I never did a DSP setup so you are going to have to figure that out. It’s part of DIY and you will learn as you go. It’s not that hard. You will need a microphone, REW software, and miniDSP 8 channel.
You can look at the crossover curves I posted and try to recreate that with DSP. You will of course, do better as DSP and EQ gives you lots of options.
PM me if you would like a sketch of the XSD to play with. Please note that this is strictly for your personal DIY use. Here is a redacted version (dimensions provided with one from PM request):
Front baffle and base is 3/4in BB plywood. Wings are 1/2in BB plywood. Woofer manifold is made from 5 sheets of 3/4in MDF with the interior 3 sheets cut like a comb pattern to form the woofer chamber dimensioned as 2.25in wide x ~5.5in high or whatever your woofer cutout diameter is. Make sure cutout hole on the exterior two sheets of MDF is wide enough to fit driver magnet/basket in. The wings are removable and held in place with screws to beefy 3/4in square ledgers cut from scrap 3/4in BB ply or solid hardwood like oak or beech. Wings need to be removable in order to install drivers. I use square head drive wood screws The woofer manifold is glued to the baffle for the best structural integrity as there is a lot of pressure generated with 8 woofers.
Woofers used were GRS 6PR-8 6.5in rubber surround polycone 8ohm woofer. If you use another kind, you will have to adjust the cabinet dimensions accordingly. Midrange that I suggest is PRV 5MR450NDY 8ohm, tweeter is GRS PT2522-4 planar. A Heil AMT here would be superb as well as Beyma TPL-150. Other choices for midrange might be 5FE100, JBL LE5, B&C 6MDN44 etc. One could use a dome tweeter and forgo the rear dipole pattern. I am using a custom CNC waveguide and bezel but you could just mount it however you normally mount these things (which is not very visually appealing). If swapping out drivers, keep in mind that you will need high sensitivity drivers in the 90dB+ range as the woofer array is about 91.5dB sensitive at 2.83v. So the mid needs to be at least 90dB, similarly the tweeter needs to be about 89- 90dB.
I would recommend that you line the inside of the wings with felt or eggcrate sound absorption foam. You may also choose to make a removable upper baffle board to play with different drivers. That adds complexity though. The speaker is heavy so use stick on felt feet to allow you to slide it around and it provides vibration isolation as well. Although the opposed cone motion cancels out most woofer induced vibration.
I can give hints with the crossover but you will need to figure that out on your own mostly. Active XO with DSP will probably be the easiest way to go.
Start with crossovers at 470Hz and 4700Hz. Midrange and tweeter are opposite polarity. Woofer and midrange are same polarity. The 470Hz is magical natural falloff from the slot loading so use it to advantage to get steep 4th order filter with simple 2nd order electrical. The 4700Hz upper crossover keeps the planars in a low distortion zone and allows the midrange to operate as a coherent single driver over most of the telephone band - so it will have the magic of a fullrange single driver speaker in terms of imaging and soundstage. But pack the slam of a high sensitivity PA system and the clear highs of a planar tweeter.
Hope this helps you guys get started. Have fun!
Front baffle and base is 3/4in BB plywood. Wings are 1/2in BB plywood. Woofer manifold is made from 5 sheets of 3/4in MDF with the interior 3 sheets cut like a comb pattern to form the woofer chamber dimensioned as 2.25in wide x ~5.5in high or whatever your woofer cutout diameter is. Make sure cutout hole on the exterior two sheets of MDF is wide enough to fit driver magnet/basket in. The wings are removable and held in place with screws to beefy 3/4in square ledgers cut from scrap 3/4in BB ply or solid hardwood like oak or beech. Wings need to be removable in order to install drivers. I use square head drive wood screws The woofer manifold is glued to the baffle for the best structural integrity as there is a lot of pressure generated with 8 woofers.
