Ultimate baffle material

Rafal · « **on:** 18 Jan 2007, 05:05 pm »

Hi All,

How would you describe an ultimate baffle material for open baffle? What would be it's characteristics and what actual materials have you found to work extremely well.

I'm thinking of building even nicer baffles (maybe a butchers block on a stone base) but would like to get ideas first.

Cheers,

Rafal

tminus · « **Reply #1 on:** 19 Jan 2007, 12:20 am »

Sorry, I posted first asking what you wanted to build, but you said it is an open baffle - then I edited my answer. I am looking at 3" thick butcher block. All solid wood is going to want to warp. Butcher block will reduce or eliminate warping over time - probably eliminate it. It really makes sense if you are looking to do some routing. Sounds like we have similar ideas for the baffles, as I am looking at granite or corian bases too. What you have described would be elegant in design and function. What drivers are you going to use?

regards,
Patrick

Rafal · « **Reply #2 on:** 19 Jan 2007, 02:15 am »

I will be using the visation B200 drivers. the baffle would be simmilar to what's descxribed in the following thread (second iteration)
http://www.audiocircle.com/index.php?topic=35192.0
when it comes to base, I was thinking of using arosan parpendicular to the baffles. I think it would be pretty cool.

tminus · « **Reply #3 on:** 20 Jan 2007, 05:15 am »

I like the butcher block idea because you can route the back out around the driver as well as around the front side edges and around the driver to "let" them into the baffle. It is labor intensive to build so the vendors are PROUD of it.I'm using a tabletop bit like this:

http://www.toolstoday.com/pc-5716-411-table-edge-router-bits-standard.aspx

It cuts a 7/8" detail that starts w/ a gentle slope and ends in a roundover. I'm using the Hawthorne 15" coax w/ the Soundsplinter RLs 15" on bass (qts .955, Xmax 3"pp, Fs 25).

The ultimate baffle material with this bass driver would have to be heavy to keep the baffle from walking - and dense. I guess the ultimate baffle material would be driver dependent, because what one driver on one topology needs, the same or another driver might not need on another topology. That sounded like lawyerspeak!

I have 5/4" cherry 18"x48" panels right now & those will have to do for starters. Johnincr is particularly interested in - and has allot of experiential knowledge of - baffles. He has access to allot of exotic hardwoods too. Hopefully he'll post.
But here's what I am going to try next: I am considering using layered up MDF to 3" thick for cost, density, ease of shaping, ect and then glassing it so I could spray automotive paints on it. Glassing also makes the substrate much more inert, and holds up to slight dings much better than wood. Think of a baffle smoothly shaped any way you want it, like your dream car, sprayed any color you want it, and the substrate is dense, free of voids, and cheap. It would be IMO the ultimate baffle material (if it didn't ever delam). Foam might be good too. Surfin' OB! I'm going to try it. Has anyone else?

I can't forget to say this. Those doors on that ultra cool 50's looking console you did are just bitchin'. I'm gonna check out your site

.

Patrick S.

Russell Dawkins · « **Reply #4 on:** 20 Jan 2007, 06:18 am »

When you are contemplating 3" thick baffles, be sure to give careful consideration to the contour of the part of the cutout behind the front surface of the baffle. You don't want a simple hole - parallel sides that deep form a cavity that will introduce an audible resonance. Almost any shape you can think of will create some sort of audible effect, whether the shape is conical or horn like. I think you will arrive at a very shallow angle as being ideal.

All of this would be a good argument for choosing as a baffle material the densest, most rigid material available, and perhaps also for thinking about using an inherently rigid shape for a start, like a curved panel.

You might even consider making up such a panel out of multiple layers of thin plywood. If you wanted to get real fancy there is a technique in boat building which would be great called wood epoxy saturation technique, or the "WEST" system. You might be able to get a boat builder to make up a simple panel for you for cheap. This would be a piece of cake for them - a lot of learning for you.

They could look good, too, and be shaped (and sized) somewhat like a shield.

