Hello Greg and Scottmoose,
I think we all apreciate the effort in calculating FR curves..
It is just not the same effort as in developing an idea, try it out on paper, build it listen to it, change it and then listen to it again.
Then realiz(s)ing it does not sound at all like what it should do according to the calculations and simulations..
Simulations always gave a vague idea about which direction to go..
I've build a few dozens of speakers, most sounding very descent, some very good and a few awfull.
Everything open at both ends just simulates pretty unpredictable.
This is one of the pretty good ones, that's why I was sharing...
I've build some other Dipoles, which actually sound better then this one, more expensive to build and a lot bigger.
Still, the simulation did not show that..
Anyway, thanks for the effort!
I think we all apreciate the effort in calculating FR curves..
It is just not the same effort as in developing an idea, try it out on paper, build it listen to it, change it and then listen to it again.
Then realiz(s)ing it does not sound at all like what it should do according to the calculations and simulations..
Simulations always gave a vague idea about which direction to go..
I've build a few dozens of speakers, most sounding very descent, some very good and a few awfull.
Everything open at both ends just simulates pretty unpredictable.
This is one of the pretty good ones, that's why I was sharing...
I've build some other Dipoles, which actually sound better then this one, more expensive to build and a lot bigger.
Still, the simulation did not show that..
Anyway, thanks for the effort!
I also appreciate the effort and computer programs and if it weren't for you guys, my speaker building hobby would have never surfaced. But I guess I'm a bit perplexed due to my lack of knowledge in actually designing speakers? Believe me, I'm not trying to question your knowledge, it is more me trying to understand the simulations.
The models were based on a round horn that was not a dipole and also using the 103 driver and no subwoofer? I'm using a 126 driver in a horn that is not round and is a dipole, and two subs. Aren't those completely different then from what was modeled and the resulting plot? Shouldn't I then be hearing something completely different from what was modeled? How does room interaction figure into the plots, especially since it is a di-pole?
Also, when I turn the subs off, the presentation seems to change even in the mids and upper mids, not just in the bass and lower midrange. Are there possibly room interactions going on that is making the sound extremely pleasing when the combination of the subs and di-pole radiation is present?
Just trying to educate myself on what is a very complex subject to a newbie.
The models were based on a round horn that was not a dipole and also using the 103 driver and no subwoofer? I'm using a 126 driver in a horn that is not round and is a dipole, and two subs. Aren't those completely different then from what was modeled and the resulting plot? Shouldn't I then be hearing something completely different from what was modeled? How does room interaction figure into the plots, especially since it is a di-pole?
Also, when I turn the subs off, the presentation seems to change even in the mids and upper mids, not just in the bass and lower midrange. Are there possibly room interactions going on that is making the sound extremely pleasing when the combination of the subs and di-pole radiation is present?
Just trying to educate myself on what is a very complex subject to a newbie.
GM said:Thanks, nice to know at least one person appreciates the effort.
They're always useful, from my POV anyway.
With difficulty.
I'd probably try to SWAG it with a combination of the old FLH & new BLH sheets & some of Keele's 6th order bandpass math. Join the club.
I've probably built a similar number; something tells me neither of us has, or ever will, approach the kind of building & testing that GM did when he had the time & funds. Anyway, neither GM nor I make any suggestion that a modelled FR plot somehow tells you everything. They're their for interest, & have a certain utility for a designer within their own limitations, which are kept in mind. When something interesting crops up, we both often run a quick sim on it, out of curiosity.
Not necessarily. I imagine AKABAK could sim it, or a SPICE model would be possible & a modified version of one of Martin's MathCAD sheets could do it easily -ditto Hornresp or SPEAK. The existing versions are of limited value, but still have some use & there are ways to fudge things to get a general idea of what's going on, which is why we looked at it. & as GM noted, from Derek's remarks, the general trend does indeed appear to be suggested by the software, which is useful to know in itself. We're not just inexperienced idiots blindly following a machine you know, nor are we attacking your speaker design
Good for you. Always nice to see some different boxes / ideas around.
Yes, and the simulations I ran on my double horns don't look pretty either due to the limitations of the software. That's where background knowledge comes in. But it doesn't mean they have no use.
That's the trick -for more complicated enclosures / whatever, they're a general guide, but you have to know how to interpret the graph, which also means you need to have sufficient background knowledge of acoustics & the software used to know what the software does & does not do.
GM's was, although I imagine he, like I, fudged things a bit so the driver would 'see' a very large air-volume to the rear. Mine was of the 126, again, no sub included because I was looking at the performance of the waveguide. Those sims don't show the radiation pattern, or room interaction -they're just there to get an idea of general FR trends in free space so we have an idea what they're up to. FYI though, a dipole typically excites less in the way of room modes than a monopole due to its directionality. Owing to the aspect ratio of the mouth / terminus, there may be be a degree of ripple in the response not shown in either sim., as GM noted above.
It will seem to, for similar reasons that people find that adding supertweeters seems to improve the midrange etc. Dipole mains with monopole subs is nothing new -Linkwitz does this with his Orion / Thor. I can't really judge what is extremely pleasing though, because you don't mention exactly what it is that you like!
Scottmoose said:
from dipole to front loaded horn then?
yes, and just how difficult would it be to bring that back radiation to the front inside the horn? how would that change the character? what would be the easiest way to do this?
there is a horn patent given to a design that adds additional drivers downstream inside the mouth of the horn - this increases horn efficiency by 3db/driver or so (i think it was)! so if the back radiation was added, then you'd get an additional boost in efficiency.
nuconz said:
I don´t think that calling this construct "dipole" could really be justified. For a dipole the back of the driver would need to radiate into an equivalent "back" horn.
Because horn-loading is missing in the back, radiation to the back will be much less than to the front. Whether you block that back radiation off or lead it to the front will not make much difference.
Yes, add back horns. First time I saw this concept from JohninCR
http://www.diyaudio.com/forums/showthread.php?postid=1178285#post1178285
I was working on similar project, now it's sitting idle, I'll have to resume it.
http://www.diyaudio.com/forums/showthread.php?postid=1178285#post1178285
I was working on similar project, now it's sitting idle, I'll have to resume it.
no, i meant JohninCR's design and mine
http://www.diyaudio.com/forums/attachment.php?s=&postid=1462509&stamp=1206131492
http://www.diyaudio.com/forums/attachment.php?s=&postid=1462509&stamp=1206131492
MisterTwister said:
that looks great, but uses a lot of wood and takes a lot of time.
i think you can bring the back radiation into the front horn mouth by venting around the woofer mounting area. just a small "inner" box for mounting the woofer and an "outer" box with about a 1/2 gap to allow the back radiation to pressurize and move forward.
all sound would be radiated forward in this design. will it work satisfactorily though?
nuconz said:
Compression horns are sealed 4th order band-pass (BP) alignments and vented variants are 6th order BPs. Tapped horns are these taken to their logical extreme and while they can perform exceedingly well down low due to their high damping they have little HF extension for the same reason.
GM
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