This may be an oddball question, but I'm asking it in earnest:
The horn on my EAW speakers is made from two pieces. Where they come together is very far from smooth. In fact, there is a very noticeable "gully" that runs the entire length of the horn, front to back, on both the top and bottom. (FWIW, this is on a BMS 4594 coaxial)
It seems to me that this should be smooth, and I'm wondering if this could be physically affecting the HF response / dispersion a little bit?
If so, would it theoretically be a good idea to try and fill these gullys in?
And if so, what might do a good, permanent job of it? (It's very slick plastic, of course.)
The horn on my EAW speakers is made from two pieces. Where they come together is very far from smooth. In fact, there is a very noticeable "gully" that runs the entire length of the horn, front to back, on both the top and bottom. (FWIW, this is on a BMS 4594 coaxial)
It seems to me that this should be smooth, and I'm wondering if this could be physically affecting the HF response / dispersion a little bit?
If so, would it theoretically be a good idea to try and fill these gullys in?
And if so, what might do a good, permanent job of it? (It's very slick plastic, of course.)
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Consider the WLs of the gap width, which is well above the horn's pass band, ergo strictly cosmetic. If you're like me though, my eyes would gravitate to it every time, so would fill it just because it's a distraction. 🙁
Thanks, GM, but I don't understand your point.
We're not talking about nodes and such, just physical deformation of the dispersion. A 10K wavelength is around 1.3" IIRC, so I assume these gullys will cause SOME kind of disruption. Maybe changing the distribution, so so its less evenly spread out?
Or maybe even time anomalies?
We're not talking about nodes and such, just physical deformation of the dispersion. A 10K wavelength is around 1.3" IIRC, so I assume these gullys will cause SOME kind of disruption. Maybe changing the distribution, so so its less evenly spread out?
Or maybe even time anomalies?
You may have a subjective feeling that the sound in the horn is something flowing trough it. Like taking a hose and have pressurized water flow over these uneven gaps.
This is wrong. Sound only moves a little forward and then back the same distance, to give it a picture. Of course, it is compression followed by depression. You will not be able to measure any difference, even if you would mirror polish one horn and sandblast another.
From a cosmetic point you are right. Looks cheap. These gaps can be best closed/ filled with plastic glue, this stuff that practically cold welds plastic by dissolving it's surface a bit. Maybe sand it before and after. For finish there is special plastic primer or even color for plastic already containing primer. My advice: Only use it if you are a very good spray painter with aerosol can's. Do multiple, very thin coats with dry in between times.
This is wrong. Sound only moves a little forward and then back the same distance, to give it a picture. Of course, it is compression followed by depression. You will not be able to measure any difference, even if you would mirror polish one horn and sandblast another.
From a cosmetic point you are right. Looks cheap. These gaps can be best closed/ filled with plastic glue, this stuff that practically cold welds plastic by dissolving it's surface a bit. Maybe sand it before and after. For finish there is special plastic primer or even color for plastic already containing primer. My advice: Only use it if you are a very good spray painter with aerosol can's. Do multiple, very thin coats with dry in between times.
The "gully" that runs the entire length of the horn is symmetrical, it won't "deform" dispersion. It won't create time anomalies.
The protruding screws and horn lip edge diffraction will cause more far more effects than the "gully", if you still want something to worry about 🙂 .
The horn is ugly, it could use a grill.
Problem is not dispersion but pressure
Simplifying, a horn is a pipe carrying pressurized air, it must not leak sideways, so:
* if the "gully" is sealed, no big deal, problem is only aesthetic, fill it if it hurts your eyes only 🙂
* If not, meaning you can see a lit lamp from the other side, then do seal it.
You can use most anything.
Won´t suggest krazy glue because it has no "body" nor hot melt because it does not stick well to very polished surfaces, but Epoxy may do the job well, or a bead of silicone sealant, which you can even get in black.
That said, I´d expect both halves to be factory glued together and that should already seal the gap.
Simplifying, a horn is a pipe carrying pressurized air, it must not leak sideways, so:
* if the "gully" is sealed, no big deal, problem is only aesthetic, fill it if it hurts your eyes only 🙂
* If not, meaning you can see a lit lamp from the other side, then do seal it.
You can use most anything.
Won´t suggest krazy glue because it has no "body" nor hot melt because it does not stick well to very polished surfaces, but Epoxy may do the job well, or a bead of silicone sealant, which you can even get in black.
That said, I´d expect both halves to be factory glued together and that should already seal the gap.
I would seal it with plasticine and be done with it. You certinly can fill it with epoxy filler and sand the front side from 100 to 800 grit, but, IMO, this horn is not worth it. May be looking better in matte though.
Use sandpaper before sticking, and do a test patch first, some plastics are hard to stick.
Oddly enough, hot melt glue sticks to most plastics.
Oddly enough, hot melt glue sticks to most plastics.
Thanks, guys.
I guess I won't worry about it. I should have realized how this worked, so time for a huge Homer "DOH !"
But hey, it was worth asking about.
And yeah, those horns aren't beauty queens, but you know what they say. "Marry an ugly girl and she'll take care of you for life." 🙂
I guess I won't worry about it. I should have realized how this worked, so time for a huge Homer "DOH !"
But hey, it was worth asking about.
And yeah, those horns aren't beauty queens, but you know what they say. "Marry an ugly girl and she'll take care of you for life." 🙂
I mean at the joint, cover the gap with thick tape, preferably duct tape, after cleaning the surface free of dust etc.
Do it from the back, so the repair is not visible.
Do it from the back, so the repair is not visible.
If I have to seal a gap in a plastic surface like this, I would back it with aluminum tape and fill with 2 part epoxy. It can be tinted with dye if needed. The aluminum tape will peel away clean and leave a perfect surface finish. The only thing to look for is that you rough up and clean the surfaces and that your not dealing with a nylon based plastic, which doesn't bond well with epoxy or cyano (crazy glue). ABS and fiberglass is no problem to glue.
First, closing the gap is enough.
Second, I am an old hand in plastics, and believe me, polypropylene and polyethylene are hard to glue.
Of the normally encountered plastics, ABS, acrylic, PVC, HIPS, and Noryl are easy to stick...the rest vary in difficulty.
So, use duct tape to seal it off, quick and easy.
Second, I am an old hand in plastics, and believe me, polypropylene and polyethylene are hard to glue.
Of the normally encountered plastics, ABS, acrylic, PVC, HIPS, and Noryl are easy to stick...the rest vary in difficulty.
So, use duct tape to seal it off, quick and easy.