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best choice for a 12" horn plans

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bob4 View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 10 May 2017 at 1:15pm
check the previous messages in this thread. DJK has one older design he calls the 12" doube mantaray. in this thread he also mentioned a new design he is working on.
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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 11 May 2017 at 12:35pm

I found this project and i tried to source out some measurement but is a big mess!


S1: 585,12 cm2 
(i take the area of the circle then the rettangle then the square in the circle--> Area of the circle minus the square--> and dived by 4 i found the area segment out the square, then i just made the circle less 2 of this hided area segment)
S2: 4065,6 cm2
L12/EXP=35cm
VRC -this drive me mad and it seems so wrong-: 276 l --> made by summing 
internal back (900-24)*(620-350-24)*(750-24)) 
plus upper and under space -where are the reflex- ((750-24)*((900-24-390)/2)*350)*2) 
MINUS THE REFLEX volume (200x8x100x2)
AP=32 (area of a single reflex x2)
lpt= 10
vtc:1500cm^3
atc:522


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Post Options Post Options   Thanks (0) Thanks(0)   Quote all bass Quote  Post ReplyReply Direct Link To This Post Posted: 13 May 2017 at 10:11pm
Originally posted by _djk_ _djk_ wrote:


I'm better after adjusting some of my meds, they had me over-medicated to the point I was unable to walk, or even see.

Wow, i haven't been on here for a while. Hope you are well, Dennis!
Get your free line array plans here!
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bob4 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 10:29am
Originally posted by _Natty_ _Natty_ wrote:




I found this project and i tried to source out some measurement but is a big mess!


S1: 585,12 cm2 
(i take the area of the circle then the rettangle then the square in the circle--> Area of the circle minus the square--> and dived by 4 i found the area segment out the square, then i just made the circle less 2 of this hided area segment)
S2: 4065,6 cm2
L12/EXP=35cm
VRC -this drive me mad and it seems so wrong-: 276 l --> made by summing 
internal back (900-24)*(620-350-24)*(750-24)) 
plus upper and under space -where are the reflex- ((750-24)*((900-24-390)/2)*350)*2) 
MINUS THE REFLEX volume (200x8x100x2)
AP=32 (area of a single reflex x2)
lpt= 10
vtc:<span style=": rgb251, 251, 253;">1500cm^3</span>
atc:522




oh dear........

Thats an old 15" jbl midbass hybrid design. It will be no good for 1 kHz and higher, too big overall. Build some mt121s instead. I thought you wanted a real mid horn??
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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 10:34am

yes good idea, but mt121 with 12mh32 give me very bad simulation results... im looking for a decent design but i think that i should project it by myself... big lack of knowledge but i will try to mods some plan... so for you 121 is the best overall plan, should i start from that one?
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cravings View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cravings Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 10:54am
mt121 also no good for 1khz and above though.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keen Quote  Post ReplyReply Direct Link To This Post Posted: 19 May 2017 at 2:12pm
Originally posted by _Natty_ _Natty_ wrote:


yes good idea, but mt121 with 12mh32 give me very bad simulation results... im looking for a decent design but i think that i should project it by myself... big lack of knowledge but i will try to mods some plan... so for you 121 is the best overall plan, should i start from that one?
Good you're aiming to design something.

Start with this simple conical horn layout. Mouth area and horn length will load the driver in free space (4pi) to approx 160hz.

Driver:12MH32

S1:200
S2:2000
L12:60(Con)
Vrc:10
Vtc:1500
Atc:200

Use Loudspeaker Wizard (input parameter page - tools) to experiment with different things.

Also use the directivity tool (acoustic pressure page - tools) to identify on axis response. 

Important to keep rear chamber volume low to get past 500hz (approx mass corner for these 12" mid drivers) and then think about phase plugs to reduce throat chamber for going even higher. 

have a look here: http://forum.speakerplans.com/increasing-upper-rolloff-corner_topic42001.html




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bob4 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 2017 at 8:35am
Originally posted by cravings cravings wrote:

mt121 also no good for 1khz and above though.


It defo needs eq to get there, but no good? I realise its a compromise, but i've worked many times with a rig that uses these crossed at 1 kHz to some 2" drivers (2445 or dh1), and to me it has always sounded acceptable....

Can you elaborate a bit more? interested in your arguments and experience
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 2017 at 12:25pm
(suggested use for old large-throat short horns)
Originally posted by djk djk wrote:

As the horn mouth and length approach infinity the output becomes smoother, but output at the Fc of the horn drops to zero (you can have too big of a mouth).

Increasing the throat size makes the horn shorter, but also raises the Fc.

Hornresp knows all this, but you knowing this will save you time in using Hornresp.

On selecting drivers, the higher the mass corner, the higher the response will go before needing EQ. For a bass horn pick the lowest efficiency driver that has a mass corner close to where you intend to cross it at. 

Mass corner = 2(Fs/Qes).

These are simplifications, but they should help you get started.



Edited by bob4 - 20 May 2017 at 12:37pm
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cravings View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cravings Quote  Post ReplyReply Direct Link To This Post Posted: 20 May 2017 at 3:10pm
I haven't found they really do anything above 900. I have a pair I built... Haven't used them in a while, but I have used them a lot. ive always wanted to put an xtro type upper mid above to see how they go.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Keen Quote  Post ReplyReply Direct Link To This Post Posted: 21 May 2017 at 10:49am
Originally posted by Keen Keen wrote:

Originally posted by _Natty_ _Natty_ wrote:


yes good idea, but mt121 with 12mh32 give me very bad simulation results... im looking for a decent design but i think that i should project it by myself... big lack of knowledge but i will try to mods some plan... so for you 121 is the best overall plan, should i start from that one?
Good you're aiming to design something.

Start with this simple conical horn layout. Mouth area and horn length will load the driver in free space (4pi) to approx 160hz.

Driver:12MH32

S1:200
S2:2000
L12:60(Con)
Vrc:10
Vtc:1500
Atc:200

Use Loudspeaker Wizard (input parameter page - tools) to experiment with different things.

Also use the directivity tool (acoustic pressure page - tools) to identify on axis response. 

Important to keep rear chamber volume low to get past 500hz (approx mass corner for these 12" mid drivers) and then think about phase plugs to reduce throat chamber for going even higher. 

have a look here: http://forum.speakerplans.com/increasing-upper-rolloff-corner_topic42001.html




sorry, there's a mistake - the bold text should be approx 200hz
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