After Christmas I hope to start building a set of 2 way open baffle Line arrays, based on 12x Slim 8” from GRS GRS PT6816-8 8" Planar Slim Tweeter 8 Ohm and 9x WS25e woofers from Visaton (cheap driver and I got nice results from them in previous builds).
All drivers will be used nude, I will use 2.5mm stranded wire for hanging them from the ceiling (and power the drivers). The crossover point will be somewhere around 750Hz (unfortunately cannot get lower as the Slims start distorting). With time I may add some sort of subwoofer to the system.
I have been thinking how to arrange the arrays to each other to obtain the “best results”. One consideration is the gap (distance) between the woofer and slim array: higher value would probably be better to let either array operate without influence from the others array “baffle”, OTOH the distance should be low thinking about the “ideally less than ¼ of wavelength” distance between drivers.
The other consideration is alignment of the acoustic output, for time (or phase) alignment of the drivers. It can be expected that, seen from the top, the slims will have to be shifted back for best time alignment. But that would put the woofers in the way of the dipole radiation of the slims, which I do not think is a good idea. So maybe mount the slims aligned with the front of the woofers and add the delay in the crossover, like shown in the picture?
I will have a wooden plate attached to the ceiling and will be able to shift the drivers in an area of about 360 (wide) x 200mm (deep), so there will be some experimenting on its way. Still, very curious about your opinions!
Many thanks, Erik
All drivers will be used nude, I will use 2.5mm stranded wire for hanging them from the ceiling (and power the drivers). The crossover point will be somewhere around 750Hz (unfortunately cannot get lower as the Slims start distorting). With time I may add some sort of subwoofer to the system.
I have been thinking how to arrange the arrays to each other to obtain the “best results”. One consideration is the gap (distance) between the woofer and slim array: higher value would probably be better to let either array operate without influence from the others array “baffle”, OTOH the distance should be low thinking about the “ideally less than ¼ of wavelength” distance between drivers.
The other consideration is alignment of the acoustic output, for time (or phase) alignment of the drivers. It can be expected that, seen from the top, the slims will have to be shifted back for best time alignment. But that would put the woofers in the way of the dipole radiation of the slims, which I do not think is a good idea. So maybe mount the slims aligned with the front of the woofers and add the delay in the crossover, like shown in the picture?
I will have a wooden plate attached to the ceiling and will be able to shift the drivers in an area of about 360 (wide) x 200mm (deep), so there will be some experimenting on its way. Still, very curious about your opinions!
Many thanks, Erik
Attachments
Well it will certainly look unusual! 😀
How are the GRS slim planars? I remember seeing something about them on the Exotics forum. Are they worth buying?
To me your ideas above seem reasonable, but you are getting close to uncharted waters and will likely need to experiment a good bit. While some of what you are doing is known, how all the elements influence each other and the room is much harder to predict. I'm not sure about using the drivers without any baffles, your bass losses on OB are bad enough with a baffle, with none at all won't you just get mids?
We will want to see pictures, of course.
How are the GRS slim planars? I remember seeing something about them on the Exotics forum. Are they worth buying?
To me your ideas above seem reasonable, but you are getting close to uncharted waters and will likely need to experiment a good bit. While some of what you are doing is known, how all the elements influence each other and the room is much harder to predict. I'm not sure about using the drivers without any baffles, your bass losses on OB are bad enough with a baffle, with none at all won't you just get mids?
We will want to see pictures, of course.
Very curious how you will like the WS25E! It is so cheap and ideal as dipole woofer.
I decided to use 1x15" in a H-frame but think about changing that to 2xWS25E per side.
Their Qts is ideal but haven´t heard of many people using it in a plane baffle. (only the WS17E)
H-frame supposedly works very well for the WS25E (there are plans available too).
I decided to use 1x15" in a H-frame but think about changing that to 2xWS25E per side.
Their Qts is ideal but haven´t heard of many people using it in a plane baffle. (only the WS17E)
H-frame supposedly works very well for the WS25E (there are plans available too).
