As far as I know that box (Nautaloss) does not have an exit. It's a stuffed tapered sealed enclosure.
Can't wait to hear/see more about it 🙂. Is that one 15" for each cabinet (I assume)? If you have it nearer to the top (or bottom) you could see if it makes a difference by flipping the box upside down and measure at the listening position. Just to see if having it close to the floor actually helps.
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The Nautaloss and the Dagger are both *sealed* tapered TL's - no opening. Like a Wood's horn light trap but for sound.
SB65 Rear Chamber
I got lazy and found a round cover from a CD spindle that fit perfectly around the horn flange and adapter. So I lined it with several layers of felt, sealed it up and took a spectrum. It's actually very good everywhere and has low HD but still suffers a rear wave cancellation at 1.5kHz corresponding exactly to the 4in round trip distance from the cone to the side wall. It's a sharp dip though so not very noticeable. I will use this for now until I build a proper "starfish" Dagger rear chamber. It does make a difference to use a Dagger or Nautaloss vs a cylinder rear chamber.
Here is the inside of the chamber:
Installed on horn (white disc is foam core with a layer of latex caulking in between for CLD and to give more mass and stiffness to rather thin flat end which may vibrate in a drumhead mode):
Here is measurement of frequency response with 600Hz 2nd order Bessel HPF (electro-acoustic target profile):
I got lazy and found a round cover from a CD spindle that fit perfectly around the horn flange and adapter. So I lined it with several layers of felt, sealed it up and took a spectrum. It's actually very good everywhere and has low HD but still suffers a rear wave cancellation at 1.5kHz corresponding exactly to the 4in round trip distance from the cone to the side wall. It's a sharp dip though so not very noticeable. I will use this for now until I build a proper "starfish" Dagger rear chamber. It does make a difference to use a Dagger or Nautaloss vs a cylinder rear chamber.
Here is the inside of the chamber:
Installed on horn (white disc is foam core with a layer of latex caulking in between for CLD and to give more mass and stiffness to rather thin flat end which may vibrate in a drumhead mode):
Here is measurement of frequency response with 600Hz 2nd order Bessel HPF (electro-acoustic target profile):
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I guess I'm not explaining myself..........I mean no exit at all....no baffle.....no part of the driver exposed to the air outside of a box. This way, you get to hear/measure the enclosure.
That's ridiculous - a driver sealed inside a box. How does the sound get out? Where does the mic go? You have a dipole resonator inside a sealed box. How is that like any speaker in any way?
It's not 'like a speaker' at all, it's a way of evaluating the materials of the box itself. The point is to hear how much sound radiates through the walls of the box by eliminating the direct sound of the driver. If the box was perfect no sound should 'get out'. Implicit is that Mayhem apparently believes that your foam-core enclosures would fail his test miserably. Never tried it myself, but it could be interesting.
Bill
What does the passive re-radiation of sound of foam core speakers have to do with the topic of increased HD when a driver is fitted to a sealed box? I realize that the foam core acts as a passive radiator - it's about -25dB to -40dB depending on the frequency and number of layers, amount of bracing behind it, or if CLD is used. The box in this case is half inch plywood and 3/4in on front baffle with acoustic foam lining. If I stand right next to ten front and block the horn mouth with my body - the speaker goes pretty much silent. The walls don't transmit much.
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Very nice looking black cabinets, blends really well with the waveguide and the holes are less obvious too.
What sort of EQ have you used on the low end to get that result?
I have been considering using a large woofer underneath a synergy as a stand for a while myself. 15" pro woofers usually have a fairly high Fs and lower Xmax that 15" Hifi sub drivers. When put in a sealed cabinet they will tend to have an F3 of 80 to 100 Hz you can use a Linkwitz transform to get a lower F3 but as they don't have much Xmax the max volume is quickly reached.
In a sealed cab they work very well as high output mid bass that can go higher into the midrange which isn't really what you want to complement your speaker as you would probably still need a true subwoofer below.
