What you all think should the speaker be designed for against front wall or further out position? Personally I have no option but speakers against the wall since listening happens in living room that is for whole family and activities and not just for hifi.
I'd be interested how to make a passive speaker that is adjustable between close to wall or furher out position. I have active solution just for that and it is the easy way. In addition to easily adjustable active solution close wall position can be addressed with cardioidish mid and waveguide to reduce sound to the first reflection point at front wall. Also the bass box can be very shallow effectively mating the woofer to the wall below 1/8wl or a bit higher up. This would mean ~20cm box depth for ~200Hz xo.
Now, If I'd pull the thing with cardioid /waveguide out from the wall into the room only thing that would change is the bass I think. How would one tune bass level with passive xo? Only feasible option is to biamp or be active? Is there way to add huge capacitor or something, additional high pass or pad to reduce bass level when against the back wall? Change the bass enclosure volume to affect the bass? Alternatively the baffle could be huge so that it doesn't matter if there is a wall behind or not? Or does the bass level matter at all when the woofer is crossed ~200Hz where the sound is almost dominated by the room? Maybe a strategic notch filter somewhere around the xo to tame the frequencies that are not dominated by the room yet? I mean which is the best option for builder if there is need to optimize for either position?
If there is no good way to compensate the front wall proximity then a passive speaker should be designed to work against front wall OR further out otherwise it is a compromise and not good for either.
Main effects of the proximity to front wall is the SBIR that hurts the high bass / low mids usually depending on where one pulls the speaker out. This might be compensated with careful speaker positioning relative to side walls and height. Also, I could imagine the overall imaging changes if the speaker radiates all around on the high frequencies as well.
I'd be interested how to make a passive speaker that is adjustable between close to wall or furher out position. I have active solution just for that and it is the easy way. In addition to easily adjustable active solution close wall position can be addressed with cardioidish mid and waveguide to reduce sound to the first reflection point at front wall. Also the bass box can be very shallow effectively mating the woofer to the wall below 1/8wl or a bit higher up. This would mean ~20cm box depth for ~200Hz xo.
Now, If I'd pull the thing with cardioid /waveguide out from the wall into the room only thing that would change is the bass I think. How would one tune bass level with passive xo? Only feasible option is to biamp or be active? Is there way to add huge capacitor or something, additional high pass or pad to reduce bass level when against the back wall? Change the bass enclosure volume to affect the bass? Alternatively the baffle could be huge so that it doesn't matter if there is a wall behind or not? Or does the bass level matter at all when the woofer is crossed ~200Hz where the sound is almost dominated by the room? Maybe a strategic notch filter somewhere around the xo to tame the frequencies that are not dominated by the room yet? I mean which is the best option for builder if there is need to optimize for either position?
If there is no good way to compensate the front wall proximity then a passive speaker should be designed to work against front wall OR further out otherwise it is a compromise and not good for either.
Main effects of the proximity to front wall is the SBIR that hurts the high bass / low mids usually depending on where one pulls the speaker out. This might be compensated with careful speaker positioning relative to side walls and height. Also, I could imagine the overall imaging changes if the speaker radiates all around on the high frequencies as well.
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That wasn't the reaction I was expecting. While I did have a point, I didn't need it to come across as strongly as that.
Edit time over, continuing my last post:
In general, it would be important to know what kind of listening environment the target group for the design have. If there is no option for most people to position speakers optimally then all features that reduce effect of the room and positioning should be taken account in the design. This separates people into two rough target groups, those who have dedicated listening space vs. those who have to put the speakers where ever they fit, usually somewhere around the living room. Design for either.
To cater most I'd say design for the living room people since the dedicated listening room folks can put the speakers in living room positions as well, if that is the optimal position But, structures like TV or fireplace or the HiFi equipment shrine between the speakers could hinder the performance though, if speakers are back against the wall... maybe best option was if there is a good/handy way to alter the design for either situation.
edit.
Thinking of it, small box size for living room folks and bigger box with mo' bass for the listening room people feels logical. Small speakers easy to fit where ever they fit in living room and big speakers more impressive for those with the listening space and want to pull them out for best possible position. I haven't checked out in simulator how this would play out. Anyone? Don't we have tone controls in the receivers anymore?