Hi Pano,
many thanks for your reply. The overall impression of the slims seem to be good. More people measured them and they look nice. Also, Parts Express had them sold out for a while, but they are in stock again.
Two recent dipole arrays shown here at Diyaudio are those of Mlee and Darkheart. https://www.diyaudio.com/forums/mul...t-line-array-floor-ceiling-3.html#post6161857 and https://www.diyaudio.com/forums/multi-way/337631-radian-audio-lm8k-2.html#post6366395. Both have used larger drivers for the bass. In my room I can not fit such a wide baffle, so I decided to go for the 245mm wide Visaton units. There could be other advantages as well by limiting the width of the baffle. I played with 6 nude units per side in a previous build, and that was quite nice already, now with 9 and the "increased efficiency" of running them in a line array I think I will be fine (also, not listening to Bach fugues or watching action movies...). But, yes, our living room still needs a coffee table, and I am thinking about some sort of folded dipole subwoofer with 4 long stroke 12" woofers that I have, with the external dimensions of a small coffee table playing up to about 60Hz.
A fast question: could you replace the OB in the thread title with dipole? OB is often associated with big baffles that consequently do not have dipole characteristics ovhe the whole frequency response. And I am trying to run dipole as high as possible.
many thanks for your reply. The overall impression of the slims seem to be good. More people measured them and they look nice. Also, Parts Express had them sold out for a while, but they are in stock again.
Two recent dipole arrays shown here at Diyaudio are those of Mlee and Darkheart. https://www.diyaudio.com/forums/mul...t-line-array-floor-ceiling-3.html#post6161857 and https://www.diyaudio.com/forums/multi-way/337631-radian-audio-lm8k-2.html#post6366395. Both have used larger drivers for the bass. In my room I can not fit such a wide baffle, so I decided to go for the 245mm wide Visaton units. There could be other advantages as well by limiting the width of the baffle. I played with 6 nude units per side in a previous build, and that was quite nice already, now with 9 and the "increased efficiency" of running them in a line array I think I will be fine (also, not listening to Bach fugues or watching action movies...). But, yes, our living room still needs a coffee table, and I am thinking about some sort of folded dipole subwoofer with 4 long stroke 12" woofers that I have, with the external dimensions of a small coffee table playing up to about 60Hz.
A fast question: could you replace the OB in the thread title with dipole? OB is often associated with big baffles that consequently do not have dipole characteristics ovhe the whole frequency response. And I am trying to run dipole as high as possible.
Hi Joensd
As commented in my previous post, I have the WS25e since years and they have not let me down. In a more recent build I used the SB34NRX75-16, which has more swept volume (higher SD and higher XMax). I thought a lot about using these for the line arrays, but besides being more expensive, they are 100mm wider than the WS25e and I am not sure they would play up well up to the 800Hz I need. THe datasheet shows some wiggles in both frequency response and impedance at around 680Hz
SB Acoustics SB34NRX75-16 12" Woofer, 16 ohm I think I will end up putting these in a folded dipole woofer, maybe a ripole as it is the most compact build and reduces Fs. Ripoles can't be used that high, but the WS25es's must work a bit as well 🙂
As commented in my previous post, I have the WS25e since years and they have not let me down. In a more recent build I used the SB34NRX75-16, which has more swept volume (higher SD and higher XMax). I thought a lot about using these for the line arrays, but besides being more expensive, they are 100mm wider than the WS25e and I am not sure they would play up well up to the 800Hz I need. THe datasheet shows some wiggles in both frequency response and impedance at around 680Hz
SB Acoustics SB34NRX75-16 12" Woofer, 16 ohm I think I will end up putting these in a folded dipole woofer, maybe a ripole as it is the most compact build and reduces Fs. Ripoles can't be used that high, but the WS25es's must work a bit as well 🙂
Before the Slims became available I ordered a box of the new 3" Fullrange driver from SB. SB Acoustics SB10PGC21-4 - 3" Full-range and made a first dipole line array with 32 units (the other 32 units are in their boxes...). I have this mounted in our cellar, which I transformed in my hobby space. The bass is being provided by 8 units of the very cheap MCM drivers 55-3212, another alternative I considered along with the VIsatons and the SB acoustic drivers.
