Thanks for the PHL suggestion but it crosses a bit too high.
Yes it will be an high SPL / low distortion active 3-way (Hypex Fusion FA503) with dual PHL 6021MNd crossed over at 200Hz to dual Purifi PTT6.5M08 and crossed over at 2500Hz to the (probably) Bliesma T34A. I want to hold on to that 200Hz crossover to keep the most important midrange band in one driver.
That´s why the Bliesma M142-6 would be a very nice alternative to keep midrange and tweeter acoustically very close together.
Yes it will be an high SPL / low distortion active 3-way (Hypex Fusion FA503) with dual PHL 6021MNd crossed over at 200Hz to dual Purifi PTT6.5M08 and crossed over at 2500Hz to the (probably) Bliesma T34A. I want to hold on to that 200Hz crossover to keep the most important midrange band in one driver.
That´s why the Bliesma M142-6 would be a very nice alternative to keep midrange and tweeter acoustically very close together.
There are PHL 6,5" which fit the 200Hz perfectly - but I would not let them run to 2500Hz cause this would produce a jump in directivity. (Also with the Purify)
Depending on your room I would aim for a higher crossover, at least 250Hz. Cause the 2 15" will probably behave better in the room in the critical 80-250Hz transition area. Also there are important parts of Instruments in the 200Hz area (e.g. bottom of snare), I would put these to the 15".
I would also cross lower to the tweeter - with a PROPER crossover you can make that seamless between M142 and T34 and the lower crossover and close acoustic centers will get you a better "point source".
The good thing - you can test and try different settings with the Hypex and even do blind comparisons.
Depending on your room I would aim for a higher crossover, at least 250Hz. Cause the 2 15" will probably behave better in the room in the critical 80-250Hz transition area. Also there are important parts of Instruments in the 200Hz area (e.g. bottom of snare), I would put these to the 15".
I would also cross lower to the tweeter - with a PROPER crossover you can make that seamless between M142 and T34 and the lower crossover and close acoustic centers will get you a better "point source".
The good thing - you can test and try different settings with the Hypex and even do blind comparisons.
Thanks for the insight 
Yes the crossovers are THE challenge of this whole project. The tweeter needs a passive 2nd order HPF for protection against possible Hypex hiccups. All other drivers wil get active filtering. Not shure what order they'll have to be for best result? I need further reading into filter design to do thing right from the start.
The project will be quite unique as all drivers will be built into an extremely sturdy concave AV wall and will be hidden behind cloth grills. The center speaker module will be straight and will be the base for an 85" TV or larger. All speaker cabinets will be fully braced and at least for the midranges I'm thinking of a special internal shape. If the M142-6 would be used, I'd put even more effort in the enclosure to minimize resonances and reflections.
What would be the best size and shape for the back chamber for the M142-6?
Yes the crossovers are THE challenge of this whole project. The tweeter needs a passive 2nd order HPF for protection against possible Hypex hiccups. All other drivers wil get active filtering. Not shure what order they'll have to be for best result? I need further reading into filter design to do thing right from the start.
The project will be quite unique as all drivers will be built into an extremely sturdy concave AV wall and will be hidden behind cloth grills. The center speaker module will be straight and will be the base for an 85" TV or larger. All speaker cabinets will be fully braced and at least for the midranges I'm thinking of a special internal shape. If the M142-6 would be used, I'd put even more effort in the enclosure to minimize resonances and reflections.
What would be the best size and shape for the back chamber for the M142-6?
Before thinking about orders of filters ... how will you measure the whole thing?
In room will not give you the precision you would like for a project at this league and outside is not easy for a in wall design.
I just finished a good setup for normal speakers but still working on a reliable setup for in wall speakers. (Best - dig a hole and make a wooden baffle which fits the speaker)
I would not put anything in front of the Hypex. Useing it for long now with 1" tweeters and never had a problem. These T34 can take a lot of short impact if needed. But of course you will need to be careful when doing your connections and filters - user error is the main source of destruction here
Standard is 4th order filtering - but ACOUSTICALLY 4th order! So you must use the electronic filter order to achieve that with your chassis. Best is to linearize your chassis in the speaker housing with EQ and then apply your filters. Get delays correct (invert phase and aim for biggest chancellation), fine tune filter.
I normally fill cavities with sheep wool enough dense that all resonances are dampened. Most fancy shapes for midranges are totally useless! The strongest and main resonances are lambda/2 of the dimensions - and these don't care about some variations. When you get rid of these - you automatically don't have higer frequency ones.
Your setup is pretty common by the way - with screens and projectors. I use a special acoustic transparent screen (not the ones with micro holes) and have all my stuff behind it. This solves SO many problems (e.g. I have a soft soffit front wall with 40cm absorption between the speakers, benefits the room massive).