In general, it would be important to know what kind of listening environment the target group for the design have. If there is no option for most people to position speakers optimally then all features that reduce effect of the room and positioning should be taken account in the design. This separates people into two rough target groups, those who have dedicated listening space vs. those who have to put the speakers where ever they fit, usually somewhere around the living room. Design for either.
To cater most I'd say design for the living room people since the dedicated listening room folks can put the speakers in living room positions as well, if that is the optimal position
But, structures like TV or fireplace or the HiFi equipment shrine between the speakers could hinder the performance though, if speakers are back against the wall... maybe best option was if there is a good/handy way to alter the design for either situation.edit.
Thinking of it, small box size for living room folks and bigger box with mo' bass for the listening room people feels logical. Small speakers easy to fit where ever they fit in living room and big speakers more impressive for those with the listening space and want to pull them out for best possible position. I haven't checked out in simulator how this would play out. Anyone? Don't we have tone controls in the receivers anymore?
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Mo' thinking on it. Design for separate boxes for bass and the rest or better all 3 drivers in individual structures. One could possibly build big and small bass box to see what is the difference, other for close wall other for full space radiation. This would enable the xo built so that the varying size bass box doesn't matter too much and could be swapped at will? Also, dedicated structure for the highs would allow to optimize performance for the short wavelengths. Dedicated structures would allow other stuff as well like individual toe in (bass flat against the wall, but top can turn), height adjustment and what not. Something for the folks who want to experiment and tinker. Optimize performance of the structures independently. I think manufacturing becomes a lot easier as box size and complexity is reduced. Total raw material price might rice a bit since more total surface area with separate structures than with one monolith.
I have no idea how this would affect passive crossover though. I would guess having 3 different size structures have 3 different "baffle steps" and thus extra components and price with passive xo? For active DSP system this is no problem.
edit. before anyone gets annoyed my multiple mentions to active / DSP solution I have to say that I'm not promoting DSP over passive crossover as is. I've just noticed the optimal acoustic structure solutions pretty much demand DSP since the price is constant while adjustability is infinite enough. Passive xo, especially with price limit, seems to always be the dead end while thinking through various physical design options / paths. Of course I haven't thought all design options, it is just my limited experience with a personal living room system that led me believe so. I admit I don't value xo too much and have no feelings over it. Sole purpose is to knit the system together (split signal in electronic domain so that it combines back in acoustic domain) and it feels trivial to "perfect" a crossover in VituixCAD for given set of measurements. From this I've reasoned that while thinking a speaker design crossovers can be taken like anything is possible and only cost varies. The performance of loudspeaker system comes from the measurements, the physical structure that operates in the acoustic domain! designing and tuning xo to that is just a necessary step in the process nothing more, it is the acoustic output of the system we listen to. I'd gladly take the cheapest option that gets the job done be it passive or active system.
I have no idea how this would affect passive crossover though. I would guess having 3 different size structures have 3 different "baffle steps" and thus extra components and price with passive xo? For active DSP system this is no problem.
edit. before anyone gets annoyed my multiple mentions to active / DSP solution I have to say that I'm not promoting DSP over passive crossover as is. I've just noticed the optimal acoustic structure solutions pretty much demand DSP since the price is constant while adjustability is infinite enough. Passive xo, especially with price limit, seems to always be the dead end while thinking through various physical design options / paths. Of course I haven't thought all design options, it is just my limited experience with a personal living room system that led me believe so. I admit I don't value xo too much and have no feelings over it. Sole purpose is to knit the system together (split signal in electronic domain so that it combines back in acoustic domain) and it feels trivial to "perfect" a crossover in VituixCAD for given set of measurements. From this I've reasoned that while thinking a speaker design crossovers can be taken like anything is possible and only cost varies. The performance of loudspeaker system comes from the measurements, the physical structure that operates in the acoustic domain! designing and tuning xo to that is just a necessary step in the process nothing more, it is the acoustic output of the system we listen to. I'd gladly take the cheapest option that gets the job done be it passive or active system.
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I want to come back to my previous post. Only 1 reaction came so far saying it's thinking of a beginner..which I am
I dont want to create just an other 3-way speaker. it should be a platform base that is easy to adapt for further alterations.
I got the remark that it is costly and it will just make music if you adapt the design.
I still don't agree with that. re-use drivers(BTW for me 600 euro for drivers only in this project) reduce the cost a lot. woodwork and XO can be done for 100 euro.