With my Umik I measured the response, put a xover and some equalization in there, and have been listening to some nice stuff from ECM records and the sound is very nice indeed. So the plan was to move these 3" to the living room, but then the Slims popped up and I decided to use them. The MCMs provide the bass I need, but as 12" they are also quite wide and have therefore decided against them.
With my Umik I measured the response, put a xover and some equalization in there, and have been listening to some nice stuff from ECM records and the sound is very nice indeed. So the plan was to move these 3" to the living room, but then the Slims popped up and I decided to use them. The MCMs provide the bass I need, but as 12" they are also quite wide and have therefore decided against them.
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Sorry Erik, I obviously missed that remark about your previous builds..
These were of the dipole kind too I guess?
What kind of baffle (if any) and do you use EQ?
These were of the dipole kind too I guess?
What kind of baffle (if any) and do you use EQ?
Looking forward to seeing these monsters! I'm sure you will like the presentation.
Hopefully you can move the GRS Slim XOVER down a bit once the arrays are in position. I wanted to try and get close to the 1/4 wavelength between the midrange and woofer panel due to the side by side forced placement of the drivers but it might not matter that much in your room/listening position.
Hopefully you can move the GRS Slim XOVER down a bit once the arrays are in position. I wanted to try and get close to the 1/4 wavelength between the midrange and woofer panel due to the side by side forced placement of the drivers but it might not matter that much in your room/listening position.
Hi Erik,
Interesting project, good luck with it!
I´m not sure if it is helpful, but as I´m flying my black flowers from the (well reinforced) ceiling as well, please find 2 photos of my mounting device attached, which allows for shifting positions and adjusting angles. Maybe it´s good for some inspiration.
Another issue is the ratio between moving mass of the bass drivers versus physical mass, which led me to added weight at the woofers motor. I ended up around 1:250 and found that quite a bit better than around 1:120 I had before, bass was more precise and clear, even better located in space. Just a thought...
All the best
Mattes
Interesting project, good luck with it!
I´m not sure if it is helpful, but as I´m flying my black flowers from the (well reinforced) ceiling as well, please find 2 photos of my mounting device attached, which allows for shifting positions and adjusting angles. Maybe it´s good for some inspiration.
Another issue is the ratio between moving mass of the bass drivers versus physical mass, which led me to added weight at the woofers motor. I ended up around 1:250 and found that quite a bit better than around 1:120 I had before, bass was more precise and clear, even better located in space. Just a thought...
All the best
Mattes
Attachments
Looking forward to seeing these monsters! I'm sure you will like the presentation.
Hopefully you can move the GRS Slim XOVER down a bit once the arrays are in position. I wanted to try and get close to the 1/4 wavelength between the midrange and woofer panel due to the side by side forced placement of the drivers but it might not matter that much in your room/listening position.
Hi mlee,
thanks for the reply. Member Darkheart mentioned he uses two xover points between woofers and his Radian drivers, and this would surely be a possibility in my case as well.
Next week I hope to have these finished!
Erik
Hi Erik,
Interesting project, good luck with it!
I´m not sure if it is helpful, but as I´m flying my black flowers from the (well reinforced) ceiling as well, please find 2 photos of my mounting device attached, which allows for shifting positions and adjusting angles. Maybe it´s good for some inspiration.
Another issue is the ratio between moving mass of the bass drivers versus physical mass, which led me to added weight at the woofers motor. I ended up around 1:250 and found that quite a bit better than around 1:120 I had before, bass was more precise and clear, even better located in space. Just a thought...
