No by default Vituix chooses the peak of the impulse which in this case causes the phase to bend back up.
Manually moving it to the rephase value corresponds to the mid point of the impulse. I have read various theories on the correct impulse position which is either the peak or the start. I have not seen halfway up be suggested. In this case it seems to be right though.
Manually moving it to the rephase value corresponds to the mid point of the impulse. I have read various theories on the correct impulse position which is either the peak or the start. I have not seen halfway up be suggested. In this case it seems to be right though.
Yeah, i noticed that as well. Also the article does not give a resolution on how to consistently get the "right" measured phase.
The other problem is is the time of flight aka the real distance of mic from baffle, given the sensitivity for measured phase result as demonstrated. Tomorrow afternoon i have time to test , will report.
The other problem is is the time of flight aka the real distance of mic from baffle, given the sensitivity for measured phase result as demonstrated. Tomorrow afternoon i have time to test , will report.
I could spend a few minutes, so i did the following:
In arta open an impulse, (sample 192kHz) use excess phase with Delay to remove time of flight, then switch to M+P.
Then in VituixCAD open the same impulse in IR2FR, select the Far (it sets the 0 at the start of the impulse!) and get phase-wise a very good correlation iwt Arta:
Note: the windowing is not the same compared with Arta
So not so bad after all. Whether it is more or less correct , that i do not know. A difference of only 0.02msec is enough for a significantly different phase:
The excess phase is then:
So, right or wrong, this use of excess phase is quite workable and reproducable.
Looking forward to reactions ;-)
In arta open an impulse, (sample 192kHz) use excess phase with Delay to remove time of flight, then switch to M+P.
Then in VituixCAD open the same impulse in IR2FR, select the Far (it sets the 0 at the start of the impulse!) and get phase-wise a very good correlation iwt Arta:
Note: the windowing is not the same compared with Arta
So not so bad after all. Whether it is more or less correct , that i do not know. A difference of only 0.02msec is enough for a significantly different phase:
The excess phase is then:
So, right or wrong, this use of excess phase is quite workable and reproducable.
Looking forward to reactions ;-)
My speakers are reaching their new place.. in parts.. 
The 4 Satori WO24Ps and the BMS 4550 on horns have reached first. The cabinets and other things need to follow.
In the meanwhile, I have been toying with the idea of building a pair of small (relatively) speakers for my PC (Just unable to stop thinking about building more new speakers and exploring different concepts..). They are supposed to sit on the desk on either side of my monitor. I can accommodate a dimension of about 45cm(Height) x 30cm (depth) x any reasonable width less than 25ish cm.
One thing I want to make use of for this project is my Sica 5inch coaxial drivers. Apart from that, what are the considerations to be taken into account in building a desktop speaker? Interference from the desk? Interference from the wall at the backside? Does a cardioid-like concept help in this kind of scenario?
I have been toying with the idea of supplementing the coax with dual woofers (so a 3way speaker overall) in 3 different ways
1) one on each side like a mini KEF blade (Does force cancelling help?)
2) One woofer on the front baffle along with the coax and one on the back
3) An MTM with the woofers in a form like MrSticha's project:
or like the below AMphion krypton but with a coax mid-tweeter
The problem with the above concepts is the height of the speaker as it can easily exceed 50+cm, which I don't want them to. I am ok with it if the height is approx 45ish+ cm. (In that sense, having woofers on the sides helps with the overall dimensions)
Please advise me on how to go about this. I want to develop the concept around the Sica coax. Other than that, I am up for all kinds of variations
Thanks & Regards
Vineeth
The 4 Satori WO24Ps and the BMS 4550 on horns have reached first. The cabinets and other things need to follow.
In the meanwhile, I have been toying with the idea of building a pair of small (relatively) speakers for my PC (Just unable to stop thinking about building more new speakers and exploring different concepts..
). They are supposed to sit on the desk on either side of my monitor. I can accommodate a dimension of about 45cm(Height) x 30cm (depth) x any reasonable width less than 25ish cm.One thing I want to make use of for this project is my Sica 5inch coaxial drivers. Apart from that, what are the considerations to be taken into account in building a desktop speaker? Interference from the desk? Interference from the wall at the backside? Does a cardioid-like concept help in this kind of scenario?
