I found this 'little' driver that seems a possible candidate for mid-driver on a synergy. It has enormous high output between 150 - 2khz @ 102db. (109db when horn loaded) Has a closed back design, has very high BL factor, Xdamage @ 20mm.
Only catch, it is damn expensive...
The 10 inch
RCF MR10N301
the 8 inch (300hz - 3khz):
RCF MR8N301
Only catch, it is damn expensive...
The 10 inch
RCF MR10N301
the 8 inch (300hz - 3khz):
RCF MR8N301
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OK so all this talk of CD, synergies etc, has led me to order some bits to experiment.
I have ordered 2x 18 Sound XT1464, 15 x 12 inch CD horns. Along with 2x SB65WBAC25 2.5 inch drivers.
My plan is to try various throat geometries (horn is 1.4 inch throat) and take multiple measurements to get the best compromise.
Given these full range drivers will happily play down to 300hz, and the 1/4 wavelength of 300hz is 11 inches, I am not sure if I will even need to tap bass units into the horn - I could probable achieve close to 11 inches with a couple 8-10 inch drivers mounted above/below or both......
Given the experience of the people on this thread - do you think there is much to be gained by making holes in the horns if I am crossing as low as 300 hz?
Thanks in advance - I will start posting some results when I start experimenting (I have already ordered 1 kg of modeling putty to make up a variety of throat geometries.
I have ordered 2x 18 Sound XT1464, 15 x 12 inch CD horns. Along with 2x SB65WBAC25 2.5 inch drivers.
My plan is to try various throat geometries (horn is 1.4 inch throat) and take multiple measurements to get the best compromise.
Given these full range drivers will happily play down to 300hz, and the 1/4 wavelength of 300hz is 11 inches, I am not sure if I will even need to tap bass units into the horn - I could probable achieve close to 11 inches with a couple 8-10 inch drivers mounted above/below or both......
Given the experience of the people on this thread - do you think there is much to be gained by making holes in the horns if I am crossing as low as 300 hz?
Thanks in advance - I will start posting some results when I start experimenting (I have already ordered 1 kg of modeling putty to make up a variety of throat geometries.
Now that's the spirit! Good just to try it out and see how it goes. You may want to look for inexpensive fiberglass clones oh JBL 2386 as that horn has ample wall space to mount woofers. Or you could even use compression driver and add mids and woofers.
If you don't do bass injection via band pass ports you don't have a synergy. You just have the basic horn as designed, albeit driven with a full range.
It's not just about the center to center spacing requirement being under 1/4 wavelength. It's the whole "point source" philosophy. With injection ports on horn you have summation to a virtual point source and no directional lobe effects at XO frequency for uniform image.
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Thanks for the encouragement xrk!!
OK - on this part I am a little confused though.
I thought if the crossover is within 1/4 wavelength - then the drivers do behave like a point source. A bit like grouped subwoofers.
To my simple brain, it seems the synergy is a necessity if you are using a compression driver and therefore require a crossover around 1000hz or higher - as the synergy is the only way to physically get the sources close enough.
But, if we use a full range driver, that can reach down to 300hz, we can cross within a 1/4 wavelength without using the synergy technique (but only if using a smaller horn of course). Therefore we should keep the point source magic as the crossover is low enough to behave as a point source.
Having modeled the lobing behavior on Tolvan's XDir it seems at 300hz within 25cm or less there is no significant lobing at all.
I appreciate really this is only useful with the smaller horns - otherwise C-C distances increase.
So I am struggling to see the benefit of making holes in the horn to make a synergy, if the low crossover and horn size allow 1/4 wavelength spacing in the conventional way.
Please put me right if I am wrong??
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300Hz may be close to limit where lobe angles don't matter. It depends on your xo frequency. Most likely it will be 500H to 600Hz despite the full range going down to 300Hz that has a lot of distortion as the cone is moving a lot. Xo at 500Hz and it takes cone movement and HD down by orders of magnitude. Byrtt has shown me simulations of a FAST mid tweet and offset woofer before for many low XO frequencies and they were never as a good as a coaxial or a point source. There is always some angled steering. It may not be a big audible factor at 300Hz as you say and personally, I think worth a try to put a waveguide above a woofer. You are essentially running a FAST "Econowave" with a full range. It think it can sound very good so don't give up. Just saying it's technically not a synergy once you lose band pass injection holes.
Good to know! So it's likely the sb65 will be better crossed at 500-600hz then?
In which case - I will probably look into making it a two way synergy like yours - with some woofers to cover 600 or so down, then sub below that.
Just received my horns in the post - looking at the exterior - I am thinking 4 x 4 inch woofers would fit nicely between the ribs on the exterior. My plan is to use two part epoxy putty to connect the woofer to the curved outer horn surface.
