Hi hifi enthusiasts / DIY:er
Need help regarding my hifi-project and MTM solution!
I have build a fullrange 3-way speaker with 2x 12 inch woofers and 2x 8 inch midrange and a Mundorf AMT tweeter, xover att 285 and 1850 hz.(active with passive xover in the MTM)
Mundorf tweeter have a sensitivity @ 2,83 V/1m at 100 dB, and Audax midrange is 99 dB and Peerlees XXLS woofers at 92 dB ( all 8 Ohm´s speaker, but the xxls have 2x8 Ohm´s coils connected in serie at the bobbin for 16 Ohm, and parallelconnected outside so 8 Ohm)
To "lift" the sensivity for the xxls woofers (to better match the tweeter/midrange output), i had luck and got a hold of 2 more xxls 12 of the same model (despite being discontinued in 2006)
I now have W-W-MTM ( MTM ordinary vertical), but with the "2 extra" xxls on top ( 55 kg each) i was forced to have the MTM horizontal as a W-W-horizontal MTM-W
And thats a disaster for deliver good "poit-source" hi end audio!
Now the total midrange-area is 52 centimeters wide, and regardless of placement the sound just "make me angry".
So i must somehow re-build the MTM and try place the midrange close on each other, and try put the Mundorf tweeter as near as possible on the inside.
Do you guy´s think its going to work out?
Or must i re-build it in another way?
Simple drawings in Paint so you can see how i think, left how it is today Right how i plan to re-build it.
Also a pic how i started with 2x 5,35 inch in the MTM ( blow 3 of 4 midrange coils after 3 week´s)
So i made a new MTM with 2x 8 inch, and placed the MTM on top
But now i have 3x 12 inch woofer per side, so must figured out a stabile/good MTM solution.
Best regard John/Sweden
Need help regarding my hifi-project and MTM solution!
I have build a fullrange 3-way speaker with 2x 12 inch woofers and 2x 8 inch midrange and a Mundorf AMT tweeter, xover att 285 and 1850 hz.(active with passive xover in the MTM)
Mundorf tweeter have a sensitivity @ 2,83 V/1m at 100 dB, and Audax midrange is 99 dB and Peerlees XXLS woofers at 92 dB ( all 8 Ohm´s speaker, but the xxls have 2x8 Ohm´s coils connected in serie at the bobbin for 16 Ohm, and parallelconnected outside so 8 Ohm)
To "lift" the sensivity for the xxls woofers (to better match the tweeter/midrange output), i had luck and got a hold of 2 more xxls 12 of the same model (despite being discontinued in 2006)
I now have W-W-MTM ( MTM ordinary vertical), but with the "2 extra" xxls on top ( 55 kg each) i was forced to have the MTM horizontal as a W-W-horizontal MTM-W
And thats a disaster for deliver good "poit-source" hi end audio!
Now the total midrange-area is 52 centimeters wide, and regardless of placement the sound just "make me angry".
So i must somehow re-build the MTM and try place the midrange close on each other, and try put the Mundorf tweeter as near as possible on the inside.
Do you guy´s think its going to work out?
Or must i re-build it in another way?
Simple drawings in Paint so you can see how i think, left how it is today Right how i plan to re-build it.
Also a pic how i started with 2x 5,35 inch in the MTM ( blow 3 of 4 midrange coils after 3 week´s)
So i made a new MTM with 2x 8 inch, and placed the MTM on top
But now i have 3x 12 inch woofer per side, so must figured out a stabile/good MTM solution.
Best regard John/Sweden
Attachments
AllanB
No the tweeter is on about 90 to 110 centimeter from the floor so thats okey, but the sound from the MTM when it lies horizontal is clearly heard coming from the left and right MTM speakers and not Imaging "in the middle"...Like it should and did before, when i had a vertical MTM
Regards John
No the tweeter is on about 90 to 110 centimeter from the floor so thats okey, but the sound from the MTM when it lies horizontal is clearly heard coming from the left and right MTM speakers and not Imaging "in the middle"...Like it should and did before, when i had a vertical MTM
Regards John
But i can´t place the third 55 kg big heavy 12 inch xxls woofer over the slim MTM.
The MTM in that way was 65 cm in height, only 22 cm deep and 39 cm wide, so the woofer have nothing to lie on.
Woofer is 40 cm high, 65 cm deep and 51 wide, and i want a stable safe construction because things move when i play load and i dont want the top woofersektion to suddenly fall down and crash in the middle of a song.
So in frustration a week ago (after a few beer) i saw the MTM in 2 pieces, so i could lie it down and also rotate the tweeter (becauce the AMT was lying otherwise)
So it become a horizontal MTM that sounded bad.
