125dB is a strange number to be stated. Roland said 110dB per speaker on ASR which seems much more realistic.
https://www.audiosciencereview.com/...yes-m3-formerly-known-as-m2.14656/post-976163
If his measurements are correct the directivity is held very low in the cardioid mode
https://www.audiosciencereview.com/...yes-m3-formerly-known-as-m2.14656/post-994126
8ms latency for an FIR filter is not unreasonable, they aren't claiming phase linearity below 80Hz. Low order FIR filters can be made successfuly with those sort of latencies. I made a 60Hz 2nd order filter for my example with 10ms latency.
I think all marketing blurb has to be taken with a large dose of salt, but the underlying acoustic design is plausible and reasonable.
Yes because most of the output below that point is coming from behind the speaker 🙂
In reality it may end up being better to design for a smoothly increasing power response than a flat on axis result. Or it may not matter as that is where the room is in complete control and in room EQ is likely to be helpful in taming the overall response.
Easy enough to check with an active system if you build one.
If you really like the circle look you could probably stack one on top of each other one facing forwards one facing backwards and end up at a similar point.
Just drawing the concept to see how it all looks 🙂
The mini fridge-sized 3-way speaker
Box of size 45cm width by 80cm height by 28cm depth. Internal volume to be estimated.
Currently front driver is in a slotted cardioid enclosure (can also be converted into sealed to accommodate the concept discussed in above posts) and back woofer in sealed enclosure.
Next iteration, I can try to see if something wilder can be drawn 😀
The mini fridge-sized 3-way speaker
Box of size 45cm width by 80cm height by 28cm depth. Internal volume to be estimated.
Currently front driver is in a slotted cardioid enclosure (can also be converted into sealed to accommodate the concept discussed in above posts) and back woofer in sealed enclosure.
Next iteration, I can try to see if something wilder can be drawn 😀
I'm not sure that you will need the slots, the waveguide will be higher directivity and having the woofer rise up to meet it will make the transition smoother. Use a diagonal separator between the drivers to separate them and brace the box at the same time.
If you do decide you need that slot, it's probably wise to round off the top to follow the woofer edge to keep all path-lengths the same.
Sort of like a minion...
Sort of like a minion...
@wesayso: As per the recent posts above, and as fluid pointed out, I dont need a slot in the box for cardioidish radiation, The woofer on the 45cm baffle has about 5ish dB directivity down to about 300Hz. Above that most of the pattern control is probably done by the baffle/woofer size itself and it makes the woofer directivity rise up to meet the waveguide.
Below 300Hz, the dual woofer setup appropriately bandpassed and delayed give about 4.5ish dB of directivity down to about 100Hz. So this thing should work with just two sealed woofers.
But still, I am confused about the box size and shape etc. Especially about the comments that people say about "boxiness" of sound when that 15pr400 kind of woofer is put in small volume boxes. Maybe it has something to do with ineffective resonance control. I am not sure though. The hope with the slotted open cardioid enclosure was to eliminate that boxiness aspect and to get decent pattern control. Once the wavelengths become woofer sized, there is probably no advantage with the passive cardioid enclosure anyway..
I am still thinking about which direction to go with this 2x15 inch woofers + EXAR 400 concept. I dont have the space to accomodate a dipole radiating speaker as there is close wall at the back of the final placement of this speaker nor is there enough space to pull out the speakers into the room by more than about 60cm from the wall. This is sort of guaranteed even if I move to another rented accomodation in future. One thing that I am sure of is that I want to reduce the space occupied by the speaker... 😀
Below 300Hz, the dual woofer setup appropriately bandpassed and delayed give about 4.5ish dB of directivity down to about 100Hz. So this thing should work with just two sealed woofers.
But still, I am confused about the box size and shape etc. Especially about the comments that people say about "boxiness" of sound when that 15pr400 kind of woofer is put in small volume boxes. Maybe it has something to do with ineffective resonance control. I am not sure though. The hope with the slotted open cardioid enclosure was to eliminate that boxiness aspect and to get decent pattern control. Once the wavelengths become woofer sized, there is probably no advantage with the passive cardioid enclosure anyway..
I am still thinking about which direction to go with this 2x15 inch woofers + EXAR 400 concept. I dont have the space to accomodate a dipole radiating speaker as there is close wall at the back of the final placement of this speaker nor is there enough space to pull out the speakers into the room by more than about 60cm from the wall. This is sort of guaranteed even if I move to another rented accomodation in future. One thing that I am sure of is that I want to reduce the space occupied by the speaker... 😀
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Did one more sim with the 15PR400 & SB 15inch nero sub in 45L sealed cabinets. Diffraction response on a 48cm baffle for both drivers were merged with their 2pi in box response. The nero was kept 220mm above the floor at the back of this 48cm wide box with 27cm depth and total 90cm height
Boxiness seems like the eyes helping the brain along, a bit like speakers being near the front wall having no depth. There may be elements of truth to both old wives tales but the real answer is never so simple. If you make a sealed box the idea is to make a good one. One that has no objectionable resonance from the cabinet and that the rear wave is well contained. So bracing and damping. Damping could be just internal or extend to panel damping.
