Cool ScottG, thats the driver I was trying to link. I thought it was a good price but know nothing about modeling a sub. Is there a way a person could make that sub work sealed and go low enough with a special sub amp that has boost or with eq?
What about loading the front of the drivers like the Method does by having them fire against a baffle about a 1/4 inch away from the front of the drivers, would that make any difference to the design etc? I wish I could go for the tapped horn but no room at this time..
Thanks to all for the help and for putting up with my questions.. Dave
What about loading the front of the drivers like the Method does by having them fire against a baffle about a 1/4 inch away from the front of the drivers, would that make any difference to the design etc? I wish I could go for the tapped horn but no room at this time..
Thanks to all for the help and for putting up with my questions.. Dave
DaveCan said:
Thats exactly what I was describing.
Don't bother with the "Methods" low pass acoustic "filter".. just do it electronically with a 24 db filter. Make sure that filter is set below 40 Hz however AND expect the resulting lowpass response to be closer to 12db an octave. (..for best integration also have a full *variable* phase adjustment capability.)
At 20 Hz in the design I gave you - just one sub should net you just a bit more than 90 db at 1 meter for one watt.
It doesn't have a lot of excursion though, so be wary of very low freq. fundamentals at higher spls without 2 or more subs (each in their own corner). (i.e. organ music, some club music, and the occasional action movie could bottom out the driver.)
Note that my previous post above should read lowpass where its stated incorrectly as highpass.
G'day DaveCan
ScottG is giving you good advice, and doesn't the driver look remarkably similar to the drivers used in the Zu Method? Not just a coincidence, I'd imagine....
You might want to explore an EBS design (LLT) similar to the one described on the Madisound site. A well designed EBS box can sound just as good as a sealed box, but has a little more sensitivity down low as well as lower distortion and greater output capability.
Cheers
William Cowan
ScottG is giving you good advice, and doesn't the driver look remarkably similar to the drivers used in the Zu Method? Not just a coincidence, I'd imagine....
You might want to explore an EBS design (LLT) similar to the one described on the Madisound site. A well designed EBS box can sound just as good as a sealed box, but has a little more sensitivity down low as well as lower distortion and greater output capability.
Cheers
William Cowan
Thanks guys... Maybe I should try the EBS style? Here's another company that uses the high eff paper cone sealed route. You can clearly see the Eminence drivers in the review and in one shot can almost see what model it is, but I can't make it out..
http://6moons.com/audioreviews/wlm2/duo12.html
Here's some advice Sean gave me from ZU;
For sure using drivers below resonance,with big motors and light cones, with electronic manipulation can result in some great, non boom kickin' tight, diggin' deep sound that can be small enough to use in your home. Look at some of the bass guitar speakers....
low xmax (neutral and under hung better yet if you can get the impendance mismatch down)
high Bl is good, work with it. More motor, tight tolerance
Paper cones are yet to be bested.
Check out BC,18 Sound, EV, JBL, Eminence, Selenium and other pro audio companies.
Dave
http://6moons.com/audioreviews/wlm2/duo12.html
Here's some advice Sean gave me from ZU;
For sure using drivers below resonance,with big motors and light cones, with electronic manipulation can result in some great, non boom kickin' tight, diggin' deep sound that can be small enough to use in your home. Look at some of the bass guitar speakers....
low xmax (neutral and under hung better yet if you can get the impendance mismatch down)
high Bl is good, work with it. More motor, tight tolerance
Paper cones are yet to be bested.
Check out BC,18 Sound, EV, JBL, Eminence, Selenium and other pro audio companies.
Dave
The WLM sub is even closer to what I suggested (though no isobaric loading). (..looks like a Kappa Pro 15.)
Note that what I proposed will go a lot lower in freq. with a less distortion at those very low freq.s.
A bass reflex design*can* give you less non-linear distortion, but it won't extend nearly as low in freq., and near its resonance both linear and non-linear distortion increase dramatically.
Yes, I could suggest a good design for bass reflex, but I won't because I think the solution I've given you will please you more.
Note that what I proposed will go a lot lower in freq. with a less distortion at those very low freq.s.
A bass reflex design*can* give you less non-linear distortion, but it won't extend nearly as low in freq., and near its resonance both linear and non-linear distortion increase dramatically.
Yes, I could suggest a good design for bass reflex, but I won't because I think the solution I've given you will please you more.
