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Kick design..

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jethrocker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Topic: Kick design..
    Posted: 19 June 2007 at 6:52pm

Ok..this is my first attempt at actually putting together a design from scratch. I'm going to run the gauntlet and post it.. having only a matter of weeks of experience with Hornresponse I'm still at the point of playing and learning, and there are still plenty of questions being thrown up. Rather than pestering bit by bit to iron out the doubts I figured it best to show what I came up with so far so you can all point out where I went wrong.

I know there are folks here who seem to think that if you don't know it all already you shouldn't be posting, but hopefully some knowledge can be shared and everyone can benefit from seeing a newbie project tweaked anbd developed..
 
The design is for a folded kick horn. It has bandpass chambers, I know this is not considered ideal by many for kick, but I'm working around the Kappa 15LF as it's one of few drivers available at reasonable cost here that seems to have around the spec required for the app. The aim is to play 70-160.
I'm trying to acheive the flattest response possible with two bins on a stack. My plots so far say this should play 60ish-190ish flat enough, with a slight rise in response at top end (+<1db).
One cab will play from 70up, but has a large peak above cut off in tghe high hundreds.
two is optimum, seems more cabs than that and low end drops off.
 
I'm designing this to sit above the HOG scoop (actually slightly adapted version, 6mm longer), there is wasted space, but thats hard to avoid with this design and it suits my requirements size wise so I'm happy with dimensions. It will stack on a vertical Hog, or you can stack them horizontally with Horn Mouth coupled on one/two hogs on their sides... Dimensions are 992x496x636mm
 


 
Unlike other BP horns (eg. HD15) it has a longish horn path, around 90cm. I found it was necessary to use both front chamber and a reasonable horn path to keep excursion reasonable with this driver. Possibly this is due to the lowish cut off I aim for here.
I am modelling things using the expected full input power as ref.  ...is this Ok? My thinking (one of many assumptions that I'm hoping to check here)  is that I need to know the max excursion at peak power to be safe. Do folks generally consider excursion at RMS power to be the limit, or as I have done, excursion at peak??
 
The front chamber is largish, around 25 litres, don't remember exactly but I will post some hornresponse screenshots to show exact figures. Throat is about 540cm2 and mouth 2825cm2. rear chamber is around 30 litres.
 
I have tried to apply the "driver edge loaded into horn" theory, though I'm not sure if this is at odds with the bandpass aspect.
 

 
I know it looks like a complex build, but as it's for personal use and construction, that just adds to the fun AFAIAC... The idea was to make the internal construction of the chambers and initial horn flare self bracing for a solid cab, horn mouth is obviously braced and more braces will probably go in behind the front flare angle.
May seem overboard working out full construction for a model which may/may not be worth building, but hey, bored evenings and my mind wants to be thinking speakers, also an excuse to learn to use googlesketch, nice program for free...
 
Comments, slating, applause (not expected), any response appreciated please!
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Disco Stu View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Disco Stu Quote  Post ReplyReply Direct Link To This Post Posted: 19 June 2007 at 8:08pm

I think the baffle board needs to be angled the other way, i.e. the right hand side in the bottom picture higher than the left - this should help with the projection.

You could also use up some of that wasted space by doing something like this
 
 
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Sensitivity + Power Handling - Power Compression = Max Output

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jethrocker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Posted: 19 June 2007 at 9:52pm
The reason I chose the layout I did is to limit the number of bends in the horn path, and to keep them as close to the throat as possible.
 
My plan has one bend directly after the throat of around 100deg.  your suggestion has effectively a 180deg bend into first flare section followed by another 90deg. bend. I wanted to avoid that, and had sketched out various layouts including one very similar previously. If you look at those Selenium double 15 plans the driver mounting and horn layout is very similar to your suggestion.
It does make more effective use of space but as mentioned, as long as I can get it into the dimensions I require I'm happy.
 
