I have a couple of questions about the entry ports:
1. How do you decide on the size of the diameter (assuming they are circular) ?
2. Why are they off centre (in relation to the centre of the drivers) - is that driven by (see what I did there ) the need to have the ports in a particular place vs where the drivers can physically be mounted ?
1. How do you decide on the size of the diameter (assuming they are circular) ?
2. Why are they off centre (in relation to the centre of the drivers) - is that driven by (see what I did there ) the need to have the ports in a particular place vs where the drivers can physically be mounted ?
Can you guys provide some insight into the feasibility of building up just the upper-mid_&_treble section to use as a Synergy-like driver?
Scaling up a 4inch upper mid and tweet output
Thanks. Can it be simulated?
Scaling up a 4inch upper mid and tweet output
Thanks. Can it be simulated?
If you drill a series of holes in a waveguide, it's going to screw up the response off axis.
The midrange taps on a Unity horn are in the corners because it's better to have good off-axis response on the X and the Y axis than the diagonals.
IE, when you're listening in a room, you'll probably find yourself moving about the room (X axis.)
But chances are good, you're not moving about the diagonal axis 😉
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I've come to believe the reason ports are in the horn corners is mainly about how to actually fit all the drivers into the cabinet.....
such that port-to-throat distances work, which generally means as close to the throat as possible.
I think this is particularly true when smaller mid range drivers span between the low drivers and and the CD.
Construction realities simply manifest when trying to maximize SPL and also low freq extension, in as small a box as possible.
My experiments that skip smaller mid drivers, and just use a CD that reach down to low-mids, using anywhere from 8" to 12" drivers, have allowed the port locations to be centered in the horn...or kept in the corners.
I haven't measured any axial response differences worth noting, one way or another.
Mouth termination differences, like secondary flares vs without, seem to effect polars more than port location interferences.
What I like about centering a single port, is the cone's response measures noticeably smoother, and also reaches higher in freq, than when the port is located out near the edge of cone (as required by putting the ports in corners).
What I don't like about centering is that it's harder to decrease volume under the cone, to raise freq response if needed ...and also gain a better acoustic low-pass.
But on the whole, I'm currently sold on a centered round port...especially given the greater ease of construction.
It would be very interesting I think, to try using 2 small mids, with ports in the center on one set of opposing walls, along with the 2 lows having posts in center on the other set of walls. Might be my next syn experiment..
I'm not really sure how to best decide the size of the round ports. I've been using 1/10th of the cone's SD or a tad bigger, on every size driver. But I think I need to learn how to optimize port size also bringing in Xmax, to fully account for displacement compression ratio (not just ratio of area vs Sd)
Sorry to revive an old thread but I'm looking to build a pair of these horns, partly due to the only other design I can find being the cosyn by bill, these will be used as part of a small PA setup and my only real question is whether they will be able to keep up with a pair of pd1850 loaded othorn subs? Everything I have read about these, bar the cost, absolutely screams build them but I'm just a little concerned they might not be able to keep up in a bar or small outdoor gathering. Any help appreciated!
Watafu,
As far as output, the design in the OP probably is good for around 120dB SPL peak, similar to what a typical decent 12" + 1" throat PA speaker on a stick(SOS) could do. Should sound cleaner than an SOS doing that level, but 60 degree coverage is a bit narrow, typical SOS are 90 degrees, though the 22.5" multiple entry horn will hold it's pattern to a far lower frequency than the typical 90x40 HF horn in a small SOS.
A PD1850 loaded Othorn subs should be able to hit near 10 dB louder, which if you like heavy bass, may be the right ratio top/bottom.
Crossing around 100 Hz, if you would like the bottom of the snare hit to be equal in level to kick drum, a single top won't keep up.
If you do desire more upper output than a single would provide, the narrow pattern is an advantage, less pattern overlap, cleaner transition.
Art
As far as output, the design in the OP probably is good for around 120dB SPL peak, similar to what a typical decent 12" + 1" throat PA speaker on a stick(SOS) could do. Should sound cleaner than an SOS doing that level, but 60 degree coverage is a bit narrow, typical SOS are 90 degrees, though the 22.5" multiple entry horn will hold it's pattern to a far lower frequency than the typical 90x40 HF horn in a small SOS.
A PD1850 loaded Othorn subs should be able to hit near 10 dB louder, which if you like heavy bass, may be the right ratio top/bottom.
Crossing around 100 Hz, if you would like the bottom of the snare hit to be equal in level to kick drum, a single top won't keep up.
If you do desire more upper output than a single would provide, the narrow pattern is an advantage, less pattern overlap, cleaner transition.
Art
Cheers Weltersys, thats absolutely perfect information The system is going to be mainly playing dub and bass heavy music so it should work out perfect then! There will be some additional cabinets in the mid and highs, think the plan may be to add some hd15 kicks aswell. Suppose now is the part where I need to learn to build crossovers and splash some money!
SpeakerScott included the passive crossover design for the speakers in post #88.
For what you want to do, active crossovers using DSP would be the way to go. Decent passive crossovers are difficult to design and build, the components are expensive, and in a sealed cabinet the attenuation resistors add more heat to the already hot drivers.
For what you want to do, active crossovers using DSP would be the way to go. Decent passive crossovers are difficult to design and build, the components are expensive, and in a sealed cabinet the attenuation resistors add more heat to the already hot drivers.
Sorry to revive an old thread! Thank you for all the work you've done on this!!
I'm working on making a 3d model of this so I can build one 🙂 I have a quick question if anyone who has built on is still around...
It seems like the the highlighted dimensions make an angle that is 49.4 degree, not 50... It could very well be the case that I'm missing something, I was just curious if anyone had any insight. Thank you!