Yes, i do in fact =)
Luca, yes, i have been compiling a list of suitable drivers of many sizes, what did you have in mind?
Luca, yes, i have been compiling a list of suitable drivers of many sizes, what did you have in mind?
Methods
USRFobiwan,
Part of it is related to the expansion profile, take a look at the image included in post #348 .... Compare the severity of the midbass dips between the left and right graphs in that post .... Notice the improvement in the flared option .... It is a very easy modification for that layout.
The dip we see in the midbass is located between the Fb*5 and Fb*7 harmonics which are shifted downward by the path's expansion if i understand it correctly ......
I have noticed that this dip can be alleviated somewhat by smoothing the expansion (i mean by making the main path more like a traditional horn shape) ...... I have also noticed that the dip can be remedied with some driver-offset (or a tuned stub) .....
It can explain why the Club Tops featured in post #1 were such a success , because those tops were using both methods mentioned in the paragraph above......... Expansion was accomplished in a few steps instead of one big jump , and the drivers were set up in an offset fashion both sharing the same path so there are two different driver-offsets here really , i call this "spanned" along the path ..
USRFobiwan,
Part of it is related to the expansion profile, take a look at the image included in post #348 .... Compare the severity of the midbass dips between the left and right graphs in that post .... Notice the improvement in the flared option .... It is a very easy modification for that layout.
The dip we see in the midbass is located between the Fb*5 and Fb*7 harmonics which are shifted downward by the path's expansion if i understand it correctly ......
I have noticed that this dip can be alleviated somewhat by smoothing the expansion (i mean by making the main path more like a traditional horn shape) ...... I have also noticed that the dip can be remedied with some driver-offset (or a tuned stub) .....
It can explain why the Club Tops featured in post #1 were such a success , because those tops were using both methods mentioned in the paragraph above......... Expansion was accomplished in a few steps instead of one big jump , and the drivers were set up in an offset fashion both sharing the same path so there are two different driver-offsets here really , i call this "spanned" along the path ..
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1 or 2 drivers 10" or 12" (each one of 8-16 Ohm for parallel config ) with less spl max but more extension in the deep bass (25-30 hz).
I want to use a couple of sub for home hi-fi .
Thanks a lot !
Alright
Luca ,
These very high efficiency designs tend to get very large with lower tunings ....Even tuning these cabinets at 35hz is pushing it in many cases...... I am working on a modified version of the Super Planar 8th that can be made more compact, but in the meantime yes , there are a few 12" drivers that we could turn to for a 30hz tuning (i would need to model them to verify)... Response would likely be "rising" which is not necessarily bad, and we would be talking about some sizeable cabinets
What part of the world are you in Luca?
Luca ,
These very high efficiency designs tend to get very large with lower tunings ....Even tuning these cabinets at 35hz is pushing it in many cases...... I am working on a modified version of the Super Planar 8th that can be made more compact, but in the meantime yes , there are a few 12" drivers that we could turn to for a 30hz tuning (i would need to model them to verify)... Response would likely be "rising" which is not necessarily bad, and we would be talking about some sizeable cabinets
What part of the world are you in Luca?
I would not call this an "improvement". Flared paths sound different then straight sections. In my experience comparing tapped horns with tapped pipes and now with the ROAR series, I would argue that the flared quarter wave resonators lack the raw physical energy compared to straight pipes. A tapped pipe is a much better home theater sub then a similar tapped horn, due to the very physical character and tactile reproduction.
This difference is even more pronounced at high spl. See post #309 in this thread where everything starts to buzz and vibrate violently in his car.
My ROAR12 is not really useful at home, since everything vibrates and buzz even at a few watts. No tapped horn have behaved the same - and I have build many of them throughout the years.
Cheers,
Johannes
My 2 12" drivers in their sealed enclosure do the same thing in my car when I crank them up. It's all to do with the level of SPL generated, not what is generating it. One could argue though that the high GD of these ROAR designs makes them less suitable for home audio use.
With only two watts and at the opposite side of your house??
My ROAR12 rattles our plates in our kitchen from our living room.
Yes, but real life use shows easy integration with a wide selection of loudspeakers, indoors as well as outdoors. It seems to blend seamlessly with most speakers, with a steep crossover around 100 to 120 Hz.
I am using my ROAR12 instead of the built in 5 inch bass driver in my Logitech 2.1 computer loudspeaker system. It is not perfect (to high crossover frequency) but it is a great upgrade in sound quality.
So, you measure SPL in watts then?
