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MTH-30 (again!)

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Tonskulus View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2018 at 5:55am
Comparsion beetween Cubo 15 extended (RCF L15P540) vs. MTH-30 (Impact 6712)
Measured 10cm away from the mouth.  Not so scientific tho, still cell phone spl meter was used here!


Now I need to find out which drivers to get for 4 x mth's.  B&C 12PS100 seems like a good choice. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote doller Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2018 at 11:27am
I have 6 and I love them. With hard trance the puond it out. I am using an cheap chinese driver in mine. can feed a pair off a xti 4000 to clip and they have never broken. I have tryed very hard to break them. Really like marco's stuff.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doller Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2018 at 11:32am

I made my first ones square to the plan. The next four I made like this. I really think that they sound better with the rounded corners. I made the box wider to compensate for the lost volume.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 10 December 2018 at 2:57pm
That is a great idea I love it! I made a pair with extra 45 degree pieces in the corners - I didn't alter the width though, as conceptually the corners represent "bulges" in the horn path if you have no reflector there - so when you round them or put a reflector in place, you are actually making the horn path closer to the ideal linear expansion? I was guessing that Marc O left such details out to make the build easier. Not that it could be *much* easier!

Anyway good to see many people appreciating these magic little bins. If you want a right laugh, try putting a (disposable) 50 watt guitar amp driver in one and see how much bass comes out...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doller Quote  Post ReplyReply Direct Link To This Post Posted: 11 December 2018 at 9:09am
I felt the same way about the corners and I did do the same as you with the frst ones. That looks like alot of work but it isn't you only have one panel. instead of 4. It was quick and easy. less scews. that is a center brace in the middle to use as a former. I would love to hear 6 a side. In a block of 6 they do go surprisngly low. not sub but low enough.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 12 December 2018 at 6:04am
Measured JBL 2206H, really smooth response with this one.  Very nice and tight sounding too, just not as loud around 50-60Hz as Impact 6712 car sub driver but much smoother and better control. 

-10dB point was around 46Hz. 

mth-30/2206 vs. Cubo15/l15p540.. not much difference except cubo drops lower. (did not make any max spl measurements tho..)



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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 13 December 2018 at 4:13pm
Finally got calibrated umik-1 + measuring software.  So here are my first real world response tests.
Mic placement: 15cm from mouth/cone and 10cm from the floor.   As I did notice previously, 2206H indeed has amazingly smooth response there!




Cubo15 vs MTH-30  (mic in plane with mouth, 10cm from the floor).  Top: cubo, bottom: mth30

Even tho cubo drops lower,  I have to say mth-30 is better sounding overall and gives more punch for l psytrance/house music as example. At least with these drivers I have tested so far..
So MTH really shines where lower bass is not requred. 

Next thing to do, is going outside for some max SPL measurements at a distance. And ofcourse, directivity tests as they claim TH does have some "throw" compared to ported/reflex. Who knows.. let's see.




Edited by Tonskulus - 13 December 2018 at 4:25pm
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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 13 December 2018 at 5:06pm
I doubt you will find much in the way of directivity as the horn mouth really is too small for that at the frequencies involved. Maybe if you have a block of 4 it will be a little bit louder in the upper bass on-axis, compared to behind the stack. 
I do know they respond extremely well to corner placement. You get a full 6dB more output in the room. It is very noticeable compared to having them in the middle of the room, but in both cases the sound pressure is quite even everywhere, there's no directivity.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tonskulus Quote  Post ReplyReply Direct Link To This Post Posted: 13 December 2018 at 5:14pm
Originally posted by studio45 studio45 wrote:

I doubt you will find much in the way of directivity as the horn mouth really is too small for that at the frequencies involved. Maybe if you have a block of 4 it will be a little bit louder in the upper bass on-axis, compared to behind the stack. 
I do know they respond extremely well to corner placement. You get a full 6dB more output in the room. It is very noticeable compared to having them in the middle of the room, but in both cases the sound pressure is quite even everywhere, there's no directivity.

I now, low freq directivity requires large radiating area - at least in theory.  Maybe there is something else going on?  
Well I have two hog scoops and they DO have some "throw" in front of them when stacked together, at least in 50-80Hz range there is much more bass 20m in front of them compared to back side. 

When it comes to small tapped horns, there is just a myth that has to be busted :)



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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 14 December 2018 at 1:50am
Originally posted by Tonskulus Tonskulus wrote:

Finally got calibrated umik-1 + measuring software.  So here are my first real world response tests.
Mic placement: 15cm from mouth/cone and 10cm from the floor.   As I did notice previously, 2206H indeed has amazingly smooth response there!




Cubo15 vs MTH-30  (mic in plane with mouth, 10cm from the floor).  Top: cubo, bottom: mth30

Even tho cubo drops lower,  I have to say mth-30 is better sounding overall and gives more punch for l psytrance/house music as example. At least with these drivers I have tested so far..
So MTH really shines where lower bass is not requred. 

Next thing to do, is going outside for some max SPL measurements at a distance. And ofcourse, directivity tests as they claim TH does have some "throw" compared to ported/reflex. Who knows.. let's see.









Where did you take these measurements? How did you window them? You’re too close to the box to be honest to get trustworthy data especially for a horn. The acoustic centre is often several inches in front of the cabinet. Measure at 4m with 20v input and calculate back to 1m if you want to compare sensitivity. Do it outdoors with nearest boundaries a good 5m+ away at least and window the measurement to get it usable. The mic should also be as close to the floor as possible, at an angle pointing down.

As it is, the data you have is likely ‘inside’ the box and adding in room modes too.

As for directivity, a TH118 has a measured 4dB broadband front to back level difference so they are more directional than a reflex by nature. I guess this is part of the diffraction effect of the small mouth vs the large face.

Edited by toastyghost - 14 December 2018 at 1:52am
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