Open Baffle Experience

Spatial Audio sounds better to me - which is surprising since I'm not a fan of horns, and tend to ignore all but the most botique giant horn models. What did you use to record that? Recordings sound great!

My open-baffle experience (after building many ’box’ speakers) goes like this...

I was enjoying my truck stereo one Spring day, and warming weather allowed me to roll the driver & passenger window down. What just happened!?... suddenly, despite the additional wind and road noise - the system suddenly sounded amazingly better. I’ve been missing something - but what? I also have a curiosity for unique speaker designs. My first speaker build (in high-school) was my attempt to recreate Ohm/Walsh omni-directional design (early 80’s) with drivers from Radio Shack that I put on my Christmas list (along with a jigsaw - which I used to build the speakers in my bedroom) - townhome living with no garage. As an adult, armed with new-found open-back curiosity, I found Martin Logan e-stats. I liked the sound, but despite the panel curvature, they have an unacceptably narrow sweet-spot. Digging further, I found Linkwitz. Not convinced, I ordered the inexpensive Madisound kit including flat-pack to test the waters.

Also note another influence. I saw the writing on the wall decades ago... due to technical innovation, audio systems (like everything else) will become more consolidated, condensed, smaller, all-inclusive, ’lifestyle’. Also, cable believers and nay-sayers alike can agree on one thing... the fewer cables the better (especially analog).

So with Linkwitz LXmini, there is potential for these two factors to coincide. I built the LXmini, and was rewarded mightily, inexpensive, beautiful, natural, enveloping sound. This is compared to the other speakers in the stable at that time (ML estats, ML motion-series, GoldenEar Triton, Tekton DI-upgrad, B&W, Elac, SVS Ultra, Buchardt). Only problem was the ported sub I had did not keep up with the LXmini’s... they need an open-baffle sub to match their accuracy. Back to the genius Linkwitz for a solution in the Phoenix[alt] sub. I built a pair with the recommended Peerless XLS drivers and could not be happier with the result. So, how does this coincide with ’lifestyle’?

My current normal listening rig consists of Node N130, a pair of Hypex FA123 (each mounted into the Phoenix[alt] OB-subs powering everything) and LXmini speakers. This is a ’lifestyle’ system - just one piece of gear and it’s half the size of a ream of paper. Cables are minimized down to one digital coax to Hypex FA-123(master), and one digital coax cable going from the master to the other Hypex FA-123(slave) - two cables total, and they are carrying digital signals (not analog).

What do I think of the Hypex FA-series + LXmini + Phoenix[alt] combo? It sounds like being on the stage listening to a performance first-person, as opposed to sitting in the audience listening through mic/mixer/amp/speakers. Rather than bore wax-poetic, let’s review the truths about this and potentially similar systems:

• These are the least room-dependent speakers I’ve ever heard. Why? Because they have omni-directional midbass and cardioid mid/treble, so there is very little side dispersion to reflect off walls/ceiling/floor.
• These speakers are no further in the room than any other speaker would need to be to sound good - mine are 30" from the front wall.
• Open-baffle bass doesn’t pressurize the room, so your house doesn’t become a giant vibrating box. Also, someone said, "Magico and KEF... balanced-force...". Take a look at Linkwitz Phoenix OB-sub design to see a simple example of cancelling cone inertia - there is no cabinet vibration in this configuration.
• No analog cables (caveat here, I do use balanced XLRs with NAD C658, when using that as source/pre). Node doesn’t have phono input or the suite of HDMI In/Out that the C658 has with MDCmodule.
• And finally, the #1 best reason for a system like this. The sound is fully controllable, at-will, on the fly, while listening/measuring - because it uses DSP crossovers and filtering within the Hypex FA-series DSP/amps. Let’s say you suddenly think the highs are too bright - adjust the filters (2minutes = done). Or, you want more bass (2minutes = done). Maybe you want a different adjustment for night-time or party-time listening, dial it in as you wish and save it as a preset (2minutes = done). Try doing that with most mega-buck monkey coffins. With these, you have the freedom to make them sound however you want, whenever you want. This benefit alone is worth the cost of admission, and why I can’t imagine making another speaker system without this capability. Note, Hypex FA-series amps are not the only way, as I started with the miniDSP2x4HD, to the nanoDIGI 2x8 (and 4 stand-alone Topping DACs), 4x10HD, DDRC-88A/BM (its been a journey of passion) - they all worked very well, but the FA-123 (also have new pair of FA-251 sitting idle) is the most ’lifestyle’ solution.

So, there you have it @erik_squires go out and get some open-baffle goodness. And I’ll leave you with this

And for those that doubt the bass...

@jaytor Wave-guides, yes that makes more sense, open-back - nice!

