I can't seem to find anything about that subject either here or on tubes ,
would be greatful if you knowledgeable guys could chime in a bit on that to enlighten a total noob as meself 🙂
So simply, what would be the result of using a large quantity of smaller diameter woofers or midranges against using traditional single dual or few pretty large woofers/subwoofers .
Not trying to go into specifics here, only trying to understand how all this works slowly so my little brain can process it one bit at a time
This questioning came to mind when trying to understand relation between mass of drivers ( moving mass ? ) vs speed and sound pressure .
Wouldn't a multitude of lower mass drivers have better response and decay than a much larger single unit for the same perceived volume ?
Thanks for your time 🙂
would be greatful if you knowledgeable guys could chime in a bit on that to enlighten a total noob as meself 🙂
So simply, what would be the result of using a large quantity of smaller diameter woofers or midranges against using traditional single dual or few pretty large woofers/subwoofers .
Not trying to go into specifics here, only trying to understand how all this works slowly so my little brain can process it one bit at a time
This questioning came to mind when trying to understand relation between mass of drivers ( moving mass ? ) vs speed and sound pressure .
Wouldn't a multitude of lower mass drivers have better response and decay than a much larger single unit for the same perceived volume ?
Thanks for your time 🙂
Depends how you calculate it.
If you want highest motor strength and lowest weight per membrane area then probably multiples of 15" high sensitivity pro drivers.
Varies from driver to driver though, hard to find 12" high sensitivity pro drivers with good parameters for subs, midrange yes, but then it's probably better to go for a good 10" instead.
Edit:
Not sure what SPL you're chasing and what size boxes you're looking at building, so without any guidelines that's my answer.
If you want highest motor strength and lowest weight per membrane area then probably multiples of 15" high sensitivity pro drivers.
Varies from driver to driver though, hard to find 12" high sensitivity pro drivers with good parameters for subs, midrange yes, but then it's probably better to go for a good 10" instead.
Edit:
Not sure what SPL you're chasing and what size boxes you're looking at building, so without any guidelines that's my answer.
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Well, if we take a sort of middle value of about 140cm2 (somewhat generous perhaps) and multiply that by 20 we get 2800cm2 which is quite respectable.
With such a nice membrane area you are not really hampered by lack of xmax and higher fs and would get pretty nice sensitivity, but the weight per membrane area would probably be higher than if you chose multiples of 15" pro drivers (860 x 3 = 2580cm2, 860 x 4 = 3440cm2).
Another thing is that I highly doubt you can get 20 x 6.5" cheaper than 2-4 x 15", and that's ignoring quality and T/S parameters, xmax and FS would likely be much better for the 15" unless you're talking very expensive and special 6.5".
Edit:
I would perhaps evaluate a quad of 12" per channel before thinking about 10 x 6.5" per channel. Cheapest 12" with low-ish fs and light membrane area that I can get is probably the Fane 12-300, alot cheaper than getting a pile of 6.5". Not sure where you can get cheap drivers in Canada though. Perhaps better off ordering something from PE.
With such a nice membrane area you are not really hampered by lack of xmax and higher fs and would get pretty nice sensitivity, but the weight per membrane area would probably be higher than if you chose multiples of 15" pro drivers (860 x 3 = 2580cm2, 860 x 4 = 3440cm2).
Another thing is that I highly doubt you can get 20 x 6.5" cheaper than 2-4 x 15", and that's ignoring quality and T/S parameters, xmax and FS would likely be much better for the 15" unless you're talking very expensive and special 6.5".
Edit:
I would perhaps evaluate a quad of 12" per channel before thinking about 10 x 6.5" per channel. Cheapest 12" with low-ish fs and light membrane area that I can get is probably the Fane 12-300, alot cheaper than getting a pile of 6.5". Not sure where you can get cheap drivers in Canada though. Perhaps better off ordering something from PE.
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Generally speaking, smaller drivers will have more distortion in the lowest couple of audio octaves, a higher Fs, and lower Xmax than larger/subwoofer type drivers.
Input power requirements and voltage sensitivity are a couple of other things to consider.