Woofers used were GRS 6PR-8 6.5in rubber surround polycone 8ohm woofer. If you use another kind, you will have to adjust the cabinet dimensions accordingly. Midrange that I suggest is PRV 5MR450NDY 8ohm, tweeter is GRS PT2522-4 planar. A Heil AMT here would be superb as well as Beyma TPL-150. Other choices for midrange might be 5FE100, JBL LE5, B&C 6MDN44 etc. One could use a dome tweeter and forgo the rear dipole pattern. I am using a custom CNC waveguide and bezel but you could just mount it however you normally mount these things (which is not very visually appealing). If swapping out drivers, keep in mind that you will need high sensitivity drivers in the 90dB+ range as the woofer array is about 91.5dB sensitive at 2.83v. So the mid needs to be at least 90dB, similarly the tweeter needs to be about 89- 90dB.
I would recommend that you line the inside of the wings with felt or eggcrate sound absorption foam. You may also choose to make a removable upper baffle board to play with different drivers. That adds complexity though. The speaker is heavy so use stick on felt feet to allow you to slide it around and it provides vibration isolation as well. Although the opposed cone motion cancels out most woofer induced vibration.
I can give hints with the crossover but you will need to figure that out on your own mostly. Active XO with DSP will probably be the easiest way to go.
Start with crossovers at 470Hz and 4700Hz. Midrange and tweeter are opposite polarity. Woofer and midrange are same polarity. The 470Hz is magical natural falloff from the slot loading so use it to advantage to get steep 4th order filter with simple 2nd order electrical. The 4700Hz upper crossover keeps the planars in a low distortion zone and allows the midrange to operate as a coherent single driver over most of the telephone band - so it will have the magic of a fullrange single driver speaker in terms of imaging and soundstage. But pack the slam of a high sensitivity PA system and the clear highs of a planar tweeter.
Hope this helps you guys get started. Have fun!
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Hi @xrk971, currently playing with this one but have a few questions, if I may:
Many thanks!
- 5 deg. lean back is for time alignment or aesthetic? (therefore redundant if going active/DSP)
- Is the tweeter over Mid arrangement to aid mid/sub integration or can it be swapped to mid over tweeter (tweeter ends up at 1100mm if using the racetrack driver )
- You mentioned your woofers are magnet to cone and polarity reversed/aligned i.e all cones load the slot on +v ? ...how is this beneficial/different to 'cone to cone' and straight polarity aligned?
- This ones a bit 'out there' - How feasible/beneficial/silly would it be to mirror the SLOB and have an MTM in the middle? (giving a, almost, floor to ceiling tower) Id assume, given that the OB already helps with bass nodes, that it would just increase maximum SPL/dynamics?
...maybe @wesayso should add a pair of tower SLOBs to the Two Towers
Many thanks!
1. Both, and helps stability too. But can be vertical if DSP for sure.Hi @xrk971, currently playing with this one but have a few questions, if I may:
Amazingly, the cutout dimension, and Sd, of the SBA SB15SFCR39-8 combined with 3x18mm material width gives you a perfect 1/3 slot dimension ((Sdx2)/3)
- 5 deg. lean back is for time alignment or aesthetic? (therefore redundant if going active/DSP)
- Is the tweeter over Mid arrangement to aid mid/sub integration or can it be swapped to mid over tweeter (tweeter ends up at 1100mm if using the racetrack driver )
- You mentioned your woofers are magnet to cone and polarity reversed/aligned i.e all cones load the slot on +v ? ...how is this beneficial/different to 'cone to cone' and straight polarity aligned?
- This ones a bit 'out there' - How feasible/beneficial/silly would it be to mirror the SLOB and have an MTM in the middle? (giving a, almost, floor to ceiling tower) Id assume, given that the OB already helps with bass nodes, that it would just increase maximum SPL/dynamics?
...maybe @wesayso should add a pair of tower SLOBs to the Two Towers
Many thanks!
2. I thought about doing this too but felt it was important to keep the distance from the mid point of the woofer array as close to the mid as possible as that is the main driver where the mic is aligned on axis with. In order to preserve the effect of keeping the drivers sounding like they are from one source, it has been suggested that drivers not be spaced more than 1/3rd the the wavelength of the crossover frequency. For 470Hz, that is about 9in. The aperture of the top woofer slot is about 9.2in away at present.
