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Open Baffle Epiphany!

tomlinmgt said:
Very interesting stuff, EV. The Goldwood woofer tower is especially intriguing. Have you measured them?

- Michael
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Yes. With the Parts Express DATS (WT3 replacement) and the OmniMic system. Running with a First Watt F1 current source as the amp, in room, I get a bass hump that could be room or the F1 and the driver resonance interacting, but I get good level below 30. And by listening, I'd say it's rolling off slow beyond that. You get some output on down.

If you want to eq or trap, which I really don't, you could flatten and get pretty far down I'd think with as much movement as the total of the four drivers gets you.

The TB and 4 10's is outstanding on the famous drum solo from Jim Keltner on the Sheffield Drum & Track Disc, it'll will rock you're world. I also have a Chinese drum solo long track where they use all kinds of drums including huge. Had a long term professional audio friend look wide-eyed at the huge end on that. He said it was the first time he'd ever heard height change and such great stage depth.

The large cone area does get you something...something beside the questions about comb filtering. :)

EV3
 
I love my line source Infinity QLS-1's for their sheer sonic scale and top to bottom dynamics. I love my Acoustat Spectra 22 ESL's and Maggie MG-IIIa's for their vast sound stage and realistic sonic presentation. If I could combine all of them I'd be very pleased. Your line source OB set up may well be capable of just such a feat.

And I'll have to look into that Keltner solo.
 
Poultrygeist said:
Some of you have probably already seen the Kick Start Project otherwise here's Open Baffles as art objects ( high WAF ).

http://urbanfidelity.com/collections/all
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This more about art on the board... the speaker is an afterthought.

evsentry3 said:
For bass, here is a economical driver that works very well OB....

http://www.parts-express.com/goldwood-gw-410d-10-poly-dvc-subwoofer--290-362
EV3
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I thought one needs a qts close to 1 for OB work... at least that what Martin King writes. These, at .6 may not be the best choice.
 
Ok...bragging on OB's abilities. The box gone, the crossover elements gone, the impact of the line source....

See the barely visable top of a head in the listening chair?

[URL=http://s926.photobucket.com/user/evsentry3/media/BoblisteningtotheOBsystem.jpg.html][/URL]

That's Bob Carver listening to the 3 TB's and 4 GW system. He played his favorite track...a Patricia Barber cut, loud. When it got done...he got up and had tears on his cheeks! All the endorsement I'll ever need!

EV3
 
eddantes said:
I thought one needs a qts close to 1 for OB work... at least that what Martin King writes. These, at .6 may not be the best choice.
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I have a friend who tried some a bit above 1. I think more like 1.2 or so. It made kind of flabby bass to me. Maybe just that driver, who knows.

The Hawthorne Augie's are around .9 and they certainly do well, though maybe a smidge towards at least not tight bass. He also recommends against getting too high of a Q driver, BTW. I have a big batch of them I'm getting ready to implement, so we'll see....

But a bit higher than around .6 might be good. But the higher you go, the more you tend to go towards a looser bass. It's all a question of your taste I suppose. With a lower Q, you can correct with eq, to loose and you're not going to fix a whole lot that way.

My experiences, FWIW, is you're best off to be in the neighborhood of that .7 area. Specifically to be dead on that probably isn't so important.

EV3

PS...also remember the criteria of cheap! Those Goldwood's fit that well and still work for OB. Better drivers exi$t.
 
I keep reading posts here that state you need a high qts driver for open baffle. That is only true if you use a single driver. If you add a helper pro woofer that is not the case. MJK uses a pair of Fostex FE103E which have a low qts of .36. They don't need high qts as they aren't required to make bass which the Alphas provide.

Here's a link to OB bass types: "the fun is in the folds" :D

http://www.hifizine.com/2012/12/subwoofer-origami/

FWIW - The 10" GW woofers would be a good candidates for storage cube H-Frames: These are "Way Basics Storage Cubes" sold at Target and online. Their z-board construction is pretty amazing.
 
EV3,

Very nice system. I too love the Tang Band W8-1808 but bought mine back when they were affordable. That was before the neo magnet prices went through the roof.
 