Is it worth the extra wood/back pain and boxed off air that no-one can ever breath to avoid the folds though?
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Disco Stu View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Disco Stu Quote  Post ReplyReply Direct Link To This Post Posted: 20 June 2007 at 1:21am
Why not build in 2 sections, rear section with driver and horn then a separate horn flare - an extension that you can screw/bolt on old skool style?
 
Stu
All you need to know is:
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jethrocker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2007 at 9:52pm
Nice idea stu but not sure it's worth the extra hassle considering mosty of the weight is in the rear chamber/driver section, that front flare section isn't going to add too much (the plan is for 15mm ply anyway...
 
Anyone else got anything to say.. perhaps I should post Hornresponse inputs so folks can comment more directly on the specifics of the horn design.
I was really hoping to get a few more opinions on how this design might work out and if I'm even slightly on the right track.. Forget the dimension issue, I'm happy with that for a personal project.. Is it going to sound ok...anyone want to risk a prototype??
 
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Jay Lawless View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Jay Lawless Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2007 at 1:05am
my question is... how well is the upper end of what your aimed response going to sound when it's stil a bent horn?
 
i'm sure you remember some of the kick style designs i did Jeth, there was a reason why they were straight horns and not bent. i'm sure you could push them to that area, but the qulity of the sound may be off compared to the rest. i know the HD15's go up pretty high and hear great results, just iffy about that upper top end is all.
 
looks good though! you could go thinner on the wood thickness, those response bands wont have much flex problems and you could make the horn expansions out of 6-7mm ply aswell aslong as your bracing is designed just right, you wont have any issues.
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Background: Automotive, Live and Home Custom Design. mid/high level based design and feild experience. Bass specialist
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mykey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mykey Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2007 at 4:13am
My version is much simpler, I sometimes think you guys are trying a little to hard
All though the designs are interesting
Its the 2 outside un-painted boxs in the pic
It also loads from the front, no door

Shot with unknown at 1969-12-31
 



Edited by mykey - 23 June 2007 at 4:37am
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jethrocker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2007 at 6:55pm
Thanks for responses folks..
Jay..the idea was to go for a compromise..I figured this layout has more of a  full horn aspect then the HD, and is straighter. The limitations of the driver would require a very long cab to go for a totally straight horn. I was also looking at other cabs that play a similar range and have good rep, Martin 215s etc and figured that this layout is certainly no worse in terms of bends. I don't need extra extention, this is basically going to cover the same range as HDs.
Mykey, your design is interesting and not far off some of my sketched ideas.. after modelling though I found once again that the limitations of the driver mean that your layout would require a longish horn and a far larger cabinet. What are the dimensions of your cab and what drivers work well in it? Any chance of getting a look at full plans?
Thanks again..
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mykey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mykey Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2007 at 3:40am
the front is 24'' x 24'' 610mm x 610mm
its not rocket science Jeth
give it a go
 
There is a guy (sound engineer) that copied them he uses them as actual bass bins
I think he just left the shelf out though to give the rear chamber more
volume
cheers
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jethrocker View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jethrocker Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2007 at 6:35pm
So...you'd model that with s1=driver SD and no vtc I guess? Path length would be basically internal depth of cab? Had a quick play yesterday but don't think that configuration will work with the Kappa, excursion just goes crazy without vtc to hold it back.
 
How deep is the cab mykey?
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Mark James View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 26 June 2007 at 7:59pm
mykey.. that looks fantastic... been toying with that sort of layout for a while......... can never seem to get enough horn length in for 70hz though........ hmmm, that for 12" or 15" drivers??? very nice........... and very straight!!! [comparatively]
If you want people to feel the bass then a reflex design is probably best as you get the most air movement per decibel from those.      errrrr yes wtf?
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mykey View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mykey Quote  Post ReplyReply Direct Link To This Post Posted: 27 June 2007 at 5:05am
its for a 15'', very tight and quick bin
I can get the depth for you, I dont have the drawings here though
look what happens when you place 2 together on their sides 
Shot at 2007-06-26
 
 
 
 
 


Edited by mykey - 27 June 2007 at 5:52am
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