I have been toying with the idea of supplementing the coax with dual woofers (so a 3way speaker overall) in 3 different ways
1) one on each side like a mini KEF blade (Does force cancelling help?)
2) One woofer on the front baffle along with the coax and one on the back
3) An MTM with the woofers in a form like MrSticha's project:
or like the below AMphion krypton but with a coax mid-tweeter
The problem with the above concepts is the height of the speaker as it can easily exceed 50+cm, which I don't want them to. I am ok with it if the height is approx 45ish+ cm. (In that sense, having woofers on the sides helps with the overall dimensions)
Please advise me on how to go about this. I want to develop the concept around the Sica coax. Other than that, I am up for all kinds of variations
Thanks & Regards
Vineeth
Hi,
If you'll listen nearfield then only one woofer will allow 'point source' behaviour ( ctc under 1/4 wl at xover).
Side located make sense from a vibration attenuation pov ( force canceling). That said i'm not sure it'll bring many things wrt your situation ( on desk).
Mtm is nice but will limit to 5" woofer size given your constraints.
Worth studying it though.
Look for Tysen V2 from Dave ( Planet10), take a look at LS50mk2 at Erin'scorner ( check the desk mode in dsp setting ) and look for Thread Fluid started, there is one with simulation of directivity behavior of side located woofer ( Blade style).
If you'll listen nearfield then only one woofer will allow 'point source' behaviour ( ctc under 1/4 wl at xover).
Side located make sense from a vibration attenuation pov ( force canceling). That said i'm not sure it'll bring many things wrt your situation ( on desk).
Mtm is nice but will limit to 5" woofer size given your constraints.
Worth studying it though.
Look for Tysen V2 from Dave ( Planet10), take a look at LS50mk2 at Erin'scorner ( check the desk mode in dsp setting ) and look for Thread Fluid started, there is one with simulation of directivity behavior of side located woofer ( Blade style).
Does cardioid radiation work/help/make any sense in a near-field listening environment? (approx 50-60 cm away from the speakers)
Is it even possible to achieve either in a passive configuration or active configuration at this distance
Also, what is the highest possible crossover point from the mid to woofer for a nearfield application like this?
I was wondering about taking this speaker
https://www.donhighend.de/?page_id=6812
and make it look a little like MrStica's MTM shown above (smooth transitions all around, especially around the coax); poke holes around the sides of all drivers (like the amphion krypton) and use some damping material such as basotect or polyester wool near the holes to experiment with whether a cardioid can be made with this MTM (with the speaker standing up). Or, instead, even add more drivers to the sides for active cardioid like configuration along with the MTM coax
I don't need a whole lot of bass or very high SPL levels with these speakers due to nearfield listening, and I have all the drivers listed in Donhiend's project available at home and some spare Sb15CAC midbasses (These have been used in the passive cardioid directiva R2 over at ASR)..
Is it even possible to achieve either in a passive configuration or active configuration at this distance
Also, what is the highest possible crossover point from the mid to woofer for a nearfield application like this?
I was wondering about taking this speaker
https://www.donhighend.de/?page_id=6812
and make it look a little like MrStica's MTM shown above (smooth transitions all around, especially around the coax); poke holes around the sides of all drivers (like the amphion krypton) and use some damping material such as basotect or polyester wool near the holes to experiment with whether a cardioid can be made with this MTM (with the speaker standing up). Or, instead, even add more drivers to the sides for active cardioid like configuration along with the MTM coax
I don't need a whole lot of bass or very high SPL levels with these speakers due to nearfield listening, and I have all the drivers listed in Donhiend's project available at home and some spare Sb15CAC midbasses (These have been used in the passive cardioid directiva R2 over at ASR)..
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Mabe the relatively low coax driver xmax & the relatively high (2.5 to 3kHz) crossover to the tweeter might make it difficult to make a cardioid radiation pattern with the mid and achieve a directivity match at crossover. Acoustical intermodulation effects can be high I guess..