JohninCR · « **Reply #5 on:** 20 Jan 2007, 06:35 am »

Patrick,

I appreciate the vote of confidence, but based on some JohnK's posts I have to stay non-committal at this point regarding baffles, until I do a lot of measuring of my own. There are 2 issues involved. Something I can comment about is that using a driver with 3" P2P excursion you'll want to isolate the augmenter from your baffle unless a very high mass baffle is used (3" of MDF IMHO isn't sufficient), and I find a magnet mount structure to provide more flexibility in baffle construction. The other issue relates to flat vs contoured baffles for the main driver. If a very thin baffle is the ideal regarding diffraction effects, then the main driver(s) needs to be isolated as well, making the actual baffle material unimportant. On the other hand, if there are shapes and/or foldings that minimize diffraction effects, then baffle construction at the main driver level is a factor virtually ignored in every OB design.

Sorry to be little or no help at this time.

John

tminus · « **Reply #6 on:** 20 Jan 2007, 07:34 am »

I've been doing allot of lurking on threads dealing w/ baffle shapes. The jamo's are curved IIRC. CR John did some curved some baffles too, using the belt sndr. CR John, yeah, I am thinking of ways to isolate the augmenter but have it look like it is one continuous baffle. I bought a 3'x5' sheet of stuff that's very heavy, has peel & stick on one side (other side brown), and is about 1/8" thick. I can't remember the name. Seems like I got it from Tweekgeek. Some commercial mfr's have used materials like this or leather on the front of the baffle (i.e. noHr) for sonic reasons, but could aesthetically be nice too. RD, thanks & yes, I'm thinking about the rear wave. I have a great table edge bit to use on that (see above link). Should solve any restriction issue at the rear lip. If you picture two auto tire tubes one above the other with drivers sitting in them, that's what I'm considering for a baffle (that shape).

The thread's about materials, not specifically shapes - I know. But I would like to submit that the material used lends itself well -or not - to compound shapes. That's what my idea is about. Materials that can damp sufficiently and are easy to shape/glass.

RD, the west sys is where I originally got the idea. The cabin deck on my boat has no flex at all - it's west sys.

Rafal, what is that you are sculpting out of? Would that work for baffles?

regards,
Patrick S.

Peter Clements · « **Reply #7 on:** 20 Jan 2007, 10:09 pm »

To me the low weight but ridged baffles always sounded better. Less energy retention?? I have wondered about foam and resin as in a surf board,with a ply insert for the driver.

JohninCR · « **Reply #8 on:** 21 Jan 2007, 01:50 am »

Tminus,

FYI that curved look took very little sanding. I cut triangles off of the top corners of a rectangle at a shallow angle, 30 degrees if I remember correctly. Then I glued the 2 pieces cut to the backside and only needed to round the front edge of original cut. I have a baffle for an MTM almost complete for which I used a similar approach, and the top portion looks almost like it was carved out of a log, but was in reality very little effort. Sorry, no pics yet. I need to make sure it sounds as good as it looks.

tminus · « **Reply #9 on:** 21 Jan 2007, 03:54 am »

John, that's the one I'm talking about. I thought it looked pretty interesting. But I guess it's all about the measurements, in the end. I have been thinking that curved shapes would be advantageous, but that's a vague statement, I know. The only thing that's sure is that a curved shape is stronger than a flat surface.

Rafal · « **Reply #10 on:** 22 Jan 2007, 12:25 am »

Quote from: tminus on 20 Jan 2007, 07:34 am

Rafal, what is that you are sculpting out of? Would that work for baffles?

Patric, I usually sculpt in stone. This stuff can be quiet heavy (1 cubic foot weighs 100lbs). There are panels of soapstone available (used for countertops) but that would be incredibely heavy, expensive and not very strong.

JLM · « **Reply #11 on:** 22 Jan 2007, 12:43 pm »

The primary attribute of any loudspeaker panel material is a high Young's Modulus (an engineering term that descriibes relative stiffness). Every doubling the thickness will decrease flexing (self noise) by a factor of 16 (power of 4). For open baffles the high mass (to counter/nullify the moving mass of the drivers) is of particular importance. Obviously the material must be tough enough (tensile strength) to accommodate transport, etc.

Durnig use the highest stresses will be the driver mounting points.

mcgsxr · « **Reply #12 on:** 22 Jan 2007, 01:05 pm »

I am exploring options around bamboo ply, having reviewed the work of Paul, with his Nomad line, and liking the natural grass as a product. There is a place in Markham (not far from where I live, around 45 miles) that stocks bamboo ply in 18mm and 22mm thickness, in 2x8 pieces.

