wanting to try a d'Appolito crossover on an MTM speaker with IIR DSP.
woofers are covering only 2+ octaves 80-400hz, large horn with coax CD above
1. develop LR4 crossover slopes
2. time align the drivers using digital delay
3. adjust the delay by 1/4 wavelength at the crossover frequency
is it that simple?
woofers are covering only 2+ octaves 80-400hz, large horn with coax CD above
1. develop LR4 crossover slopes
2. time align the drivers using digital delay
3. adjust the delay by 1/4 wavelength at the crossover frequency
is it that simple?
You don't need to perform step 3.
When performing step 2 reverse the polarity of the tweeter and adjust your digital delay to achieve a deep interference null at your chosen crossover frequency.
Then change polarity back for normal usage.
The MTM configuration has pro's and con's...........as you're probably aware.
Dave.
When performing step 2 reverse the polarity of the tweeter and adjust your digital delay to achieve a deep interference null at your chosen crossover frequency.
Then change polarity back for normal usage.
The MTM configuration has pro's and con's...........as you're probably aware.
Dave.
Curious to know what horn with such a steep LR4 is big enough for 400 hz cut off. Or if the size is as big as I believe, the MTM is not a great choice.
Or maybe a bi-axial horn to reduce the vertical patern ? Anyway I would not going too much higher than one wave length between the CTC of the horn with each woofer. Although a horn is not a dome, I do not know how it looks like at the side of the mouth which is closer from the center of the woofer VS the center of the horn ?!
Hum I can not remember this guy on PE forum who made a MTM with two 10" excel woofers and 18thSound horn ? Raptor from PaulW ?
Or maybe a bi-axial horn to reduce the vertical patern ? Anyway I would not going too much higher than one wave length between the CTC of the horn with each woofer. Although a horn is not a dome, I do not know how it looks like at the side of the mouth which is closer from the center of the woofer VS the center of the horn ?!
Hum I can not remember this guy on PE forum who made a MTM with two 10" excel woofers and 18thSound horn ? Raptor from PaulW ?
B&C ME464 with 15" woofers. CTC spacing will be approx 1/2WL @ 400Hz.
BTW, here are lobing errors at XO with 1/2WL spacing and a zero/90deg phase shift. I understand the 90deg phase lag is the real "d"Appolito" alignment, traditionally done with 3rd order crossover to get the shift. But the pattern should be independent of the XO slope and dependent only on the phase at XO.
BTW, here are lobing errors at XO with 1/2WL spacing and a zero/90deg phase shift. I understand the 90deg phase lag is the real "d"Appolito" alignment, traditionally done with 3rd order crossover to get the shift. But the pattern should be independent of the XO slope and dependent only on the phase at XO.
Attachments
Using 18dB on woofers low pass ?
I am wondering also for a smaller MTM (5.5" and 1" - eventually with a WG). Seems D'Apolitto used LR24 later and didn't mind because of the far fieeld listening >=2.5 metrs in most living room ?
I assume you need some distance in case of such big MTM... 5 meters and more ? Wonder if LR24 on the woofers and BUT6 on the horn with an asymetric XO could work too !
Have you simed MMT as well ?
I am wondering also for a smaller MTM (5.5" and 1" - eventually with a WG). Seems D'Apolitto used LR24 later and didn't mind because of the far fieeld listening >=2.5 metrs in most living room ?
I assume you need some distance in case of such big MTM... 5 meters and more ? Wonder if LR24 on the woofers and BUT6 on the horn with an asymetric XO could work too !
Have you simed MMT as well ?
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Diyiggy: TH4001 is cut around 400hz in Kinoshita's RM7 and variants.
I would not say they are not a great choice 😉
And no you don't need 5m for them to sound coherent, it's the whole point of mtm 'simulating' point source behavior. If ctc spacing is 0.333 wl then they behave as one source only.
Raptors are the one you thought about.
D'Appolito first used 18db/octave and then shifted to 24db/octave on latest implementation.
If you can try steep FIR filters they solve a lot of issue imho.
I would not say they are not a great choice 😉
And no you don't need 5m for them to sound coherent, it's the whole point of mtm 'simulating' point source behavior. If ctc spacing is 0.333 wl then they behave as one source only.
Raptors are the one you thought about.
D'Appolito first used 18db/octave and then shifted to 24db/octave on latest implementation.
If you can try steep FIR filters they solve a lot of issue imho.
... those big Kinos... wonder if they ever care of the soundstage using that big loudspeaker in near field ! But the dynamic (and spl) should be... wow ! Studios' needs perhaps !
Maybe better to clone the one with two 15" side to side to reduce the horizontal pattern, sorta cardioid pattern and the horn above only ?
edit : you firered before I ! So I assume you need the stacking for your specific use...
ahah too big for me as I wonder how to reduce a cabinet for a 12" to 85 liters max (home listenings)
edit : you firered before I ! So I assume you need the stacking for your specific use...
ahah too big for me as I wonder how to reduce a cabinet for a 12" to 85 liters max (home listenings)
You obviously never heard a pair. Soundstage is HUGE and flawless on this one. They were by far the best implementation in comparison to RM4 (the one with side by side woofers) which are extremely directive ( moove 10cm each side of sweetspot and sound change with a big 'whoosh').
Don't judge big drivers based d'Appolito based on your experience of small drivers based one ( which cannot be in the ctc sweetspot so are 90% of time flawed design - exception being FAST/WAW) or what you can read from 'theorical' flaws. People judge without having heard 'correctly' implemented ones, or even heard one...
Would you have off axis measurement of MTM in middle field (3 to 5 m) sous le coude by luck, please ? I am very curious about that for my needs.
yes I eventually asked above about an hybrid FAST (A slow?) with the BUT6 on the horn with asymetric XO.
And no I didn't heard the RM7, see one in a Studio (Suresnes or Neuilly iirc) from a guy that was distributing Lavry 15 y ago...
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do I need that?
would an allpass filter work better here? (I don't fully understand how to use them)
It can be simulated.
An interesting read about allpass filters:
https://audioxpress.com/article/Using-All-Pass-Filters
An interesting read about allpass filters:
https://audioxpress.com/article/Using-All-Pass-Filters
Butterworth gives you 90 degrees with no effort required, as voodooless says.. but as you say, it doesn't matter as long as you get the phase shift. Are you using a crossover simulator, because you can usually fudge these things in unexpected ways by making small adjustments?
Many do it. Why not try Vituixcad. It has generic filters ready to go which should point you in the right direction.