uneven compression in unknown 18 bph |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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Posted: 10 April 2014 at 9:00am |
Hello cyber-friends, I need your advice.
One material friend from my hometown just picked up these babies & blew them right away: As you can see they are curved short folded horns, turbo-style bph (measuring 55X76X76) But the front loading of the driver is very assymetrical, I guess this could be a reason for the drivers failing, other know reasons are overexcursion & overpowering. One cone is stuck the other scratching. Oh yeah, the cab have been loaded with rcf rcf l18-851kn. I guess a lot of drivers would do a better job. QUESTION: Would it be a good idea to drill some round holes in the half-moon plate to achieve more symmetrical loading of the cone? I've seen this in the "invader cab". I don't know how much this will affect the horn path lenght. Right now 40% of the cone plays straight into ply! Edited by tv00 - 10 April 2014 at 9:13am |
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Mark James
Old Croc Joined: 15 January 2006 Location: rig side Status: Offline Points: 5309 |
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it will change the throat area.... shame it wasnt a central slot tbh
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me so horny me love you long throw
horn loaded for her pleasure |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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I could put a plate from the other side & make it a slot, but that would leave a "dead end"
I don't know if the designer ever calculated chambers of this design. The horn throat seems to be right there at the ply in front of the cone, making the start of the horn conical until the bend! That's quite different from normal bph, that starts at the corner. This design has a very small uneven front chamber. |
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Mark James
Old Croc Joined: 15 January 2006 Location: rig side Status: Offline Points: 5309 |
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i see waht you mean the horn should start expanding imediatly from the semi circle half moon has it got a chamber after efectively? ie the second picture you can sort of see the shadow from the half moon is that empty area? or is it boxed in? if empty that means a chamber after the alf moon? in that case you might have two front chambers one feeding the other before the horn expands does that make sense? i might be wrong i cant see the pics too well on this tiny screen lol
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me so horny me love you long throw
horn loaded for her pleasure |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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ok, let's see if I can put this in English, otherwise I can draw it:-)
The horn starts around the straight side of the throat where you can see the black paint (top of cutout in pic), theres no second front chamber, after leaving the straight side of the throat there's a conical expansion, no further compression or narrowing, it just continues as a curved horn around the corner Edited by tv00 - 10 April 2014 at 1:07pm |
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Mark James
Old Croc Joined: 15 January 2006 Location: rig side Status: Offline Points: 5309 |
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so there is no gap after the moon? its just the picture? in that case my theory is wrong lol
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me so horny me love you long throw
horn loaded for her pleasure |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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Yes it's very simple, like a hd15, but with the last of the curve cut of to remove the front chamber, if i put my hand in front of the horn and around the corner there's no edge, and if it was long enough it would come out of the throat:-)
The horn starts in top of the pic, at the straight cut in the moon, where you se black paint (as it have been painted by reaching in from the mouth) |
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Mark James
Old Croc Joined: 15 January 2006 Location: rig side Status: Offline Points: 5309 |
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aha yes i understand and i think you understand what i meant lol ok errrrr any more details on what happened when they died??? can you take some measurements and maybey we can elp horn response simulate it and find out the problems..... looks like potentialy a nice cab ave you ruled out incorect hi pass flter too much power etc? im guessing you have cos i know you are not an idiot lol very interesting looking cabs very much want to see more discussion on tese :-]
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me so horny me love you long throw
horn loaded for her pleasure |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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Here's a drawing showing the principle:
As you can see there's no front chamber before the bend as in traditional bph. The start of this horn between mouth & bend seems to be straight conical. I didn't fry the subs, my friends did, I never fry subs. I always tell people to spent £3 on a lock for their racks. But they never do and then they loose thousands and keep me occupied:-) Edited by tv00 - 10 April 2014 at 1:36pm |
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tv00
Old Croc Joined: 10 August 2009 Location: Denmark Status: Offline Points: 1886 |
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But my question is essentially if I should try to alter the throat slot or just stick a new one in there.
I have a couple of 18lw1400 I think they should do a better job than the old rcf driver, don't you think so? Bigger bl & xmax, don't know the rcf ebp. |
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Mark James
Old Croc Joined: 15 January 2006 Location: rig side Status: Offline Points: 5309 |
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hmmmmm from the drawings i think i may have been right actualy the area imediatly after te throat is alot bigger tan the troat so maybey the sudden expansion losses control of the driver?
or much more likely the drivers were unsuitable or the settings were wrong [ie hi pass or even power/limiters wrong] what damage was done to the driver? torn cone? burnt coil? or just deformed so scraping? sorry for all the questions just hoping me asking daft questions will make others who are more knowledgable suddenly tink of a solution :P look like potentialy good cabs tho :-]
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me so horny me love you long throw
horn loaded for her pleasure |
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Mircea Bartic
Old Croc Joined: 18 February 2005 Location: Romania Status: Offline Points: 2581 |
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cut the cones and post some pictures of the cones and the voice coils
maybe they blew because of other reasons than asymmetrical loading. |
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