Thanks Scott,
The WLM in the review is actually 12'' drivers and I just e-mailed them to see if they would let me know the model of the drivers... It looks like from what I can see in the review that each driver is in it's own sealed cavity one firing up at the ceiling and the other down at the floor wired in parallel but not totally sure.. Thanks for the enclosure idea. Could it work well with 10 or 12'' drivers as I'd like to use 10's if I could or 12's and 15's as a last choice... Dave
The WLM in the review is actually 12'' drivers and I just e-mailed them to see if they would let me know the model of the drivers... It looks like from what I can see in the review that each driver is in it's own sealed cavity one firing up at the ceiling and the other down at the floor wired in parallel but not totally sure.. Thanks for the enclosure idea. Could it work well with 10 or 12'' drivers as I'd like to use 10's if I could or 12's and 15's as a last choice... Dave
Perhaps if WLM gets back to me I'll use 12'' drivers.. I searched Eminence at Partsexpress and there is a few that look like the one in the pics. It's kind of nice that the Eminence drivers seem very reasonably priced compared to say JBL etc... In any event this has been a fun project for me to research even though I know I'm looking very noobish with all the dumb questions.. I'd love to do a horn like that 16hz tapped horn or a huge BIB but space will not allow
Dave
Dave
Basically that eminence 15 inch is the only one I know of that is both relativly high in eff., low in fs, with fairly low mms with a modest vas (for its low fs).
any choice to go to a smaller diameter driver with a similar high eff. sound will typically result in not only needing a fair bit of equalization on the low end (to boost the response), but also end in considerably higher non-linear distortion.
This cheap pioneer 10" pro driver NOT in an isobaric AND with 2 drivers (a'la WLM) paralleled each in their own 2 cubic foot enclosure *may* produce something similar:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-094
(..one of the problems here is I'm not sure how the "top" driver will couple to the room corner. The other is that the excursion is low and the sd even * 2 is low - the net effect being power handling less than half that of the eminence 15 inch.)
Another problem here is that the pioneer (because of its higher fs and lower sd and xmax) almost certainly has more non-linear distortion intrinsic to the driver near its fs.
Note that there are other more "efficient" solutions at lower freq.s via more traditional drivers.. BUT the sound isn't quite the same.
any choice to go to a smaller diameter driver with a similar high eff. sound will typically result in not only needing a fair bit of equalization on the low end (to boost the response), but also end in considerably higher non-linear distortion.
This cheap pioneer 10" pro driver NOT in an isobaric AND with 2 drivers (a'la WLM) paralleled each in their own 2 cubic foot enclosure *may* produce something similar:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-094
(..one of the problems here is I'm not sure how the "top" driver will couple to the room corner. The other is that the excursion is low and the sd even * 2 is low - the net effect being power handling less than half that of the eminence 15 inch.)
Another problem here is that the pioneer (because of its higher fs and lower sd and xmax) almost certainly has more non-linear distortion intrinsic to the driver near its fs.
Note that there are other more "efficient" solutions at lower freq.s via more traditional drivers.. BUT the sound isn't quite the same.
DaveCan said:Perhaps if WLM gets back to me I'll use 12'' drivers.. I searched Eminence at Partsexpress and there is a few that look like the one in the pics. It's kind of nice that the Eminence drivers seem very reasonably priced compared to say JBL etc... In any event this has been a fun project for me to research even though I know I'm looking very noobish with all the dumb questions.. I'd love to do a horn like that 16hz tapped horn or a huge BIB but space will not allow
Dave
This is the likely driver:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-424
At 2 cubic feet it marginally outperforms the pioneer 10 with respect to sp-level at low freq.s, BUT it has both a larger sd and a higher xmax. Neither the curve nor the Qtc is quite the same though - so it will have a little less damping (..and a closer approximation would be 4 cubic feet).
Note that I'd still recommend the 15 inch eminence solution..
It has two other factors going for it that aren't immediately apparent:
In an isobaric loading there is twice the motor and twice the mass in effectively a single driver - as a result force increases and it sounds more "tactile" without reducing the drivers apparent reproduction of detail (at low freq.s).
Also, the box air turbulence and its effect on driver operation of the driver loading into the room is typically reduced - sometimes marginally reducing even-order non-linear effects.
