I picked up these horns online, took a risk because the seller didn't have published specs, they are either extras from a large order or cosmetic blems I think (the flange where they bolt to the cabinet was curled up a little but screwing them in corrected it).
Anyway, I've tested one and I'm very pleased, balanced frequency output and excellent control of dispersion (at least where I hoped to have it, not much focus of 500hz!).
But one thing feels off, even if i didn't hear an issue in my I initial test... the rear face of the phase plug has a lot of odd topography (see pic). Should I fill the crevices in? The white part is just a pvc cap tucked into the plug, otherwise the driver would have been firing into a half liter cup. But should I worry about the more subtle crevices? Also the white part is inset an eighth inch or so. Maybe use bondo? It's a medium-hard plastic.
Anyway, I've tested one and I'm very pleased, balanced frequency output and excellent control of dispersion (at least where I hoped to have it, not much focus of 500hz!).
But one thing feels off, even if i didn't hear an issue in my I initial test... the rear face of the phase plug has a lot of odd topography (see pic). Should I fill the crevices in? The white part is just a pvc cap tucked into the plug, otherwise the driver would have been firing into a half liter cup. But should I worry about the more subtle crevices? Also the white part is inset an eighth inch or so. Maybe use bondo? It's a medium-hard plastic.
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Difficulty seeing the reason that this plug exists. In any case it doesn't go down to the cone. The highs will be limited. When you anticipate that and cross them lower, the problems will (to some degree) go away with it.
It goes up to 1400/1500hz (TBD, active crossover, 24db butterworth curve). How close to the driver does the cone need to be to be effective? I could adjust the way it's configured and get it 3/4" closer (there's plywood between the horn and driver, I could mount the driver with the wood behind it, just harder to service that way).
What does the back of a normal phase plug look like? Should I be trying to extend it back past the plane of the outer edge of the cone?
Typically it is used in the woofer cavity and is as close to the cone as possible. Also, while the needs of the horn are a part of the design, the phase plug itself is not typically a part of the horn, although there may be exceptions. I just wonder whether this is a gimmick or is functional.
In any case it would be advisable to measure to see what it all does. I would probably do this first to also decide whether the horn itself is useful.
In any case it would be advisable to measure to see what it all does. I would probably do this first to also decide whether the horn itself is useful.
OK so now that I am reconfiguring so that the speaker is set into the word and directly connecting with the Horne, the airtight box on the back of the speaker can get way way smaller.
Do I have to be concerned about making it too small? I mean as long as I don't go crazy...
Attached is the old box. It cleared the magnet by 1/2". Since the driver was completely inside of it I cut the hole to the size of the horn. I will have to cut it bigger now, and have shorter walls so it comes close to the magnet.
Do I have to be concerned about making it too small? I mean as long as I don't go crazy...
Attached is the old box. It cleared the magnet by 1/2". Since the driver was completely inside of it I cut the hole to the size of the horn. I will have to cut it bigger now, and have shorter walls so it comes close to the magnet.
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I borrowed a PC but it couldn't predict the coverage of a two-stage horn (not parabolic just one angle then another). Which seems weird but oh well. Coverage was my main concern at that time.
I was entering in the specifications from a driver I was told was the off-the-shelf exact match of the EAW driver I am using, but when I was building the box I realized the dimensions don't match exactly so I don't think the on the shelf one is an exact match, it's just really similar.
So I don't actually have the kind of detailed information on the driver that you would need anyway.
I know a pro build would have so many more tools that I don't have and so much more information, I'm not giving you guys much to work with LOL
I was entering in the specifications from a driver I was told was the off-the-shelf exact match of the EAW driver I am using, but when I was building the box I realized the dimensions don't match exactly so I don't think the on the shelf one is an exact match, it's just really similar.
So I don't actually have the kind of detailed information on the driver that you would need anyway.
I know a pro build would have so many more tools that I don't have and so much more information, I'm not giving you guys much to work with LOL
You would still be able to predict the low end caused by the box size in hornresp. As far as dispersion you could have an educated guess using the angles and mouth dimensions of the different sections combined with some creative single section work in hornresp.
I swept the sine wave through the range it's reproducing and metered the output and it seemed pretty balanced. Using crude tools but definitely nothing unworkable at the very least.
Also now that I have tested it, I'm very happy with the coverage. I set it up and walked around laterally and then turned it on it so I didn't do the same and I'm very pleased.
If proximity to the phase plug is beneficial, that's great information, I've already worked out a new configuration (setting it in the wood instead of behind it) and that white thing in the plug can actually extrude a little bit and I'm gonna seal it in there and it's going to be just under an inch from the cone.