Poultrygeist said:
I keep reading posts here that state you need a high qts driver for open baffle. That is only true if you use a single driver.
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Exactly so - many of the OB-curious are drawn to that full-range/extended range single driver (or coax), point-source mystique and don't really want to complicate things ("less is more" as the architect Mies van der Rohe put it). Now, going from that ethos to what are in essence, typical multiway loudspeakers sans boxes is... a matter of taste.

I don't have any philosophical problem with adding help at either frequency extreme - as long as the helpers are kept well clear of the midrange.

FWIW - The 10" GW woofers would be a good candidates for storage cube H-Frames: These are "Way Basics Storage Cubes" sold at Target and online. Their z-board construction is pretty amazing.
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mmmm... now that is interesting.
 
Instant OB H-frames

Way Basic Storage Cubes awaiting some 10" bass woofers.


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I spotted this thread this morning and thought I'd throw this together. It probably doesn't qualify as an OB design but I was curious and had the components. It's a start anyway.

It sounds nice but there is an obvious lack of bass. I have the same EV 12TRXB in an Aristocrat cab and the bass is much better. It's hooked up to a 12 watt mono tube amp.

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I suppose I could chime in a bit more on this thread, as I am a recent adopter of open baffle speakers. I have to say there is a lot to like about them, as I bought a nice pair of Hawthorne Trios for my system. I am sure some might be tired of this pic, but they are so pretty I cannot resist posting their image one more time.....


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Since I use SET amplification, I need speakers that are higher efficiency, and the Hawthorne fits the bill. But the drivers are expensive, that is no doubt. If I were to explore another version of the the OB design I think I would like to find the OEM equivalent of the 10" driver without the coax portion. The speaker I have uses a Radian tweeter in the middle driver, and the speaker has an open back that allows the back wave of the diaphragm to radiate out the back of the speaker. I like the full range dipole arrangement.

So I would try to find the 10" mid driver, and couple it up with something like the high efficiency version of the Fountek ribbon. It would be interesting to use two of them, one forward facing, one rear. Then a pair of bass drivers in the H frame baffles could also be used.

What would be fun to do is use an electronic DSP with them, for time alignment equalization, and electronic x over. Of course in my case this means another SET style amplifier to take care of the tweeter duties.

If a person were to use less efficient speakers for their OB design, and would need more power..say 60 to 100 wpc. It might be interesting to find one of the high end 90's era SS amplifiers that was built for high end home audio by some of the well regarded companies. For instance Kinergetics built the Chiro line, Soundstream built some nice multi channel amps, as did Butler audio, I think Sunfire did. Anyways, a 4 channel amp could be a great way to get affordable high quality amplification and still have a relatively compact and clean system layout, of course this is in context of a system using a DSP. Just a thought. Yes I understand that Emerald Physics or Linkwitz have products based on this component arrangement.....it is not a novel idea.

Now if a person were going to lower efficiency OB with ribbon mids and hghs. Well I guess we have just basically described the Carver Amazings right? I have never been a fan of Carver products, but given what I hear from OB...perhaps I would change my mind. I am not sure of the layout of the later Carver speakers, but finding a good used pair might be a way to short cut to a high end OB arrangement, even if you choose to select different bass drivers. Yes I know Carver people would think thats a bad idea...and perhaps it is. Was just throwing the thought out there.

But for now I am content with the Hawthornes, they work well with my 8 wpc SET amp.

Regards
Mister Pig
 
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The Carvers are an "Amazing" speaker. Their character is the ribbon plus the OB bass. The biggest issue to deal with on them is the power required to run them. In that, they are the perfect fit for Bob. But it does lock you into the sonic qualities of the amp you mate with them.

I spent well over a decade in the much the same situation with Martin Logan Monoliths. Their character is bit different than the Carvers of course, the stat instead of the ribbon and ported bass instead of OB. For me, the biggest weakness is the quality of that bass. But again, locked into the need for power. A bit easier load than the ribbons but still power.

Now, go to the short line OB. Much of the same attributes of both these well regarded designs. Much, much more economical...plus...the freedom from power requirements. Among the challenges, to get the kind of quality of two very fine, excellent systems.

