[Vapor Audio]

I just posted this info on the baffle forum but since we are here and now.....here goes.  To follow up on what Danny was saying.....you will never get the low distortion sound of an open baffle from a box.  The air pressure behind the driver limits its ability to track small variations in signal.  This I have heard directly.  Also a two way speaker is always compromised.  The woofer is modulating the midrange and also the back EMF from the woofer excursions also screws with both the mids and highs.  Also you can never get great bass from a small box.  And, if you biamp you can use equalization on the woof and remove the back emf all together from the mids and highs.  Have you ever heard bass in your room equalized to plus and minus 1db?  So, what is the purpose of a monitor?  They look cute.  If you have very little money then they make sense.  But why would you want to spend serious money on an expensive 2 way monitor when something like what Danny will be making shortly will simply kill any monitor.  3 servo 8s with open baffle mids and tweet above?  You are not going to touch this with a tiny squeeky boxey two way...no way.  The footprint of an open baffle system can be as little as 10 inches wide.  So, basically the same as a monitor on a stand.  If you do not like the mids radiating to the rear you can simply hang some felt on the back of the speaker.

I don't want this thread to turn into any sort of bickering, so I'll just leave it as a simple I disagree with most of the conclusions you draw here.  And I'm only posting that so nobody will assume silence means I concur. 

Since we're talking about building the ultimate monitor, can we please continue to do so instead of saying things like monitors are cute, for people with little money, and are tiny squeeky boxes? 

[Vapor Audio]

"From all the testing and research I've done, you want the highest possible tensile strength AND internal damping" So is there any truth to the claim by Magico that an over-damped cabinet is one that removes resolution to bass detail or is just about balancing the different attributes? http://magico.net/Technology/Enclosures/Enclosures_02.php While we are at it is there a concise definition of "damped" available as it relates to speaker building? Lastly, where does open baffle fall in the "damped" category?

I don't think so.  The energy going into the cabinet structure is there, no matter what material the cabinet is made from.  Damping is the ability to shorten the life of that energy in the time domain.  The more damping, the quicker that energy is converted from vibrational into some other form like heat.  Aluminum has near 0 damping so any resonances are going to live a long time, but it takes more energy to create a resonance in an equal size cabinet simply because the aluminum cabinet has much more mass ... and because the aluminum has higher tensile strength, hence more resistant to bending (which is all a resonance in on a very small scale).  Aluminum is better than MDF no doubt, MDF is a terrible terrible material.  But it's certainly IMO not the holy grail. 

[Tyson]

Open Baffle.....

[kwarny]

Typically when we talk about opposing woofers canceling anything it's in regard to odd order distortion harmonics ... notcabinet resonances.  But with how they're doing it, with the two drivers coupled together into one opposing unit, I can see how it would reduce energy put into the cabinet.  Reduce, but of course not eliminate.  When talking about 10" subs there's a LOT of vibrational energy being created, motors like that can generate in the range of 2hp.  Coupling the drivers will help, but all that energy doesn't just disappear, a lot is still going to go into the cabinet as vibrations.

The push-pull configuration reduces even order harmonic distortion due to phase cancellations.  Now back to enclosures  .   

[Ric Schultz]

A sense of humor is always a good thing.  Enlightenment......means to lighten up.  About monitors, I think Ryans speaker is probably the bees knees.  The only thing that I would do is to try felting the whole front for better diffraction control, try setting back the tweeter for possible time alignment and use my binding post bypass system.  Maybe Bybee thangs inside......maybe cryoing stuff.

I stand by my previous statements about an open baffle biamped equalized speaker being mucho better.  Of course the baffle would be made like Ryans speaker and the magnets of all the woofs would be magnet braced along with the baffle.  An open baffle speaker does not have all the sides like a box so the baffle must be made seriously well and braced seriously.  I would love to hear Ryans speaker with the back cut off and Dannys woofs underneath.....now we are talking!  With just two of Dannys servo woofs underneath, the whole speaker would not be very tall.   Of course, Dannys new drivers and waveguided tweeter will be killer too.

Fun stuff coming!

[Vapor Audio]

A sense of humor is always a good thing.  Enlightenment......means to lighten up.  About monitors, I think Ryans speaker is probably the bees knees.  The only thing that I would do is to try felting the whole front for better diffraction control, try setting back the tweeter for possible time alignment and use my binding post bypass system.  Maybe Bybee thangs inside......maybe cryoing stuff.

In person I got jokes, a real yuk fest.  On this website though humor is always lost, so I save it for the Gateway circle with people who know me.  Everybody else get's corncob-up-the-arse Ryan. 

Felt would be pointless on the Cirrus.  The 3" roundover eliminiates diffraction, none, nada.  Felt only reduces diffraction anyway, but on that cabinet there's none to begin with.

Time alignment is a theoretical that's rarely achieved in reality.  I'm not big, nor should anybody else be, at focusing on theoretical advantages and letting them dictate the direction your design takes. 