18" pro woofers usually have a lower Fs and more xmax and will work well in a range of cabinets. As your speaker is about 20in wide an 18" woofer below would fit in and would be well placed near to the floor to take advantage of floor loading. Precision Devices have a really nice driver with very good specs but it is expensive at 438 GBP.
PD.185N02 - Sub Bass Driver
I am very close to buying a pair of Beyma SM115N/8 drivers as they seem to have a low Fs reasonable Xmax flatish response and a good price. In a 100 to 150 vented cabinet tuned to ~30Hz they have an extended but slow roll off that doesn't need a big port. Room gain should help to boost the output at the low end and result in a reasonably flat in room response in theory. If it doesn't work then they can still be used in a sealed cab to 80Hz and subs below.
Beyma SM115N8 Bassbox pro sims
Red 150 litre vented 29 Hz
Orange 150 vented 29 Hz with 30 Hz high pass
Yellow 41 litre sealed 89 Hz F3
Output
Excursion
fluid admit have no experience PD pro woofers but think a couple 15 inchers models as recommended by Overkill Audio looks like good theory.
PD.1550 is 99dB SPL, 600 watt, Xmax 8,2mm, in sealed 25,56 liter for a Q 0,7 resonance at 112,6Hz.
PD.155N01 is 98dB SPL, 700 watt, Xmax 10,5mm, in sealed 26,99 liter for a Q 0,7 resonance at 102,6Hz.
Feed them with a low cost digital pro amp from Behringer or diy some hypex module.
Below example is PD.1550 with 512 watt overlayed with a 55Hz F3 full range system at 102dB SPL. Filter with EQ and or LT all the HF away for woofer and XO with low pass filter in 50-80Hz area. For 512 watt example excursion is only in area of 4,3mm out of 8,2mm so no problem for home audio setup, enclosure is small and resonance bump is up in mids so passband is without any resonance bumb.
PD.1550 is 99dB SPL, 600 watt, Xmax 8,2mm, in sealed 25,56 liter for a Q 0,7 resonance at 112,6Hz.
PD.155N01 is 98dB SPL, 700 watt, Xmax 10,5mm, in sealed 26,99 liter for a Q 0,7 resonance at 102,6Hz.
Feed them with a low cost digital pro amp from Behringer or diy some hypex module.
Below example is PD.1550 with 512 watt overlayed with a 55Hz F3 full range system at 102dB SPL. Filter with EQ and or LT all the HF away for woofer and XO with low pass filter in 50-80Hz area. For 512 watt example excursion is only in area of 4,3mm out of 8,2mm so no problem for home audio setup, enclosure is small and resonance bump is up in mids so passband is without any resonance bumb.
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Hi Byrtt,
I have also never used any of these woofers and am basing a lot of my thoughts on how the simulations come out. I have seen the information Derek has posted on these before but as it is part of his commercial interests the details are a bit scant on how he uses them.
I can't really understand the graph you posted before. I have attached here some PDF's of the output from Jeff Bagby's Woofer designer spreadsheet as this is very good at modelling Linkwitz transforms and other filters when applied to box models.
I have used a Linkwitz transform target of Q=0.7 and Fp of 40Hz which is quite conservative as Q=0.5 and Fp of 20Hz would reduce the level a lot further. If you relax the LT to have a higher F3 then more output is available.
The PD 1550 can produce 105dB when given 600 watts in 27L
The Beyma SM115 can also produce 105dB but with 120w in 100 litres
Beyma SM115 vented in 150L tuned to 29Hz with 30Hz highpass produces 115dB with 100 watts
The roll off is quite gentle for a vented cab and the group delay and phase may be able to be "fixed" somewhat with FIR.
The PD18N02 can produce 113dB but it needs 1600 watts to get there!
For me the PD1550 is almost 100EUR more than the Beyma and feeding it 600 watts to get 105dB isn't something I want to do, others may disagree.
The reason I will probably choose the Beyma is that it is flexible and can work in sealed or vented so I can try out the different options to see what I prefer as all the theory is great but the proof will be in the building and listening to the output 🙂
I have also never used any of these woofers and am basing a lot of my thoughts on how the simulations come out. I have seen the information Derek has posted on these before but as it is part of his commercial interests the details are a bit scant on how he uses them.