Of course no one will build all aterations but use his/her base and modify according to the interest one has. Interest which grow during their DIY journey.
If one would like to experience the bass of a TL design you can build that. If you like to experience wide baffle, waveguide, ...
Maybe make some combinations of some designs. etc...
For me that will be the real strength of this project. High quality speakerbuild to the best ability with middle of the road drivers.
Ok to start of we need to limit the possible designs.
I would propose to start with a 3-way bookshelf/narrow tower TMW.
600 euro budget on drivers.
Volume? difficult to decide...I don't want to exclude a great driver if it is just out of spec. lets say 40L max?
8"-10"woofer (keep in mind the max volume around 40L)
4"-5"mids
dome tweeter. (one alteration could be a ribbon tweeter, so if the base design has higher XO point would make it easier to adapt)
I would like to see the mid handle around 300- 3000 Hz point. (Pushing BSC to the woofer, possibility to use ribbon)
Ported and closed design.
Lower order XO.
XO complexity isnt an issue (maybe a base XO with minimal components for those who don't feel comfortable, but that may have some trade-offs which should be pointed out)
easy (very easy) to use drivers. (We want to end with some different XO's (high/low order, serial, ...))
Mid should be paper or Poly.
Minimum load > 4.5 ohm. 3.5 is to low for my taste
roomsize 40 m2 (5mX8m)
100-105 db peak is fine.
relative close to the wall (roomsize isn't that big). front baffle to back wall : 50-80cm. (I saw some designs which can be adpated easly to Far/Near Speaker Design Works )
Listening position 2,5-3m
What more is needed? Difficult for a newby like me. (=easy to requests impossible things.)
Alterations of the base design for further developments.
Use of passive radiator
TL design
Waveguide
Time-alignment (electric / slanted baffle)
Wide baffle (ala troels PMS)
higher order XO
serial XO
MTMW design
TMWW design
Everything else I can't think of
When newbies grow and learn/understand more the can adapt their base speaker accordingly.
From all the alterations which can be derived my personal interest goes out most to TL-design, serial XO and wide baffle.
If those alterations exist I can combine those to make my personal speaker.
(of course XO and baffle goes hand in hand).
Once the base speaker is made those alteration can be build on it.
Maybe/hopefully this one base speaker will grow into 10-20 alterations.
There is a lot of knowledge on this site with specialist in 1 or more area's. If they could combine their strength here in this project, that for me would make it "reference".
I dont want to create just an other 3-way speaker. it should be a platform base that is easy to adapt for further alterations.
I got the remark that it is costly and it will just make music if you adapt the design.
I still don't agree with that. re-use drivers(BTW for me 600 euro for drivers only in this project) reduce the cost a lot. woodwork and XO can be done for 100 euro.
Of course no one will build all aterations but use his/her base and modify according to the interest one has. Interest which grow during their DIY journey.
If one would like to experience the bass of a TL design you can build that. If you like to experience wide baffle, waveguide, ...
Maybe make some combinations of some designs. etc...
For me that will be the real strength of this project. High quality speakerbuild to the best ability with middle of the road drivers.
Ok to start of we need to limit the possible designs.
I would propose to start with a 3-way bookshelf/narrow tower TMW.
600 euro budget on drivers.
Volume? difficult to decide...I don't want to exclude a great driver if it is just out of spec. lets say 40L max?
8"-10"woofer (keep in mind the max volume around 40L)
4"-5"mids
dome tweeter. (one alteration could be a ribbon tweeter, so if the base design has higher XO point would make it easier to adapt)
I would like to see the mid handle around 300- 3000 Hz point. (Pushing BSC to the woofer, possibility to use ribbon)
Ported and closed design.
Lower order XO.
XO complexity isnt an issue (maybe a base XO with minimal components for those who don't feel comfortable, but that may have some trade-offs which should be pointed out)
easy (very easy) to use drivers. (We want to end with some different XO's (high/low order, serial, ...))
Mid should be paper or Poly.
Minimum load > 4.5 ohm. 3.5 is to low for my taste
roomsize 40 m2 (5mX8m)
100-105 db peak is fine.
relative close to the wall (roomsize isn't that big). front baffle to back wall : 50-80cm. (I saw some designs which can be adpated easly to Far/Near Speaker Design Works )
Listening position 2,5-3m
What more is needed? Difficult for a newby like me. (=easy to requests impossible things.)
