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my kick horn plans - The Coffin Bin

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biotec View Drop Down
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    Posted: 15 March 2011 at 5:44pm

Hi all,

 

As there’s been a few requests for kick horn plans recently I thought it might be an appropriate time to dig out the plans for my kick horns. I've been using them for a while now and so I'm confident that there are no major design flaws.

 

Below is a link to the original build where some questions have already been answered:

 

http://forum.speakerplans.com/new-kick-horn-build-pics_topic14565_page1.htm

 

The renders below show what the cabinet looks like. The final phase plug design is different and none of the braces are shown but it is correct apart from these things.

 


 

The cab is designed for the RCF MB15N401 and this is the only driver I have tested for any extended period. I tried the PD1550, it worked well but rolls off very early (about 200Hz). In my opinion if you are using a driver like the PD1550 you may as well use a folded horn as it will never go high enough to take advantage of the lack of folds. 

 
I have built 4 using the RCF driver and use them from 85hz to 300hz. They perform well, sound good and I have had no driver failures; they are very efficient and I have never needed to use more than about 450w per cabinet. With 450w you can barely see the cone move and I am almost certain thermal failure would come before mechanical. Havuing said this I have not tested whether the cone is stable at higher power, but no evidence of problems have arisen during the time I have used them.

 

I have not RTAed the speakers but would be happy to do so if someone has the inclination to help!

 

The front dimensions of the cabinet are 610mm wide and 486mm high. The total depth of the cabinet is 1491 mm and at the back of the cabinet the width narrows to 463 mm.  This is obviously a very deep cabinet and will only be useful if you have cabinets like terrahorns, labhorns or psychos to stack them on.  These cabinets are heavy and awkward to move and despite performing well, I would probably build something more user friendly if I was to do it again and just accept the compromise.  I designed the cabinet to be built out of 18mm plywood but I think the entire horn assembly could be built from 12mm plywood with no ill effects as it is well braced.

 

Unfortunately the computer which I originally designed them has given up the ghost so at the moment I don’t have access to the design drawings. However I did find an accurate build sheet which I cut the pieces from. All the pieces are sketched with dimensions and angles and the cut-sheet I used is also attached, these are shown below.

 
All the information to cut the pieces for one of these kick horns is provided, but a more efficient and easy to use cut sheet could be made if you are making several of these. The image files are large so that you can read them, I have made them as links so that your browser doesn't go catatonic.
 
The dimensions and angles on the build sheet are done to a silly level of accuracy because I measured them off a CAD model, I am not suggesting that you try to build to this accuracy (I didn’t) but I only ever intended that it would be me who looked at the sheets.
 
Cut sheet:
 
Build sheet:
 
Phase plug:
 
 
You will have absolutely no problem cutting all the pieces from this sheet, but a few key dimensions needed to assemble the cabs again are missing from the cut sheet.  I have worked these out from the drawings and have described them below. 

 

1. The Baffle should be fitted 197.5 mm from the back of the Top and Bottom panels. Given that it is 18mm thick, the front of the baffle will be 1275.5 mm from the front of the cabinet.  Once the 18mm thickness of the hatch is considered, the depth of rear chamber is 179.5mm; the recommended driver is 160.6 mm deep and so there is a clear space of about 19mm behind the driver.  I have had no problems with overheating but I have made sure there is no wadding blocking the vent.  The RCF is a deep driver so most drivers will physically fit without trouble.

 

2. The assembled horn module should be located 20.5 mm from the front of the cabinet. You can work this out from the location of the baffle given above but I thought I’d do it for you! This enables a grill and foam to be fitted. I made a wheel board which slots into the mouth but I found the height of the cabinet upright made it unstable and so I always move the boxes on a sack barrow now. The 20.5 mm lip can be seen in the picture below.

 

 

2. The rebates for the vertical flare modules and front chamber pieces in the top and bottom horizontal flares and front chamber pieces are 5 mm deep.  The dimensions of Horn Flare Part 1, 2, 3, 4, 5 and 6, and Front Chamber Vertical accommodate this rebate and so if you want build the cabinet without these rebates you will need to remove 10mm from the height of these panels. I did not use rebated construction on any other panels and so if you want to use rebates anywhere else you will need to add a few mm here and there.  The whole construction is very well braced and so rebating isn’t necessary. The only rebates I did can be seen in the image below, an identical rebate was used in the top horn flare and front chamber piece.

 

 

4. The horizontal and vertical front chamber pieces should be located on the baffle so that they touch the driver cut-out at the centre-line. Mark the centre of the baffle and draw a 354mm circle for the driver cut-out. Draw one horizontal line touching the circle at the top, and one touching the circle at the bottom, and then do the same but vertically touching the circle on the left and right. The lines will all be 48mm from the edges of the baffle and denote the inside edge of the front chamber pieces.