All in all, there are some good reasons that subwoofers are built from a single larger diameter driver and not N smaller ones. Although many modern lower priced (e.g. under $2k) consumer tower speakers use three or four 6.5" class woofers in a vented enclosure for bass, they are not going into "subwoofer" territory and this design approach is mostly driven by cost and the ability to put out a "slim" product that can be placed on either side of a large TV, etc.
I did build something along these lines once - I used IIRC six Seas L21RNX/P in a ten or fifteen cubic foot vented box that I hid in my attic, with only the drivers visible thru the wall. It was capable of low bass into the mid 20s, but suffered from flabby bloated bass. I used for a few years and then dismantled it.
Input power requirements and voltage sensitivity are a couple of other things to consider.
All in all, there are some good reasons that subwoofers are built from a single larger diameter driver and not N smaller ones. Although many modern lower priced (e.g. under $2k) consumer tower speakers use three or four 6.5" class woofers in a vented enclosure for bass, they are not going into "subwoofer" territory and this design approach is mostly driven by cost and the ability to put out a "slim" product that can be placed on either side of a large TV, etc.
I did build something along these lines once - I used IIRC six Seas L21RNX/P in a ten or fifteen cubic foot vented box that I hid in my attic, with only the drivers visible thru the wall. It was capable of low bass into the mid 20s, but suffered from flabby bloated bass. I used for a few years and then dismantled it.
Smaller drivers typically have less cone excursion ability than larger drivers do, so enough small drivers would need to be used to make up for that, as well as providing the total cone radiating area of the original driver.
+1 There's no 'replacement for displacement', so need to compare 'apples to apples' to get comparable performance. 😉
Thanks all for your great input . Much appreciated.
a few things though ...
i ain't asking about all this for any project or planning, rather trying to understand and learn basics here , so please keep in mind all this only theoritical
First, about moving mass .... wouldn't each smaller lighter drivers count individually against larger heavier ones ?
I meam, transient/speed/decay is for individual driver and total movement/speed required is inversly affected by the quantity of drivers used to attain X pressure ?
Then, is there data out ( or you guys might already know the answer/info ) on how using mulitpled drivers affects their distortion/speed/decay etc ?? Does everything improve when using less power on a driver ? surely there is some diminishing return in there...
Lastly, let's use an example .. the Tekton midrange " tweeter " arrays .
With my very limited knowledge and the little info i have on those, they seem to perform very well down in the "midrange " for a bunch or " tweeters " , is there some kind of drawback that the manuf isn't talking about here? ( manuf exposing drawbacks on their products is a rarity i guess lol )
That example could bring us to something like :
Would an array of 10 12" drivers perform better than 2 15" of similar properties?
or even i could go with as simple as : Does using a larger amount of the same driver, for bass and sub bass specifically, produce higher quality sound with the same/similar setup ??
a few things though ...
i ain't asking about all this for any project or planning, rather trying to understand and learn basics here , so please keep in mind all this only theoritical
First, about moving mass .... wouldn't each smaller lighter drivers count individually against larger heavier ones ?
I meam, transient/speed/decay is for individual driver and total movement/speed required is inversly affected by the quantity of drivers used to attain X pressure ?
Then, is there data out ( or you guys might already know the answer/info ) on how using mulitpled drivers affects their distortion/speed/decay etc ?? Does everything improve when using less power on a driver ? surely there is some diminishing return in there...
Lastly, let's use an example .. the Tekton midrange " tweeter " arrays .
With my very limited knowledge and the little info i have on those, they seem to perform very well down in the "midrange " for a bunch or " tweeters " , is there some kind of drawback that the manuf isn't talking about here? ( manuf exposing drawbacks on their products is a rarity i guess lol )
That example could bring us to something like :
Would an array of 10 12" drivers perform better than 2 15" of similar properties?
or even i could go with as simple as : Does using a larger amount of the same driver, for bass and sub bass specifically, produce higher quality sound with the same/similar setup ??
