Well if simulated well or with measurements off axis.
You will probably get over MTM.
Very low crossover point likely good start though.
Center to center on just the woofers, plus the horn
be fun to dial in.
You will probably get over MTM.
Very low crossover point likely good start though.
Center to center on just the woofers, plus the horn
be fun to dial in.
I wonder if 1/4 WL rule still apply when going farer with the listening spot, i.e. from near field (1 m) to far field listening distance (>3 m ; typical living room listening distance).
At 3 meters the drivers sound should merge easilier, shouldn't it ?
Sligthy off topic but still in the crossover and layout discussion,, what do you think about that pattern with two 15 cm midwoofers and a 10 cm tweeters if listened far field near 3 to 4 meters ? See picture... of course the baffle step must be commpensated. I have hard time to sim that due to the baffle shape.
Theorical advantage : closer edges and closer CtC between all the drivers. Theorical disadvantage : tweeter is not vertically aligned with the woofs.
Thougths ?
At 3 meters the drivers sound should merge easilier, shouldn't it ?
Sligthy off topic but still in the crossover and layout discussion,, what do you think about that pattern with two 15 cm midwoofers and a 10 cm tweeters if listened far field near 3 to 4 meters ? See picture... of course the baffle step must be commpensated. I have hard time to sim that due to the baffle shape.
Theorical advantage : closer edges and closer CtC between all the drivers. Theorical disadvantage : tweeter is not vertically aligned with the woofs.
Thougths ?
Attachments
Except in very large room at 3m you most listen to the room than the loudspeakers themself.
That said i don't get your concerns about driver's merging: with well implemented mtm it works close distance ( with Kino i didn't noticed anything more than the horn own vertical coverage limit up close - less than 1m away) and is maintained in the farfield ( it's the whole intersting point regarding the 'point source-ness' of the principle).
That said i don't get your concerns about driver's merging: with well implemented mtm it works close distance ( with Kino i didn't noticed anything more than the horn own vertical coverage limit up close - less than 1m away) and is maintained in the farfield ( it's the whole intersting point regarding the 'point source-ness' of the principle).
In my case I need it to rise the sensivity cause I choosed a particular woofer with 87/88 db/2.8V sensivity and a PA 12" below. So I needed 2 midwoofs in //.
@krivium, I should have said in my illustration the CtC is still between 1 to 1.2 WL at crossover point because not big 15" and horn as the op. So the cut off in that illustration is near 1900 hz... My point is to reduce the honey comb behavior but maybe it is a lost cause ?
Do you mean MTM are not made for distance above nearfield ?
Do you mean MTM are not made for distance above nearfield ?
It can be of help to mitigate floorbounce if the M drivers replay frequency involved in the floor bounce, depending on sweet spot location and overall loudspeakers dimension.
@ AlllenB,
I wondered about that. with // you jump from 87 dB to 93 dB which is ok with a 94 dB PA driver to cross around the usual 200 to 500 hz. But with 2.5 I have found to have sligthy less on the midwoofs and the band was verry narow for a 0.5 filter between 250/300 hz and 2k hz. I lean there is less baffle loss when climbing up towards the 1k to 2 k hz than below. Though with such narrow baffle the half baffle step transition is pretty high VS a large baffle !
I wondered about that. with // you jump from 87 dB to 93 dB which is ok with a 94 dB PA driver to cross around the usual 200 to 500 hz. But with 2.5 I have found to have sligthy less on the midwoofs and the band was verry narow for a 0.5 filter between 250/300 hz and 2k hz. I lean there is less baffle loss when climbing up towards the 1k to 2 k hz than below. Though with such narrow baffle the half baffle step transition is pretty high VS a large baffle !
Maybe it is the purpose of Tommius op with still the higher spl/less distorsion to go that way and the 90° phase offset at the crossover area ?
I do not find ridiculous to reduce also the close surface bouncing with a MTM at home, but maybe a lost cause due to the longer listening distance (again 3 to 4 m) VS reccording studio with close desktops ?