As always, YMMV. I've abandoned systems that seem to have a great FR, but sounded audibly unacceptable, and the only thing that stood out seemed to be high GD, so when I design my systems I keep an eye on that.
Luca ,
These very high efficiency designs tend to get very large with lower tunings ....Even tuning these cabinets at 35hz is pushing it in many cases...... I am working on a modified version of the Super Planar 8th that can be made more compact, but in the meantime yes , there are a few 12" drivers that we could turn to for a 30hz tuning (i would need to model them to verify)... Response would likely be "rising" which is not necessarily bad, and we would be talking about some sizeable cabinets
What part of the world are you in Luca?
Which are the ideal T/S parameters for your compound to go down to 30 Hz with a not enormous box ?
A good example =)
Luca ,
You read my mind! Hehe ... I was wanting to show you an example of a driver with enough motor force to allow for a tuning of 30hz in a reasonably sized Super Planar 8th ....
You basically want to look for drivers with:
A couple of the B&C 12s like the 12NW100 and 12NBX100 might be worth modeling , although they are limited by their excursion, and the low tuning that you desire does demand a lot of displacement....... These options may work for you since you said you are ok with less extreme SPL
Take a look at the following from Twisted Sounds (link below) ... They are currently on sale, maybe they will ship to Italy???
Hopefully the shipping costs won't be prohibitive..
TS X1000 D2
The company has been contacted about the excursion capability of the TS X1000, they claim it is capable of 25mm one-way which seems like a lot to me.... Even if it turns out to only have 15mm one-way linear this driver still models VERY well (assuming their published parameters are accurate).
I plan on posting a list of compatible drivers soon of various types and sizes (PA drivers and Car Audio driver options, basically whatever i could find that would work.. )
Luca ,
You read my mind! Hehe ... I was wanting to show you an example of a driver with enough motor force to allow for a tuning of 30hz in a reasonably sized Super Planar 8th ....
You basically want to look for drivers with:
- a very high BL^2/Re figure,
- a Qts that isn't too high (.2 to .4 range) ,
- an Le figure that isn't too high relative to the Re,
- an Fs that isn't too far off from our desired cabinet tuning,
- high linear excursion (15mm one-way linear would be nice)......
A couple of the B&C 12s like the 12NW100 and 12NBX100 might be worth modeling , although they are limited by their excursion, and the low tuning that you desire does demand a lot of displacement....... These options may work for you since you said you are ok with less extreme SPL
Take a look at the following from Twisted Sounds (link below) ... They are currently on sale, maybe they will ship to Italy???
Hopefully the shipping costs won't be prohibitive..
TS X1000 D2
The company has been contacted about the excursion capability of the TS X1000, they claim it is capable of 25mm one-way which seems like a lot to me.... Even if it turns out to only have 15mm one-way linear this driver still models VERY well (assuming their published parameters are accurate).
I plan on posting a list of compatible drivers soon of various types and sizes (PA drivers and Car Audio driver options, basically whatever i could find that would work.. )
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JBL GT-X 1200 less than 70 €
X-max 12 mm Qt 0,54 Vas 77 90dB Fs 28 Hz Bxl
http://demandware.edgesuite.net/aauj_prd/on/demandware.static/-/Sites-masterCatalog_Harman/default/dw3cae66ab/pdfs/GT-X1200 Data_Sheet1.pdf
Or the similar JBL CS-1214 less than 60 €
Or the JBL GT 5 12" (also for less than 70 € now available again) with a a little bit high Qt 0,58 but X-max 14 mm Fs 29 and Bxl 15,2
Sensitivity (2.83V/1m) 90dB and low inductance
GT5-12 | Quality 12 inch Single Voice Coil (SVC) Subwoofer
Yes .....The B&C are better ( and they are made in Italy near Florence!) but they cost a little bit and have an high Fs
Or this economical Lanzar but I don't know Bxl and inductance
Lanzar MAX12 12" Subwoofer 4 Ohm
X-max 12 mm Qt 0,54 Vas 77 90dB Fs 28 Hz Bxl
http://demandware.edgesuite.net/aauj_prd/on/demandware.static/-/Sites-masterCatalog_Harman/default/dw3cae66ab/pdfs/GT-X1200 Data_Sheet1.pdf
Or the similar JBL CS-1214 less than 60 €
Or the JBL GT 5 12" (also for less than 70 € now available again) with a a little bit high Qt 0,58 but X-max 14 mm Fs 29 and Bxl 15,2
Sensitivity (2.83V/1m) 90dB and low inductance
GT5-12 | Quality 12 inch Single Voice Coil (SVC) Subwoofer
Yes .....The B&C are better ( and they are made in Italy near Florence!) but they cost a little bit and have an high Fs
Or this economical Lanzar but I don't know Bxl and inductance
Lanzar MAX12 12" Subwoofer 4 Ohm
I would go for the B&C 12BG76 driver 9.5mm xmax, 14mm xvar and a BL of 22.7T or the 12BG100 with 10.5mm xmax, 14mm xvar and BL of 23T
Other candidates:
BMS 12N630
Other candidates:
BMS 12N630
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I would avoid all drivers with a Qts over 0.3 in this kind of box.