And now i have to re-build the MTM and was wondering if my idea of 2 midrange over eachother, and a close mounted tweeter beside is going to work great for Imaging?
In that case i build the MTM like that but deeper and wider, so the woofer is sitting good on top.
Regards John
The MTM in that way was 65 cm in height, only 22 cm deep and 39 cm wide, so the woofer have nothing to lie on.
Woofer is 40 cm high, 65 cm deep and 51 wide, and i want a stable safe construction because things move when i play load and i dont want the top woofersektion to suddenly fall down and crash in the middle of a song.
So in frustration a week ago (after a few beer) i saw the MTM in 2 pieces, so i could lie it down and also rotate the tweeter (becauce the AMT was lying otherwise)
So it become a horizontal MTM that sounded bad.
And now i have to re-build the MTM and was wondering if my idea of 2 midrange over eachother, and a close mounted tweeter beside is going to work great for Imaging?
In that case i build the MTM like that but deeper and wider, so the woofer is sitting good on top.
Regards John
And i was also thinking that because the woofer works up to 285 hz, i was better if the woofer was placed as close together as possible.
And a "smaller" MTM will help bringing the woofer closer to eachother.
Is im thinking wrong here ?
And a "smaller" MTM will help bringing the woofer closer to eachother.
Is im thinking wrong here ?
285Hz is still within the room mode band, so what you say is only partly true. I know there are benefits to controlling your wavefronts, but in some respects it can be good to spread things around down low.
I understand this is a vague answer.. but if you get measurements that show the result is good then ok. It is not like mixing up too many tweeters.
I understand this is a vague answer.. but if you get measurements that show the result is good then ok. It is not like mixing up too many tweeters.
Making stand for woofer on top of mtm to support should be doable. From the front it would look like its sitting on it, but in the back you have plenty space for sturdy stand.
adason:
Sure making stand for woofer on top of mtm to support should be quite easy, my questing was more about "getting the best out of it/MTM".
Putting 2 midrange on top of eachother and placed the tweeter beside on inside in the middle of them (as close as possible, look at the erlier pic´s)
OR
Making a ordenary MTM as i have from the begaining
Imaging in sound is most important, and i like "point-source-wise sound" and not all over the place.
AllenB:
Have no skills for measurements ( even if i would love to learn), so my ears and many hour´s are my tools....and 40 years of hifi love.
BTW room is 10 x 5 meter and 2,47 m in hight with some acoustic treatment.
/John
Sure making stand for woofer on top of mtm to support should be quite easy, my questing was more about "getting the best out of it/MTM".
Putting 2 midrange on top of eachother and placed the tweeter beside on inside in the middle of them (as close as possible, look at the erlier pic´s)
OR
Making a ordenary MTM as i have from the begaining
Imaging in sound is most important, and i like "point-source-wise sound" and not all over the place.
AllenB:
Have no skills for measurements ( even if i would love to learn), so my ears and many hour´s are my tools....and 40 years of hifi love.
BTW room is 10 x 5 meter and 2,47 m in hight with some acoustic treatment.
/John
How about trying it both ways and listen? Typical MTM like in post # and the right drawing on post #1 with both MMT o the side of the T? Don't need to make it a fully finished box; an experimental prototype should do.
FWIW, I have a larger AMT (Beyma TPL) and two 8" in vertical MTM and I have a hard time hearing lobbing, currently crossing at 1.8kHz. I'm still prototyping, though. BTW, an idea I got from another member: I was planning to use an inductor before the bottom M, so both 8" would play at the xo frequency from midbass (275Hz), but then I would cut off one M so by the xo frequency to T (1.8kHz) I had one M at -6dB to minimize lobbing from the large spacing. Bought the copper wire to wind the inductor, but I'm having second thoughts because I'm not perceiving lobbing.
Regarding how to implement the top 12": maybe you could extend the side panels of the bottom two 12" up until where the top 12" sides would be and complete their enclosure resting on the two side panels that go down to the floor. Maybe leaving the back behind the MTM open and leave the MTM section isolated from the three 12" vibrations...just a thought. Would be stable.
FWIW, I have a larger AMT (Beyma TPL) and two 8" in vertical MTM and I have a hard time hearing lobbing, currently crossing at 1.8kHz. I'm still prototyping, though. BTW, an idea I got from another member: I was planning to use an inductor before the bottom M, so both 8" would play at the xo frequency from midbass (275Hz), but then I would cut off one M so by the xo frequency to T (1.8kHz) I had one M at -6dB to minimize lobbing from the large spacing. Bought the copper wire to wind the inductor, but I'm having second thoughts because I'm not perceiving lobbing.