Thanks Scott the 15's it is then .. I wish I understood all the math stuff better as related to loudspeakers because its all quite confusing to me, but I know what I like for sound and I'm all about SQ and realism.. I'm just looking to augment my fullrange drivers and it's not for HT just music and I'm not looking for massive spl just a modest dose of low end lol... Now how to go about it??? Birch ply? plans? lol Dave
.. I wish I understood all the math stuff better as related to loudspeakers because its all quite confusing to me, but I know what I like for sound and I'm all about SQ and realism.. I'm just looking to augment my fullrange drivers and it's not for HT just music and I'm not looking for massive spl just a modest dose of low end lol... Now how to go about it??? Birch ply? plans? lol Dave
Sean from Zu gave me some info and ideas yesterday in response to my e-mails.. I told him about the 15'' driver at Madisound with the low fs but couldn't link it . He didn't see it but his advice was paper is good,big motors are good, low fs can be bad, usually means a high moving mass.. Another driver to check out is the Eminence Beta, just ok specs but it has great bass tone and performance...
The e-mail before that one he suggested this one for me to try:
Get your hands on a basic DPS or parametric eq with a low pass filter. You don't need any speaker level transient killing coils in our sub. Find a good class A/B amp to feed the sub. Stuff a 15'' Eminence 11oz neo or Definimax driver in 4 cubic feet and then goes on to tell me how to construct and brace the box etc. Lots of good ideas to try.. Dave
The e-mail before that one he suggested this one for me to try:
Get your hands on a basic DPS or parametric eq with a low pass filter. You don't need any speaker level transient killing coils in our sub. Find a good class A/B amp to feed the sub. Stuff a 15'' Eminence 11oz neo or Definimax driver in 4 cubic feet and then goes on to tell me how to construct and brace the box etc. Lots of good ideas to try.. Dave
Keep in mind that isobaric results in half the efficiency, since you have to drive twice as many woofers. And the reduction in cabinet isn't all that much since you have to allow for the volume of the second driver and the tunnel that links them. If you want efficient, use two drivers in some normal configuration, since that doubles efficiency over a single driver, and is 4 times as efficient as the isobaric loading. It should also result in 4 times the maximum SPL, since you've both doubled the efficiency and the power handling.
Unless Bill Gates is asking you to build a sub for his yacht where space is very limited and cost is no object, I can't see any justification for the isobaric configuration. Consider mass loading a driver if you want a smaller box, but that will also, inevitably, reduce efficiency.
It sure sounds like the Zu sub is awfully similar to the Bag End design. If you read the review in SGHT, they mention that the mastering studio for Black Hawk Down needed a large number of the subs to achieve usable output below 20 Hz. The problem with EQ is that it also requires limiting or you'll run out of both amplifier power and Xmax at low frequencies. It is an excellent solution for many practical purposes, because it gives high efficiency where most of the "bass" in music is located, 80 Hz and up, yet provides the illusion of much deeper extension, without the risk of unpleasant noises from overloading. Bass guitars don't need anything much below 82 Hz, since the lowest string on a 4-string is 41 Hz, and the second harmonic is around 10 dB stronger than the fundamental.
Consider going with a good 12" sealed-box driver like the NHT1259 in about 3 cubic feet (or whatever the usual box is). Most reviews of the NHT SW3P sub that used that exact same driver remarked on its musical quality compared to other subs. Presumably the 2nd order roll-off is a good thing, so going with a similar design should yield something equally satisfactory. It isn't particularly efficient, but since amps are so cheap that shouldn't be a problem.
Unless Bill Gates is asking you to build a sub for his yacht where space is very limited and cost is no object, I can't see any justification for the isobaric configuration. Consider mass loading a driver if you want a smaller box, but that will also, inevitably, reduce efficiency.
It sure sounds like the Zu sub is awfully similar to the Bag End design. If you read the review in SGHT, they mention that the mastering studio for Black Hawk Down needed a large number of the subs to achieve usable output below 20 Hz. The problem with EQ is that it also requires limiting or you'll run out of both amplifier power and Xmax at low frequencies. It is an excellent solution for many practical purposes, because it gives high efficiency where most of the "bass" in music is located, 80 Hz and up, yet provides the illusion of much deeper extension, without the risk of unpleasant noises from overloading. Bass guitars don't need anything much below 82 Hz, since the lowest string on a 4-string is 41 Hz, and the second harmonic is around 10 dB stronger than the fundamental.
Consider going with a good 12" sealed-box driver like the NHT1259 in about 3 cubic feet (or whatever the usual box is). Most reviews of the NHT SW3P sub that used that exact same driver remarked on its musical quality compared to other subs. Presumably the 2nd order roll-off is a good thing, so going with a similar design should yield something equally satisfactory. It isn't particularly efficient, but since amps are so cheap that shouldn't be a problem.