When the driver was behind the word I think the best I could do at making that cavity small was going to be just enough. But now that it's set in front of it, it's conceivable I could overdo it. But I don't think so.
??? We can input up to (5) distinct horn segments in HR.
OK, which one, specs can be 'close enough'/same though in a different frame, which is a somewhat typical occurrence for prosound drivers.
Yes, you can use that software with a horn like mine, but it will not yield coverage data. When I got stuck I started googling and I saw people commenting that they had the same issue and there were some workarounds.
RCF L10-750YK is what I was told was the equivalent. It's labeled EAW 804022.
I've said this in other threads about this project, I used to have EAW KF 650s, I have downsized from box trucks and box trailers to a minivan, but it was always in the back of my mind that half of those boxes produce 100-200hz when you use a sub.
I already had these drivers as backups in case I had a failure during the festival, and I saw the compression drivers on eBay for a great price.
I always wanted something lighter that didn't go so low.
So I built these two ways that go down to 200. I'm will use double 15 subs as woofers (90-200) and double 18's as sub woofers (30-90. But all that will be on the ground.
The random horn I'm using has similar dimensions to what was integrated into the horn for the eaw 650 except it's a little bit wider and a little bit less tall, which is great because I'm going for roughly 90° and the KF 650 was 60° (horizontal). I got some 90 x 40 JBL horns that fit the compression drivers, those horns have lots and lots of specs (and no "box" to build for a compression driver) so I'm much less concerned about them.
I took a gamble with the mystery horns but so far everything looks amazing, I just kept fishing for more advice because I don't know what the hell I'm doing. Which thankfully lead to your information about the proximity of the phase plug. And now that it's easier for me to make a tight box I think I'm gonna have that they'll be an even better.
I did generate a result for what the vokume should be of the sealed box for the driver that I was told was the equivalent, and I had not yet achieved something that tight, now I will be closer.
That I did not know 🙁, just that it was full featured with horns.
Nice driver! Designed to load to ~2*68/0.25 = ~544 Hz.
Nice driver! Designed to load to ~2*68/0.25 = ~544 Hz.
It's been such a crazy journey trying to glean what I can about engineering speakers.
I've been curating systems of pre-manufactured sound equipment for twenty years. Which is a fancy way of saying that I've just bought gear... except I have experimented with different combinations from different brands etc. yada yada.
But I will say that I've worked with a lot of competent sound technicians who didn't understand half of what I do about the data you can read about the performance of speakers, coverage areas, efficiency, how directional they are a different frequencies, yada yada.
But when I started trying to learn how horns work, and how to build a cabinet? I felt like I was walking into a PhD in physics class with just a high school education! LOL
Case and point, I have absolutely no idea what the second half of your comment means!
I can't meter the ohms by frequency and I don't have a decent reference mic.
(if you poke around, there IS a forehead slap emoji)
I actually have decent ears.
I look at the angles and dimensions of the horn and compare it to what I see in pics of cabs that do what I want, and it lines up.
You have given me not one, but TWO super useful clues today, even though the normal procedures you would advise people to try aren't an option for me. But remember, I'm not building a horn, I'm just trying not to botch using the horn with my driver.
1) proximity to a phase plug is desirable
(The phase plug has gone from .75" from the plane of the driver to NEGATIVE .5" (because the cone is concave). With plenty more room 3/4"? for it to move and move air.
2) the TINY difference in dimensions isn't a good reason to disregard the specs from the RCF driver. Thank you for suggesting that it's probably close if not exactly right.
so THANK YOU
i'm not building a horn from scratch, I wasn't sure what the precise coverage area was of the horn I was buying, I was actually given a number but the person selling it did not have the kind of knowledge I would expect from the person who engineered it so I wasn't confident.
But someone engineered it, even if it was not the person who sold it to me. I just need to USE it properly.
You've helped. If anything else in that context occurs to you (or anyone else who is reading this), let me know.
I should add that the driver I am using was originally deployed in a similar horn, with an even larger phase plug. So it's not like it needs a compression-free application.
Even if the phase plug isn't preventing acoustic cancellation across the cone it's still reducing the throat area of the horn so will have some effect, whether that's desirable or not would require some calculation/simulation using the drivers T/S parameters. You might be able to extend the HF response of the horn if you add onto the phase plug such that it terminates much closer to the cone.
You don't necessarily need one to measure dispersion on a mid horn. If it has response anomalies they will show up on each mesurement and you can see and ignore them. It's the differences you are trying to measure.