Alterations of the base design for further developments.
Use of passive radiator
TL design
Waveguide
Time-alignment (electric / slanted baffle)
Wide baffle (ala troels PMS)
higher order XO
serial XO
MTMW design
TMWW design
Everything else I can't think of
When newbies grow and learn/understand more the can adapt their base speaker accordingly.
From all the alterations which can be derived my personal interest goes out most to TL-design, serial XO and wide baffle.
If those alterations exist I can combine those to make my personal speaker.
(of course XO and baffle goes hand in hand).
Once the base speaker is made those alteration can be build on it.
Maybe/hopefully this one base speaker will grow into 10-20 alterations.
There is a lot of knowledge on this site with specialist in 1 or more area's. If they could combine their strength here in this project, that for me would make it "reference".
Here is my view on some of the topics, with some experience like so: I've spent more time on simulator and thinking than building, although have several prototypes of single system under the belt. Never done passive xo.
I was interested on all the things you mention but some of them don't feel relevant currently in regards of audio performance. For example TL bass. I've got no interest on it until I need long narrow bass box for some application where TL stuff matters, when simple slumped model doesn't explain the (mis)behavior anymore. Otherwise more traditional boxes feel appropriate since they are easier to design and build and more compact and operate where the room dominates the response anyway.
Serial XO, might be nice but there is only one xo configuration that works best for given application and situation in my view. Yes, I don't know what that is when ever and it is a sliding concept. I just tweak in the simulator until best possible looking stuff, listen, figure out if something needs tuning, rinse and repeat. It is good to know serial XO but I won't use it until application for it comes. Just like low order XO, not sure when it works. Or high order for that matter. I might have used all these, but I don't care as long as the system works as a whole. I haven't checked what the acoustic slopes have ended to be but it looks like close to phase aligned filters most of the time, LR4 stuff. I know that some "worse" looking sims could sound better, just don't have enough experience what those situations might be. Comparing xo versions with DSP is trivial, just pick the better sounding if there is any difference.
Wide baffle I see as diffraction problem unless hard to manufacture big round overs but here I'm thinking with DSP in mind (not limiting to passive xo vs. bafflestep). I'm open to it but I'm all in to minimal / no baffle solutions since they are easiest to do with very little effect on the acoustic performance of the transducer output even without roundovers what so ever. By diffraction problem I mean what I see on the screen. I don't know at what bandwidth the diffraction is most audible and where it is not a problem.
I haven't looked into cone materials yet, I've been interested on the acoustic output of the system for now. I imagine there is differences in sound depending on the materials and other structural and mechanical things with drivers. Some are better than others but they all perform rather similarly in regards to their physical size in relation to wavelengths they produce. I imagine a well designed system will sound good as long as the drivers don't have obvious problems, while a bit better sound (detail) might happen with better transducers (of same size!). None of this makes much difference if the system design is not right, diffraction and other acoustic features will persist on a system no matter how expensive the driver is.
Anyway, many ways to approach things. Sorry preaching mine again, I just see it very different so thought to open up a bit more. I don't want to push it since the best thing anyone can do is to have fun with the hobby! Knowing the different perspectives of participants can help to align the minds into some common ground though, helpful for reaching the end goal I think?
I was interested on all the things you mention but some of them don't feel relevant currently in regards of audio performance. For example TL bass. I've got no interest on it until I need long narrow bass box for some application where TL stuff matters, when simple slumped model doesn't explain the (mis)behavior anymore. Otherwise more traditional boxes feel appropriate since they are easier to design and build and more compact and operate where the room dominates the response anyway.
Serial XO, might be nice but there is only one xo configuration that works best for given application and situation in my view. Yes, I don't know what that is when ever and it is a sliding concept. I just tweak in the simulator until best possible looking stuff, listen, figure out if something needs tuning, rinse and repeat. It is good to know serial XO but I won't use it until application for it comes. Just like low order XO, not sure when it works. Or high order for that matter. I might have used all these, but I don't care as long as the system works as a whole. I haven't checked what the acoustic slopes have ended to be but it looks like close to phase aligned filters most of the time, LR4 stuff. I know that some "worse" looking sims could sound better, just don't have enough experience what those situations might be. Comparing xo versions with DSP is trivial, just pick the better sounding if there is any difference.