 

5. The phase plug is designed so that the back of the largest circle is flush with the front of the baffle.

 

I think that with the build sheet this is all the information you will need to build the cabinets.  I am obviously happy to help if anyone is confused and wants to build some of them. They are complicated and it may be difficult to work certain things out from my crude drawings.  The following information will be helpful to anyone building these cabinets:

 

Horn flare rebate: I have marked the edge of the rebate on the Horizontal Horn Flare panels on the build sheet, you will obviously need to mark the same line on the other side of the panel, these lines denote where the vertical horn flare modules sit. I used an 18.5mm cutter to rebate a groove towards the edge of the panel from the marked line and it  worked perfectly, I simply moved a fence to route each section of the line. With four cabinets this was fine but it would be a chore with more boxes. You could make a jig if you don’t have an 18.5mm cutter. I have not marked the rebate line on the horizontal pieces of the front chamber but it is easy to work out as it meets the marked rebate at one side and meets the baffle at the other side allowing a 354mm spacing between vertical chamber pieces.

 

Mitres: A number of the pieces are marked as having mitres on all sides. The angles on some of them are very close to 90 degrees and I think all of them except the vertical front chamber pieces could be built with 90 degree cuts on two of the sides with no major problems. The cabinet is complex to cut out but there are no mitres greater than 45 degrees so as long as you take your time and think things through you shouldn’t have any problems.

 

Front braces:  I did not end up using the horizontal or vertical front braces. I fitted them to one cab but they are absolutely not needed for structural strength and so I removed them

 

Concealed braces: I used two braces behind the top, bottom, left and right horn flares, and have included this number in the cut sheet.  Using to two braces on horizontal and vertical flare modules is very useful for construction as shown in the image below, but it is not necessary structurally and if you want to build the flare modules in a different way, then one concealed brace in the centre is more than enough, this would mean that only two of each piece, rather than 4 would be required

 

 

Expanding foam:  I pumped expanding foam into the areas behind all the horn flares. I did this buy drilling holes to fit the nozzle of the gun and blocked up the holes when the cavity was filled.  If you are confident that the construction is solid enough then you can make the foam set harder and denser by filling up the cavity before the foam has expanded fully and block the holes thoroughly. The foam has nowhere to go and sets extremely hard. This isn’t really necessary given the amount of bracing I used!

 

Wadding: I thoroughly wadded the rear chamber. I used thick needled wool felt and held it in place by stapling polyester wadding over the top.  I completely filled the rear chamber and even stapled a load to the hatch. It is important to leave a gap in the centre of the hatch to allow some space around the driver vent. I actually taped some pipe guaze over the driver vent as it is large enough for bits of wadding to get sucked in.

 

Making the phase plug: The phase plug is made up of 10 circular pieces of wood which can be cut out with a jigsaw or router. The router is the better option as all the circles will be perfect. I originally thought that I could cut the angles on the edge with a jigsaw to make smoothing easier but this doesn’t work and you are better leaving all edges at 90degrees to be smoothed later. I would drill a small hole in the very centre of each circle so that a piece of wire or a long screw can be used to make sure all the circles are concentric when you laminate them together.  I smoothed the shape over on a lathe but you could do it with a rasp if you have lots of time and no router. Below are some pictures showing how I did it.

 

 

 

 

Rear of phase plug:  The only purpose of the phase plug is to reduce the volume of the front chamber, it serves no real purpose in minimising path length differences or affecting dispersion as this is not necessary or possible at the frequencies the cabinet plays.  I never got round to shaping the back of the plug and I think it is this which restricts the usable upper cut-off of the box. The sound hits the back of the phase plug and bounces back through the driver, and then bounces back off the hatch.  The back of the plug does not need to be moulded to the dust cap and does not need to get particularly close to it; When I get round to it I will simply make a rounded piece to stick on the back to prevent the sound reflecting back through the cone. The shape of doobers plug is what I had in mind:

 

 

Supporting the phase plug: As can be seen below I supported the phase plug using threaded rod, I think I used M12. You need to use a bit of care doing it this way to make sure all the holes line up and it is not particularly elegant. Pieces of plywood would be better but I went for the easy option as each plug was very slightly different after lathing.

 

 

Assembly: I built the four horn modules independently and then assembled them as shown below. I then attached the baffle to this and built the boxes around the assembled unit. I’m sure there are other ways of doing it but this is how I did it and it worked well.

 

 

Hatch battens:  The only pieces not included in the sheet are the battens for the hatch, this is because I made them out of planed hardwood. Remember that the battens on the side panels will need to have an angled edge so that the side facing the hatch is at the right angle . If you cannot work out the batten dimensions then I don’t think you will be able to build these cabinets!

 
 
 
me so horny, me love you long throw.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote biotec Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2011 at 5:46pm
I realise I have just written a stupidly long post but if anyone wants to build them you will need this information and it saves me having to repeat it.
me so horny, me love you long throw.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pfly Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2011 at 5:55pm
I just love this design.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote greeef Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2011 at 6:04pm
that's pretty awesome!


thought it was going to be about them at first...