And 85" isn't cinema anyway ... unless you sit REALLY close
(I understand a TV has a lot of benefits too - but I'm a sound guy, a screen behaves so much better. And when you are used to a 3m wide picture ... let's talk again when screens have 130-140" and are "affordable")
In room will not give you the precision you would like for a project at this league and outside is not easy for a in wall design.
I just finished a good setup for normal speakers but still working on a reliable setup for in wall speakers. (Best - dig a hole and make a wooden baffle which fits the speaker)
I would not put anything in front of the Hypex. Useing it for long now with 1" tweeters and never had a problem. These T34 can take a lot of short impact if needed. But of course you will need to be careful when doing your connections and filters - user error is the main source of destruction here
Standard is 4th order filtering - but ACOUSTICALLY 4th order! So you must use the electronic filter order to achieve that with your chassis. Best is to linearize your chassis in the speaker housing with EQ and then apply your filters. Get delays correct (invert phase and aim for biggest chancellation), fine tune filter.
I normally fill cavities with sheep wool enough dense that all resonances are dampened. Most fancy shapes for midranges are totally useless! The strongest and main resonances are lambda/2 of the dimensions - and these don't care about some variations. When you get rid of these - you automatically don't have higer frequency ones.
Your setup is pretty common by the way - with screens and projectors. I use a special acoustic transparent screen (not the ones with micro holes) and have all my stuff behind it. This solves SO many problems (e.g. I have a soft soffit front wall with 40cm absorption between the speakers, benefits the room massive).
And 85" isn't cinema anyway ...
unless you sit REALLY close (I understand a TV has a lot of benefits too - but I'm a sound guy, a screen behaves so much better. And when you are used to a 3m wide picture ... let's talk again when screens have 130-140" and are "affordable")
Does the M142B have a separate spider as a secondary suspension other than just the dome surround? It just seems awfully gutsy to rely on the surround itself to control the moving asy, being such a setup usually permits diaphragm rocking at lower frequencies closer to Fs. With as much xmax as this driver is capable of, a single suspension would be counterproductive IMO.
The ATC 3" dome has a separate spider. There are others with the same setup. I was under the impression some of the Accuton domes also had this arrangement?.
IMO, the biggest benefit to having a single suspension element is keeping the back of the diaphragm unobstructed for less internal reflections.
IMO, the biggest benefit to having a single suspension element is keeping the back of the diaphragm unobstructed for less internal reflections.
I only know the ATCs with this setup - never opened a 2" or 3" or 2,5" dome with a spider. (Btw - is there a picture of the ATC interns? How did they solve that?)
I also never detected a problem with 2-3" domes to be honest. Even when I tend to cross over as low as possible.
A huge dome like the M142B ... would be more prone for these effects, that's for sure. But there is an underhung coil in a very strong magnetic field, maybe that's enough to have a controlled movement. Moving mass is very low too.
I also never detected a problem with 2-3" domes to be honest. Even when I tend to cross over as low as possible.
A huge dome like the M142B ... would be more prone for these effects, that's for sure. But there is an underhung coil in a very strong magnetic field, maybe that's enough to have a controlled movement. Moving mass is very low too.
I was thinking of making a 120cm x 120cm x 120cm cavity with 30cm of mineral wool boards to minimize room reflections during measurements. OTOH why make all that effort when they get installed in a normal decorated living room with dips up to 15dB at the listening position and where the AVR Dirac or Audyssey does it's own correction on top of all room modes?Before thinking about orders of filters ... how will you measure the whole thing?
In room will not give you the precision you would like for a project at this league and outside is not easy for a in wall design.
I just finished a good setup for normal speakers but still working on a reliable setup for in wall speakers. (Best - dig a hole and make a wooden baffle which fits the speaker)
I would not put anything in front of the Hypex. Useing it for long now with 1" tweeters and never had a problem. These T34 can take a lot of short impact if needed. But of course you will need to be careful when doing your connections and filters - user error is the main source of destruction here
Standard is 4th order filtering - but ACOUSTICALLY 4th order! So you must use the electronic filter order to achieve that with your chassis. Best is to linearize your chassis in the speaker housing with EQ and then apply your filters. Get delays correct (invert phase and aim for biggest chancellation), fine tune filter.
I normally fill cavities with sheep wool enough dense that all resonances are dampened. Most fancy shapes for midranges are totally useless! The strongest and main resonances are lambda/2 of the dimensions - and these don't care about some variations. When you get rid of these - you automatically don't have higer frequency ones.