Wide baffle I see as diffraction problem unless hard to manufacture big round overs but here I'm thinking with DSP in mind (not limiting to passive xo vs. bafflestep). I'm open to it but I'm all in to minimal / no baffle solutions since they are easiest to do with very little effect on the acoustic performance of the transducer output even without roundovers what so ever. By diffraction problem I mean what I see on the screen. I don't know at what bandwidth the diffraction is most audible and where it is not a problem.
I haven't looked into cone materials yet, I've been interested on the acoustic output of the system for now. I imagine there is differences in sound depending on the materials and other structural and mechanical things with drivers. Some are better than others but they all perform rather similarly in regards to their physical size in relation to wavelengths they produce. I imagine a well designed system will sound good as long as the drivers don't have obvious problems, while a bit better sound (detail) might happen with better transducers (of same size!). None of this makes much difference if the system design is not right, diffraction and other acoustic features will persist on a system no matter how expensive the driver is.
Anyway, many ways to approach things. Sorry preaching mine again, I just see it very different so thought to open up a bit more. I don't want to push it since the best thing anyone can do is to have fun with the hobby!
Knowing the different perspectives of participants can help to align the minds into some common ground though, helpful for reaching the end goal I think?
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This is part of the process of zeroing in on a design but it would helpful to know why. I am guessing it is because the design is sticking to a 3 way?
I too will be out in terms of building the speaker and likely much of the design because, as stated earlier, the approach is not adopting the idea of optimising the performance of a speaker as a whole for a given budget and use. No problem, it is a group design which obviously has to keep the OP in the group. I have floated the idea of increasing the woofer area for better balanced 3 way main speakers for a room without it gaining traction. Then decreasing the size of the midrange for a compact 3 way speaker for closer listening which I am less interested in but might still commit to but again without gaining traction. This is all progress in helping to improve the definition of what the design is going to be. It is clearly not there yet and nobody, including the OP, has fully committed to it but that could still happen around an 8" woofer, 4" midrange, $600 budget, plus a few other things that need to be agreed on before any serious design could commence. It would be good to see but, as the age of the thread suggests, it isn't straightforward.
until a goal is set
then it becomes just an iterative excersice with few possible outcomes from which it is possible to choose the most appropriate weighting in with the goal in mind once more.Without a goal it is just buncho random stuff floating in the air.
@tmuikku. Seems you have some first hand experience on some topics and made your own evaluation.
This is something newbies didnt do yet and hence the different views.
Of course for some alterations big changes has to be made. But what stay are the drivers. Those are the most expensive I think.
I do believe that TL makes a difference compared to BR or passieve radiator.
I do believe that serial XO, low order, high order, BW, LR, etc make difference.
If wide baffle have diffraction problems compared to narrow band, i like to experience and learn how to deal with it. Understand what is the benefits and downsides.
You talk from your own experience and believe...and it is good that you have this experience and view. But it is something personal...and good for newbies to understand those so they can make their own experience/believe. And like I said, no one will be interested in all setup's...maybe for learning purpose but not for building. (weighting the bennefit vs complexity vs cost ...)
what more is needed to make the goal more clear?
This is something newbies didnt do yet and hence the different views.
Of course for some alterations big changes has to be made. But what stay are the drivers. Those are the most expensive I think.
I do believe that TL makes a difference compared to BR or passieve radiator.
I do believe that serial XO, low order, high order, BW, LR, etc make difference.
If wide baffle have diffraction problems compared to narrow band, i like to experience and learn how to deal with it. Understand what is the benefits and downsides.
You talk from your own experience and believe...and it is good that you have this experience and view. But it is something personal...and good for newbies to understand those so they can make their own experience/believe. And like I said, no one will be interested in all setup's...maybe for learning purpose but not for building. (weighting the bennefit vs complexity vs cost ...)
what more is needed to make the goal more clear?
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I don't know why you are thinking this, but others have thought that if a baffle causes diffraction, then make it as small as possible.
*This is wrong by the way, but is it what you want to learn?
MrHifiTunes, For sure I've got one valuable advice that helps you to find the questions and answers first hand: think wavelengths!