Yes I remember reading comments about the NHT and how it was very musical...
The Peerless 10'' with the matching PR says it has an f3 of 20hz in a 1.25 cubic foot enclosure, which would be great for the small size but I'm real intrigued with the hi eff paper cone ideal... Things would be so much easier if I could just do a monster horn or IB or just settle for the usual cookie cutter ported box or the like...
To bad they can't just make a woofer that has all the good stuff like, small box ready, high enough power handling,paper cone design, ultimate sq,95+dbsens 1w, good x-max ,and gets down low in a small box... Dave
The Peerless 10'' with the matching PR says it has an f3 of 20hz in a 1.25 cubic foot enclosure, which would be great for the small size but I'm real intrigued with the hi eff paper cone ideal... Things would be so much easier if I could just do a monster horn or IB or just settle for the usual cookie cutter ported box or the like...
To bad they can't just make a woofer that has all the good stuff like, small box ready, high enough power handling,paper cone design, ultimate sq,95+dbsens 1w, good x-max ,and gets down low in a small box... Dave
On an isobaric push push..
-3db for the doubling of mass +3db for the parallel connection = 0 db alteration.
Vas is halve that + the space for the additional driver and chamber - in the case of the eminence 15 that can be quite low (as its motor is not terribly intrusive). Net volume a little more than 5 cubic feet (prob. 5 and a half).
vs.
2 drivers in their own sealed enclosure..
+3db for the doubling of drivers and +3db for the parallel connection = +6db alteration.
In the case of the eminence under the conditions I spec.ed = 10 cubic feet per driver.
.........................................................
Now then,
Is +6db in this fashion worth almost 15 extra cubic feet in a domestic setting?
Only Dave can make that decision (or rather if he has a significant other - that person will likely make the decision for him).
...........................................................
And Dave, the reason that such a driver hasn't been made is that its pretty much impossible. (..hmm, could make a driver specifically designed for sulfur hexafluoride as an air substitute for the sealed enclosure - then you could servo it to improve performance with longer strokes.)
-3db for the doubling of mass +3db for the parallel connection = 0 db alteration.
Vas is halve that + the space for the additional driver and chamber - in the case of the eminence 15 that can be quite low (as its motor is not terribly intrusive). Net volume a little more than 5 cubic feet (prob. 5 and a half).
vs.
2 drivers in their own sealed enclosure..
+3db for the doubling of drivers and +3db for the parallel connection = +6db alteration.
In the case of the eminence under the conditions I spec.ed = 10 cubic feet per driver.
.........................................................
Now then,
Is +6db in this fashion worth almost 15 extra cubic feet in a domestic setting?
Only Dave can make that decision (or rather if he has a significant other - that person will likely make the decision for him).
...........................................................
And Dave, the reason that such a driver hasn't been made is that its pretty much impossible. (..hmm, could make a driver specifically designed for sulfur hexafluoride as an air substitute for the sealed enclosure - then you could servo it to improve performance with longer strokes.
)DaveCan said:Now how to go about it??? Birch ply? plans? lol Dave
No plans - but it should be an easy build.
Remember its 5 cubic feet + the space for the additional driver and any bracing. Also IF you can get a plate amp that will drive a 2 ohm load.. BUT make absolutely sure that it has a variable lowpass filter selection that extends to at least 30 Hz that is 24 db an octave AND that it has a variable phase adjustment (not simply a phase switch). (..if you have to give up anything then give up the ability to drive a 2 ohm load and just figure that if you decide to build another one that you will have to purchase another plate amp.)
Anyway..
If you follow the column/pedestal that I suggested then its likely to be about 18 inch length, 18 inch width, and 40 inch height externally (not including spikes to lift the thing off of the ground by about 2 inches depending on floor surface). (..using a full inch of plywood on all sides drops the figure closer to 16 by 16 by 38 internally). The internal driver should be about 4 inches above the external driver.
It *will* take some planning on your part - but with the exception of the additional interior baffle and bracing, its little more than a box with driver baffle.
This is the amplifier with crossover I'd recommend:
http://www.creativesound.ca/details.php?model=A400
quite inexpensive for what it is.
And unlike everything else - it is 2 ohm capable.
(note that while the lowpass only extents to 40 Hz that it also has additional eq.s available to better tailor the response.)
http://www.creativesound.ca/details.php?model=A400
quite inexpensive for what it is.
And unlike everything else - it is 2 ohm capable.
(note that while the lowpass only extents to 40 Hz that it also has additional eq.s available to better tailor the response.)
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