hm....
I think people here can handle it... we're not talking about an "Audio Review" level crowd. But if you need to keep a hat on it I suppose we'll do without. Please continue to share your other results!
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Good try but I'm not in a position to release any of it. End of story unfortunately.
But I applaud your diligence!
I agree that this is not a low level group of individuals. I wouldn't post such a design if I thought you guys were not capable of appreciating it! But I can only do what I can do.
Very safe to say the published specs are very conservative. That I can say emphatically.
Guess what ? It rained this morning and this afternoon.
I can't win.
Mark
But I applaud your diligence!
I agree that this is not a low level group of individuals. I wouldn't post such a design if I thought you guys were not capable of appreciating it! But I can only do what I can do.
Very safe to say the published specs are very conservative. That I can say emphatically.
Guess what ? It rained this morning and this afternoon.
I can't win.
Mark
Yep there will be plans and such. Bob over at CSS the driver vendor has the rights to the design. What I do know is that there are some great things coming concerning this design. THere will be 3D renderings as well as a build thread. But this stuff takes some time.
I'm fighting the weather to get decent ground plane measurements. I know anecdotaly how low the sub goes. I was there when we ran the RTA as well. It performs very well.
It is a large box but has quite a few placement possibilities. The design has been refined to have an exhaust at the lower portion of one of the 16.5" sides. This will allow placement horizontally, vertically or on edge. Better ways to hide a big ugly box.
So please be patient.
If you have good build skills and can work off of a napkin sketch then conact Bob at CSS. He'll help you out.
Mark
other than bandwidth restriction do you think Trio12 would make a good BP4 bandpass sub? WInISD "online" suggests the following response for one BP4 alignment
An externally hosted image should be here but it was not working when we last tested it.
- wanted to pick up DTS10 kit but didn't have help to unload one then they sold out so BP4 might be fun - here's basic numbers for BP4 and Trio12 with no rear chamber stuffing. Might use a panpipe sliced on one end vertical vent trimmed to Fb
S=0.5 S=0.6 S=0.7
40 liters total 61 liters total 90 liters total
F3 28/93 F3 25/74 F3 23Hz/59
Fb = 51 Fb = 42.6 Fb = 36.5
S=0.5 S=0.6 S=0.7
40 liters total 61 liters total 90 liters total
F3 28/93 F3 25/74 F3 23Hz/59
Fb = 51 Fb = 42.6 Fb = 36.5
hey Mark - I've collected stuff for 30+ years and its built up so a Minimus7 can hardly fit. Looking at Trio12 and a 600uF polypropylene cap in my pile here's one possibility with 15mH in 30L/30L BP (that cap is limiting what can fit including inductor) - maybe BP aren't always sensible but I haven't done one for awhile. Best, Freddy
2Vrms, Red trace = floor + wall, Black trace = half-space
2Vrms, Red trace = floor + wall, Black trace = half-space
An externally hosted image should be here but it was not working when we last tested it.
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here's one of those 600uF 500v caps - oughta hold up for passive "boost" duty http://img84.imageshack.us/img84/6024/salt.gif
on another forum an old one-fold pipe with ~4.9 cubic internal feet volume was being being discussed and it sims pretty nice with Trio 12
pipe with 0.46 qts, fs ~20Hz 6mm xmax Eminence outdoors - a 3" or 4" ID vent might compress a bit
sim with Trio12
on another forum an old one-fold pipe with ~4.9 cubic internal feet volume was being being discussed and it sims pretty nice with Trio 12
pipe with 0.46 qts, fs ~20Hz 6mm xmax Eminence outdoors - a 3" or 4" ID vent might compress a bit
An externally hosted image should be here but it was not working when we last tested it.
sim with Trio12
An externally hosted image should be here but it was not working when we last tested it.
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I posted parts of this on another thread and at different times. But in the context of this subwoofer I thought it really is interesting. I changed the math slighly to correct a problem on the last number that was missing in the first power progression.
The distortion in most subs is due to driver nonliterary pushing them so hard that they are no longer in control of the motor structure design. The ways to get around that are rather simple. Use more drivers. But to have any appreciable difference we have to remember that to drop an octave in bass we need four times the volume of air moved to keep the SPL equal. You need quite a few woofers. The second solution is to provide a better acoustical match between the driver and the air in the room. This is the method that is being discussed in this thread. I don't recall seeing a figure of actual box gain over raw data from Patrick's posts. But in the horn I'm fooling with the gain is between 8 and 10 db over the raw driver. That is an increase of efficiency of just over and around four times that of a driver on it's own mounted in a conventional enclosure. So the driver in a horn has to move one quarter the amount of air to get the same sound pressure level of that same driver in a vented enclosure.
Gain? Well the distortion is cut down dramatically. More than the 1/4 you would think. If you use a driver that has a very linear motor structure like the XBL type in the TRIO12 you are getting great control of the driver over a far longer stroke. A stable BL is very important in keeping all forms of distortion low. The BL is the number of turns of wire in the voice coil that are saturated by the magnet and motor structure. It is the best measurement of how in control the cone remains at any position. It is also a curve that most manufacturers will not provide.
No matter how much power you throw at a driver it is only a repulsive force from the existing motor structure. So the inherent linearity of the driver itself is very important. The other very interesting thing about drivers and actual speaker boxes is that the more power we push into the driver the more they heat up. Then the voice coil parameters change drastically. If we can create an enclosure where the driver is better coupled to the room we are in the required power is greatly diminished and the resulting sound from the driver/enclosure system is cleaner. There is no warmed up voice coil that is now two to three tikes the resistance of one at room temperature. The amplifier does not have to try and push gobs of power into a voice coil that is literally compressing the power instead of tracking it. Nope we can get a driver that will track the music signal and produce what we are after. The idea that we can take a driver and push hundreds of watts into it and get a louder response is more a myth than reality.