I am very impressed with the build quality of these. Very solid.
My understanding having read the patent for the synergy, is that a crossover at 5-600hz should be much easier than higher mid-point crossovers - ports placed 1/2-3/4 from throat to minimize diffraction and yet be close enough for point source behavior and that the first cancellation dip is above the required pass-band. Is this about right?
Also - am I right in thinking driver selection is much easier than it is for true mid driver selection?
Any suggestions for 4 inch woofers that might fit the bill?
In which case - I will probably look into making it a two way synergy like yours - with some woofers to cover 600 or so down, then sub below that.
Just received my horns in the post - looking at the exterior - I am thinking 4 x 4 inch woofers would fit nicely between the ribs on the exterior. My plan is to use two part epoxy putty to connect the woofer to the curved outer horn surface.
I am very impressed with the build quality of these. Very solid.
My understanding having read the patent for the synergy, is that a crossover at 5-600hz should be much easier than higher mid-point crossovers - ports placed 1/2-3/4 from throat to minimize diffraction and yet be close enough for point source behavior and that the first cancellation dip is above the required pass-band. Is this about right?
Also - am I right in thinking driver selection is much easier than it is for true mid driver selection?
Any suggestions for 4 inch woofers that might fit the bill?
I'm not trying to be condescending, but you keep asking the same questions about how to build a not-quite-synergy in synergy threads and the answers haven't changed. I think xrk hit the nail on the head. The ports make the apparent mid source much smaller than the cone, along with the other benefits that myself, Patrick, and xrk have mentioned. I'd think with the mids exposed the fr would be worse with greater inconsistencies off axis.
Why not try it? Should be easy enough to knock up a prototype. Who knows......maybe it will work really well.
4 inch isn't exactly a "woofer"
I would highly discourage epoxying a driver directly to WG. You need to be able to move and redo. The glue is one time and ruins the driver.
Try using tools to remove the ribs. Then use industrial adhesive like Liquid Nails to glue a plywood plate to each wall to form basis for woofer mount. If clever you can get a larger woofer than the WG mouth as injection hole is maybe 20% of Sd.
Basically enshrine your plastic waveguide in a four side plywood pyramid as basis of your synergy.
Make sure you use VOC compliant LN. The other stuff might melt your WG.
Then you can properly cut a ring groove for the surround to clear and cut a nice port with a Dremel tool after all the LN dries.
If you must use 4in, there is probably no better choice than Faital Pro 4FE35 wired series parallel will get you 97dB.
I you can squeeze in a 5.25 woofer. DC130A is very nice. Trying to give you cost sensitive items.
Faital Pro 5FE120 works well too but more money.
I would highly discourage epoxying a driver directly to WG. You need to be able to move and redo. The glue is one time and ruins the driver.
Try using tools to remove the ribs. Then use industrial adhesive like Liquid Nails to glue a plywood plate to each wall to form basis for woofer mount. If clever you can get a larger woofer than the WG mouth as injection hole is maybe 20% of Sd.
Basically enshrine your plastic waveguide in a four side plywood pyramid as basis of your synergy.
Make sure you use VOC compliant LN. The other stuff might melt your WG.
Then you can properly cut a ring groove for the surround to clear and cut a nice port with a Dremel tool after all the LN dries.
If you must use 4in, there is probably no better choice than Faital Pro 4FE35 wired series parallel will get you 97dB.
I you can squeeze in a 5.25 woofer. DC130A is very nice. Trying to give you cost sensitive items.
Faital Pro 5FE120 works well too but more money.
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Great advice! Thanks.
Don't worry I wasn't going to stick them in! I have used cling film, oil and various other techniques that allow you to make a 'molded, hard gasket' without it sticking, You can then sand it and drill it and it will be separate to both the horn and the driver. Allowing a perfect seal on curved surfaces without mucking about with mdf or ply.
However - this will be an experiment- so although this has worked for me with previous builds, I may end up using my router and ply!
I was looking at these as possible cost sensitive options:
SB Acoustics :: 4? SB12NRX25-8
I can pick them up fairly cheap in the UK, Fs of 57, QES - 0.41 and 10mm xmax.
PS - I am gonna have a look at removing the ribs - may be better to mount a couple 8 inch woofers this way.
Don't worry I wasn't going to stick them in! I have used cling film, oil and various other techniques that allow you to make a 'molded, hard gasket' without it sticking, You can then sand it and drill it and it will be separate to both the horn and the driver. Allowing a perfect seal on curved surfaces without mucking about with mdf or ply.
However - this will be an experiment- so although this has worked for me with previous builds, I may end up using my router and ply!
