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
Re: Open Baffle Speaker build
Posted: Thu Jan 18, 2018 11:27 pm
by Ivor
Lovely. Fair play.
Re: Open Baffle Speaker build
Posted: Thu Jan 18, 2018 11:53 pm
by 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
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 1:09 am
by 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.
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 1:25 am
by nige2000
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 1:42 am
by 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
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 8:51 am
by 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.
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 11:33 am
by Georgi
Nice work. :)
If they sound close to Ken's ones, that's mean you are on the right track.
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 2:04 pm
by 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!
Re: Open Baffle Speaker build
Posted: Fri Jan 19, 2018 4:17 pm
by sdiesel77
WoW Really cool! I was looking at this Pure Audio model !
What drivers did you use?