If there is a box problem, putting a hole in it is only going to help in letting the problem out, just like midrange leakage from a port messing things up.
When the woofer starts to beam there is less sound going to the sides for any slots to interfere with. The idea becomes less effective, if you want directivty control higher up from the slots the woofer needs to be smaller.
I don't... In fact, I don't know or haven't heard what boxiness sound like, even on my bigger speakers.. 😀
But they all had smaller drivers. Since I am using this big a driver for the first time and was searching around for how other people have used it, I saw comments about boxiness and universal recommendations for the 15pr400 to be put in large ported boxes.. This is how and why I have been confused 🙂
Because they want to use it in a 2 way without a sub driver. In a small sealed box there would be virtually no bass. In your application this is exactly what you want. The sub driver needs to be able to go quite high so it's frequency response isn't a problem in the overlap region.
This is my setup,(not finished yet)the components are: Faital 15PR400 & Faital HF10AK in a custom waveguide crossed at 750hz, powered by DSP Hypex plate amps.
I can't attach the measurements as I don't have access to my laptop right now, but if anyone is interested I could do that.
Attachments
Pics of the setup if we stick to the plain sealed box for each woofer
40L enclosure for top woofer. 42L enclosure for bottom woofer.
Cabinet dimensions (Height x Width x Depth) = (920mm x 500mm x 270mm)
40L enclosure for top woofer. 42L enclosure for bottom woofer.
Cabinet dimensions (Height x Width x Depth) = (920mm x 500mm x 270mm)
I would go with a significantly smaller volume for the rear woofer. This woofer's radiation cancels the front woofer to create cardioid response. To get max low end extension in this scenario, equalize the front woofer down to 20 Hz or so but high pass the rear woofer at 50 Hz. If you are doing that, it doesn't need so much volume or volume displacement. With equal volumes and more elaborate DSP scheme, you could arrange rear woofer to be phased for cancellation above a transition frequency such as 50 Hz and in phase for support below that frequency. Transition frequency might be related to distance from front wall.
I think boxiness is the way we describe hearing the way a monopole speaker radiates into the room vs omni or other multipolar speaker. It also seems to refer to resonance and moderate reflection mostly from the rear. I often muse about what “perfect” radiation looks like, and come back to concert halls often. The amphitheater itself is a big waveguide, preferably throwing into an infinite outdoor field, reflecting back into the sky infinitely. That’s a monopole with no rear wall reflection, maybe a bit of floor bounce. Also maybe a bit of apparent reverb if anything reflects off of the back wall; and only one kind of stage. I’m often stumped at how a speaker designer would apply variable directivity, as some instruments have varying dispersion. A vibraphone, for example, plays very high in omni, while a voice is monopole. Often, I arrive at the same conclusions, that capturing the radiation pattern is the job of the recording studio/production engineers, and this is how we end up at the two styles of DI. High DI, like horns and cardioid, or low DI, even approaching omni, like good flat faced monitors, a la Philharmonic’s nearly 180 degree radiating BMR or good quality dipoles playing front to back. Wider directivity uses the room to reinforce sound and cue reflections, but personally, it falls apart when the rooms are too different or resonate. The “they’re here” method. Contrary to this, I have started to think of high DI much more like headphones, which have a massively high directivity and hopefully skips unrecorded reflections altogether. I guess this is what I was talking about in reference to flavors of perfect speakers about a page ago. There are a lot of perfect speakers with their associated compromises, but it’s only in situations like these that we get to dig into what that means for one another.
That got a little long winded and rambling. If you keep making a variety of top tier loudspeakers @vineethkumar01, we’re all hoping YOU will tell us what “boxy” means.
That got a little long winded and rambling. If you keep making a variety of top tier loudspeakers @vineethkumar01, we’re all hoping YOU will tell us what “boxy” means.
@D1sco: My own rudimentary ideas of "boxiness" was being able to identify sound coming from a speaker in the overall reproduced soundfield. The speaker calls attention to itself due to some reason. I thought such a phenomenon could be attributed to resonances and imperfect construction of the box..
But you have given me a lot more to think about.. Thanks a lot 🙂
But you have given me a lot more to think about.. Thanks a lot 🙂