I can't really understand the graph you posted before. I have attached here some PDF's of the output from Jeff Bagby's Woofer designer spreadsheet as this is very good at modelling Linkwitz transforms and other filters when applied to box models.
I have used a Linkwitz transform target of Q=0.7 and Fp of 40Hz which is quite conservative as Q=0.5 and Fp of 20Hz would reduce the level a lot further. If you relax the LT to have a higher F3 then more output is available.
The PD 1550 can produce 105dB when given 600 watts in 27L
The Beyma SM115 can also produce 105dB but with 120w in 100 litres
Beyma SM115 vented in 150L tuned to 29Hz with 30Hz highpass produces 115dB with 100 watts
The roll off is quite gentle for a vented cab and the group delay and phase may be able to be "fixed" somewhat with FIR.
The PD18N02 can produce 113dB but it needs 1600 watts to get there!
For me the PD1550 is almost 100EUR more than the Beyma and feeding it 600 watts to get 105dB isn't something I want to do, others may disagree.
The reason I will probably choose the Beyma is that it is flexible and can work in sealed or vented so I can try out the different options to see what I prefer as all the theory is great but the proof will be in the building and listening to the output 🙂
Hi - I am using minidsp 4x10HD.
Unfortunately my cabinet is only 18 inches wide - so 15" woofer is max.
Brytt and fluid, thanks for the sims - what do you guys reckon to this Faital pro - I can get for a similar price to the PD, but it has a hefty 12.45mm x-max, and 1000W AES power handling - looks to be fairly useful.
FaitalPRO | LF Loudspeakers | 15HP1030
Stereo, sort of, with uTrynergy and xBush
I have a micro Trynergy (uTrynergy) on the left channel EQ'd to have the same response as the xBush point source horn on the right channel. It sounds quite integrated with good stereo imaging and sound stage. Both are tractrix horns with about the same pattern. I am listening to several test tracks and just enjoying it. Nice to have stereo, even if not perfectly symmetric (level wise and frequency response, and time alignment though, they are matched). Through total coincidence, the speaker centerline heights are matched within 1 inch so the height works out just fine.
I have a micro Trynergy (uTrynergy) on the left channel EQ'd to have the same response as the xBush point source horn on the right channel. It sounds quite integrated with good stereo imaging and sound stage. Both are tractrix horns with about the same pattern. I am listening to several test tracks and just enjoying it. Nice to have stereo, even if not perfectly symmetric (level wise and frequency response, and time alignment though, they are matched). Through total coincidence, the speaker centerline heights are matched within 1 inch so the height works out just fine.
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I have done quite a bit of research on pro woofers and the Faital Pro HP1030 series (either 12in or 15in) are actually unique in their class and price range. Huge xmax and great sensitivity with the right Qts for many applications. I would use it for FLH for bass/sub. For that, it excels in the sims. I can see how it would work in sealed too with a LT, again, watch out for excessively small volumes and air compression ratio on HD. The Vas is about 3 cubic ft so, I probably would not put in anything less than 1.5 to 2 cu ft. 1 du ft is too small and constricting in my opinion. If you have 3 cu ft even better.
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Thanks X. Nice to see the stereo set up! How is distortion with the new woofers? Any better?
If I make a width and depth identical cuboid box for the 15" woofer as I did for the horn (18" width x 17" depth) but taller - likely 28" to get the horn centre to ear height. It will give a total internal volume of 3.9 cu ft.
So take 0.2 cu ft out for the driver, and another 0.8-1 cu ft for extensive bracing/damping (which is all important in a sub enclosure to try to get the lowest enclosure resonance above driver pass-band of ~60hz) leaves about 2.9 cu ft or the same as the Vas.
It will also give the two cabs a nice symmetry having identical width/depth.
I will then use rubber feet on the woofer and sorbothane hemispheres on the horn cab to isolate it from the woofer below. This should raise the horn up to listening height nicely.
If I make a width and depth identical cuboid box for the 15" woofer as I did for the horn (18" width x 17" depth) but taller - likely 28" to get the horn centre to ear height. It will give a total internal volume of 3.9 cu ft.
