I am still not finished building my monster OB line array speakers but am already looking ahead for a next build
My next build will run also use a ESS Heil tweeter >3khz
The mids will be two alpair 12p's
For the woofers I am eying the 21" Lii Song OB drivers. Problem is there are 2 versions from 2 different Lii Songs.....
Version A
Version B
Version A has higher QTS and QMS and dual voice coil.
Version B has vented pole piece, higher VAS and thicker plates and looks a little more premium to me, even though it is slightly cheaper.
Which one would you pick and why?
My next build will run also use a ESS Heil tweeter >3khz
The mids will be two alpair 12p's
For the woofers I am eying the 21" Lii Song OB drivers. Problem is there are 2 versions from 2 different Lii Songs.....
Version A
Version B
Version A has higher QTS and QMS and dual voice coil.
Version B has vented pole piece, higher VAS and thicker plates and looks a little more premium to me, even though it is slightly cheaper.
Which one would you pick and why?
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LiI song is not really known for their realistic specs i'm affraid, so that MMS is probally not on spec.
I would also rather use Aucoustic Elegance dipole woofers as endgame for OB's than Lii Song. But if you already ordered them... Measure them before use and adapt your design to it.
I would also rather use Aucoustic Elegance dipole woofers as endgame for OB's than Lii Song. But if you already ordered them... Measure them before use and adapt your design to it.
It may be my endgame speaker, but not cost no object. A 21" Lii Song costs about the same as a 15" acoustic elegance.... And I am in Asia so shipping for the AE's would be a killer too. So per displacement unit the AE drivers would cost about 2.5x more I guess.
Some users raved about the Lii song W15 (similar to version A) (including well known reviewer Thomas and stereo) so they can't be that bad....
A vented pole is going to have an unusual rear radiator pattern and will have wind noise at higher excursions…..neither are desirable for dipole use.
Those cone profiles and baskets are very deep…..it’s going to be challenging aligning the acoustic offset of those woofers to your Heil……as a line source, this will present significant design challenges to the baffle layout
Those cone profiles and baskets are very deep…..it’s going to be challenging aligning the acoustic offset of those woofers to your Heil……as a line source, this will present significant design challenges to the baffle layout
Good point
The idea is to have a 250cm tall welded stainless steel frame made from tubes filled with sand. Only the 21" bass drivers have 65x80cm baffles. The other drivers are baffleless and suspended from wires. They can easily be moved backwards and forward.
Understood…..but the problem remains…….you’ll still have to offset the nude midwoofers behind……and given their Omni patterns, having fwd energy reflecting off the back side of the woofer baffle is going to create very deep dipoke cancellations at frequencies related to distance……this will get very messy very quickly………especially in the crossover region of the woofers and midwoofers…….you won’t be able to produce any phase quadrature and this will be very audible. Where the wavelengths are long, the changes will be abrupt but out in the room, after time delay the number of lobes will be exponential.
Don’t use sand……use a heavy weight motor oil instead……much better elasto viscosity and won’t compress like sand over time…..sheer factor is vastly lower than sand as well. Create a fill spout on top.
I guess some kind of thick felt shelf should alleviate this. Another option is using a horn in stead of the alpairs.
I don't have the alpairs yet but do own a pair of 18 sound nd3st compression drivers and a few horns. On the best horn it sounds amazing and has very low distortion. But I still.hear a slight "horny" sound. A proper biradial horn with fins should eliminate this. I was already thinking about making biradial horns out of concrete so this would be a good excuse to actually make them.
So a possible alternative is 2x18" Woofers, 1x 12" Neodymium midwoofer, 1x nd3st + biradial, 1x ESS Heil or horn loaded super tweeter. So not fully dipole anymore but for me dipole bass is the most important. I may even put the 12" midwoofer in a aperiodic enclosure so it increasingly becomes more monopole the higher the frequency.
I kind of like this arrangement. It potentially is 100dB sensitive if using a super tweeter instead of the heil.
Also there is a lot of frequency overlap. After many tests with dsp crossovers I always favor first order crossovers so the overlap is needed.
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No……I think you have the right ‘idea’ for OB bass with lots of displacement as the only real option……but avoid having those large drivers play OB into the midbass……….this is where you’re going to run into significant directivity issues and time smearing. Dedicate the midbass to its own subset of drivers into the midrange……..say 100hz to 800hz……EASILY served with a single 15” driver in an OB alignment
Are you saying a 200 or 250 Hz crossover frequency is too high for a 98db sensitive low Le 18" driver with a frequency graph that doesn't start dropping off until 2khz? A 18" driver shouldn't start beaming before 900 Hz or thereabouts. With a 1st order crossover @200hz it is already more than 12db down at that point and most sound is already produced by the 12" midbass driver.