Binding post bypass?  Bybees?  Cryo? 

I stand by my previous statements about an open baffle biamped equalized speaker being mucho better.  Of course the baffle would be made like Ryans speaker and the magnets of all the woofs would be magnet braced along with the baffle.  An open baffle speaker does not have all the sides like a box so the baffle must be made seriously well and braced seriously.  I would love to hear Ryans speaker with the back cut off and Dannys woofs underneath.....now we are talking!  With just two of Dannys servo woofs underneath, the whole speaker would not be very tall.   Of course, Dannys new drivers and waveguided tweeter will be killer too.

Fun stuff coming!

I've done plenty of open baffle stuff.  One that I remember Danny at RMAF '08 calling "one of the 5 best speakers at the show no matter cost", or something along those lines.  He might not remember, but I certainly do.  It also had a big waveguide, so yes I've worked with more than just ribbons and 2-way monitors.  Point is there's no right answer.  OB's solve some problems, but introduce others.  Waveguides do the same, solve and complicate at the same time.  Like I said above you can't focus on one thing and think it's what makes or breaks a design, it just doesn't work like that.  It's a culmination of lots of variables, and then executing the fusion of them all.  Certainly the design can incorporate one of those things you're focusing on, but it's not mandatory for success.

[srb]

Felt would be pointless on the Cirrus.  The 3" roundover eliminiates diffraction, none, nada.  Felt only reduces diffraction anyway, but on that cabinet there's none to begin with.

Although the tweeter has a greater horizontal than vertical dispersion, what about vertical diffraction?  The side roundovers would only eliminate horizontal diffraction, right?  What about vertical diffraction from the sharp cabinet top edge and woofer/cabinet bottom?
 
Steve

[Jonathon Janusz]

No worries, Ric, no offense taken at all.  Just trying to keep this topic. . . you know, on topic. . .   What you describe sounds like a load of good ideas; if you can point us to somewhere we can see that sort of thing implemented in a commercial/production monitor speaker design, then let's put that speaker's hat in the ring.

Although the tweeter has a greater horizontal than vertical dispersion, what about vertical diffraction?  The side roundovers would only eliminate horizontal diffraction, right?  What about vertical diffraction from the sharp cabinet top edge and woofer/cabinet bottom?
 
Steve

I'm not sure about the top, but maybe this is another plug to put Danny's suggestion about small floorstanders (meaning in this case, monitors with attached, floor length stands) in the mix?  Would take one of the offending edges straight to the floor and out of the equation?

[jtwrace]

Baltic Birch is good because it is very high in both regards.  Metals like aluminum are higher in tensile strength, but have 0 internal damping.  With an accelerometer you absolutely can measure ringing in a cabinet.  My last CNC cut stone as his primary line of work, so I had me make me baffles out of Granite, Marble, Onyx, and some cast stone material he had.  They were just slabs of material with no driver cutouts, and for testing I mounted one of those NXT drivers to them and an accelerometer at the far end of the slab.  Granite in my informal testing was worst, transmissing as much vibration from one end of the slab to the other, marble was best.  To keep things short I'll save my speculation why that is, but I think I know. 

There is an ultimate material if you ask me, Phenolics ... or potentially another type of thermoplastic.  I do have a couple specifically in mind, there are literally hundreds of all different composition and intented purpose.  For just a taste, take a look at this:

http://norplex-micarta.com/products/product-detail.php?page=30

You got me thinging now.  If this is true for cabinets (which it is) then what would be the ultimate material for a shelf under a turntable?

[S Clark]

Would a laminate of Baltic Birch, HDF, marble epoxy, etc be better than any of these individually? 

Scott

[brj]

Speaking of stiffening cabinets, what about carbon fiber composites?

Examples:

• Birch ply core CF sandwich
• Closed cell foam core CF sandwich  (Probably best for damping and sound absorption, but not as stiff as the others)
• Honeycomb core CF sandwich

Lots of other nifty products on the same site that could be used for braces.

[Vapor Audio]

The push-pull configuration reduces even order harmonic distortion due to phase cancellations.  Now back to enclosures  .   

I was going to reply with "that's what I said", but for some reason I typed odd not even.  So yes, even order distortion harmonics are what's cancelled.  Well, not  cancelled but lowered somewhat.  I've actually built a box to test this and saw I'd say around 25% reduction in even order distortion.

