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MT-121 Not completly Satisfied - Mysteries
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LeruSound View Drop Down
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Points: 171 		Post Options Post Options   Thanks (0) Thanks(0)   Quote LeruSound Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2015 at 8:43pm
Originally posted by levyte357- levyte357- wrote:

Originally posted by LeruSound LeruSound wrote:

I would try many different drivers, but it is something i could not afford for now. That's why i'm trying to look for a good one, that can give me the lower end response. 
What do u think about 12MB700? 
B&C
12PLB100? 12PLB76? 12FW76?


Where are you based, and which brand of drivers are best priced for you to buy?

In UK, nice budget driver is Fane 12MB, plenty of low end in MT121, top end extension not as good as PD 123ER or others.

Paudio SN12B very sensitive, but low Xmax, so can't run too low.

Celestion TN1230 sounds apparently very good.

Fane looks good, as weel, has 140 Hz Fb-3 in closed box. 
I'm sure the horn could not lower it..


Edited by LeruSound - 30 November 2015 at 8:43pm
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Points: 11776 		Post Options Post Options   Thanks (0) Thanks(0)   Quote ceharden Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2015 at 8:44pm
I would doubt that the 12MB700 is your problem.  The specs suggest that it is a very good driver and definitely suitable for the application.

As the others have said, trying to match the horn loaded midrange with a 1" compression driver is never going to work properly.  You need a larger format (3" diaphragm, 1.4" or 2" exit) driver and a large horn flare (the XT1464 from 18Sound would be ideal) to give you the control at the lower end.  I would be looking to bring the crossover point down, maybe 1.2kHz as a starting point.

What are you using as your low mid (kick bass) cabinet up to 180Hz?  That may also be affecting how you're hearing the MT121.

It's also worth bearing in mind that the MT121 is only half of the original cabinet design and is intended to be used in multiples.  One horn at close range may not sound very impressive but several from further back should be.
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Points: 1019 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Peter Jan Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2015 at 9:13pm
Originally posted by LeruSound LeruSound wrote:

I would try many different drivers, but it is something i could not afford for now. That's why i'm trying to look for a good one, that can give me the lower end response. 
What do u think about 12MB700? 
B&C
12PLB100? 12PLB76? 12FW76?

12PLB76 would be my choice
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LeruSound View Drop Down
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Why u think it is very good? Why should the compression driver influence the lower freqs driven from the 12"? I thought that MB700, like PE32 have an high Vas and a very low Qts, this gives them an higher cut off (190 200 hz) caused from the rear closed chamber. I thought that this could be the problem in the lower end. Let's forget the 1" driver for now please . One my option is to try remove the passive xover and drive the 12" alone, and lets test it.. 
I mean, the response curve seems to be not so bad, but ears do not completely agree yet.

I got hybrids 18", but now i have a simple 18" relfex as midbass. Overall, my complain was on the hearing of midtops only, IMO them should be more agressiv and "deep" from the 12". I would like to hear them "vibrate" (try to get it :D ).
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For example, SN12MB gives the MT121 a 100 Hz cut off (-3db)in the lower end freqs, caused by the rear closed chamber. Baybe to let it sound good u need more aggressive drivers. I think that it should be important to match the Vas with the Real ch volume to get a good response in 100 - 200 Hz (even if 100 is still not able to be heard, but the filter may have something to filter in that area). I will try for sure to drive them in active.. But everything is overall good, just not as i wanted in the lowers...
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Points: 7442 		Post Options Post Options   Thanks (0) Thanks(0)   Quote cravings Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2015 at 9:53pm
have you measured it at all? i think you can get simple RTA apps for phones.. i've never checked them out.

i haven't done any proper measurements of my mt121s, but it really looked like the 12 didn't play above about 900hz at all. maybe there's just a lot of information missing because of the high crossover point, which will indeed make the box sound off.

i've never really figured out the best way to run mine either if i'm honest. sometimes they're great, other times.. i'm not sure about them at all. but i crossover at 150 and 900 i think.
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Points: 4553 		Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2015 at 9:58pm
the only 1" worth using in the mt121 is the bms4550 as you can run it from 900hz....

getting the 12" to play above 900hz forget it....

best 12" 1" combinations ive personally heard used

BMS 12n610 and bms4550
B&C 12ndl76 and bms4550

non budget option
bms12n610 with the bms 4590 2" 1" coaxil... (the 4590 will easy keep up in the mt122 so prob overkill in the mt121)

no driver in real world will play to 100hz, just not going to happen in the mt, 150hz for most drivers, -6 at 140hz for some drivers...



Edited by bee - 30 November 2015 at 10:00pm
https://www.elements-audio.com
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LeruSound View Drop Down
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So if i choose a driver which can handle 100 Hz in that box, for sure it will handle 150 140 as u say..
My choiche would have been 12PLB100
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the box full stop will not allow a driver to play 100hz, your kill the driver. By design its not designed for that frequency....

There are 100's of threads re the mt, and best possible drivers, There is only 1 1" driver currently available in the world worth trying in the mt and that's the bms4550, as its capable of playing from 900hz... if you want 100hz your need to use a suitable high bass cab or a dedicated kick cab....

ive listed already for a b&C the best driver is 12ndl76 from bms its the 12n610,

Ive tested and measured mant many 12" drivers in horns, and listened to many more...

possible 1" horns worth looking at are faital pro lth102 or the rcf


Edited by bee - 30 November 2015 at 10:27pm
https://www.elements-audio.com
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your looking at the cab the wrong way.... look at drivers to play up as high as possible, almost all 12" drivers can handle 150hz... but very few can play to 900hz in the mt before the frequency waves start breaking up inside the horn...
https://www.elements-audio.com
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LeruSound View Drop Down
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An example could be the PAS5MA1 or other Selenium 2x12". The plan got a similar horn and a very similar small closed rear chamber. If u get a look of the suggested driver u will se that them have the same parameters as the SN12B in MT121. 
Volume is around 18 L for 1 woofer.
The woofer got small Vas (45 l) high Qts (0.44) and Fs 63 Hz.

All togheter, after calculation, returns me an Fb -3 around 100 Hz.
On the plan is written to HPF the 12" section at 200 Hz, seems legit. The most of the drivers u have showed me give results around 160 230 Hz of Fb. 160 could be a good choice, but why choose it when i could do better? 
So Fb -3 is around 100 Hz, but i will also cut it at 180 Hz, 24dB/oct slope. It means that in 90 Hz there will be -24 dB, but at 160 there will be the add of MB and MT that gives me the right feeling. So, unless it is not a reflex midrange, that could help me reach the lower possible, i would like to choose the best sounding driver for it, like the P audio SN12MB, but i would prefeer to get a better brand. So B&C, 18Sound and RCF are my choice. U still think it is better to place a 12PE32 inside it and cut it at 150 Hz but a right tuned one with the parameters that seems legit for that supersmall box?
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MarjanM View Drop Down
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Points: 7816 		Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2015 at 10:49pm
Originally posted by LeruSound LeruSound wrote:







Am i the only one seeing the problem here?
If this is the real measurement of the box then you need to attenuate the HF for at least 3-4db to even out the response. 
Marjan Milosevic
MM-Acoustics
www.mm-acoustics.com
https://www.facebook.com/pages/MM-Acoustics/608901282527713
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