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Mt-121 simplified plan

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Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smoore Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 3:21am
I'm not entirely sure on the driver model as the labels were ripped off. But speaking to a few more knowledgable folk they seemed to think they were fane studio 12s. Either mb or b model. Either way, I've never, ever noticed distortion in them (apart from doing a test with a HPF at 50hz and running them fairly loud) usually running around 4-500w each. But again, not sure on the power rating of the drivers etc as they have no labels. Lovely sound though
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 22 June 2014 at 10:59am
Would it be easier just to make horn slightly longer, and slightly enlarge chamber?

I'm thinking most half decent 15" kick bins are good for 150hz, so an MT that will comfortably reach down to 130hz, without excessive cone displacement, with good sensitivity, should be the guy.


Edited by levyte357- - 22 June 2014 at 10:59am
Global Depopulation - Alive and Killing.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote smoore Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 3:03am
Yes you could do that but your also talking a completely different sound from a 15" and a 12". I wasnt saying my aim is to reach 120hz or so. Just that I DO run my MT121's that low and I am happy with the sound and have never noticed significant distortion from them.. 

 I am selling my mid tops (MT121 with an XT8 and coaxially hanging BMS 1"). But my next build is a 15" closed box with a 6" horn that reaches 500hz with a 1" above
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Post Options Post Options   Thanks (0) Thanks(0)   Quote turbo7 Quote  Post ReplyReply Direct Link To This Post Posted: 23 June 2014 at 10:23am
"Would it be easier just to make horn slightly longer, and slightly enlarge chamber?"

exactly what i was planning...


 "I am selling my mid tops (MT121 with an XT8 and coaxially hanging BMS 1")"

Why are you selling ? My plan is to do a slightly ( 3cm maybe ) longer horn to gain some bottom end and combine it with something like RCF H6000 8" horn or similar xt8 ( new version out ?! ). The H6000 plays very fine up to 3k and i will go for 2-3 coaxially mounted Faital FD371 bullets. I guess it could sound nice on axis, but what will happen off axis...

The H6000 is 80X60 degrees which is a bit too wide for me ! I plan to run clusters of 3. It is hard to find 8" phase pluged horn with a bit narrower dispersion. Of course the H6000 will beam too the higher the frequency...

i would love to see plots of new xt-8 horn, especially off axis !



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Post Options Post Options   Thanks (0) Thanks(0)   Quote WaveLength Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 11:19am
hi guys this is my second post.. just trying to learn something more..
so ... would an original MT121 with a longer horn (and a PD121 inside) hold a 150hz or lower xover point?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote b grade Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 2:48pm
In general longer and a larger mouth will get you lower frequencies. I highly recommend getting a basic understanding of Horn Resp if you want to make a bunch of modifications. You can figure out where you can make some compromises while getting an educated guess on how to reach your goals.
150 hz in free space is a pretty long and wide horn. Not unachievable but you may want to model it and find out how long and how wide. It will start becoming awkward to stack on the bass section if you go too low.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WaveLength Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 4:31pm
Really thx for that b grade..yes maybe its time for me to learn more about HR ....
but just another question : in the original MT121 with the driver i mentioned before (PD121) can i xover at 180hz  without blow the driver?
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Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote b grade Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 4:51pm
Without running a sim, I am not absolutely sure, but my horns are bigger than MT121s and I don't have excursion issues until almost 100HZ, but the frequency response just drops like a rock below 180 hz, and I would not recommend making up for that with eq or you will get into excursion trouble and distortion up high where they work properly.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WaveLength Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 5:27pm
thx again 
so you are just saying i can't go lower than 200hz?  and in this case i can use a little eq in the low end.. 

or 180hz will work but with no eq ?



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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 7:23pm
I really need to connect up my Berry ECM mic, to my Berry Ultracurve 8024, and measure one of my MT121s. Confused


However I know Fane 12MB is great in there, especially below 150hz, even if it's not as great higher up, like PD123ER or B&C12PE32.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote b grade Quote  Post ReplyReply Direct Link To This Post Posted: 11 November 2015 at 9:37pm
Originally posted by WaveLength WaveLength wrote:

thx again 
so you are just saying i can't go lower than 200hz?  and in this case i can use a little eq in the low end.. 

or 180hz will work but with no eq ?




If you look at the plot Rog posted he has some eq suggestions. I would not suggest boosting the low end and instead reducing the highest points you will be less likely to have problems. http://forum.speakerplans.com/mt122-plot_topic24135.html
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WaveLength Quote  Post ReplyReply Direct Link To This Post Posted: 12 November 2015 at 4:54pm
thx for your help guys
just to be clear ,right now we don't have an MT121 (just trapezoidal 12" reflex + 1,4" (that we use in small pubs above 2x15"scoop ).
i'm trying to figure out wich is the best way to go for an outdoor rig.

Levyte: i know i maybe did the wrong decision  buyng the 121 (i have 4 of them) but have no money to make a change ... 
        i just want to reach 180hz to meet a USB (or ES18 :) 


b grade: ok got it... always better to reduce than to boost..  
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