I was looking at these as possible cost sensitive options:
SB Acoustics :: 4? SB12NRX25-8
I can pick them up fairly cheap in the UK, Fs of 57, QES - 0.41 and 10mm xmax.
PS - I am gonna have a look at removing the ribs - may be better to mount a couple 8 inch woofers this way.
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Those SB woofers are way nice cast frame high BL drivers. Should be perfect. I still say make the plywood pyramid base board. Just a lot cleaner and you can ensure that you get a good tight grip with screws clamping the driver down. This is a huge source of rattle if not done well as there is a lot of woofer motion and pressures involved.
Looking at the horns, I think you are probably right xrk (plus you have a lot more build experience with these than me!!)
So I think I will look at getting four plywood pieces attached (gonna prob go with those SB woofers, as they will enable me to keep the whole thing really compact.)
Right I better get measuring!
So I think I will look at getting four plywood pieces attached (gonna prob go with those SB woofers, as they will enable me to keep the whole thing really compact.)
Right I better get measuring!
I'm going to try it with this one:
0005 XT1464 - Coaxials XT1464 : Eighteen Sound - professional loudspeakers
Do you have any tips for transitioning the 2.5" driver into the 1.4" throat?
I was going to use modelling putty to gently flare the 1.4 inch opening out to the size required over a cm or so of depth...
Ps this is why I have posted in this thread. At 15" by 12", the horn is hopefully small enough for my build to be considered a 'bookshelf synergy monitor'!
0005 XT1464 - Coaxials XT1464 : Eighteen Sound - professional loudspeakers
Do you have any tips for transitioning the 2.5" driver into the 1.4" throat?
I was going to use modelling putty to gently flare the 1.4 inch opening out to the size required over a cm or so of depth...
Ps this is why I have posted in this thread. At 15" by 12", the horn is hopefully small enough for my build to be considered a 'bookshelf synergy monitor'!
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For throat you want to remove any sharp corners. I would start with a file and sand paper/Dremel tool to put a 0.2in or so radius smooth lip on the WG throat. Then take a disc of ply or plastic or whatever that is deeper than the half roll surround at xmax but keep as thin as possible. I am guessing 5mm thick is good and cut a circle exactly larger than outer dia of rubber surround. Lay this spacer and center on WG flange that has now been filed smooth. Drill holes and mount driver. Use thin rubber or Eva foam gasket to seal it. This is where foam core is handy. I used it as the spacer and gasket in one. Important to make sure surround doesn't bump. That adds distortion.
Now the fun. Test the WG and SB65WBAC24-4 in waveguide. Put a thick blanket on back to prevent reflections from back messing with measurement.
You may see a pretty nice curve. In all likely hood you will get +10dB gain up to about 3kHz. Will start to see dips and roughness and typical power falloff of -12dB from there to 20kHz.
Now wherever you see a sharp edge or roughness in horn profile at driver interface you can sand and file smoother or use a dab of putty and stick it in and re measure.
Once you are happy with HF then move onto adding woofer ports. You also have reference now of before and after injection holes. Really they don't impact HF much if done right.
Is 12x15 in a "bookshelf" size?
Depends on how big your books are
If rotated so 12in is width then yes.
Now the fun. Test the WG and SB65WBAC24-4 in waveguide. Put a thick blanket on back to prevent reflections from back messing with measurement.
You may see a pretty nice curve. In all likely hood you will get +10dB gain up to about 3kHz. Will start to see dips and roughness and typical power falloff of -12dB from there to 20kHz.
Now wherever you see a sharp edge or roughness in horn profile at driver interface you can sand and file smoother or use a dab of putty and stick it in and re measure.
Once you are happy with HF then move onto adding woofer ports. You also have reference now of before and after injection holes. Really they don't impact HF much if done right.
Is 12x15 in a "bookshelf" size?
Depends on how big your books are
If rotated so 12in is width then yes.
An idea...
Hasn't anyone ever explored disguising the desk "bottom" as an enclosure for the bass portion of alleged "desk top" speakers? Skillfully executed, you could have plaster cracking bass "apparently" from a pair of featherweight xrk971 desk top speakers
I mean, some of my ideas are so simply brillaint I can't see why others did not think of them earlier
It's akin to the banker's astonishment on this Monty Python sketch:
https://www.youtube.com/watch?v=YUhb0XII93I
On a (scarcely) more serious note I am enthralled by the idea of foam core horns. Keep at it guys!
Hasn't anyone ever explored disguising the desk "bottom" as an enclosure for the bass portion of alleged "desk top" speakers? Skillfully executed, you could have plaster cracking bass "apparently" from a pair of featherweight xrk971 desk top speakers
I mean, some of my ideas are so simply brillaint I can't see why others did not think of them earlier
It's akin to the banker's astonishment on this Monty Python sketch:
https://www.youtube.com/watch?v=YUhb0XII93I
On a (scarcely) more serious note I am enthralled by the idea of foam core horns. Keep at it guys!