(already there are enough problems with this coax at the highest frequencies).
When I had the coax driver attached to the teardrop shaped 3D printed cabinet, this is how the normalized polars looked for the tweeter & mid of the coax
Tweeter normalized polars
Tweeter spin data
Mid normalized polars
Thinking about what if we could/if it is possible to have higher directivity for the mid to even lower frequencies like 200-300Hz
(already there are enough problems with this coax at the highest frequencies).
When I had the coax driver attached to the teardrop shaped 3D printed cabinet, this is how the normalized polars looked for the tweeter & mid of the coax
Tweeter normalized polars
Tweeter spin data
Mid normalized polars
Thinking about what if we could/if it is possible to have higher directivity for the mid to even lower frequencies like 200-300Hz
Attachments
Cardioid makes sense when there will be a wall behind the speakers that would otherwise cause boundary interference. If the speaker is really close to the back wall then the cardioid isn't really going to do much at the typical boundary interference frequencies.
An MTM configuration is either for narrowing vertical directivity or increasing power handling to go louder. Neither of which are much use in a near field setup.
Putting a driver on each side gives you the best chance of maintaining something resembling a single source but the front baffle could get wider to accommodate the side by side configuration. It can also be an active cardioid.
A passive cardioid can be made from the MTM configuration but active is much more flexible and easier to tune.
Having a single apparent source is good in a near field setup as there is not much distance for the drivers to integrate together.
An MTM configuration is either for narrowing vertical directivity or increasing power handling to go louder. Neither of which are much use in a near field setup.
Putting a driver on each side gives you the best chance of maintaining something resembling a single source but the front baffle could get wider to accommodate the side by side configuration. It can also be an active cardioid.
A passive cardioid can be made from the MTM configuration but active is much more flexible and easier to tune.
Having a single apparent source is good in a near field setup as there is not much distance for the drivers to integrate together.
Thanks @fluid
I thought that with an MTM, the vertical narrowing could help from interference from the table. And the horizontal narrowing from the cardioid would help with interference from the wall behind the speakers.
In the intended placement of these speakers, the wall will be about 15-20cm behind the speaker. Assuming about 25-30cm depth for the speakers, the driver-to-back wall distance would be about 45-50cm.
I was looking at some room sims with ideal driver in VituixCAD with the above settings and I saw results like this (I dont know how effective these simulations will be in this particular use case though)
Effect of wall at the back
Effect of the table
Combined effects of both the wall & the table top
In this scenario I see a one octave wide deep notch in the 600Hz region.
This is the reason why I was thinking about narrowing the directivity both vertically and horizontally.. But if these kind of artifacts are not a problem/no solution exists at the kind of close listening distances involved, then it might not help much to go with an MTM I guess.
I like the looks of side-by-side woofers. Like the Kii-3
In this case, I can get rid of the tweeter, apply the largest possible roundings atleast on 3sides of the coax I guess.
What kind & size of a woofer/mid woofer would be good for such a side-by-side woofer setup (if I want to explore effects of active cardioid also). Is it better to go with a subwoofer like driver or a woofer/mid woofer?
I am not looking beyond larger than 8inch drivers & not thinking of extending the baffle width beyond 20-25cm. This (https://en.toutlehautparleur.com/speaker-sica-5-5-h1-5cp-8-ohm-5-9-inch.html) sica midwoofer that I have will probably help with keeping the baffle width in the above range since they have only about 8cm depth. Same is the case with the SB15CAC that I have.
A 7inch subwoofer driver like this (https://www.wavecor.com/html/sw178wa01.html) also has similar depth but the inductance rise above 200Hz might cause problems with crossover with the coax I think
Please suggest any other driver which you think might help in this application
I thought that with an MTM, the vertical narrowing could help from interference from the table. And the horizontal narrowing from the cardioid would help with interference from the wall behind the speakers.
In the intended placement of these speakers, the wall will be about 15-20cm behind the speaker. Assuming about 25-30cm depth for the speakers, the driver-to-back wall distance would be about 45-50cm.