Resonant high Qts drivers lack definition and punch, and even more so in this kind of multitresonant tuning. You want all the motor-force possible. I wish B&C would make a 12DS115 or a 12IPAL based on the 21DS115 or 21IPAL motor and voice-coil.
Cheers,
Johannes
The box size will often increase with any increase in Qts, so as an answer to his original question I advice agains high Qts drivers (Qts above 0.3).
A Qts of 0.33 is probably useful. Bl, Vas, Fs and Mms also effects the box size. I would prefer a Qts of 0.2 - 0.25 to keep the size of the box down,but I am aware of the cost usually associated with those drivers.
MMJ commented on the suitability of the rather unique B&C 18DS115 in this kind of multi-resonant box, and after developing the ROAR series I can only concur with the suitability of those modern high power density drivers.
So, to wrap it up. I hope B&C will start selling cheap 12IPAL and 12DS115 drivers. 12 inch 4ohm drivers needs a Bl in excess of 40....
Cheers,
Johannes
driver suitability chat
Hey guys,
Johannes and USRFobiwan have the right idea , and Obi's 12BG100 looks like it has the right stuff! ....
(Using the Twisted 12D2 for the following example, voicecoils in series) A BL value of 26 for a driver with 3.9 ohm Re is sufficient The Twisted 12 D2 has an Re value that is really at the very high end of what could be considered "4 ohm" , it is really more of a 6 ohm driver (impedance).. .... Higher Re values call for a higher BL in order to have the same motor force , and the reverse is true for drivers with lower Re values .. .......
We have to use the BL^2/Re formula to properly compare the motor force of drivers with different impedances .. .
Very high Le to Re ratios will negate much of the motor force, and this is a problem for some high-excursion drivers ...
The B&C 12BG100 has a BL of 23 for an Re of 5.1 ohms (only 1.2 ohms higher than the Twisted) and the 12BG100 has a low Le figure relative to it's Re so that is very favorable.
The drivers that Luca posted don't have enough motor force to get the cabinet down to a reasonable size if we are making a Super Planar 8th tuned in the low 30s ..... The Lanzar 12 doesn't have enough of it's parameters listed to calculate out the rest ......... Lanzar is one of a family of brands under the parent company "SOUND AROUND" , and other members of this family include Pyramid and Pyle brands ..... The parameters on their drivers should always be measured because they often won't match what is published ....
Hey guys,
Johannes and USRFobiwan have the right idea , and Obi's 12BG100 looks like it has the right stuff! ....
(Using the Twisted 12D2 for the following example, voicecoils in series) A BL value of 26 for a driver with 3.9 ohm Re is sufficient
The Twisted 12 D2 has an Re value that is really at the very high end of what could be considered "4 ohm" , it is really more of a 6 ohm driver (impedance).. .... Higher Re values call for a higher BL in order to have the same motor force , and the reverse is true for drivers with lower Re values .. ....... We have to use the BL^2/Re formula to properly compare the motor force of drivers with different impedances .. .
Very high Le to Re ratios will negate much of the motor force, and this is a problem for some high-excursion drivers ...
The B&C 12BG100 has a BL of 23 for an Re of 5.1 ohms (only 1.2 ohms higher than the Twisted) and the 12BG100 has a low Le figure relative to it's Re so that is very favorable.
The drivers that Luca posted don't have enough motor force to get the cabinet down to a reasonable size if we are making a Super Planar 8th tuned in the low 30s ..... The Lanzar 12 doesn't have enough of it's parameters listed to calculate out the rest ......... Lanzar is one of a family of brands under the parent company "SOUND AROUND" , and other members of this family include Pyramid and Pyle brands ..... The parameters on their drivers should always be measured because they often won't match what is published ....
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Hi Mathew Morgan J,
The equation: BL^2/Re does not include motor losses (eddy currents and magnetization in the pole piece and magnet).