After a PM showing a system with extremely low crossover points for 18" followed by a 15" with still a quite low crossover frequency I may have seen the light.
I think now I get where mayhem13 is coming from.
A 18" can play higher but you don't want it to. At 200 or 300 Hz a smaller driver is arguably better so if striving for perfection you want a smaller driver there. I am stubborn so it took a while to sink in.
New concept:
<80Hz 2x 18" (or 21")
<240Hz 15" p audio SNII-15LF
240-720Hz 12" P.AUDIO SN-12MB II
720-2160Hz Alpair 12
2160-6480Hz Biradial Horn 18 sound nd3st
+6480Hz ESS Heil
I think now I get where mayhem13 is coming from.
A 18" can play higher but you don't want it to. At 200 or 300 Hz a smaller driver is arguably better so if striving for perfection you want a smaller driver there. I am stubborn so it took a while to sink in.
New concept:
<80Hz 2x 18" (or 21")
<240Hz 15" p audio SNII-15LF
240-720Hz 12" P.AUDIO SN-12MB II
720-2160Hz Alpair 12
2160-6480Hz Biradial Horn 18 sound nd3st
+6480Hz ESS Heil
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1. distortion is in the bass - so go for 2 21” - i understand that
wouldn’t it be better to choose only one woofer and one midrange to cover the range to the 18 sound nd3st ?
if you want more units in between because of low order filtering, i think you shouldn’t double them
2. biradial horn 18 sound nd3st - why did you choose this driver which is one-directional?
wouldn’t it be better to choose only one woofer and one midrange to cover the range to the 18 sound nd3st ?
if you want more units in between because of low order filtering, i think you shouldn’t double them
2. biradial horn 18 sound nd3st - why did you choose this driver which is one-directional?
I also think your driver choice is not very logic. I would do it different for a fullrange system OB.
I would use Ripole style subwoofers, or something like a Dayton UM18-22 (high q, high xmax low FS) woofer in a H frame
For midbass i would use probally a Faital 12FE300 (high q, decent xmax and higher fs) to about 1.5kHz where that Heil or a good compression driver and horn could take over. You can split those bands above that, but i would do it in one horn (coaxial compression driver), not mixing up types of tweeters that you can't phycially put close enough to avoid lobbing. That ND3T can easely cross at 1.5kHz in the right horn (XT1086)
That would be end game for me, what you do is throw a bunch of drivers you like toghetter, but you don't really consider how they will fit to each other. And that Heil is recommend to use down to about 1kHz and works very well that low, why do you want to use it as super tweeter? It makes no sense to me.
Off course, just my thoughts about this project. You do with it what you want.
I would use Ripole style subwoofers, or something like a Dayton UM18-22 (high q, high xmax low FS) woofer in a H frame
For midbass i would use probally a Faital 12FE300 (high q, decent xmax and higher fs) to about 1.5kHz where that Heil or a good compression driver and horn could take over. You can split those bands above that, but i would do it in one horn (coaxial compression driver), not mixing up types of tweeters that you can't phycially put close enough to avoid lobbing. That ND3T can easely cross at 1.5kHz in the right horn (XT1086)
That would be end game for me, what you do is throw a bunch of drivers you like toghetter, but you don't really consider how they will fit to each other. And that Heil is recommend to use down to about 1kHz and works very well that low, why do you want to use it as super tweeter? It makes no sense to me.
Off course, just my thoughts about this project. You do with it what you want.
If you use 12" in range <400Hz, this mean, frame must be relatively small, dipole peak must be little lower than 400 and this mean that response will fall out before 80Hz so there will be gap between 21" response, as 12" and 21" drivers are connected to same DSP channel, there is not possible to use separate compensations for them.
My driver choices may not seem logical but are derived from the following criteria:
The speaker has to play loud in a very large room.
I only want to use first order crossovers. So each driver has to overlap at the top and bottom the next driver for at least 2 octaves flat. I know you can cross the Heils at 1 or 2khz but not with a first order crossover at 110db
I wonder what is a safe 1st order crossover point for the Heil tweeter? 3khz? 4Khz? Couldn't find any info on this.
The speaker has to play loud in a very large room.
I only want to use first order crossovers. So each driver has to overlap at the top and bottom the next driver for at least 2 octaves flat. I know you can cross the Heils at 1 or 2khz but not with a first order crossover at 110db
I wonder what is a safe 1st order crossover point for the Heil tweeter? 3khz? 4Khz? Couldn't find any info on this.