Open Baffle Speaker build

[nige2000]

As ive been often down with Ken i was fond of the sound of his Pure Audio Project Beyma Trio 10,
especially when paired with my amps

Although i've no previous speaker building experience or knowledge to speak off
thought id might be able to give it a crack

drivers, tweeters and crossovers got from pure audio project
http://www.pureaudioproject.com/product ... -speakers/




i soon realised it was just not that simple, id had serious resonance and vibration issues
after much thought and consultation with the lads and a pile of research this is the current solution

feet



then bracing


then baffle strengthening 12 mm aluminium



great soundstage, great kick drum but still a little resonance
enter dampening material cork sheet




trial tweeter mounting


had them down at Kens today and was pleased the way they preformed

[Ivor]

Lovely. Fair play.

[nige2000]

believe it or not i'm at this project since last may or june, took ages to get the mdf frame and design done,
then try and figure out all the 'issues' and then solutions to them involved much research and thought.

this is just the first revision though, as i knew id hardly get it right the first time
the next i hope will be the final version that's more 'aesthetically' pleasing

[rickmcinnis]

Nobody gets it right the first time but I cannot imagine you not being bale to make this work to your satisfaction.

I always liked the sound of dipoles but I am not about to make a pair. My amps are not up to the power required. And I am not as industrious as you. Sticking with horns.

The aluminum plate for the woofers is fantastic. Why you would want to use MDF mystifies me. I would make a panel using house framing lumber. Here it is about 1 1/2 inches/38 mm thick. Plane it and straighten the sides and glue it up. I would use those wafers between (can't think of what they are called; substitute for dowels).

With those aluminum plates (do you say aluminium in Ireland?) I think it would be more harmonious in many ways than MDF. With a dark stain the finish can look surprisingly good. I have used this material with my horns.

I am baffled (ha!) by your placing the tweeter on the baffle and then having that channel almost surrounding it. If you must retain this I would get some soft felt like ROGERS used in their LS3/5a. I have no real idea and am just spouting off received audiophile wisdom but it could be worth considering removing the baffle length above the woofers and letting the tweeter have its own baffle - more easily positioned to find the best spot in both planes. Unless you are using that diffraction for some purpose it would seem best to eliminate it.

have you tried Bill Waslo's XSIM for crossover design? I assume you are taking measurements. Find out the frequency response and impedance curves of those drivers inject it i9n to XSIM and get a really good idea of what is actually happening with a crossover. Very different from what the forumlas predict. You will need to go back and forth - take measurements of the result of each crossover scheme (you will have to try many - I am speaking of minor changes most of the time) to get a better idea of how the XSIM prediction works out in reality. I find it useful to consider the room when choosing values for the crossover. You are stuck with the room so you might as well see how you might be able to use it.

With stuff like ROOM EQUALIZATION WIZARD and XSIM AND your ears you can come up with something better than you would have imagined.

I know with my system it was a great puzzle and a good excuse to learn some more useless for anything else audio knowledge which I crave.

One thing to try is the series connected crossover if you haven't, yet.

[nige2000]

[nige2000]

yea im trying to decide what the best solution for the tweeter mounting and or baffle is
i see some dipole tweeters hung with string

which id assume thats the most antivibration effective solution

although im also curious to what it would sound like mounted on a decoupled large 12mm aluminium plate
would that be the most detailed?
maybe it dont matter

[Ken Moreland]

Great sounds yesterday in the company of Nigel and Tony. As well as Nigel's speaker developments we compared Mono amps, Nigels prototype improvements , but the latest evolution of the speakers is superb. They are now a very substantial pair and almost impossible to carry! All resonance issues are largely eliminated and the sound quality is now indistinguishable from mine. Still , there are opportunities for further efforts like tweeter mounting, absorbent surfaces etc and maybe a coat of Ferarri red paint. Overall they're a great success.

[Georgi]

Nice work. :)

If they sound close to Ken's ones, that's mean you are on the right track.

[tony]

Both sets of speakers sounded fantastic yesterday. Mono's are incredible. Huge soundstage, detail and huge tight bass.
Would concur with Ken sound was among the best I have ever heard. They are getting very heavy alright!

[sdiesel77]

WoW Really cool! I was looking at this Pure Audio model !
What drivers did you use?