a question of compromise and clearly you don't want a mono sub covering the bottom octave while I don't see a problem with that as long as it's a high quality sub (or multiple subs) that are integrated well.

So I don't think we are really disagreeing on this point, just picking different compromises. The real difference is that I could make a very acceptable full range system for a tiny fraction of the price of Orion but it would be monopole in the top and bottom octave (a sub and a regular mono tweeter), and the dipole baffle would be significantly smaller. Pick your poison.

[Paul Carmody]

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

I'd agree with several points here. First, open-baffle speakers do tend to be large--ergo, low SAF. There are a few exceptions, but for the most part 12"-48" baffles just don't go with most living room decors nowadays.

Also, they can get complex quickly. Even open-baffle mids, I have learned, create a whole new set of challenges that one would never face if the drivers were in a box. (the XO for the new Sunflowers will demonstrate this)

And dipole woofers--fuggedaboutit! If you're going passive, so much power is wasted just compensating for dipole roll-off (yes, Martin does have a novel idea with his large Sd, high Qts solution--but still size becomes an issue again). So then your best bet is to go active, and that's just not something audiophiles are into. They like their $4-figure amps and cables.

I eschewed the dipole bass dilemma by using a standard cabinet for the response up to 200-250 Hz. So I can't comment on dipole bass, but I CAN comment on equalized dipole mids... which I feel as though I have finally "nailed" with the new Sunflowers. Basically, they have the same imaging and detail as a monopole speaker (really), but the midrange is completely free of any sort of "boxiness" or coloration from the cabinet. It's not an obvious thing, like I once thought it should be. It just makes for a less colored sound, and is easy to listen to for long, long periods of time.

[Saurav]

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

For what it's worth...

I spent a couple of years with a monopole woofer / dipole mid / monopole tweeter design. Then I went to a dipole woofer, with the same midrange. The improvement wasn't subtle. Granted, my design skills improved over the years, so I'm not comparing apples to apples. But even just looking at it theoretically, it's in the upper bass / lower midrange where dipole really has an advantage over monopole, because of how it loads the room.

Spastic said he already has a DCX and enough channels of amplification, so there's no cost hurdle to going active. I think he should try a full-range dipole. It's a bigger challenge, if nothing else The WAF issues are a good point, and that may dictate the overall design more than anything else.

Just my 2c, all IMO, etc.

[diy speaker guy]

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

I'd agree with several points here. First, open-baffle speakers do tend to be large--ergo, low SAF. There are a few exceptions, but for the most part 12"-48" baffles just don't go with most living room decors nowadays.

Also, they can get complex quickly. Even open-baffle mids, I have learned, create a whole new set of challenges that one would never face if the drivers were in a box. (the XO for the new Sunflowers will demonstrate this)

I agree that most of the OB designs you typically see are both large and complex. But there's really no reason for that as long as you choose your drivers and baffle size, and driver position on the baffle properly. (And use a sub.)

There is a project on my site that uses a 4 inch coax driver on an 8x20 inch baffle with good response down to 150 hz and the crossover consists of a single capacitor.

I'm not claiming this is a super hi fi design, in fact it's just a cheap, junky car audio coax mounted to a small board. It could probably use a notch at 700 hz to deal with the diffraction bump. And it could definitely use a better xo than a single cap between the woofer and tweeter to fix the hole at around 5 khz but that's the fault of the driver, not the design. And it's extremely displacement limited, especially if not high passed steeply.

Here's the actual measured response.



So while I do not claim this ultra budget project is a great hi fidelity miracle, it clearly shows that if you pick your drivers and baffle sizes appropriately, passive xo design is not complex or even difficult.

[fastbike1]

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

This argument would be a lot more compelling if there was at least a proto design. Nothing on the home page either.

It's supposedly "extremely easy". ;)

So I don't think we are really disagreeing on this point, just picking different compromises. The real difference is that I could make a very acceptable full range system for a tiny fraction of the price of Orion but it would be monopole in the top and bottom octave (a sub and a regular mono tweeter), and the dipole baffle would be significantly smaller. Pick your poison.