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bushmeister,
Nice project reminds me think remember you mentioned 10F and XT1464 over at Trynergy thread.
Regarding SB ACOUSTICS their XMax specs is peak to peak so for SB65WBAC25-4 XMax is not 5,3mm one way but 2,65mm and for SB12NRX25-8 XMax is not 10mm one way but 5mm.
Also maybe you can get a couple SS 18W/8434 or Faitals 6FE100 to inject mid bass they both can get down to around 80Hz in sealed Q 0,7, SS need less than 10 liter volume per driver with stuffing and Faitals maybe less than 15 liter with stuffing to hit f3 corner around 80Hz, if XO target example is set LR4 80Hz then a electric BW2 80Hz cascaded the acoustic BW2 80Hz roll off will form slope.
If you want to look at 2" throat in future there is below three possibilities at low cost in UK, if I had the time would like a pair of the first or second one as trial for 10F or TC9FD.
P-Audio PH-2723 2" Horn Flare 60 x 40 Dispersion 24.95 IN STOCK (9 Jan 2016)
P-Audio PH-4528 2" Throat Horn Flare 60 x 40 Dispersion 31.75 IN STOCK (9 Jan 2016)
P-Audio :: P-Audio PH-2380 2" Throat Horn Flare 90 x 40 Dispersion ONLY 22.68 IN STOCK (9 Jan 2016)
Nice project reminds me think remember you mentioned 10F and XT1464 over at Trynergy thread.
Regarding SB ACOUSTICS their XMax specs is peak to peak so for SB65WBAC25-4 XMax is not 5,3mm one way but 2,65mm and for SB12NRX25-8 XMax is not 10mm one way but 5mm.
Also maybe you can get a couple SS 18W/8434 or Faitals 6FE100 to inject mid bass they both can get down to around 80Hz in sealed Q 0,7, SS need less than 10 liter volume per driver with stuffing and Faitals maybe less than 15 liter with stuffing to hit f3 corner around 80Hz, if XO target example is set LR4 80Hz then a electric BW2 80Hz cascaded the acoustic BW2 80Hz roll off will form slope.
If you want to look at 2" throat in future there is below three possibilities at low cost in UK, if I had the time would like a pair of the first or second one as trial for 10F or TC9FD.
P-Audio PH-2723 2" Horn Flare 60 x 40 Dispersion 24.95 IN STOCK (9 Jan 2016)
P-Audio PH-4528 2" Throat Horn Flare 60 x 40 Dispersion 31.75 IN STOCK (9 Jan 2016)
P-Audio :: P-Audio PH-2380 2" Throat Horn Flare 90 x 40 Dispersion ONLY 22.68 IN STOCK (9 Jan 2016)
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Byrtt,
Thanks for the excellent info!
I decided on the SB65, as I felt the larger 10F may be a bit of a squeeze into the 1.4inch throat of the horn I have chosen.
I also chose the 18 sound one as it has a fair amount of measurements documented online and appears to be a really nice CD horn.
I have now routed out a nice 1/2 inch curve on the throat entrys and then sanded and polished the throats to get a smooth transition. I have measured the start of the throat transition as 55mm (2.2 inches) which - should put me just at the edge of the cone and therefore be a snug fit (excluding the surround)
Just awaiting arrival of the SB65s then I will cut a gasket and get measuring!
Thanks for the excellent info!
I decided on the SB65, as I felt the larger 10F may be a bit of a squeeze into the 1.4inch throat of the horn I have chosen.
I also chose the 18 sound one as it has a fair amount of measurements documented online and appears to be a really nice CD horn.
I have now routed out a nice 1/2 inch curve on the throat entrys and then sanded and polished the throats to get a smooth transition. I have measured the start of the throat transition as 55mm (2.2 inches) which - should put me just at the edge of the cone and therefore be a snug fit (excluding the surround)
Just awaiting arrival of the SB65s then I will cut a gasket and get measuring!
Attachments
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bushmeister,
You right 18 sound have good documentation and good chance it will shine combined SB65WBAC25-4.
Both 5th element and xrk971 have had good experience that full ranger so look forward follow your build progress and nice idea.
Wow picture with modification for throat transition looks super pro tooled as it was ab fabric.
You right 18 sound have good documentation and good chance it will shine combined SB65WBAC25-4.
Both 5th element and xrk971 have had good experience that full ranger so look forward follow your build progress and nice idea.
Wow picture with modification for throat transition looks super pro tooled as it was ab fabric.
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