Wish I had more time. And besides - I'm very very very happy with the way they sound, so I dont have a rush to modify a lot right now.
The currents plans are to test a little more on the 2nd prototypes before building a third version:
1. separate woofer and mid/hi baffles
2. add some concrete here and there at the bass baffles for stiffness and mass
I'd be very interested to see the off axis measurements - particularly from 1k up.
At what angles?
Will look into it, I might get good anechoic measurements from 1 kHz, lets see.
The 90 degree off-axis "dead spot" is not at 90 degrees, but slightly rearwards because if the wings. Will measure there and maybe at 45 degrees.
OK, here an anechoic measurement showing on-axis and off-axis at the deadest point, which is a bit further back than 90 degrees. Distance: 60 cm from the tweeter, at tweeter height.
Looks pretty good, much better than regular monopole box-type speakers.
Looks pretty good, much better than regular monopole box-type speakers.
An externally hosted image should be here but it was not working when we last tested it.
I usually look at 0,15,30,45,60,90 at 2meters (or whatever the listening distance is), but I'd be happy just to see 0,45,60 at a meter.
What I've been looking into lately is what happens above the dipole peak - in particular, the smaller the separation between front and back, the more ideal the off axis response. Someday, I'm very interested to see what happens when the tpl-150 is used with no baffle at all - my experiment with a neo3 suggests the improvement in off axis behavior is worth the trouble.
Cheers,
Patrick
Erik,
I'm really only speculating in this case, but my own measurements indicate that the uneven sideway response around 2 and 5 kHz could be due to some resonances in the backward radiation. I would suggest to measure 180 degree and see if those peaks and valleys are there too. In that case you might have to widen/taper the rear openings for the midrange and tweeter.
Rudolf
I will try them in a month or so, have to wait for delivery from Beyma, takes 2-3 weeks normally.
I'm also interested in testing a MTM setup with two Excel W22's.
Its been quiet for a while here now, bigger projects had to get first priority for a while.
I have ordered some 8" Beyma mids just to try them out, will look into that later.
The biggest news is that I have made a few modifications to the baffle. I've separated the mid/tweeter and woofer baffle to avoid vibrations from the woofer to affect the mid and tweeter. This trick really worked well. I've also removed the wings around the tweeter, and made the rear side flush with the tweeter surface. I measured some bad peaks in the rear and off-axis response, and as someone pointed out this could be due to cavity resonance behind the tweeter. This proved to be the problem, rear radiation is much smoother now with the modified baffle.
I have ordered some 8" Beyma mids just to try them out, will look into that later.
The biggest news is that I have made a few modifications to the baffle. I've separated the mid/tweeter and woofer baffle to avoid vibrations from the woofer to affect the mid and tweeter. This trick really worked well. I've also removed the wings around the tweeter, and made the rear side flush with the tweeter surface. I measured some bad peaks in the rear and off-axis response, and as someone pointed out this could be due to cavity resonance behind the tweeter. This proved to be the problem, rear radiation is much smoother now with the modified baffle.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Like all large planar tweeters, the vertical dispersion is low at high frequencies. I stand up close to the speakers, the top treble disappears.... but then I only listen to them when I sit in my chair.
*updates*updates*updates*
I guess I f*cked it all up, trying too hard to get a rigid baffle! The wings was a bad idea. Very bad. They're all gone now, never to return. Without them it measures a LOT better off-axis, and sounds vastly better as well.
A other change is a sand-filled midrange/tweeter baffle made from 6 and 19 mm MDF. The woofer baffle is the old 2x 30 mm MDF, without wings.
Pictures below! Its getting uglier and uglier....
I guess I f*cked it all up, trying too hard to get a rigid baffle! The wings was a bad idea. Very bad. They're all gone now, never to return. Without them it measures a LOT better off-axis, and sounds vastly better as well.
A other change is a sand-filled midrange/tweeter baffle made from 6 and 19 mm MDF. The woofer baffle is the old 2x 30 mm MDF, without wings.
Pictures below! Its getting uglier and uglier....
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I am getting good results using similar baffle shape as you are getting with your midrange and tweeter. Also, there are no wings attached to the sides. I use an L-shape bracket on the baffle similar to yours, however this combo does not look good. Maybe someone can suggest a design that will improve the looks.
One step further, that horizontal base plate of M-H section can also be removed
Yes of course. I made that one when I still had the wings on the woofer baffle... will replace it with smaller brackets - need some support here or else the baffle can not stand up by itself.
I've started to think in an entirely new direction now - maybe a baffel-less speaker would be a better idea? I'm thinking making a steel og alu tube frame just to hold the drivers. What do you think?
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