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excuse my unexperienced self here ..
was trying to look up something like " power against distortion "
after some time ended up on mr Linkwitz website ( brings up pas memories there lol )
So quickly interpreting this simple page ... looks like most of the distortion
from increases quite linearly to SPL increase ??
Anyone has a good link for definition of distortion on audio drivers ?
thinking about it i've never actually read about that and always assumed it is some kind of cumulative result of a few different problems ??
So then using multiple drivers to get to the same desired spl should theoritically reduce the driver induced distortions ?
was trying to look up something like " power against distortion "
after some time ended up on mr Linkwitz website ( brings up pas memories there lol )
So quickly interpreting this simple page ... looks like most of the distortion
from increases quite linearly to SPL increase ??
Anyone has a good link for definition of distortion on audio drivers ?
thinking about it i've never actually read about that and always assumed it is some kind of cumulative result of a few different problems ??
So then using multiple drivers to get to the same desired spl should theoritically reduce the driver induced distortions ?
Attachments
Something to note here: the speed at which cones move, below 100Hz, is very very slow. Any conventional driver will have no trouble following a waveform that only contains low frequencies.
As you increase the frequency, the cone must move faster:
https://www.diyaudio.com/forums/multi-way/358425-questions-baffle-speakers-2.html#post6302335
Chris
1. An opportunity to spread them in multi-sub style.. or
2. An opportunity to put them in series and build an OTL, if that's your thing.
3. Bass array.
2. An opportunity to put them in series and build an OTL, if that's your thing.
3. Bass array.
Brings back memories of when I first got into diy.
Those 12's look like midbass drivers these days.
Those 12's look like midbass drivers these days.
Wow ok , much much appreciated but all that stuff takes me hours to read, grasp and reflect upon ..lol
Sorry still a slowish noob here so i will try to work with you guys 1 at a time,
hope i understand most of it correctly...
Than i thank you all for making me work my brain and learning new things like that, awesome stuff already 🙂
chris661 : thanks mate, took me quite a while looking at your graphs to understand what it was about .. lol
Not going to pretend i understand it all here,
but very interesting relation between displacement/frequency/velocity/acceleration
may i ask why the crazy dip in both the velo and acell graphs at around 65hz ish ??
If i kinda understand correctly, it means that there would be some kind of range or point at which using smaller drivers to try and match larger ones is definetely not worth it because the required tradeoff of motor strength against the much slowish acceleration drops immensly
( i fully agree that many commercial designs might be largely influenced by other characteristics than real efficiency and performance , which is usually the case is any commercial product neway )
AllenB hi mate from the other side of the world 🙂
I am not sure exactly what you meant there ...
Opportunity to use lots of drivers and have fun with crazy setups ?? 🙂
freddi thanks for taking time to post those
Unfortunately i am not familiar enough to interpret most of it
What kind of conclusion can we take from your graphs there ?
The first iteration is already at 100db at 30hz ? ouch lol
2Pi 90v ? is that some standard of measurement ?
2Pi = half spherical dispertion ? ( can't believe i forgot all that )
those numbers look crazy to me
What about the displacement charts ? it is a little bit small to get details
and since i have zero experience with cone displacement i have nothing
to compare it to
Sorry still a slowish noob here so i will try to work with you guys 1 at a time,
hope i understand most of it correctly...
Than i thank you all for making me work my brain and learning new things like that, awesome stuff already 🙂
chris661 : thanks mate, took me quite a while looking at your graphs to understand what it was about .. lol
Not going to pretend i understand it all here,
but very interesting relation between displacement/frequency/velocity/acceleration
may i ask why the crazy dip in both the velo and acell graphs at around 65hz ish ??
If i kinda understand correctly, it means that there would be some kind of range or point at which using smaller drivers to try and match larger ones is definetely not worth it because the required tradeoff of motor strength against the much slowish acceleration drops immensly
( i fully agree that many commercial designs might be largely influenced by other characteristics than real efficiency and performance , which is usually the case is any commercial product neway )
AllenB hi mate from the other side of the world 🙂
I am not sure exactly what you meant there ...