All the best
Mattes
Hi Mattes,
Thanks for the reply and input. The plan is to hide these line arrays behind white speaker fabric, turning them in a sort of room divider. So yes, I have been considering some sort of rail system for the speakers, but it must not look as nice as yours: I will use Bosch RExroth extrusion profiles and some acessoires in my first attempts!
Regarding the mass relation, indeed, when looking at the WS25e I would not mind a bit more mass on them. I just calculated that I am at about 1 to 40 now, and if I would want 1 to 250, I should add about 50kgs to each side. I think the ceiling can take it, so yes, will make it so strong to be able to add additional mass later.
thanks again!
Erik
Mattes... fascinating build. Is there a thread where you discuss performance?I´m not sure if it is helpful, but as I´m flying my black flowers from the (well reinforced) ceiling as well, please find 2 photos of my mounting device attached, which allows for shifting positions and adjusting angles. Maybe it´s good for some inspiration.
Another issue is the ratio between moving mass of the bass drivers versus physical mass, which led me to added weight at the woofers motor. I ended up around 1:250 and found that quite a bit better than around 1:120 I had before, bass was more precise and clear, even better located in space.
I am no speaker expert, but it seems you have incorporated many good concepts here.
Minimal baffle
irregular edges of baffle
rounded surface of baffle
small baffle for the full range
time alignment between full range and bass unit
the mass you mentioned
I'd assume you need active crossover to get low octaves of bass. I could imagine very good sound from this approach. 🙂
Hi Wlowes,
Sorry, missed your post.
Hope Erik don´t mind too much if I answer you in his thread: The Black Flowers have been shown in the ultimate baffle gallery, and there was a little bit of discussion, but I never opened a thread for them.
They are not active, I prefer passive crossovers. Despite this, low octaves are there, in-room response is fine into the middle 20´s.
Best regards
Mattes
Sorry, missed your post.
Hope Erik don´t mind too much if I answer you in his thread: The Black Flowers have been shown in the ultimate baffle gallery, and there was a little bit of discussion, but I never opened a thread for them.
They are not active, I prefer passive crossovers. Despite this, low octaves are there, in-room response is fine into the middle 20´s.
Best regards
Mattes
I “finished” the speakers in mid January and doing the fine tuning since then.
They are at about 40% of the room (like a room divider). The shelves are 23cm wide and 20cm deep. My wife liked the idea of the shelves, and I think they are indeed good to allow the space for the figure of 8 to be formed (at least theoretically). The overall construction is about 56 cm wide, 250cm high.
The 12 slims are connected in groups of 4 in series, and these in parallel, for about 8 ohm load. The 8 ohm woofers are connected three in series, and then in parallel, for 8 ohms. Theoretically there is space for a 10th woofer, but that would make for a weird impedance. No shading is applied.
I am using 2.5mm2 stranded wire to both hang the speakers and feed the music signal. The Slims are attached with tie wraps, the woofers with rod ends.
The speaker cloth is stretched on a frame based on 2020 aluminum extrusion profiles, m6 rods, some 3D printed parts and a lot of tie wraps. It can be taken away relatively easily, also the speakers are hung from some rails, so that for “serious listening” I could move them farther from the shelve part, theoretically becoming “more naked” and better dipole behavior. I haven’t actually done it yet.
The initial xover was with a miniDSP, but since replaced with an analog xover that applies 600Hz 24dB LP on the woofers and 12dB HP on the mids. A protection cap does another 6dB and the dipole rolloff does the other 6dB, for a theoretical total of 24dB. I apply some equalization in the the moode audio player. This part is very much in progress… an Arcam multichannel receiver is used for powering everything. One of the first measurements is attached.