For example room size wavelengths are dominated by the room not the speaker. If a transducer is relatively small for the wavelength it is producing it will have omni response but when the wavelength shortens sound radiation from different locations on a transducer will start to cause interference which shows up as beaming etc. Baffle step and baffle edge diffraction happen with wavelengths related to baffle size. In general sound interacts with objects when they are big enough in relation to wavelength. All resonances within a box or a pipe like reflex port happens by the wavelength. Room interaction. Hearing system frequency / phase / level sound source positional cues happen by wavelength in relation to the head size. It all comes down to wavelengths and then the answers are easy to find and explain. Even if perfect ideal drivers were assumed and perfect crossovers the output was dictated by the physical construct, transducer size and their position to each other. Even if it was possible to build ideal transducers it would be impossible to get them not to interact with each other if they were physical objects, for example not possible to get multiple transducers share same physical space which directly affects the output of the system.
Thinking wavelengths for few moments will reveal that 1 and 2 way speaker systems don't quite cut it if there is SPL and bandwidth requirement. 3 way system does it, until you realize there is room sized wavelengths at the very bottom one would like to reproduce nicely one might consider 4 way system depending on the situation. This is something that is related to the transducer size alone in relation to wavelengths and does not require getting any deeper into details to realize.
Yeah the electric domain within transducers and crossover topologies is a bit different, there is no physical size to wavelength but the frequency is more relevant in that domain.
As you might see choosing the driver make and model and wondering about xo slopes is kind of the most trivial and even boring stuff in speaker building, at least for me It is just matter of time and patience to find transducers ( and xo ) what the design calls for. If there is none, then throw money at it and try to get some invented and manufactured, or go few steps back in the process and limit design to all available transducers / xo topologies and exclude the imaginary ones
^ AllenB yes if analyzing with simple simulation, as one minimizes baffle around the driver the bandwidth where diffraction happens gets narrower = less of a problem. This observation doesn't account in what bandwidth diffraction is audible and where it might not be. But, as baffle size is widened the diffracting bandwidth gets wider assuming sound source stays the same, direct radiating driver outputs sound along the baffle wavelengths that are long relative to its size. Higher frequencies beam and don't cause diffraction as long as they don't radiate along the baffle and meet the edge. Baffle size defines what is the longest wavelength diffraction happens. Longer wavelengths just diffract less and less until the baffle becomes acoustically small, a baffle step, until omni. This in mind, minimum baffle seems to equal minimum diffraction (bandwidth). However, if there are slants or roundovers the diffraction interference gets even less but also in this case the slant or roundover should start immediately beside the transducer or it is not big enough for minimal effects. This in mind, smaller flat baffle area around drivers yields less diffraction interference is a good rule of thumb in my view. It would be useful to know where hearing is most sensitive to diffraction but until that minimizing diffraction feels the most logical thing to do unless compromising some other more important aspects, like baffle step stuff on a passive xo system.
I've got one valuable advice that helps you to find the questions and answers first hand: think wavelengths! For example room size wavelengths are dominated by the room not the speaker. If a transducer is relatively small for the wavelength it is producing it will have omni response but when the wavelength shortens sound radiation from different locations on a transducer will start to cause interference which shows up as beaming etc. Baffle step and baffle edge diffraction happen with wavelengths related to baffle size. In general sound interacts with objects when they are big enough in relation to wavelength. All resonances within a box or a pipe like reflex port happens by the wavelength. Room interaction. Hearing system frequency / phase / level sound source positional cues happen by wavelength in relation to the head size. It all comes down to wavelengths and then the answers are easy to find and explain. Even if perfect ideal drivers were assumed and perfect crossovers the output was dictated by the physical construct, transducer size and their position to each other. Even if it was possible to build ideal transducers it would be impossible to get them not to interact with each other if they were physical objects, for example not possible to get multiple transducers share same physical space which directly affects the output of the system.
Thinking wavelengths for few moments will reveal that 1 and 2 way speaker systems don't quite cut it if there is SPL and bandwidth requirement. 3 way system does it, until you realize there is room sized wavelengths at the very bottom one would like to reproduce nicely one might consider 4 way system depending on the situation. This is something that is related to the transducer size alone in relation to wavelengths and does not require getting any deeper into details to realize.
Yeah the electric domain within transducers and crossover topologies is a bit different, there is no physical size to wavelength but the frequency is more relevant in that domain.