I was looking at some room sims with ideal driver in VituixCAD with the above settings and I saw results like this (I dont know how effective these simulations will be in this particular use case though)
Effect of wall at the back
Effect of the table
Combined effects of both the wall & the table top
In this scenario I see a one octave wide deep notch in the 600Hz region.
This is the reason why I was thinking about narrowing the directivity both vertically and horizontally.. But if these kind of artifacts are not a problem/no solution exists at the kind of close listening distances involved, then it might not help much to go with an MTM I guess.
I like the looks of side-by-side woofers. Like the Kii-3
In this case, I can get rid of the tweeter, apply the largest possible roundings atleast on 3sides of the coax I guess.
What kind & size of a woofer/mid woofer would be good for such a side-by-side woofer setup (if I want to explore effects of active cardioid also). Is it better to go with a subwoofer like driver or a woofer/mid woofer?
I am not looking beyond larger than 8inch drivers & not thinking of extending the baffle width beyond 20-25cm. This (https://en.toutlehautparleur.com/speaker-sica-5-5-h1-5cp-8-ohm-5-9-inch.html) sica midwoofer that I have will probably help with keeping the baffle width in the above range since they have only about 8cm depth. Same is the case with the SB15CAC that I have.
A 7inch subwoofer driver like this (https://www.wavecor.com/html/sw178wa01.html) also has similar depth but the inductance rise above 200Hz might cause problems with crossover with the coax I think
Please suggest any other driver which you think might help in this application
Attachments
The MTM in this case would be around 300Hz to 400Hz crossover I would imagine, it is debateable if any vertical narrowing there would be helpful, easy enough to model in Vituix and see what you would get.
Looking at the reflections in the Vituix Room sim is fine to look at the frequencies and effects of absorption from the surfaces but I wouldn't get too hung up on seeing horrible dips. In reality there will be many more reflections than one and the more you add the better the whole thing looks.
Genelec have a good page on monitor placement and it shows graphically what happens
.https://www.genelec.com/monitor-placement
More than 60cm from the wall is getting into danger territory where the 150Hz down area starts getting big dips in it. This can really be a problem especially if it ends up at 60 to 100Hz. Then having a sub and satellite setup works better as the sub can be close to the wall and avoid the dips in it's passband and the dips in the main speakers are outside their passband.
There is an Audioholics article that is not bad, elevating and angling can be good. The wall behind is less of a problem for imaging and other problems from close wall placement as most speaker are quite forward directional. Near side walls and corners not so much. Absorbent panels can be good here too.
https://www.audioholics.com/diy-audio/good-sound-from-desktop-audio
Many manufacturers include a dip at 160Hz as a desktop preset as common desk placements give a boost at 160Hz. That is what is shown the in LS50II measurements krivium mentioned.
If it was me I would probably use a similar size woofer underneath (to relieve the coax from playing too low) in a fairly shallow cabinet to make it easier to get close to the wall, use a subwoofer and think about absorption panels rather than cardioid.
Cardioid is something that comes into it's own when you are unwilling or unable to use absorption to address boundary interference. A lot of level is lost in the cancellation. Active allows that to be tailored so all the bass isn't lost but still retain the directivity in the main SBIR frequency range.
This makes it good for a manufacturer or someone that wants their speaker to be more room independent as they will tend to be more similar rather than wildly room dependent. For a single setup in a specific room there are simpler more efficient ways to get there.
Looking at the reflections in the Vituix Room sim is fine to look at the frequencies and effects of absorption from the surfaces but I wouldn't get too hung up on seeing horrible dips. In reality there will be many more reflections than one and the more you add the better the whole thing looks.
Genelec have a good page on monitor placement and it shows graphically what happens
.https://www.genelec.com/monitor-placement
More than 60cm from the wall is getting into danger territory where the 150Hz down area starts getting big dips in it. This can really be a problem especially if it ends up at 60 to 100Hz. Then having a sub and satellite setup works better as the sub can be close to the wall and avoid the dips in it's passband and the dips in the main speakers are outside their passband.