Things I am thinking about:
I used the WS25e woofers because I already had 12 of them and they are actually used in a couple of dipole projects. From about 35Hz they play well with enough SPL, but that leaves almost a whole octave with lacking SPL. Adding woofers arrays is not possible, so I am thinking about two possibilities:
- I still have some 12inch dipole woofers (SB34NR75-16) that I am thinking of putting into a (mono) H frame subwoofer to play the lower octaves (maybe up to 60Hz), extending the range and taking some of the burden from the WS25e, but where to put this box in my room…? I will start by doing some sort of baffleless experiments with these SB’s to see how they integrate with the WS25e
- Replace the WS25e with the 26W/8534G00 https://www.scan-speak.dk/datasheet/pdf/26w-8534g00.pdf This woofer has a FS of 23Hz, and is used by daudio.nl in their C1 speaker. Would cost some 2000 euros to replace all 18 units, and a lot of work, so reluctant.
- Also looking forward to see how these play with tube amplifiers, another subject I like a lot!
For the moment I do like them a lot! Currently I am mostly in the mood for some jazz and world music (ala Anouar Brahem), so I can live well without the bass. I like the soundstage a lot, even at low volumes everything stays into place, and there is no perceived distortion at higher SPL levels. I must admit that I do not have much reference in the current room, so I will probably see if I can borrow a pair of speakers to do some direct comparison.
They are at about 40% of the room (like a room divider). The shelves are 23cm wide and 20cm deep. My wife liked the idea of the shelves, and I think they are indeed good to allow the space for the figure of 8 to be formed (at least theoretically). The overall construction is about 56 cm wide, 250cm high.
The 12 slims are connected in groups of 4 in series, and these in parallel, for about 8 ohm load. The 8 ohm woofers are connected three in series, and then in parallel, for 8 ohms. Theoretically there is space for a 10th woofer, but that would make for a weird impedance. No shading is applied.
I am using 2.5mm2 stranded wire to both hang the speakers and feed the music signal. The Slims are attached with tie wraps, the woofers with rod ends.
The speaker cloth is stretched on a frame based on 2020 aluminum extrusion profiles, m6 rods, some 3D printed parts and a lot of tie wraps. It can be taken away relatively easily, also the speakers are hung from some rails, so that for “serious listening” I could move them farther from the shelve part, theoretically becoming “more naked” and better dipole behavior. I haven’t actually done it yet.
The initial xover was with a miniDSP, but since replaced with an analog xover that applies 600Hz 24dB LP on the woofers and 12dB HP on the mids. A protection cap does another 6dB and the dipole rolloff does the other 6dB, for a theoretical total of 24dB. I apply some equalization in the the moode audio player. This part is very much in progress… an Arcam multichannel receiver is used for powering everything. One of the first measurements is attached.
Things I am thinking about:
I used the WS25e woofers because I already had 12 of them and they are actually used in a couple of dipole projects. From about 35Hz they play well with enough SPL, but that leaves almost a whole octave with lacking SPL. Adding woofers arrays is not possible, so I am thinking about two possibilities:
- I still have some 12inch dipole woofers (SB34NR75-16) that I am thinking of putting into a (mono) H frame subwoofer to play the lower octaves (maybe up to 60Hz), extending the range and taking some of the burden from the WS25e, but where to put this box in my room…? I will start by doing some sort of baffleless experiments with these SB’s to see how they integrate with the WS25e
- Replace the WS25e with the 26W/8534G00 https://www.scan-speak.dk/datasheet/pdf/26w-8534g00.pdf This woofer has a FS of 23Hz, and is used by daudio.nl in their C1 speaker. Would cost some 2000 euros to replace all 18 units, and a lot of work, so reluctant.
- Also looking forward to see how these play with tube amplifiers, another subject I like a lot!
For the moment I do like them a lot! Currently I am mostly in the mood for some jazz and world music (ala Anouar Brahem), so I can live well without the bass. I like the soundstage a lot, even at low volumes everything stays into place, and there is no perceived distortion at higher SPL levels. I must admit that I do not have much reference in the current room, so I will probably see if I can borrow a pair of speakers to do some direct comparison.
Attachments
Opps, I mis-read you post. I thought replacement of the active XOVER was passive, my mistake.