Your setup is pretty common by the way - with screens and projectors. I use a special acoustic transparent screen (not the ones with micro holes) and have all my stuff behind it. This solves SO many problems (e.g. I have a soft soffit front wall with 40cm absorption between the speakers, benefits the room massive).
And 85" isn't cinema anyway ...
(I understand a TV has a lot of benefits too - but I'm a sound guy, a screen behaves so much better. And when you are used to a 3m wide picture ... let's talk again when screens have 130-140" and are "affordable")
For certainty I'll use a very high quality cap on the tweeter. Better safe than sorry
I imported both M142A-6 and Purifi PTT6.5M08 in WinISD and simulated midrange cabinets with QTC ranging from 0.5 to 0.7 combined with a 2nd order 250Hz HPF and I don't see a lot of difference. But what you say is making the enclosure even smaller (QTC 0,9 or higher) to achieve the right crossover frequency?
My concave wall will also have absorption in unused cavities that will be hidden with fabric and finished with vertical latting.
No projection here. We considered it while contructing a new ceiling with built-in Atmos speakers but voted against it as today TV's are very impressive even with a 5 meter viewing distance. We can even opt for a 98" one as they've become more affordable these days but they're very fragile and cumbersome to move.
Ya know if you really want to eliminate that back wave you could just buy a few boxs of those bendy straws and make your self a metamateial all you would have to do is take the dia of the magnet hole and fill it with straws 1/2 wavelength of 30hz so longest 225 inchs lol wouldn't be more then a few hours work just seal the straws with some silicone and add a plug of foam to each straw to increase the peak a little the spider is vented but only 3k hz comes though it strongly so just slap 8 inches of foam behind that. At the fs of 54 hz you could use even smaller straws 1mm and use a array of them at the peak so like 20 small straws from 45 to 55hz would nuke the resonance (havent tried this). I already have done this with my 34b after seeing that guys whos defective pair opened just asked a waiter friend to steal a box of bendy straws from work glued them together did 250hz to 5khz it looks like a mess and takes up a foot of space lol its a inifficent use of space but I had a 15db reduction in thd below 5k hz. Another idea I had for it would be a 2mm I'd tube that's flexible and just bend it into stacked circles then sandwich it between two ridgid boards and fill With epoxy without having to deal with 3d printing and learning fusion 360. I'll get you guys all the details once I'm back from vacation.
In order to get the filters right you need to get good measurements! That's not so hard with the tweeter, but a midrange going down to 250Hz is not easy to measure in room. Working with absorber "walls" is a good idea! I always just put a lot of absorbers at the floor, at least 50cm high.
It's Diracs work to care about the room EQ but first you must have a good working filtering.
2 methodes for filtering a midrange highpass. You can use the natural fall off (2nd order) and add a filter 2nd order. This only works when the original cut off frequency is relatively close to the wanted filter frequency. But don't overdo it in simulation - you need to do that with the real speaker.
Or you filter higher as the resonance (as I do with 2-3" midranges or tweeters) - the linearise around your filter frequency so the electrical filter can work as it should, at least in the transition area. This can also mean you boost frequencies there which you later filter away - so no problem for the driver, just don't overdo it.
use these cavities!You don't get the dynamic range of a good TV with projection, even in an optimised room. Pictures are really impressive!
But you also don't get that in a cinema, to be honest I don't need it for a movie. It sometimes feels "unreal", esp most factory settings. But I would have loved to be able to display photographs in very high quality!
On the other side - my wife was not happy about the idea to have a huge, black surface in the living room. Screen is "lighter" in this aspect.
But interested in your solution, hope you post a few pictures during the process!
Thanks for all this advice. I have a topic running on that project but the last message in there was over a year ago. As I slowly plan to proceed with the build I'll update it: https://www.diyaudio.com/community/...h-good-stereo-perfomance.384799/#post-6990102
Agreed on projection. You need a dedicated room with dark non-reflective surfaces for it to shine and our living room is just the opposite. Also agreed on photography (that I'm also heavily invested in )
Agreed on projection. You need a dedicated room with dark non-reflective surfaces for it to shine and our living room is just the opposite. Also agreed on photography (that I'm also heavily invested in
)
ALWAYS wait for the actual driver! More then once I routed something after the plan and the speaker didn't fit - simply because there was a mistake in the plan.
E.g. I rout the basket of SB Acoustic LF drivers 11mm deep instead of 10 - cause they are thicker and the sealing adds a little too.
E.g. I rout the basket of SB Acoustic LF drivers 11mm deep instead of 10 - cause they are thicker and the sealing adds a little too.
I always wondered what a driver like this could do but with one or more concentric drive coils. A "mid" that only goes up to 1k doesn't seem like all that much fun.
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