New Open Baffle Concept

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Hmm, after re-reading my last post now that I'm actually awake lol. What I meant is that was the price to buy the cabs ready made from Decware etc.. A whole lot cheaper to DIY for sure, and that option is made available for those that want to try.. I guess they just seem pricey for what they are, compared to some of his other seemingly more complicated designs.. I own and exclusively use his Taboo amp, and have no real plans on changing that anytime in the near future or at all, nice sounding unit!

Please keep your impressions of that new OB coming Nelson, and how it all seems to sound as the drivers and design settle in etc...

:)
 
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For lighter acoustic music the ZOB can get away without bass augmentation.
But are you into Pink Floyd, Roger Waters and the like they will come out thin, thin & thin.
So for me at least I need bass augmentation to live with this speaker.

Thanks for the update. Im curious as to what extent the chamber is contributing to the bass / lower midrange (if at all). I would love to see comparitve frequency response measurements with the chamber closed and open. As the measurement is relative it could be done in room. If you ever get a chance to do this and post the graphs, I would be eternally grateful!

I've listened to a lot other speakers lately. With fresh drivers in the ZOB they just sound thin in my ears. Not a little thin but thin. Listening fatigue is another issue with this driver in my system at least. I can't stand it for more than 30 minutes. So I've no leave the room to break in the drivers...

It seems that even the modded 207E is in need of a BSC circuit / active eq to correct the fatiguing tipped-up response.



 
This is what I was thinking, but I would have to build one as all of my enclosures are enormous (my wife has approved of my hobby). And, pardon me if I sound arrogant, I was already thinking on how to get a better coupling of the driver to the unbox, as event horizon suggests. My first thought was something that would end up looking like the double-mouthed BVRs we all know so well but without the mouths. Hey, why would it have to be without the mouths? Hmmm...

I find this a very insightful comment because I realize now that the BVR is a reflex box with a broad-band port (in the same way that the unbox is) so that it doesn't have a single resonance frequency. In a way, the BVR is the ideal bass reflex.

Back to the ZOB: Interesting ideas. I've read this through once. My interpretation is that the unbox acts as a bass trap. It doesn't trap all the bass, just enough to reduce cancellation of the front wave. This boosts the base, but not so much that it avoids it sounding a little thin compared with a supporting woofer. I do like how the unbox is designed as a broad frequency trap, quite ingenious. I figure the end result is that this is a dipole for mids and highs, and a dipole-monopole for bass.

FWIW, I don't think it's easy for anyone going it alone in this business to make it financially successful without practicing the 'gift of the gab' so a bit of marketing hype on the gentlemen's web site should be expected - small business is good for the industry - otherwise we'll just have the big box shifters.

Any progress since May ?
 
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Not for me...

Hello DaveCan,

The ZOB never became very good here. A BSC just sucked the dynamic and the live feelings out of the music.

ZOB is a fantastic speaker for acoustic guitar and a female voices.
For anything else it sucks IME. Maybe it will be great for any kind of music using a sub bass speaker? ;-)

The HDT is pretty good for what it is. No boom from the bass but might be better using the Silverflute for deeper bass?

Meanwhile I build the DTQWT by Troels Gravesen. Troels knows how to design and build real high end speakers!
Everything sounds right, super dynamic and all acoustic instruments sounds as good as in real life and they have same size as in real life as well. And the DTQWT can play bass and extremely loud without ANY shouting or beaming. The best speaker I've heard within the 27 years as a HiFi freak. Period.
 
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FRX2/ZOB

I'm in the process of building these speakers now. Baltic birch ply on order, 6/4 sapele for the baffles. Looking for a couple of 1/2" shank router bits to do the locking rabbets and dados. The speakers sound awful playing in their shipping boxes. We'll see what happens once the baffle and chamber are built. In the mean time I'll work them in for a few hours a day as I build them. I'm thinking of getting a full sized 3/8" aluminum baffle built that will attach to the sapele with a few blobs of 2 stage epoxy and a thin layer of green glue. The drivers will be recessed into the sapele flush mounted, and will sit on a sorbothane gasket. The holes drilled through the baffle will be oversized, and filled with green glue, so no contact occurs. The bolts will be set through the aluminum rear baffle, attached only by sorbothane bushings and washers. The idea here is to "float" the speaker against the wood baffle, and also to transmit some of the energy to the rear metal plate of the baffle. The two halves of the baffle are connected by a viscous material that will dissipate the vibrational energy as heat - a constrained layer method of dissipating what little energy the driver may create. I hope to both firmly physically mount the driver, but also to distribute its energy across two halves of a constrained layer. The rest of the box will be pretty simple. Just have to get my tools together so I don't sit around thinking more than actually doing something about it. Since I consider this a fun project, and not to be my last, I'll be more than happy to share my honest impression of these speakers when they're done. I'll try to keep any evaluation in the context of the few speakers I've owned to date - a Boston Acoustics 2.5 way bass reflex, an older pair of Martin Logans that I sorely regret selling, and a pair of sad, run-down Magnepans that don't play nicely with my present amplifier, a Sugden A21ap with a mere 25 watts that just don't impress Maggie. I strongly considered getting those Mags "Gunned" by the man himself, but Decware and open baffles have caught my attention. So, I spent some cash and I'll spend a little more, total project costs will run just north of $1500 when done, and I'll let you all know how it turns out. Since they might be bass shy, I have a perfect pair of helpers - my stereo pair of Vandersteen W2q subs. The lower registers shouldn't be a problem at all. In fact, I could mike the ports and use that to feed the Vandys!:joker:
 
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Joined 2009
Any update - have these been finished and what are your impressions?