As you might see choosing the driver make and model and wondering about xo slopes is kind of the most trivial and even boring stuff in speaker building, at least for me
It is just matter of time and patience to find transducers ( and xo ) what the design calls for. If there is none, then throw money at it and try to get some invented and manufactured, or go few steps back in the process and limit design to all available transducers / xo topologies and exclude the imaginary ones ^ AllenB yes if analyzing with simple simulation, as one minimizes baffle around the driver the bandwidth where diffraction happens gets narrower = less of a problem. This observation doesn't account in what bandwidth diffraction is audible and where it might not be. But, as baffle size is widened the diffracting bandwidth gets wider assuming sound source stays the same, direct radiating driver outputs sound along the baffle wavelengths that are long relative to its size. Higher frequencies beam and don't cause diffraction as long as they don't radiate along the baffle and meet the edge. Baffle size defines what is the longest wavelength diffraction happens. Longer wavelengths just diffract less and less until the baffle becomes acoustically small, a baffle step, until omni. This in mind, minimum baffle seems to equal minimum diffraction (bandwidth). However, if there are slants or roundovers the diffraction interference gets even less but also in this case the slant or roundover should start immediately beside the transducer or it is not big enough for minimal effects. This in mind, smaller flat baffle area around drivers yields less diffraction interference is a good rule of thumb in my view. It would be useful to know where hearing is most sensitive to diffraction but until that minimizing diffraction feels the most logical thing to do unless compromising some other more important aspects, like baffle step stuff on a passive xo system.
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Currently to me, it seems very logical to use minimal structure for least amount of interaction of the structure to the sound. Bare transducers, open baffle, would have least amount of interference due to structure because can't get any less structure than the transducer by itself. Easiest and cheapest to build "box" as well since there is none. No box or pipe resonances what so ever. Also, nulls are at 90 degrees where the other transducers(structure locate and this reduces interference even more. But, then there is the back radiation that interacts with the room and long wavelengths cancel between front and back creating some problems boxed speakers don't have. Good or bad, depends on the application. But, SPL and bandwidth requirements in mind 8" - 4" - 1" won't cut it. Also, can't position close to wall I've read. Big transducers, many ways, hard xo? can make expensive system over all. No doubt open baffle system would sound good, void of any unwanted acoustic issues at the source, only the environment the room affects the sound, and quality and capability of the transducers.
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Even with a goal/spec it can still peter out as a group project if what is agreed on becomes diluted by too wide a consensus. I have observed previous projects where those chatting are given pretty much as much say in the spec as those committed to design and manufacture. This tends to reduce the number of the committed to less than it could have been with a spec more closely aligned with their interests. Another way things can drift is by the spec becoming too closely aligned with what a single individual wants to do with the project becoming little different to a normal personal one.
People designing and building speakers for fun using their own spare time and money aren't a natural fit for group projects where some of what they would want to do in an individual project has to be modified or given up. Getting it to work reasonably well is a challenge but I would like to think an interesting one.
I also think it is wrong. I believe it has benifits but Tmuikki says it gives diffraction problems.
And that is also the point. As newby you don't know...You read a lot and for every subject you have believers and non believers. Hence this project...the more you read the more the interest in one subject grows (or fade out)... then at a certain point you can build it and experience it yourself. Re-use of drivers makes it possible for many if there are proven designs. for 100 euro you can build and MDF cabinet with basic XO components.
andy, I see, well said. For your previous post: I would also add more woofer cone area and head for nice loud sound but not sure what to suggest yet since no goal I understand Hence throwing out some relevant aspects that are not tied to particular system size, although very relevant to how the size is tied to performance.
AllenB, I'd like to get bottom of it in general so please come forward with hints where to dig out more info on this subject. My thoughts are based on observations on simulations as well as measurements of a prototype system. Oversimplification for sure, but that gives the theoretical best case scenario with and real world systems make it only worse. I have no evidence what amount of diffraction at which frequency is audible and what is not, for example, hence going after minimization which is fine oversimplified. It is easy to sim and measure and evaluate when there is more or less of diffraction interference.
