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Mods To Simplified MT121 for 130hz HPF

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levyte357- View Drop Down
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    Posted: 08 September 2014 at 2:59pm
Box builder I know,  suggests enlarging chamber from approx 166mm deep, to 230mm.

Comments ?

Will check  confirm actual increase in chamber volume later, but heard pair of his cabs, very similar to MTs, but with larger chamber, and they do play downto approx 130hz, and reach approx 1300hz  with flattening EQ.




Edited by levyte357- - 08 September 2014 at 2:59pm
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Teunos View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Teunos Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 4:42pm
Increasing rear chamber volume will also increase the cone excursion and give more ripple in the passband. If you want to get the mt121 or anything similar to play lower, it would be better to increase the horn length, not chamber volume. The smaller the better generally speaking i.m.o. Make a proto and you'll hear/measure what i am saying. Imo its not worth the compromise
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 4:59pm
Originally posted by Teunos Teunos wrote:

Increasing rear chamber volume will also increase the cone excursion and give more ripple in the passband. If you want to get the mt121 or anything similar to play lower, it would be better to increase the horn length, not chamber volume.


Won't increasing horn length also lower upper cut off?

Finding drivers with 7mm Xmax, is not a problem.
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Teunos View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Teunos Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 5:31pm
If dispersion and flare rate were kept constant, i would not see why this would be the case.
I think I know though what you're getting at though, this is another one in the quest for getting extremely flat 80-400Hz range.
Connecting a 12'' horn to a sub without using a kick cab is not as simple as increasing the rear chamber. Best way to do this would be to just accept that your cab will end up large.... and increase the horn size. Or just put a BR cab in between and be done with it, and use a 10'' or 8'' hornloaded mid.

Member Snowflake has some very large 12'' flh that i believe he crosses directly to his TH subs. Perhaps ask him towards his experiences?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 5:49pm
Originally posted by Teunos Teunos wrote:

If dispersion and flare rate were kept constant, i would not see why this would be the case.
I think I know though what you're getting at though, this is another one in the quest for getting extremely flat 80-400Hz range.


Have changed direction regarding certain areas.

Easier to get Mid playing down to 130hz, than Kick cab playing smoothly upto 250-300hz.

Kick cab playing upto 130/150hz is peanuts.

Simplified MT quoted range is 160hz upwards, slight change and right driver should acheive 130hz at upto 500w, quite easily.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 7:02pm
increase horn length and horn mouth....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote knet94 Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 8:39pm
Originally posted by levyte357- levyte357- wrote:



Have changed direction regarding certain areas.

Easier to get Mid playing down to 130hz, than Kick cab playing smoothly upto 250-300hz.



Took you long enough!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AndyWave Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2014 at 10:38pm
Originally posted by levyte357- levyte357- wrote:

Box builder I know,  suggests enlarging chamber from approx 166mm deep, to 230mm.

Comments ?

Will check  confirm actual increase in chamber volume later, but heard pair of his cabs, very similar to MTs, but with larger chamber, and they do play downto approx 130hz, and reach approx 1300hz  with flattening EQ.



I'm using one or two 12" sections crossed over 98.....120Hz depending situation and stack size. X/o straight to subs.

Top cabs are 80cm deep over all, and horn itself is 67cm deep. But this design has nothing common with MT121 than being FLH and with 12" driver (18sound 12ND930). So bit heavier cone is called in with Mms around 50g than in MT121. If I remember right 12PE32 has Mms of 37g for example.

Throat area 200cm2 and mouth 2700cm2 in my design, hypex curve and sort of phase plug assembly. Upper band max 1000Hz.

regarding back chamber size, I'm using some 12L max with some wadding.

my 2p, Andy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2014 at 9:56am
Originally posted by knet94 knet94 wrote:

Originally posted by levyte357- levyte357- wrote:



Have changed direction regarding certain areas.

Easier to get Mid playing down to 130hz, than Kick cab playing smoothly upto 250-300hz.



Took you long enough!


Aye.. LOL
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