[diy speaker guy]

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

This argument would be a lot more compelling if there was at least a proto design. Nothing on the home page either.

It's supposedly "extremely easy". ;)

I haven't done that specific OB configuration yet but that doesn't mean it's not possible. I haven't built anything in almost 2 years now but I'll be starting again soon, although the OB projects won't be first in line.

Regardless, take a look at the measurement I posted and you can clearly see that it would not be hard to work with. Any similarly high q woofer will behave the same on a similarly sized baffle. Use a bit higher qts and a bit lower fs and you can extend the response even further down. Ideally the example measurement above should be a 3 way, and crossed to a mid at 700 hz, and that would take care of the diffraction bump the same way that we do all the time with mono designs. This isn't complicated stuff.

[Deward Hastings]

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

For what it's worth...

I spent a couple of years with a monopole woofer / dipole mid / monopole tweeter design. Then I went to a dipole woofer, with the same midrange. The improvement wasn't subtle.

For what it's worth . . .

That parallels my experience. I spent years with Thiel 3.6's (10" woofer with passive radiator), which had *excellent* "rock and roll" bass, but never sounded quite right reproducing acoustic bass. Switched to full range dipole, and the improvement wasn't subtle. I simply don't buy the "monopole is fine below *** Hz." argument . . . it's demonstrably not true in my listening room/experience, for acoustic bass (though it probably is true for electric and HT bass). What "bass in a box" has going for it is smaller, cheaper and louder. It does not have the same quality as a well implemented dipole.

That said, gettting good bass is not an easy thing. It is very room dependent (even for dipoles, though to a lesser extent than with monopole sources). As a practical matter you do need a subwoofer with dipoles for boom-boom and *loud* rock . . . you also need to be able to turn it off and "go flat" with only the dipole woofer for the best orchestral and small acoustic ensemble reproduction (where the lower SPL demands permit it). But back to the original question . . . most DIYers are not fixated on accurate reproduction of acoustic music, and as a result are willing to pass on the extra cost and complexity. I completely understand (and sympathize) . . . most of the time I'm content with listening on small studio monitors myself, just as I'm OK with the TV speakers for Hells Kitchen and Rehab . . .

[dantheman]

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

My favorite part of dipoles is the midbass. One problem for DIYers is to get that to marry the mids/treble right. John K seems to have the best implementation I've seen (but not heard) so far in that regard with the note. I'd love to hear that speaker some day. Gainphile looks to be making some progress as well: http://gainphile.blogspot.com/2010/1...y-dipoles.html

Dan

[fastbike1]

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

Here's what I could use from you guys, being that I think I represent the "People who don't go with open baffle".

I need something closer to a step list than a "you just need the right drivers, active eq, design is easy" statement.

I/we know what active EQ means, what we need is how to do it. I know how to wire a passive XO. I have a rough idea how to design one. I can build a cab.

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.

[Saurav]

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

Well, here's the current state of my project, last updated in October:

http://techtalk.parts-express.com/showthread.php?t=219209

I've never posted a 'final' design, mostly because I'm always fiddling and tweaking. I can post the current DCX settings from my LspCAD project file if you're interested. I think the drivers are mentioned in that thread.

I wouldn't really suggest copying that design Now that I've spent some time with it, there are a couple of different things I will try when I start tweaking it again.

Not sure if that answers your question. I don't consider my speakers to be designed specifically for my room, but they are designed within specific constraints: they absolutely need a subwoofer below about 80Hz, and they get loud enough for me in a 13'x17' room, but they might not be loud enough for everyone. Also, you need a DCX2496 and 6 channels of amplification (in my case, an Emotiva amp), I don't know how to do this passively.

The Orion is the best-documented OB design around, no questions about that. And it's a lot better than mine. I finally got to hear one at RMAF last year.