MrHifiTunes, popout any diffraction simulator and experiment with transducer size in relation to baffle size. You'll quickly notice what is baffle step and that there is ripple above that until wavelengts are shorter than the transducer size. This phenomenon looks the same no matter if it is small transducer on small baffle or big on a big baffle. Bandwidt where the ripple happens is directly related to baffle size (giving the low frequency limit, baffle step) and transducer size (high frequencies start to beam), diffraction interference happens on this bandwidth to the listening window. I'm doing it on VituixCAD and have posted many screenshots and texts on the observations so that anyone could check it out. It is most effective to do by your self since it is more real time, you'll see immediately what the trend is when you enlarge or minimize the baffle, or add roundovers and what size roundovers are effective.
Hence throwing out some relevant aspects that are not tied to particular system size, although very relevant to how the size is tied to performance. AllenB, I'd like to get bottom of it in general so please come forward with hints where to dig out more info on this subject. My thoughts are based on observations on simulations as well as measurements of a prototype system. Oversimplification for sure, but that gives the theoretical best case scenario with and real world systems make it only worse. I have no evidence what amount of diffraction at which frequency is audible and what is not, for example, hence going after minimization which is fine oversimplified. It is easy to sim and measure and evaluate when there is more or less of diffraction interference.
MrHifiTunes, popout any diffraction simulator and experiment with transducer size in relation to baffle size. You'll quickly notice what is baffle step and that there is ripple above that until wavelengts are shorter than the transducer size. This phenomenon looks the same no matter if it is small transducer on small baffle or big on a big baffle. Bandwidt where the ripple happens is directly related to baffle size (giving the low frequency limit, baffle step) and transducer size (high frequencies start to beam), diffraction interference happens on this bandwidth to the listening window. I'm doing it on VituixCAD and have posted many screenshots and texts on the observations so that anyone could check it out. It is most effective to do by your self since it is more real time, you'll see immediately what the trend is when you enlarge or minimize the baffle, or add roundovers and what size roundovers are effective.
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Tmuikku,
If wide baffle was an issue, infinite baffle would be a no no especially in pro environnement.
It's a compromise as always. Your view on it is ok given a certain set of constraints, once you've got a different set of constraints it might be different.
Here is an hint about 'wide' baffle: once you are around 50cm width (~250hz) and you have minimum edge diffraction solution implemented (- roundover or slanted-) the diffraction happens on frequency where first reflection, diffraction and direct sound merge ( on 'typical' domestical room) ... no way to differenciate them= no more issues.
Some foods for thoughts ( not nescessarly for you Tmuikku):
Infinite-baffle
If wide baffle was an issue, infinite baffle would be a no no especially in pro environnement.
It's a compromise as always. Your view on it is ok given a certain set of constraints, once you've got a different set of constraints it might be different.
Here is an hint about 'wide' baffle: once you are around 50cm width (~250hz) and you have minimum edge diffraction solution implemented (- roundover or slanted-) the diffraction happens on frequency where first reflection, diffraction and direct sound merge ( on 'typical' domestical room) ... no way to differenciate them= no more issues.
Some foods for thoughts ( not nescessarly for you Tmuikku):
Infinite-baffle
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10"would make open baffle possible?
Im open for 8 or 10". 10 will have some consequence if one want to build a narrow baffle tower though.
Maybe it still can be one of the alteration. An OB with 10" (or 2) but with same mid and tweet. Trying to minimise cost so it stay accessible.
The "box-design demands bigger woofers. What is there to be gained and what's the down side of going OB. This can be discussed during that alternative design. A newby can learn from the experts and evaluate if he wants to built it or not.
This is exactly what I mean with believers and non believers. I dont judge, Im a newby, I want to learn.Tmuikku,
If wide baffle was an issue, infinite baffle would be a no no especially in pro environnement.
It's a compromise as always. Your view on it is ok given a certain set of constraints, once you've got a different set of constraints it might be different.
Here is an hint about 'wide' baffle: once you are around 50cm width (~250hz) and you have minimum edge diffraction solution implemented (- roundover or slanted-) the diffraction happens on frequency where first reflection, diffraction and direct sound merge ( on 'typical' domestical room) ... no way to differenciate them= no more issues.
Some foods for thoughts ( not nescessarly for you Tmuikku):
Infinite-baffle
When the subject pop's up with buidling this alterative design..ppl with experience can share their thoughts. I as a newby will make the evaluation if the benefits/down sides are worth the build. But When I built it, I know that the design is made to the best possible given the conditions.