I will report back on the pricing, as that will determine my interest level!

scorpion · « **Reply #13 on:** 22 Jan 2007, 07:40 pm »

However interesting this subject can be, I think that most improvement can be found in non direct baffle attachment. I am to test wool fibre
interlayer between baffle and speaker according to this post in Decware forum: http://www.decware.com/cgi-bin/yabb/YaBB.cgi?board=diy;action=display;num=1143087829;start=435 . I have been in touch with the guy who implemented it and got some advice. And I have found a local supplier of the wool type. This is just another way of implementing non attachment like the magnet mount. Of course very rigid material will have the same effect, but at what price ?

/Erling

Rafal · « **Reply #14 on:** 22 Jan 2007, 11:04 pm »

Quote from: mcgsxr on 22 Jan 2007, 01:05 pm

I am exploring options around bamboo ply, having reviewed the work of Paul, with his Nomad line, and liking the natural grass as a product. There is a place in Markham (not far from where I live, around 45 miles) that stocks bamboo ply in 18mm and 22mm thickness, in 2x8 pieces.

I will report back on the pricing, as that will determine my interest level!

I am very interested in this bamboo ply. I figure 1 piece would be enough for 2 baffles. This would look very cool and wouldn't need additional veneering ( = less work)

JohninCR · « **Reply #15 on:** 22 Jan 2007, 11:18 pm »

Quote from: Rafal on 22 Jan 2007, 11:04 pm

I am very interested in this bamboo ply. I figure 1 piece would be enough for 2 baffles. This would look very cool and wouldn't need additional veneering ( = less work)

You hit on exactly why I use real wood...It's easier. Plus good ply is hard to find here and can be more expensive than beautiful natural wood.

Linkwitz uses a magnet mount for the main driver on the Orions, so the benefit must be measurable. Once you have the drivers supported by their magnets, the baffle material becomes unimportant unless you fold it in some manner. That's the beauty of OB's, they're so flexible that you can start with how you want the speaker to look. Then figure out how to make it work.

mcgsxr · « **Reply #16 on:** 23 Jan 2007, 12:37 am »

http://www.silkroadtoronto.com/plywood/plyproducts.htm - these are the guys I am talking about, if you click on Bamboo Veneer, it leads to a page that outlines their solid core Bamboo Plywood, in various sizes.

Prices to follow, once I track them down live.

John - so is the approach to basically float the baffle in front of the drivers, that are held up behind, but not attached to, the baffle?

Thanks,

JohninCR · « **Reply #17 on:** 23 Jan 2007, 01:04 am »

Mark,

That's what I've done for a couple of pairs, and baffle vibration approaches nill. To keep the baffle from falling over I just use 1 screw through a screw hole on the driver basket to loosely attach it to the baffle with a foam gasket between the frame and baffle. That acts as a loose air seal while maintaining the decoupled setup. I doubt I'll ever rigidly attach a woofer to a baffle again, but I do plan to see if much of the magnet mount benefit for the higher frequency drivers can be retained using a magnet mount bracket attached to the baffle. The driver would be attached rigidly to the baffle both normally and at the magnet. That would be cleaner and easy to implement, but of course you're back to needing some significant mass in the baffle construction to keep vibrations down.

Zero One · « **Reply #18 on:** 23 Jan 2007, 11:09 am »

Now mounting by the magnets, that's a great idea, very lateral and just up my alley as I am looking into how to contruct my OBs

I want curved baffles but making them out of wood is not that easy, but heres and idea that might work if I magnet mount, lots of sheets of thin cardboard laminated together then held top and bottom by a shaped wooden channel with a frame built behind to match and the front surface covered with some sort of nice cloth with a thin stained wood panel just in front of the driver for effect.

Shouldn't be too hard in my case as I am using a seperate pair of subs for lower bass anyway.

mcgsxr · « **Reply #19 on:** 23 Jan 2007, 05:46 pm »

Hmmmmn, at the quoted $200 for a 2 foot, by 8 foot, at 18mm thickness, I think I will rethink my strategy!

I will likely turn to baltic birch, for roughly $50 or so, for a similar quantity...

Oh well, either that or hound Paul at Nomad for some scraps!