The implementation visually looks great with the shelves! I really like mine at low volume too. They seem to cruz along. Also good to know they perform at higher volumes. The implementation looks well thought out for the space. Nice work!!!! Hope you enjoy your creation for a long time
.
They are at about 40% of the room (like a room divider). The shelves are 23cm wide and 20cm deep. My wife liked the idea of the shelves, and I think they are indeed good to allow the space for the figure of 8 to be formed (at least theoretically). The overall construction is about 56 cm wide, 250cm high.
For the moment I do like them a lot! Currently I am mostly in the mood for some jazz and world music (ala Anouar Brahem), so I can live well without the bass. I like the soundstage a lot, even at low volumes everything stays into place, and there is no perceived distortion at higher SPL levels. I must admit that I do not have much reference in the current room, so I will probably see if I can borrow a pair of speakers to do some direct comparison.
The implementation visually looks great with the shelves! I really like mine at low volume too. They seem to cruz along. Also good to know they perform at higher volumes. The implementation looks well thought out for the space. Nice work!!!! Hope you enjoy your creation for a long time

Three years ago I built these line arrays, which are still playing nicely - though more for the kids than for myself.
During this time, I was looking at upgrading the woofers to the 26W/8534 from Scan Speak. Specially nice due to their low Fs and they being used by other people in dipole designs. These used to be around 120 EUR, now they are closer to 200 each, so that is too much for me.
I saw SB launched the sb26sfcl38 this year https://sbacoustics.com/product/10-sb26sfcl38-8-paper/ Fs is 27,5Hz (the WS25e measures about 43Hz) and it has more linear xmax than the 26W/8534 and the WS25e. The price is also nice, compacbel in Belgium has them for 69.90 euros and currently 25% discount.
So, the one million dollar question, shall I replace the WS25e with these for some more extension at the lower octaves? They must be able to play up to 600Hz...
During this time, I was looking at upgrading the woofers to the 26W/8534 from Scan Speak. Specially nice due to their low Fs and they being used by other people in dipole designs. These used to be around 120 EUR, now they are closer to 200 each, so that is too much for me.
I saw SB launched the sb26sfcl38 this year https://sbacoustics.com/product/10-sb26sfcl38-8-paper/ Fs is 27,5Hz (the WS25e measures about 43Hz) and it has more linear xmax than the 26W/8534 and the WS25e. The price is also nice, compacbel in Belgium has them for 69.90 euros and currently 25% discount.
So, the one million dollar question, shall I replace the WS25e with these for some more extension at the lower octaves? They must be able to play up to 600Hz...
Looks like a nice driver. I guess another question is what kind of extension are you getting in your room right now?
The bass extension is indeed the Fs of the WS25e drivers, circa 43Hz and falling sharply below that. What I really like now is that one can sit at every place in the room, and even in adjacent rooms, and hear a very nice integration of lows and highs, the advantage of constant directivity and good phase behavior. I do not want sealed subwoofers because they would go through everything, disturbing neighbors etc. I thought about some ripole sub, but this could not be well integrated with the main speakers due to positioning in the room (good integration would be only at one point in the room, contrary to now). An option I have not ruled out yet is a ripole subwoofer that I only connect for critical listening at a fixed chair...
I will see if I can get a pair of the SBs with reasonable shipping costs first. Or wait for the ship with golden coins (as they say in NL) to buy a truckload of the yet to be released 10" unit from Purifi, which checks all the boxes for a very nice dipole driver: Fs of 20Hz, lots of linear excursion.
https://ptt.purifi-audio.com/shop/p...,7541,7542,7543,7544,7545,7546,7547,7548,7603
I will see if I can get a pair of the SBs with reasonable shipping costs first. Or wait for the ship with golden coins (as they say in NL) to buy a truckload of the yet to be released 10" unit from Purifi, which checks all the boxes for a very nice dipole driver: Fs of 20Hz, lots of linear excursion.
https://ptt.purifi-audio.com/shop/p...,7541,7542,7543,7544,7545,7546,7547,7548,7603
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