So take 0.2 cu ft out for the driver, and another 0.8-1 cu ft for extensive bracing/damping (which is all important in a sub enclosure to try to get the lowest enclosure resonance above driver pass-band of ~60hz) leaves about 2.9 cu ft or the same as the Vas.
It will also give the two cabs a nice symmetry having identical width/depth.
I will then use rubber feet on the woofer and sorbothane hemispheres on the horn cab to isolate it from the woofer below. This should raise the horn up to listening height nicely.
Yes, the distortion is much improved with the new drivers. It is about 1% at 80Hz at normal listening SPL's of circa 82dB. Not crazy good like yours which was I think 1% at 100dB. The main thing is that several of the really nasty peaks like the one at 104Hz (mostly 3rd harmonic) went away completely - so that must have been some wierd thing with the driver and not the cabinet. It's about 3% at 50Hz. The original design goal of this speaker was to handle bass down to 80Hz, and I think it has almost done that - I say almost because ideally, I would have liked to see 1% at 90dB. The rest above is fine and typical of the HD I showed earlier for the SB65. The left channel uses four buyout $8 5.25in woofers, so the HD there is higher than the nicer RS180P's.
Your cabinet dimensions for the sub sound perfect and the Faital 15HP1030 should work quite nicely for you.
Your cabinet dimensions for the sub sound perfect and the Faital 15HP1030 should work quite nicely for you.
That's the question that I posed to you. And it's not just about foam core but particle board, MDF, plywood, etc
Bushmeister my question was meant to be how much EQ you used, if you could post a screen shot of your mindsp settings it would give me a better idea of what you needed to apply to get the response you posted 🙂
I have put the Faital Woofer through Woofer designer and attached the PDF's here so you can compare them against the others with the same LT parameters. I have done a small cab at 25 litres and two larger ones at 60 and 85 litres to show the difference. 60 litres gives a Q of 0.5 which is also another popular target.
Basically the larger the cab the less power you need to reach the same target so X's suggestion of 2 to 3 cubic feet (roughly between 60 and 85 litres) makes a lot of sense if you are going to use a Linkwitz Transform.
25 Litre
60 Litre
85 Litre 20 Hz Q=0.5 LT with 6dB Butterworth High pass at 20Hz
This gives about 105dB at 300W and flat extension towards 20Hz which is about as far as you can take this drive in a sealed cab with LT.
Takes 1000w in 25 litres and only 450w and 300w at 85 litres. The same would apply to the PD woofer. The faital has a fairly sharp dip in response at around 375Hz but otherwise the response is pretty good. The Faital's greater xmax gets about 5dB more output when maxed out so is probably the better choice of the two for this use.
I guess I am not understanding your question, maybe you can be a bit more verbose rather than cryptic. If what you are implying is that I am saying that increased HD comes from passive re-radiation via cabinet walls? That's not what I am saying.
I think the sealed cabinet either has internal modes that re-radiate through the cone and this may cause increased HD, or the excessive pressure causes the motor assembly making it travel non-linearly in the magnetic gap, or the cone membrane deform in a non-linear way and that causes increased HD, or possibly, it may be a lot of air pumping around in the rear chamber and that generates sound. But I don't think re-radiation through a couple inches of eggcrate foam and half in ply is a significant contributor to HD.
Sound clips of stereo uTrynergy and xBush horn setup
These are recorded with a Zoom H4 at listening position 7 ft away - so there will be room effects. My room is particularly reverberant. I have been thinking about getting some sound treatment panels one of these days. However, I feel that the controlled directivity of the horns has actually reduced the effect of the room versus a direct radiator speaker from the same position.
Change .asc to .mp3 to listen.
These are recorded with a Zoom H4 at listening position 7 ft away - so there will be room effects. My room is particularly reverberant. I have been thinking about getting some sound treatment panels one of these days. However, I feel that the controlled directivity of the horns has actually reduced the effect of the room versus a direct radiator speaker from the same position.
Change .asc to .mp3 to listen.