[AJinFLA]

I just posted this info on the baffle forum but since we are here and now.....here goes.  To follow up on what Danny was saying.....you will never get the low distortion sound of an open baffle from a box.  The air pressure behind the driver limits its ability to track small variations in signal.  This I have heard directly.  Also a two way speaker is always compromised.  The woofer is modulating the midrange and also the back EMF from the woofer excursions also screws with both the mids and highs.  Also you can never get great bass from a small box.  And, if you biamp you can use equalization on the woof and remove the back emf all together from the mids and highs.  Have you ever heard bass in your room equalized to plus and minus 1db?  So, what is the purpose of a monitor?  They look cute.  If you have very little money then they make sense.  But why would you want to spend serious money on an expensive 2 way monitor when something like what Danny will be making shortly will simply kill any monitor.  3 servo 8s with open baffle mids and tweet above?  You are not going to touch this with a tiny squeeky boxey two way...no way.  The footprint of an open baffle system can be as little as 10 inches wide.  So, basically the same as a monitor on a stand.  If you do not like the mids radiating to the rear you can simply hang some felt on the back of the speaker.

Hi Rick (it just dawned on me who you were , so thanks for the reply about the BDP mod). While I agree overall (though not necessarily with the fine details of the technical explanations ), there will always be a place for stand mount/bookshelf speakers. I've been doing OBs since '04, so I know where you're coming from. What you describe sounds a lot like Paul Hilgemans http://www.enjoythemusic.com/magazine/equipment/0907/nomad_audio_sentinel.htm . Paul and I use to converse a lot on Madisound about doing OB coaxs, he just beat me to the punch! Sadly, it appears he is no longer a manufacturer.
The problem with this approach is of course, the minimum distance needed out from walls with a dipole. Some folks simply don't have that kind of room. And no, felt has approximately zero effect on <200 hz (nearly 6'!) wavelengths, plus that negates on of the biggest strengths of the dipolar effect, the added reverberation contributing to spaciousness and depth.
Sometimes, those little boxes have their place (not just on a console ). Then it comes down to designing them to maximize the performance, given the likely constraints of placement.
Now if someone buys a $30k 6" 2 way standmount that is going to be placed 6' out from the front wall in a 20' x 25' room, then I'd say yes, they probably have rocks in their head.

cheers,

AJ

[Tyson]

I don't know why coax speakers aren't more popular.  I know there's some issues with the midrange driver being a 'waveguide' for the tweeter, but the advantage of a physical point source is pretty significant, IMO.  Every well implemented coax speaker I've heard has been outstandingly coherent.

[AJinFLA]

I don't know why coax speakers aren't more popular.

Because most suck. Badly.

I know there's some issues with the midrange driver being a 'waveguide' for the tweeter, but the advantage of a physical point source is pretty significant, IMO.

The "issues" have never been with the format, always the implementation/engineering (mainly the surround/throat). TAD, KEF and Genelec have finally stepped to the plate. More are sure to follow (think "China").

...and now back to our regular mini-monitor programming....

cheers,

AJ

[LarryB]

Speaking of the TAD Speakers. They make the best sounding stand mounted speakers that I have heard at a show.

Big ditto to that.  Andrew Jones is one of the top extant speaker designers in the world (and a helluva nice guy, to boot); in conjunction with TAD's deep pockets and extraordinary manufacturing abilities, the end result is speakers that are truly state of the art. 

Larry

[jtwrace]

Just a shout out to Danny for letting other manufacturers participate in this thread in his circle.   

Very cool man.

[Danny Richie]

Hey guys,

If my contribution is a little spotty it is because I have to put this off to when I have a few minutes. Lately I have had customers and orders to tend to and I have to put the customers first. Right now I am taking a few minutes to let my lunch settle and catching up on this thread a little.

I wanted to comment on this question though.

One thing I'm curious about is whether the opposing woofer technique you see with some subwoofers actually works in canceling out vibrations, and, if so, how well.  I'm sure Danny could probably answer this considering his experience using Rythmik subs. I ask because the discussion of enclosure resonances and what not made me think of the barefoot sound approach:

When you put a woofer on each side of the box it doesn't really elevate the pressure put on the other four sides of the box. Those panels can still resonant or flex under the pressure.

However, for every action there is an equal an opposite reaction. I think that is the way that went didn't it?    When there is one woofer on one side it does want to push and pull the box in the opposite direction of the woofer movement. The larger the woofer and the more air it is pushing the harder it is to hold the box still.

So with a woofer on each side the push and pull motion against the box is cancelled out.

This should illustrate it pretty well:  http://www.youtube.com/watch?v=vqoX4eGdE1U

[Danny Richie]

Just a shout out to Danny for letting other manufacturers participate in this thread in his circle.   
Very cool man.

Hey, its the guys that do this for a living, day in and day out, that have the most experiences to share. Why limit those with the most share? Despite what some my think, you can get great manufacturer contribution around here without a sales pitch. Certainly their experiences that they share are from development of some of their own products. So don't be surprised when they use something that they have worked on or even sell as part of an example to illustrate their point. I fall into this camp as well.

[Danny Richie]

And yes Ric, and everyone else, a small stand mounted mini-monitor is never going to do what a full sized speaker or full range open baffle design can do. There is no question about that. However, there are many applications for mini-monitors. I have sold more small two way kits than anything else that I sell.