There is an Audioholics article that is not bad, elevating and angling can be good. The wall behind is less of a problem for imaging and other problems from close wall placement as most speaker are quite forward directional. Near side walls and corners not so much. Absorbent panels can be good here too.
https://www.audioholics.com/diy-audio/good-sound-from-desktop-audio
Many manufacturers include a dip at 160Hz as a desktop preset as common desk placements give a boost at 160Hz. That is what is shown the in LS50II measurements krivium mentioned.
If it was me I would probably use a similar size woofer underneath (to relieve the coax from playing too low) in a fairly shallow cabinet to make it easier to get close to the wall, use a subwoofer and think about absorption panels rather than cardioid.
Cardioid is something that comes into it's own when you are unwilling or unable to use absorption to address boundary interference. A lot of level is lost in the cancellation. Active allows that to be tailored so all the bass isn't lost but still retain the directivity in the main SBIR frequency range.
This makes it good for a manufacturer or someone that wants their speaker to be more room independent as they will tend to be more similar rather than wildly room dependent. For a single setup in a specific room there are simpler more efficient ways to get there.
On bass, yes. But not at midrange frequencies (where it's most useful), as was shown here:
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7244940
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7246752
You actually gain in level by adding the radiation from the rear side of the cone, which is otherwise lost as heat. This of course leads to a three-way design with separate woofers.
I will plan to use a separate subwoofer below 80Hz or even lower and woofer below 2-300 Hz
mabat's simulation for 5inch driver above 250Hz here: https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7243594
is tempting to build a prototype and explore..
I have some xps foam lying around. Probably next week, when I get a chance, I am going to put that SICA coax driver in a foam cabinet like below and try to take some measurements. It is doubtful if I will be able to get reliable measurements down to 200-300Hz at home and then there could be resonance issues due to the foam cabinet itself but I will just make an attempt
mabat's simulation for 5inch driver above 250Hz here: https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7243594
is tempting to build a prototype and explore..
I have some xps foam lying around. Probably next week, when I get a chance, I am going to put that SICA coax driver in a foam cabinet like below and try to take some measurements. It is doubtful if I will be able to get reliable measurements down to 200-300Hz at home and then there could be resonance issues due to the foam cabinet itself but I will just make an attempt
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Hi, Make the cabinet as small as possible, and panels are as small as possible and all panel related issues are minimized. Also if any of the panels radiate sound its radiating surface is now minimized.
Cost is loss of bass, but otherwise you have just made the outside dimensions acoustically minimal and inside dimensions acoustically maximal, leaky, hense acoustic footprint of the box is minimal with minimal effort and cost, if prototyping is not accounted.
Diffraction is still there like with any box so experiment with roundovers, which also changes the dimensions and the pattern.
Expect usable bandwidth to be 2-3 octaves down from diffraction interference, roughly baffle size wavelength. For 5" in minimal box this is something like 500-2kHz.
Cost is loss of bass, but otherwise you have just made the outside dimensions acoustically minimal and inside dimensions acoustically maximal, leaky, hense acoustic footprint of the box is minimal with minimal effort and cost, if prototyping is not accounted.
Diffraction is still there like with any box so experiment with roundovers, which also changes the dimensions and the pattern.
Expect usable bandwidth to be 2-3 octaves down from diffraction interference, roughly baffle size wavelength. For 5" in minimal box this is something like 500-2kHz.
@tmuikku: Thanks. I will try to follow your suggestions in the prototype build
@mabat: Sure. Thanks. At the moment, I am considering only experimenting with the cardioid down to almost 200Hz before I finalize the details of this computer speaker build. I don't plan to use the 5-inch driver EQd below 200Hz anyway. For that range, plan is to use separate woofers.
@mabat: Sure. Thanks. At the moment, I am considering only experimenting with the cardioid down to almost 200Hz before I finalize the details of this computer speaker build. I don't plan to use the 5-inch driver EQd below 200Hz anyway. For that range, plan is to use separate woofers.