3. Magnet to cone so that as one cone moves in, the other moves out (but still pushes air on +ve) and this is so that the natural asymmetry of the suspension motion is cancelled more accurately. It also reduces the slot volume, thereby increasing the upper bandwidth. However, these are minor effects. Cone - cone facing in is probably fine.
4. SLOB/MTM/SLOB would be a massive tall speaker. You would need a compression driver or other horn loaded tweeter to get 100dB sensitivity to keep up with the dual SLOBS.
But that would be epic.@xrk971 thank you for the reply and clarifications1. Both, and helps stability too. But can be vertical if DSP for sure.
2. I thought about doing this too but felt it was important to keep the distance from the mid point of the woofer array as close to the mid as possible as that is the main driver where the mic is aligned on axis with. In order to preserve the effect of keeping the drivers sounding like they are from one source, it has been suggested that drivers not be spaced more than 1/3rd the the wavelength of the crossover frequency. For 470Hz, that is about 9in. The aperture of the top woofer slot is about 9.2in away at present.
3. Magnet to cone so that as one cone moves in, the other moves out (but still pushes air on +ve) and this is so that the natural asymmetry of the suspension motion is cancelled more accurately. It also reduces the slot volume, thereby increasing the upper bandwidth. However, these are minor effects. Cone - cone facing in is probably fine.
4. SLOB/MTM/SLOB would be a massive tall speaker. You would need a compression driver or other horn loaded tweeter to get 100dB sensitivity to keep up with the dual SLOBS.
Hmm, I'll look into that. You might have already mentioned the answer, but are there plans for this to be made into a commercial speaker? I'm just curious about the secrecy regarding your XO design. Thanks for the reply!
I have created a dedicated thread for the XSD speaker here:
https://www.diyaudio.com/community/threads/the-xsd-speaker.385717/
https://www.diyaudio.com/community/threads/the-xsd-speaker.385717/
Lower level, then the whole thing is out of balance.
You'll need to buffer the mid and highs, or get something with less sensitivity, then re-work the XO.
This is DIYAudio, so, why not?
Myself, I wouldn't be able to trade in the low end. I'm no bass head, but I do like a balanced FR with nice dynamics.
You'll need to buffer the mid and highs, or get something with less sensitivity, then re-work the XO.
This is DIYAudio, so, why not?
Myself, I wouldn't be able to trade in the low end. I'm no bass head, but I do like a balanced FR with nice dynamics.
It can work with six 6.5in woofers. The original in cardboard used that and it was decent bass. The 8 sends it over the top. I think 4x 8in would be similar.
Thanks X. I have used Peerless SDS160f25pr01in a simple garden BT speaker and at the price I got it for back then with UK stock I wish I'd bought a load of them. Alas anything wil be imported so will be additional taxes regardless so may aswell go with the GRS from Soundimports. I did find the Pyle but still expensive shipping.
Hi Jimk04,
That Peerless you linked would be an excellent bass array driver for the XSD speaker. It has nice flat response, wide bandwidth beyond the natural acoustic rolloff of 450Hz. 87dB and 6mm of xmax. Sounds like it should work well. The nice thing about the SLOB woofer bass is that the natural acoustic roll off is mechanically determined by the slot depth and so the crossover may only require a bit of tweaking with the inductance if going passive, or if DSP then no problem. You will get a few dB more sensitivity.
That Peerless you linked would be an excellent bass array driver for the XSD speaker. It has nice flat response, wide bandwidth beyond the natural acoustic rolloff of 450Hz. 87dB and 6mm of xmax. Sounds like it should work well. The nice thing about the SLOB woofer bass is that the natural acoustic roll off is mechanically determined by the slot depth and so the crossover may only require a bit of tweaking with the inductance if going passive, or if DSP then no problem. You will get a few dB more sensitivity.