open baffle project

[D OB G]

Hi mastarecoil,

Gilbert Briggs, of Wharfedale fame, built a small open baffle speaker with a metal baffle called the "tiny" which he insisted not to be confused with tinny!!

He maintained that metal had a high stiffness, and that energy was quickly released, rather than, in his words, being dithered to be released over a longer time (blurring of sound).

However I wouldn't go with plain metal. I have had great success with laminated metal. THICK felt (or foam carpet underlay- 8mm thick) glued to metal (I have access to a water jet cutter) glued to felt/foam glued to metal glued to felt/foam.

I then made a back plate the same way with very large perforations, and bolted the two together through the speaker mountin holes, to form a "super chassis".

Totally rigid and totally dead. Not a design for someone without CNC or similar.

I believe that the edges of a baffle need to damped just as much as the front and back. Low frequencies can emanate from the front and back of an undamped baffle, but higher frequencies propagate from the outside edges (this is a separate issue to edge diffraction).


So I reckon go with the metal if it is thick enough (probably 5-6 mm plus. One layer with HEAPS of damping material both sides (and edges) should provide enough rigidity and "quietness".

Just my opinion.

David

[MCFuryNZ]

Sorry to bring this up from the dead, but I'm quite interested in making a low budget OB project such as mentioned above, using:

HiVi B3N
Eminence Alpha 15A


Has anybody combined these two with much success? Seems like a 200hz passive crossover would be a decent choice..... I read MJK's OB Design article with the Fostex and Alpha 15, and it looks interesting, but I don't know if anybody has actually tried that plan out. I was looking at the B3N because of price and I think it's a neat little driver....


Any tips?

Thanks!

[c2cthomas]

Hi MCFuryNZ

You might find this thread of interest - look at the OB that migeO did as it seems close to what you are thinking about. Fast, fun, Inexpensive OB project

Panomaniac started the thread and is very generous with help and advice!

[JandG]

I through drivers of all kinds on very small baffle on floor close to floor to test..You in my opinion would be good to get the Bamboo Tangbang in 4" & call it good, if you like good mids, you will be happy, the OB magic will be retained....If a driver sounds like crap on a very small baffle in my tests I pitch it..............as everyone explains, low mid bass & down will be not there, but everything else will be..I all is to what you hold important, trick to the OB game is if you go further after these small fun speakers you build, is to try & get our mid bass filled without EQ & if you can't,, EQ it in digital domain,,,,then XO very low 150hz down preferably 75hz down...this will save all the magic,, XO of 500 with a GOOD fullranger is a sin..............

[MCFuryNZ]

Originally posted by c2cthomas
Hi MCFuryNZ

You might find this thread of interest - look at the OB that migeO did as it seems close to what you are thinking about. Fast, fun, Inexpensive OB project

Panomaniac started the thread and is very generous with help and advice!

Thanks, I'll keep that in mind as an option. I just noticed that Holdent mentioned using the B3N along with the Goldwood or Alpha 15.... this is exactly what I want to do, but unfortunately haven't found any information on this setup, and not having done any OB work yet, don't know where to start with these drivers.

So, Holdent, if you are still around, let me know how those projects went!

Thanks all,
Max

[c2cthomas]

Hi Max,

I am going with the Alpha 15's on an OB project I am hatching right now. The Goldwood has some nice specs to it and I looked hard at their 18" unit. GW has some good-looking stuff for the $$ involved - and lot's of $$ isn't something I can afford. The Alpha's are a known quantity tho and usable in many designs. Plus Eminence speakers are made in Eminence KY., and I like to buy my stuff local when I can.
I'm also going to use the Alpha 6 for mid's and a horn for high end and going with bi-amplification. Gotta go and get back to drawing things up.