Speakerplans.com Homepage
Forum Home Forum Home > General > Advanced Discussion
  New Posts New Posts RSS Feed - uneven compression in unknown 18 bph
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

uneven compression in unknown 18 bph

 Post Reply Post Reply Page  12>
Author
Message
tv00 View Drop Down
Old Croc
Old Croc


Joined: 10 August 2009
Location: Denmark
Status: Offline
Points: 1886
Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Topic: uneven compression in unknown 18 bph
    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
Back to Top
Mark James View Drop Down
Old Croc
Old Croc
Avatar

Joined: 15 January 2006
Location: rig side
Status: Offline
Points: 5309
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 11:15am
it will change the throat area.... shame it wasnt a central slot tbh
me so horny me love you long throw
horn loaded for her pleasure
Back to Top
tv00 View Drop Down
Old Croc
Old Croc


Joined: 10 August 2009
Location: Denmark
Status: Offline
Points: 1886
Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 12:34pm
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.
Back to Top
Mark James View Drop Down
Old Croc
Old Croc
Avatar

Joined: 15 January 2006
Location: rig side
Status: Offline
Points: 5309
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 12:52pm
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
me so horny me love you long throw
horn loaded for her pleasure
Back to Top
tv00 View Drop Down
Old Croc
Old Croc


Joined: 10 August 2009
Location: Denmark
Status: Offline
Points: 1886
Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 1:06pm
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
Back to Top
Mark James View Drop Down
Old Croc
Old Croc
Avatar

Joined: 15 January 2006
Location: rig side
Status: Offline
Points: 5309
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 1:10pm
so there is no gap after the moon? its just the picture? in that case my theory is wrong lol
me so horny me love you long throw
horn loaded for her pleasure
Back to Top
tv00 View Drop Down
Old Croc
Old Croc


Joined: 10 August 2009
Location: Denmark
Status: Offline
Points: 1886
Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 1:13pm
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)
Back to Top
Mark James View Drop Down
Old Croc
Old Croc
Avatar

Joined: 15 January 2006
Location: rig side
Status: Offline
Points: 5309
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 1:22pm
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 :-]
me so horny me love you long throw
horn loaded for her pleasure
Back to Top
tv00 View Drop Down
Old Croc
Old Croc


Joined: 10 August 2009
Location: Denmark
Status: Offline
Points: 1886
Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 1:29pm
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
Back to Top
tv00 View Drop Down
Old Croc
Old Croc


Joined: 10 August 2009
Location: Denmark
Status: Offline
Points: 1886
Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 1:31pm
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.
Back to Top
Mark James View Drop Down
Old Croc
Old Croc
Avatar

Joined: 15 January 2006
Location: rig side
Status: Offline
Points: 5309
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 2:45pm
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 :-]
me so horny me love you long throw
horn loaded for her pleasure
Back to Top
Mircea Bartic View Drop Down
Old Croc
Old Croc
Avatar

Joined: 18 February 2005
Location: Romania
Status: Offline
Points: 2581
Post Options Post Options   Thanks (0) Thanks(0)   Quote Mircea Bartic Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2014 at 2:59pm
cut the cones and post some pictures of the cones and the voice coils

maybe they blew because of other reasons than asymmetrical loading.
general manager & head designer at nexus-acoustics research
http://www.facebook.com/nexus.acoustics.research

Ex Nexus_3
Back to Top
 Post Reply Post Reply Page  12>

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.06
Copyright ©2001-2023 Web Wiz Ltd.

This page was generated in 0.078 seconds.