I've played with the Audio Nirvana, Lowthers, University, Tang Bands, Fostex and the econo drivers from Parts Express. Probably some others too that don't come to mind right now. For me...IMHO...the Tang Bands are very good drivers without the warts or the expense of the Lowthers. Maybe it'd be sweet to get the magic of the liveness of the Lowther, but dealing with it's extreme peakiness not to mention the unaffordability of doing them in multiples just won't be happening for me.

So if you'll indulge me on what I've been doing a bit more....the line source. Look at this kind of paper and all the polar patterns...

http://www.dipolplus.de/downloads/Open%20baffle%201.pdf

All these presentations depict the single driver. The question is, do we avoid more "problems" with a line source or create more? One of the big ones is of course the arrival time issue. Does the line do more "filling in" and have less dips from the timing issue of the "comb"?

But while pondering and exploring the issues, also try listening to a line. Sometimes it's easy to get bogged down in the "issues" and forget to just try it.

EV3

PS...Poltrygeist...I also got a bunch of the TB's before the price shot up. But still, at $210 each, a lot of quality for the money!
 
Johnmac,
Looks nice!

Poultry,
I know you have posted those target box woofers before but now I'm thinking I could build one. As it happens, I have a recently acquired jig for cutting baffle openings.

Mister pig,
It is interesting how open baffle designs have been used in the past. Eg, dahlquist dq10s are basically open baffles on top of a bass bin. Once I had my OBs I realized I could move on my dq10s (plus I wanted to try bozaks!).
 
JohnMac said:
I spotted this thread this morning and thought I'd throw this together. It probably doesn't qualify as an OB design but I was curious and had the components. It's a start anyway.

It sounds nice but there is an obvious lack of bass. I have the same EV 12TRXB in an Aristocrat cab and the bass is much better. It's hooked up to a 12 watt mono tube amp.

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It sure is an open baffle; just as were all of those old console hifis with open backs (well... typically masonite backs with a plethora of vent holes in 'em... not exactly "aperiodic loading", 1950s style!).
 
The mix and match combinations with OB's are endless. You can interchange many 8 inch mains as they often use the same cut outs. I started with 3/4 plywood but now use 3/4 MDF as it's denser, cheaper, and less likely to warp. A 4X8 sheet of MDF is $20 and you have enough material to make several baffles. Painting MDF is a PITA so I've resorted to using thick wallpaper which not only looks better but reduces resonance ( wonder how grasscloth would look? :-) . Here's my journey into open baffles so far.

Folding baffle single driver Betsy's ( nice but needed a little more bass )

Folding baffle single driver Pioneer BOFU ( lacked the HF of the Betsy's but better bass and with a tweeter it might have been as good )

Folding baffle single driver Tang Bands W8-1808 ( very refined but lacked bass as you would expect with it's low qts )

Flat baffle Betsy's over Alpha 15A pro woofers ( bi-amped ) - now I'm really getting somewhere and here is where I sold the Zu's

Tang Band W8-1808 over Alpha 15A H-frames ( bi-amped ) - excellent and I could have stopped here

Tekton OB4.5 over Alpha H-frames ( bi-amped ) - excellent but didn't keep them

Beta LTA12 with super horn tweeter over Alpha H-frames ( bi/tri-amped with active crossover ) - keepers and they are by far the best for the modest investment

Tang Band W8-1808 with double Neo3 planar tweeters over Alpha H-frames ( tri-amped with active crossover ) - excellent but a cabling nightmare

Flat baffle Lowther DX3 over double Alphas ( bi-amped with active crossover ) - this is where I currently am and is the best combination I've tried.

The constants through this journey are the use of HE full range drivers ( 92dbs and above ) powered by SET amps and cheap but powerful solid state amps driving pro woofers when I switched to 2 ways.

The great upside of OB is low cost and easy DIY with performance that can put box speakers to shame. I no longer consider their size to be a downside as their overall footprint is often less than box speakers. Build an acrylic baffle and they'll really disappear.
 
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Back in the day the best sounding audio in town came from a jukebox. The old jukes had open backs with large full range drivers powered by low watt tube amps.
 
poultry,

just like happy days!

love your journey. have you heard the SABA green cones? your friend's website has me curious about them now.
 

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