Opportunity to use lots of drivers and have fun with crazy setups ?? 🙂
freddi thanks for taking time to post those
Unfortunately i am not familiar enough to interpret most of it
What kind of conclusion can we take from your graphs there ?
The first iteration is already at 100db at 30hz ? ouch lol
2Pi 90v ? is that some standard of measurement ?
2Pi = half spherical dispertion ? ( can't believe i forgot all that )
those numbers look crazy to me
What about the displacement charts ? it is a little bit small to get details
and since i have zero experience with cone displacement i have nothing
to compare it to
Crazy setups, eh? Could be. Dealing with room modes is a better proposition when you can spread your bass around.
Will P What kind of monster setup is that 🙂
Crazy stuff there ... whe i quickly parsed through the first post i thought i had read 15" ..but you were referencing for the displacement or something lol
so 8 " drivers it is ... very neat setup for sure
And all that goes out through the little floor grills ? damn
" That shows the advantages of using multiple smaller subs vs one single sub even when the displacement is equal. "
So the key here would be " equal or similar " displacement ??
Are your measurements very good ? i can relate to 1%THD but not sure i can understand the details and why so many similar graphs
( you in Canada right ? red tech tape, roxul .. i might be wrong here )
GM I totally recall reading about that setup back when i started to lurk around here ( must be like 15 years ago now )
That is one sick setup for sub ... ( talking about the Shiva stuff you linked )
You might not remember because lots of folks move around here
but iirc, we discussed my HT room setup when i was on the drawing board for the new house
( found some part of the thread was in like 2007 crazy ..you helped quite a bit and i thank you again 🙂
Unfortunately, priorities changed and things happened and the HT room is still used as a storage room for now,but slowly emptying it out and installing things in the house
( still working on interior finish after 10 years .... mentally tired but can't stop lol )
I did get to build and prep the " Infinite Bass array wall " and the extreme rear baffle and port that lead to the 25X30 garage .
Crazy stuff there ... whe i quickly parsed through the first post i thought i had read 15" ..but you were referencing for the displacement or something lol
so 8 " drivers it is ... very neat setup for sure
And all that goes out through the little floor grills ? damn
" That shows the advantages of using multiple smaller subs vs one single sub even when the displacement is equal. "
So the key here would be " equal or similar " displacement ??
Are your measurements very good ? i can relate to 1%THD but not sure i can understand the details and why so many similar graphs
( you in Canada right ? red tech tape, roxul .. i might be wrong here )
GM I totally recall reading about that setup back when i started to lurk around here ( must be like 15 years ago now )
That is one sick setup for sub ... ( talking about the Shiva stuff you linked )
You might not remember because lots of folks move around here
but iirc, we discussed my HT room setup when i was on the drawing board for the new house
( found some part of the thread was in like 2007 crazy ..you helped quite a bit and i thank you again 🙂
Unfortunately, priorities changed and things happened and the HT room is still used as a storage room for now,but slowly emptying it out and installing things in the house
( still working on interior finish after 10 years .... mentally tired but can't stop lol )
I did get to build and prep the " Infinite Bass array wall " and the extreme rear baffle and port that lead to the 25X30 garage .
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In that particular simulation, it's a ported box where the port is tuned to 65Hz. In that system, the air movement in the port exerts a large amount of pressure on the cone, so that the cone itself is strongly prevented from moving. The peak excursion is almost zero, and therefore the velocity and acceleration also decrease.
IMO it becomes a point where you wish for more extension towards the top of the range, and a large driver cannot do that job. One of the best 15" midbass units in the world (Beyma 15P80Nd) is getting raggy at 2kHz. Most 15"s won't get past 1kHz without issues.
Used properly, I'd rather listen to a 15" bass driver than a 6" bass driver. Other factors may force the decision in a different direction, though.
Chris
I learnt decades ago that a very sound idea for any sub is to 'Move a Lot of Air - Gently!'. A few 8" drivers flapping around at Xmax might be able to produce the same spl as a 21" moving almost imperceptibly, however I prefer the sound of the latter. I have never entertained using multiple smaller drivers - cost being a major consideration - but it certainly sounds like fun as an experiment.