Regarding how to implement the top 12": maybe you could extend the side panels of the bottom two 12" up until where the top 12" sides would be and complete their enclosure resting on the two side panels that go down to the floor. Maybe leaving the back behind the MTM open and leave the MTM section isolated from the three 12" vibrations...just a thought. Would be stable.
That's ok. I was saying that you should try it. I know that we want to get drivers close to each other at mid and higher frequencies, but this is different.
LewinskiH01
+1
I have not notice any lobing in my "ordinary MTM" set-up either, and the explanation for Acoustic lobing is
"Acoustic lobing is an effect that occurs when two neighboring loudspeakers emit the same frequency while being a distance apart that is larger than a quarter of a wavelength of that sound."
A quarter of a wavelength at 1800 hz is only 4,03 cm, and at 1000 hz is only 7,5 cm....So quite imposible to get around that "mumbo-jumbo"
My opinion made by my ears is that upp to 1,5-1,7 wavelength can work good, even if i always tries to get under that valeu.
A 8 inch is 21 cm so about 1,25 wavelength is the best you can do at 1800 hz( if you put the tweeter beside it) in MTM.
Don´t use an inductor before the bottom M if you don´t must because of sound, why choke dB if you don´t have to and you ears is your ears.
Good idea about the side panels!
/John
+1
I have not notice any lobing in my "ordinary MTM" set-up either, and the explanation for Acoustic lobing is
"Acoustic lobing is an effect that occurs when two neighboring loudspeakers emit the same frequency while being a distance apart that is larger than a quarter of a wavelength of that sound."
A quarter of a wavelength at 1800 hz is only 4,03 cm, and at 1000 hz is only 7,5 cm....So quite imposible to get around that "mumbo-jumbo"
My opinion made by my ears is that upp to 1,5-1,7 wavelength can work good, even if i always tries to get under that valeu.
A 8 inch is 21 cm so about 1,25 wavelength is the best you can do at 1800 hz( if you put the tweeter beside it) in MTM.
Don´t use an inductor before the bottom M if you don´t must because of sound, why choke dB if you don´t have to and you ears is your ears.
Good idea about the side panels!
/John
AllenB:
From about witch hz its irrelevant to get drivers close to each other?
I know 100 hz is hard/impossible to spot, but waht about around 170 hz and up to 285hz?
/John
From about witch hz its irrelevant to get drivers close to each other?
I know 100 hz is hard/impossible to spot, but waht about around 170 hz and up to 285hz?
/John
It isn't irrelevant because you still need to find a way to fill the room. The room will help you up to maybe 200 or 400.
It is different that you have trouble hearing it. Some people say up to 700, I think much lower.
It is different that you have trouble hearing it. Some people say up to 700, I think much lower.
I have build quite a number of mtm and lobing was never an issue
as long as horizontal of axis response is fine, no issue with vertical lobing
unless your ears are crooked
seriously, i have discussed this in numerous threads, our ears are horizontally oriented for reason
as long as horizontal of axis response is fine, no issue with vertical lobing
unless your ears are crooked
seriously, i have discussed this in numerous threads, our ears are horizontally oriented for reason
this was my old comment about lobing and mtm
on other note, you can shimulate TM or TMM as long as you like, its inherently flawed because the highs and mid/lows are not coincidental
in MTM, you get more coherency because its like coaxial, highs emanating from the center of the mid/lows
in horizontal dimension off course, vertically, there is lobing
but we evolved as a species living on the planes of africa, where it was of utmost importance to follow horizon for sights and sounds, to follow pray or predators, hence we have ears and eyes in horizontal domain
horizontal performance of the speaker is important, we can tolerate minor deviations in vertical domain
my listening and measurements between TMM and MTM always favored MTM
on other note, you can shimulate TM or TMM as long as you like, its inherently flawed because the highs and mid/lows are not coincidental
in MTM, you get more coherency because its like coaxial, highs emanating from the center of the mid/lows
in horizontal dimension off course, vertically, there is lobing
but we evolved as a species living on the planes of africa, where it was of utmost importance to follow horizon for sights and sounds, to follow pray or predators, hence we have ears and eyes in horizontal domain
horizontal performance of the speaker is important, we can tolerate minor deviations in vertical domain
my listening and measurements between TMM and MTM always favored MTM
Real interesting adason and much logical explained, and exactly how i experience it.
Thank´s !
What do you call this "MTM vesion" with tweeter aside of midrange solution, like i posted in #5 , and have you ever build and measure one?
AllenB:
Is there a way/program to evaluate the room your using ( like mine ), and see gain or loss in different frequencies ?
I found this calculator but it only seems to show up to 53 hz
amroc - THE Room Mode Calculator
/John