I'm in the process of building these speakers now. Baltic birch ply on order, 6/4 sapele for the baffles. Looking for a couple of 1/2" shank router bits to do the locking rabbets and dados. The speakers sound awful playing in their shipping boxes. We'll see what happens once the baffle and chamber are built. In the mean time I'll work them in for a few hours a day as I build them. I'm thinking of getting a full sized 3/8" aluminum baffle built that will attach to the sapele with a few blobs of 2 stage epoxy and a thin layer of green glue. The drivers will be recessed into the sapele flush mounted, and will sit on a sorbothane gasket. The holes drilled through the baffle will be oversized, and filled with green glue, so no contact occurs. The bolts will be set through the aluminum rear baffle, attached only by sorbothane bushings and washers. The idea here is to "float" the speaker against the wood baffle, and also to transmit some of the energy to the rear metal plate of the baffle. The two halves of the baffle are connected by a viscous material that will dissipate the vibrational energy as heat - a constrained layer method of dissipating what little energy the driver may create. I hope to both firmly physically mount the driver, but also to distribute its energy across two halves of a constrained layer. The rest of the box will be pretty simple. Just have to get my tools together so I don't sit around thinking more than actually doing something about it. Since I consider this a fun project, and not to be my last, I'll be more than happy to share my honest impression of these speakers when they're done. I'll try to keep any evaluation in the context of the few speakers I've owned to date - a Boston Acoustics 2.5 way bass reflex, an older pair of Martin Logans that I sorely regret selling, and a pair of sad, run-down Magnepans that don't play nicely with my present amplifier, a Sugden A21ap with a mere 25 watts that just don't impress Maggie. I strongly considered getting those Mags "Gunned" by the man himself, but Decware and open baffles have caught my attention. So, I spent some cash and I'll spend a little more, total project costs will run just north of $1500 when done, and I'll let you all know how it turns out. Since they might be bass shy, I have a perfect pair of helpers - my stereo pair of Vandersteen W2q subs. The lower registers shouldn't be a problem at all. In fact, I could mike the ports and use that to feed the Vandys!:joker:
 
ZOB

I let them sit for a long time - new baby in the house. They are assembled and playing now but they aren't finished. They sound very nice to me.

The open baffle can be startling in the way it suspends voices in mid-air. Sound staging and imaging are quite impressive, and dynamics are very good. I much prefer a single driver to the huge launch surfaces of Maggies and Martin Logans. For the kind of moderate-volume listening I do, it creates more realistic size and spacing. On the top end, there is no sense of "shoutiness" or treble-forward presentation. They are capable of very nicely reproducing cymbals, flutes, and "air" around instruments. I don't have the hearing of a dog, so I'm not interested in much above 16kHz. I'm sure there are speakers that do the "top end" better, but they are quite respectable in that regard. They have no metallic, ringing, or annoying edge to them, nor do they exhibit any of the problematic treble usually associated with single full-range drivers.

Midrange is extremely nice. Female vocals and guitar are completely convincing.

I have good but not great amplification, so they are probably capable of more, but they are soft in the mid/low bass. I use them with a stereo pair of Vandersteen 2wq subs. The subs blend in nicely, though there is still a gap and the integration isn't perfect. It will improve after they are stuffed and finished. They could benefit from room treatment and correction, which would reduce their sensitivity a bit but level the bass response. I think they are around 96-97db sensitive, so my 25WPC amp is overkill. I'm going to try to pair them up with a much lower-powered SET and see if that is a better synergy.

The most impressive music I've heard on them so far is Pink Floyd. The Delicate Sound of Thunder was awesome with the subs working full tilt. I heard Floyd play at RFK stadium back in the 90s. If anyone can recall the sound system they used on the Division Bell tour, it was insane. They made the sound of a jet flying over the stadium, and it actually moved from one side to the other. They could make the sound rotate around the stadium in crazy ways. It was crystal clear and incredibly powerful. The fact that the ZOBs were able to present a little slice of that sensation in my basement was a real hoot.

Overall, I think they are excellent speakers. I will probably "Gun" my maggies next, just so I can choose from either of them. Considering I don't have a large budget for audio, I would say they are an excellent addition, well worth the roughly $1700 investment. If you accept their weaknesses - that they don't do high SPLs, and that they are a bit bass shy, I don't think there are a lot of competitors in that price range that would match the ZOBs for imaging, soundstaging, speed, and dynamics.
 
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