The 'Circles of Doom'.....Open baffleless full range speakers.

Some of you may be aware of my various speaker projects over the years.
I have built standard 3 way sealed speakers, MEH synergy speakers using small full range drivers, and some fairly unusual spherical four way speakers with high end drivers, attempting to minimise diffraction.

I posted my listening impressions of my synergies versus my spherical sealed 4 ways here:

Comparison of 'Xbush Sphere synergy horn', versus 'Balls of Prestige'.

And here is a photo of my previous reference system as a starter for ten (the spherical creations in the background), in front of them is the prototype dipole system I knocked up to try.

My listening room is fairly sorted with a ceiling cloud of broadband absorption, wall mounted panels at the first reflection points and some bass trapping in the corners. I have used book shelves and 'man cave objects' as diffraction :D

I was always very happy with my 'reference system', but wanted to scratch the open baffle itch.

After lots of research and reading, I decided if I was going to go open baffle - it had to be a full on project (like my previous ones).
Form would have to follow function as as per John K's NAO notes, and Linkwitz'z LXs I realised baffleless would be the best performance.

Ideally with true dipole behaviour as high as I could achieve - which meant dipole planar drivers for the mid and top end....

So these will probably not be to everyone's taste (I am not sure I even like their looks!!:eek:) but the aesthetics are completely determined by function.
 

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This open baffle 'prototype' system blew my mind.
It sounded better than anything I had heard before in all areas.
So I decided to try adding open baffle bass to this and upgraded the mids to the Neo10 dipole GRS clones...
I will add some photos of the build, more details, and measurements etc when back home.
The 'clamshell open baffle subs' are also a real eye opener.
 

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Very interesting. Subscribed!

Interesting: would have thought the Neo 10 would be challenged to get to 100Hz in baffleless.

I'm also blown away by OB, also using AMT tweeters, but woofers below that. And still have sealed subs...you might mean trouble for me with OB subs :D

Looking forward to the thread unfolding.
 
Here are a couple poor quality phone photos - I need to take some shots of them in daylight, but gives you an idea of the general construction.

There is some tidying up to do on them - but you can see how they are suspended and how the clam shells are in hammocks.
 

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Yes - Charlie - you have been an inspiration in my baffleless journey!
It was you who put me onto the deltalite 2515 (which I think is great).

It was one of your threads a few years back about making a 20k-20k fully dipole speaker which first got my cogs whirring and this is the result.

I use REW, UMIK-2 and the miniDSP to sort everything out. This is how I have been building my speakers for the last few years - my synergies would have been very difficult without this.

I tend to try to take as accurate measurements as possible with windowing, and removing reflections, then EQ each driver flat on axis as far above and below crossover points as feasible.

I then time align the drivers using a combination of the acoustic reference function in REW, and the null methodology.

I can then play around with crossover points, slopes and various options without too much other adjustment required. I usually choose crossover points as the best compromise between distortion, driver C-C distance, power response etc. etc.

The 100, 600, 3500 are my best first guesses at present - but I literally only screwed this together yesterday - so a big measurement sessions will take place at the weekend!

Bass - I tend to measure with a combo of nearfield close mike measurements and in room listening position moving mike RTA measurements. I EQ only peak (room modes) and aim for smoothest response in the listening area (leather sofa).

I suspect this is similar to how you do things - but any tips - gratefully received!

Once again - a massive thank you to you Charlie - without you and others on here, I would never have tried open baffle - I always thought it was a niche speaker design that was inherently compromised.

I wanted to hear for myself whether the envelopment and 'added reflections' would create a pleasing effect. I fully expected to make my prototype (in the first picture) say 'well they were nice but nothing like proper speakers' and then sell the drivers on. At least I could say I had tried open baffle.......

Little did I realise I would find them overwhelmingly better in all aspects than all my other builds and designs (and I have almost built them all apart from line arrays!).
 
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I've done a few mock ups of this style of dipole and can confirm it can sound very smooth and powerful. I think it has something to do with how the drivers couple with the air instantly from all sides. Just guessing though.

Low end does not pressurize room however and is an acquired taste. I still love listening to it.
 
Is the clam shell wired push-push, so force cancelling? interesting

No that would result in no bass output at all as they are baffleless.

I have made push-push sealed subs (if you look in the first photo of this thread you can see them in the background - giant tube subs with a driver at each end).
I have to say - as a sealed or ported sub - push-push are amazing particularly if you mechanically link them as mine are (metal rods bolted through both drivers internally). There is literally no vibration detectable at all when the drivers are going mad).