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Post Options Post Options   Thanks (0) Thanks(0)   Quote Meat Quote  Post ReplyReply Direct Link To This Post Posted: 15 March 2011 at 7:09pm
Thats a beast, a very impressive build!

I have a couple of questions if you don't mind:

The mouth seems actually quite small, whiy did you settle on this size in the end?

Why do you say 85-300? Is this due to the upper rolloff or does it sound bad crossed higher?
Don't test the champignon sound
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Post Options Post Options   Thanks (0) Thanks(0)   Quote biotec Quote  Post ReplyReply Direct Link To This Post Posted: 16 March 2011 at 9:19am
Originally posted by Meat Meat wrote:

Thats a beast, a very impressive build!

I have a couple of questions if you don't mind:

The mouth seems actually quite small, whiy did you settle on this size in the end?

Why do you say 85-300? Is this due to the upper rolloff or does it sound bad crossed higher?
 
The horn design was originally based on the selenium HB1505C1 design. I have obviously modified the original design fairly significantly but some elements remained similar. The mouth area of the coffin bin is actually larger than the selenium plan.
 
I designed the cabinet so that the mouth area in blocks of 4 was sufficient to get a decent response and efficiency. A design like this obviously lends itself for use in large horn-loaded systems so I cannot see this cabinet being much use in small numbers anway. For applications where only one or two kick bins are needed it is likely that a box like this is unnecessay.I use my 4 in a monoblock 90% of the time and so it was a good compromise for me. You could make the front of the cabinet taller to increase the mouth area for use in singles but you'd have to make it much larger to get any real benefit.
 
The RCF driver sounds good playing much higher than 300Hz; however in the boxes I built the sound started to become a little strange above 350Hz.  I am almost certain that this is limited by the fact that I have not shaped the rear of the phase plug but I did not experiment further as the 300Hz is fine for me anyway. The design should allow use to above 500Hz and probably higher but I didn't test this as my mid-tops are happy playing 300Hz and up.
me so horny, me love you long throw.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bitzo Quote  Post ReplyReply Direct Link To This Post Posted: 16 March 2011 at 1:11pm
extreme cab at all.
How much does it weight?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 02 May 2011 at 10:48pm
me damn well wants some of these puppies!
me so horny me love you long throw
horn loaded for her pleasure
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tv00 Quote  Post ReplyReply Direct Link To This Post Posted: 05 May 2011 at 7:57pm
"I realise I have just written a stupidly long post"
I completely disagree, It's a brilliant post, mine is stupid, -sorry:-)
Love straight horns, but only have 4512 and then midhighs like ev sh1810, tms-2 & so on.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mark James Quote  Post ReplyReply Direct Link To This Post Posted: 14 May 2011 at 1:22pm
i want to buuild double versions of these :p how much wood was used for one cab? and can you post hr input screen so i can see what drivers will work :p looks like the epic partner to amanos lab18 design :p [which isnt a million miles away from the terra horn in usage peramaters] im working on a full range cab like a tms but with less lf extension for smaller gigs, looks like just take more lab18 subs and these and some mid tops instead for larger gigs :P flexibility :)
realy good design btw the world is now slightly more advanced thanks to you mr biotec [and minaximal for the subs of course] keep up the good work, heard these a year or two ago at i guess a medium level. they were doing the bussiness and sounded rather nice doing it, i had void stasys at the time and i recall commenting that it sounded at least a s good as said branded name cabs [albeit with disadvantages like the size] all im saying is they sounded realy good!!! and im a tekno fanatic and speaker snob so id say thatsa compliment :) keep up the good work :)
me so horny me love you long throw
horn loaded for her pleasure
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aztor Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2011 at 4:27pm
Can you post the sims of PD1550? or PD154?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote biotec Quote  Post ReplyReply Direct Link To This Post Posted: 12 July 2011 at 5:03pm
Hi Mark, sorry I missed your post for a few months!
 
Originally posted by Mark James Mark James wrote:

i want to buuild double versions of these
 
I would strongly advise against it. The single are difficult to get on the subs with two people and so I guess they are 110Kg+. I would say a double version would be unmovable.
 
Originally posted by Mark James Mark James wrote:

how much wood was used for one cab?
 
it was the best part of 3 sheets per cab.
 
Originally posted by Mark James Mark James wrote:

the world is now slightly more advanced thanks to you mr biotec [and minaximal for the subs of course]
 
thanks! but I'm not sure building such a large and awkward cab can be seen as progress by most yardsticks!
 
Originally posted by Aztor Aztor wrote:

Can you post the sims of PD1550? or PD154?
 
I'm not even sure I ever did a complete hornresp sim but if I did it's now long gone on the dead computer. All of the necessary dimensions are on the cut sheets if you feel like working out the hornresp parameters yourself. The cabinet works well across its intended range and has proven to be kind on the drivers over the few years I've used them.
 
I can tell you straight away that the PD1550 is the more suited driver but I think it will limit the upper cutoff of the box compared with lighter coned drivers like the one I used.
me so horny, me love you long throw.
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