BL^2/Zmin (for subwoofer use only) does include these motor losses and comes very close to the effective motor power.
Zmin is usually provided by pro manufacturers (and is a requirement according to international standards).
Regards,
Djim
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Djim ,
Thank you, that should be a good way to go when comparing some pro drivers .... I wish all of the manufacturers provided that figure so that i can compare across genres..
Thank you, that should be a good way to go when comparing some pro drivers .... I wish all of the manufacturers provided that figure so that i can compare across genres..
Shall we make a list?
Lets start a list for the sake of comparison:
Twisted Sound TSX1000 12 D2
BL^2/Re = 176
Qts = .39
Fs = 37hz
Le:Re = 2.54:3.9
Xmax = (claimed 25mm but i expect at least 15mm one-way linear)
EFFECTIVE MOTOR FORCE = 99.71 (after "Lossy inductance")
Skar Audio DDX 12 D4 (coils in series)
BL^2/Re = 148.7
Qts = .37
Fs = 39hz
Le:Re = 4.44:6.8 (had to email them to get the Le)
Xmax = 15mm one-way linear
EFFECTIVE MOTOR FORCE = 81.7 (after "Lossy inductance")
B&C 12BG100 8 ohm
BL^2/Re = 103.72
Qts = .33
Fs = 39hz
Le:Re = 1.6:5.1
Xvar = 14mm one-way
EFFECTIVE MOTOR FORCE = 72.88 (after "Lossy inductance")
I used Hornresp to calculate out the Lossy inductance .... (it adjusts the BL by applying the formula that Just A Guy and his research peers came up with)
Important to note that the B&C has a little less moving mass and slight extra bit of cone area so it is likely to have a small efficiency advantage over the others listed here but also prefers a cabinet that is also marginally larger (for the same tuning) due to less motor force, so it is a tradeoff , although all three models listed above model very well
ANOTHER FUN NOTE:
Two of the B&C 12BG100 drivers in a 530 liter Super Planar 8th tuned to 39hz makes a formidable PA subwoofer ... I just modeled it and it looks pretty good The dual 12BG100s have a combined effective motor force of nearly 146 and the 18DS115 has an effective motor force of 173.6 (this is after taking "Lossy Le" into account) ..... Even though the 18 has a motor force advantage in this comparison it also suffers from a disadvantage in regards to stress on the cone because the 12s will have the pressure divided by two and placed upon much smaller cones .............................................. I can also use two of the other models listed above in such a subwoofer cabinet , and we could make the cabinet smaller in that case ....
Lets start a list for the sake of comparison:
Twisted Sound TSX1000 12 D2
BL^2/Re = 176
Qts = .39
Fs = 37hz
Le:Re = 2.54:3.9
Xmax = (claimed 25mm but i expect at least 15mm one-way linear)
EFFECTIVE MOTOR FORCE = 99.71 (after "Lossy inductance")
Skar Audio DDX 12 D4 (coils in series)
BL^2/Re = 148.7
Qts = .37
Fs = 39hz
Le:Re = 4.44:6.8 (had to email them to get the Le)
Xmax = 15mm one-way linear
EFFECTIVE MOTOR FORCE = 81.7 (after "Lossy inductance")
B&C 12BG100 8 ohm
BL^2/Re = 103.72
Qts = .33
Fs = 39hz
Le:Re = 1.6:5.1
Xvar = 14mm one-way
EFFECTIVE MOTOR FORCE = 72.88 (after "Lossy inductance")
I used Hornresp to calculate out the Lossy inductance .... (it adjusts the BL by applying the formula that Just A Guy and his research peers came up with)
Important to note that the B&C has a little less moving mass and slight extra bit of cone area so it is likely to have a small efficiency advantage over the others listed here but also prefers a cabinet that is also marginally larger (for the same tuning) due to less motor force, so it is a tradeoff , although all three models listed above model very well
ANOTHER FUN NOTE:
Two of the B&C 12BG100 drivers in a 530 liter Super Planar 8th tuned to 39hz makes a formidable PA subwoofer ... I just modeled it and it looks pretty good
The dual 12BG100s have a combined effective motor force of nearly 146 and the 18DS115 has an effective motor force of 173.6 (this is after taking "Lossy Le" into account) ..... Even though the 18 has a motor force advantage in this comparison it also suffers from a disadvantage in regards to stress on the cone because the 12s will have the pressure divided by two and placed upon much smaller cones .............................................. I can also use two of the other models listed above in such a subwoofer cabinet , and we could make the cabinet smaller in that case ....
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