One of the things that has prevented me from pursuing large front baffle designes (like Spatial, Pure Audio Project, Caintuk, etc.) is one of the same problems I hear with box speakers - reflections from the front baffle allow localization of the speaker, they don't 'disappear' so they sound like listening to speakers - ruining the 'being there' effect. Maybe a wave-guide solves this? Problm with wave-guides is they act to compress - same as horns can seem 'shouty' and broadcast forward. Maybe the AMT being open on the backside solves this? Most box speakers take these issues and add cabinet resonances, backwaves, (typically) flat side-panels and so on, stacking too many bad cards in your hand to form a winning combination unless a ton of $ is thrown at it. I once had a pair of egg'ish-shaped speakers made of concrete (no cabinet resonance), they sounded very good... until the Carver monoblocks blew a chunk off the inside in short order - returned those rattly beasts for a pair of bipole Mission spreakers that served me well for decades.

Cool thing about LXmini + OB-subs is they're inexpensive, you get to build them yourself (sense of accomplishment), they barely care about the room or treatments, you can use them to build an entire 'lifestyle' system for $2k (less than many of these guys are paying for a pair of cables), and tune them to sound however you like and whenever you like. What can be done to change the sound of most speakers... an endless game of cable-swapping, gear matching, tube-rolling, room treatments, vibration oscillators all around the room, copper screws, magic beads... the list may be infinite and infinite $.

@erik_squires

I get edge diffraction, but my speakers have 1/2" rounds on the edges and I defy anyone to tell me they can hear where the speaker is.

If a box is unavoidable, it should definitely have the largest radius edges possible, and ideally the curvature should go all the way to the driver frame - like the concrete speakers I had once. Think those were made in some Scandinavian country - wish I could remember the name. Someone on A-gon probably knows this company. But I wasn’t referring to edge-diffraction (that’s a whole separate issue), I was talking of flat front baffle reflecting surface area (initial reflections allow acoustical localization).

I’ve heard many other speakers that do a great job of disappearing as well, some with very narrow (Vandersteen)...

Yes, to maximize ’disappearance’, surface area perpendicular to the listener should be minimized - like you said... narrow baffle. My GoldenEar Tritons are an example of this, also most KEF and many others including the Anthony Gallo Strada’s as an extreme example and the tweeter pods on most B&W - for that matter we all know what the B&W Nautilus looks like (all the same philosophy).

Both of my above statements are witnessed in the KEF Blades and B&W Nautilus (extremely rounded and narrow-as-possible front baffles) - I count these as great designs (judged soly by their visual aspects).You can look at either of these and say, "Those are likely to disappear in a room" because of how they are shaped. Now, there are other factors that can draw attention to a speaker, like resonances, drivers sounding forward or unnaturally bright - but at least these designs have a shape that will allow greatness.

and some with broad baffles (SF Amati Heritage). I’ve never felt this was an attribute of baffles which could not be dealt with.

Yes, your correct in the statement, "...which could not be dealt with." Notice what SF have done to "deal with it"; front baffle narrow as the drivers will allow (does this sound familiar?), entire front baffle surface covered in (expensive) absorptive material, the front-baffle is also curved and the cabinet sidewalls are curved and form a triangular profile. I said in previous post of this thread, "...throw $ at it", and Sonus Faber exemplifies this method.

Also note that controlling reflections in a room can cover-up speaker localization too - I put that in the category of "throw $ at it".

@coralkong 

I switched to OB speakers (Emerald Physics) a while ago, and I don't think I could ever go back to a box speaker. ...they sound absolutely glorious when you get them dialed in. Anyone who tells you differently is talking out of their ass.

With respect to my experience with dipole speakers, I agree completely - very well said!

They need lots of room to breathe and placement can be tricky

I haven't found this to be the case with LXmini + Phoenix[alt] OB-subs; however, the only other OB-like dipole speaker I have experience with is Martin Logan e-stats, and they needed breathing room, critical placement and very limited listening position. The carioid/omni dispersion pattern eliminates those issues.

@twoleftears For those interested, that track was Birds by Dominique Fils-Aimé from the album Nameless. Nice track.

@reimarc Those 521's are beautiful. I've never heard them, but have a spare 4x10HD and 12-ch amp and intend to build them one day.

LXmini plans are available here:

Phoenix open-baffle sub plans are free from Linkwitz Labs website, here:

https://www.linkwitzlab.com/woofer.htm

The specific Phoenix[alt] version I built is here:

https://www.linkwitzlab.com/woofer3.htm

I made a slight alteration (think it was 1/4" taller?) to fit built-in Hypex FA-123 (could also fit wider FA-253), and you can build a pair of the subs with one (4’x8’) sheet of wood.

While searching for that file, I also found the in-room measurement (used REW and Omni Mic)...