These baffle less subs are wired push-pull so the move together - which causes lots of vibrations - but because they are completely swinging free in 'hammocks' - no vibration is transmitted anywhere else.

I don't think I would want to mount these big 15" drivers to a baffle - unless it was incredibly dense and heavy - they have very heavy cones, and 22mm x-max!
 
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Hi BM,
Super cool new project! Years ago, I made a quick and dirty slot loaded woofer open baffle that sort of reminds me of your clamshell sub but I used 6x 6.5in woofers in a slot loaded design. That speaker sounded amazing and I told myself that I must revisit it one day in real wood. Maybe that day is near seeing your progress. :)

Cheap and FAST OB, Literally

The bass was so clean and non pressurizing as I recall and it went down quite deep.

397658d1391479751-cheap-fast-ob-literally-slot-ob-photo-01.jpg


Redoing this with the GRS B&G clone planers would be very cool indeed. Those drivers sound excellent.

Congrats on your new build!
:cheers:
 
That looks good. This is similar to how I am building systems these days, except also with all drivers physically decoupled from each other.

I forgot to add - the subs are physically decoupled - they are 'floating on hammocks' with a natural resonation of approx 6 hz.

And the deltalite 2515 is 'hanging' on wires - so completely decoupled.

However the neo10 and neo3 are screwed to the baffle - but they do not seem to create any vibrations at all - even at very loud volumes - presumably because of their design and very low moving mass?

The whole baffle is complete dead even at very high SpL.
 
Hi BM,
Super cool new project!
:cheers:

X!! Hi!
Long time no chat! Honestly - you really, really must get some of these GRS clones and have a go - with your foam core skills - you could knock one up in no time! Not too expensive if you go with their neo3 and neo6 clones....

Honestly - I have now done horns, synergies, sealed, ported, low diffraction, the lot.......these are the best I have heard by far!

I'd heartily recommend the deltalite too - very low distortion and great dipole behaviour naked from 100-right up to 1000 (probably higher!).

Regarding open baffle bass - with the four 15" subs I am using I have a displacement of over 6 litres - so crazy amounts of air can be moved. Without this I think you would need a big H baffle or similar to get decent low bass.

This is only achievable in this clamshell configuration due to modern high output car subs - which have relatively high QTS, low FS and massive X-max.

But the sound is something else - you still have to deal with a few room modes - but the decay times seem so much better than my sealed subs - completely different room interactions.
 
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I had some BG originals lying around from years ago and have compared the two - as have others on this site.
Gotta say - I think the GRS are just as good - there are some variations with both manufacturers - so this may be driver dependant, but mine have really good distortion measurements and very similar freq responses between the pairs.

Whether there was a learning curve initially for GRS I am not sure - but the neo10 clones I have are excellent.

I will post lots of boring graphs later for you to peruse. But I currently think the GRS drivers are the bargain of the year:)
 
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Hi Bush

I had a version of what you’re using for subs up and running for about a month after coming across the idea more than once. Vic from Trans Fi has documented his meandering with the design extensively.

My top end was completely different...Lii Audio Crystal 10 drivers baffless.

I was using (4) AE Dipole 18 drivers mounted and suspended as you are.

I had to wire the dual voice coils in parallel (with reversed phase of one driver on each side) for a 4 Ohm push-pull result.

This application required powerful amps and drivers that can really move air.

I found out the hard way that it is easy to exceed xmax once they get pumping.

It seems that setting my Hypex amps to soft clip at 300 watts into 4 Ohms wasn’t conservative enough.

I believe I bottomed out one of the voice coils when I heard a “Snap!” during a bass heavy Downtempo track that I was playing enthusiastically for my son.

Now the driver has a buzzing sound during playback unless I hold my fingers gently on the cone.

I contacted AE and they said a recone is possible for $150 and that I should check a few things like the phase plug, surround and coil gap for losseness or debris before jumping to conclusions.

I will say that while it was up and running I seemed to be going in a good direction. The sound stage was almost holographic on good recordings at times.

I think the 15mm xmax may not be enough for this design. Vic swears by his Dayton Audio Ultimax UM-18 22...which have 22mm xmax.

I thought the AE’s were designed for OB and I shouldn’t have any issues. I suppose a little knowledge is a dangerous thing.
 

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