Also finally such Tommus à la Kinoshita RM7 makes finally sense in home environent as well... two 15" ! I'm jealous ! 🙂
That's quite specialised 😉
@diyiggy maybe in practice. If you took the speaker outside, would it not be 6dB? So if you take it inside is it not about averaging comb filtering? Is there the opportunity for a wider speaker instead?
If I understand you, better swapping the two 5.5 for a bigger Sd and sensivity standalone ?
I still have good souvenirs of the 104/2 ref MTM from Kef. For my tastes it had good soundstage and disseapered from the room... with an incredible high cut off at 3k hz circa... but what a complex 24 dB filter it had.
Ok too much off topic, sorry.
I still have good souvenirs of the 104/2 ref MTM from Kef. For my tastes it had good soundstage and disseapered from the room... with an incredible high cut off at 3k hz circa... but what a complex 24 dB filter it had.
Ok too much off topic, sorry.
I think it might not be a lost cause, but for it to work i would use very steep filters ( iow FIR) to limit destructive interaction between the three drivers.
If using IIR filtering then i think i would simulate a bunch to find optimum value for xover.
I mean once drivers have 'merged' then distance is irelevant ( regarding that point). Iow they integrate in relatively close distance and past this distance it's maintained.
Studio with close desktop? What are we talking about? Nearfield ( eg Barefoot) or Mains (eg: Rm7)? I talk about Rm7 which are usually located in the 3,5m/4m range which also correspond to room's critical distance. Being that it's the usual accepted limit before a 'hole' appear in the phantom image i would not call this close desktop distance. As well with 1m depth work surface and up to 1,3m bargraph height conditions ( and thus a big obstacle right in front of you used to mitigate reflections in the better case... in the worst...) studio acoustic conditions are peculiar .
Nearfield can be whatever: using the same strategy as with mains or resting on bargraph (or whatever support) with huge reflection from desk...
Dear tommus,
Below is a document and a simplified version that might help understand MTM radiation patterns.
Below is a document and a simplified version that might help understand MTM radiation patterns.
aha I try to make the barefoot micro 27 that have my midwoofs but for the RM7 listening distance... flawed design from the beginning, my fault ! Btw the barefoot has MTM layout but 0.5 way (DSP) filter !
My point was not about using larger woofers, but to realise the negative effect of baffle step. Don't just accept it as something to adjust for. Not just the sharp edges, the wide directivity gets mixed up in the room.
@diyiggy:
https://www.stereophile.com/floorloudspeakers/1208snell/index.html
One of the last of J. D'Appolito implementation i know of his principle. He aimed for +/- 30* off axis null with a nominal 15* coverage ( vertical, tweeter located around 107cm height) in order to limit floor/ceiling bounce. Xover are 250hz/2,5khz.
If you simulate SBIR i bet you'll find an optimum listening distance involving this 250hz floor bounce well below your 3/4m target ( because usual domestic room volume give way lower critical distance dimension than 3/4m).
Anyway with the info given into the article about dimension, picture and overall behavior it should be possible to do a bit of reverse engeeniring to defind which xover profile he used. I wouldn't be surprised for it to be 24db LR though.
https://www.stereophile.com/floorloudspeakers/1208snell/index.html
One of the last of J. D'Appolito implementation i know of his principle. He aimed for +/- 30* off axis null with a nominal 15* coverage ( vertical, tweeter located around 107cm height) in order to limit floor/ceiling bounce. Xover are 250hz/2,5khz.
If you simulate SBIR i bet you'll find an optimum listening distance involving this 250hz floor bounce well below your 3/4m target ( because usual domestic room volume give way lower critical distance dimension than 3/4m).
Anyway with the info given into the article about dimension, picture and overall behavior it should be possible to do a bit of reverse engeeniring to defind which xover profile he used. I wouldn't be surprised for it to be 24db LR though.