Here is the power versus SPL progression
Base line 90 db one watt.
1-2-4-8-16-32-64-128-256-512-1024-2048 watts
90-93-96-99-102-105-108-111-114-117-120 -123 in db
These are all increments which increase the sound level by 3 db.
This is a power output progression showing the power required to raise a signal 33 db. So from about 90db to about 120 db.
There are no drivers that can sustain this amount of power input. Not even pr sound drivers. Those with 4 and even 6 inch voice coils can take a steady 1000 watts and peaks of 1500 to 1800 watts. So the usual answer when you want to get louder is to use more drivers. Every doubling of drivers will take you back a notch in power requirement. So 2 drivers could produce 123 db with 1024 watts. 4 drivers 512 watts. Etc.
The greatest magic in getting things louder happens below 128 watts. Between 128 watts and 2048 watts there is a 12 db rise in sound pressure level. A little over twice as loud acoustically.
From 1 to 128 watts there is a 21 db increase from a 1 watt level in sound pressure.
Now lets examine the same requirement in getting this loud with the horn subwoofer.
If your bass line power is say 96 db then you get this funky thing happening
96-99-102-105-108-111-114-117-120- 123 in db
1 - 2 - 4 - 8 - 16 - 32 - 64 - 128 - 256 in watts to get to that level of db.
You get very loud with not so much power when you drive a woofer in a horn. The not so much power enables greater ability to generate peaks without there being compression electrically in the driver itself or mechanically from there being no more stroke for the cone.
Trade off?
Big box. The one in the picture is the 23 foot horn it is 16.5 " x 32" x 92". Only addicts may apply! But once you hear one of these brutes all other sub-woofers sound.....neutered is the best term.
Mark
The distortion in most subs is due to driver nonliterary pushing them so hard that they are no longer in control of the motor structure design. The ways to get around that are rather simple. Use more drivers. But to have any appreciable difference we have to remember that to drop an octave in bass we need four times the volume of air moved to keep the SPL equal. You need quite a few woofers. The second solution is to provide a better acoustical match between the driver and the air in the room. This is the method that is being discussed in this thread. I don't recall seeing a figure of actual box gain over raw data from Patrick's posts. But in the horn I'm fooling with the gain is between 8 and 10 db over the raw driver. That is an increase of efficiency of just over and around four times that of a driver on it's own mounted in a conventional enclosure. So the driver in a horn has to move one quarter the amount of air to get the same sound pressure level of that same driver in a vented enclosure.
Gain? Well the distortion is cut down dramatically. More than the 1/4 you would think. If you use a driver that has a very linear motor structure like the XBL type in the TRIO12 you are getting great control of the driver over a far longer stroke. A stable BL is very important in keeping all forms of distortion low. The BL is the number of turns of wire in the voice coil that are saturated by the magnet and motor structure. It is the best measurement of how in control the cone remains at any position. It is also a curve that most manufacturers will not provide.
No matter how much power you throw at a driver it is only a repulsive force from the existing motor structure. So the inherent linearity of the driver itself is very important. The other very interesting thing about drivers and actual speaker boxes is that the more power we push into the driver the more they heat up. Then the voice coil parameters change drastically. If we can create an enclosure where the driver is better coupled to the room we are in the required power is greatly diminished and the resulting sound from the driver/enclosure system is cleaner. There is no warmed up voice coil that is now two to three tikes the resistance of one at room temperature. The amplifier does not have to try and push gobs of power into a voice coil that is literally compressing the power instead of tracking it. Nope we can get a driver that will track the music signal and produce what we are after. The idea that we can take a driver and push hundreds of watts into it and get a louder response is more a myth than reality.
Here is the power versus SPL progression
Base line 90 db one watt.
1-2-4-8-16-32-64-128-256-512-1024-2048 watts
90-93-96-99-102-105-108-111-114-117-120 -123 in db
These are all increments which increase the sound level by 3 db.
This is a power output progression showing the power required to raise a signal 33 db. So from about 90db to about 120 db.
There are no drivers that can sustain this amount of power input. Not even pr sound drivers. Those with 4 and even 6 inch voice coils can take a steady 1000 watts and peaks of 1500 to 1800 watts. So the usual answer when you want to get louder is to use more drivers. Every doubling of drivers will take you back a notch in power requirement. So 2 drivers could produce 123 db with 1024 watts. 4 drivers 512 watts. Etc.
The greatest magic in getting things louder happens below 128 watts. Between 128 watts and 2048 watts there is a 12 db rise in sound pressure level. A little over twice as loud acoustically.
From 1 to 128 watts there is a 21 db increase from a 1 watt level in sound pressure.
Now lets examine the same requirement in getting this loud with the horn subwoofer.
If your bass line power is say 96 db then you get this funky thing happening
96-99-102-105-108-111-114-117-120- 123 in db
1 - 2 - 4 - 8 - 16 - 32 - 64 - 128 - 256 in watts to get to that level of db.
You get very loud with not so much power when you drive a woofer in a horn. The not so much power enables greater ability to generate peaks without there being compression electrically in the driver itself or mechanically from there being no more stroke for the cone.
Trade off?
Big box. The one in the picture is the 23 foot horn it is 16.5 " x 32" x 92". Only addicts may apply! But once you hear one of these brutes all other sub-woofers sound.....neutered is the best term.
Mark
Attachments
Mark - interesting post about power. Not sure I have anything to say everybody doesn't know already but...
When you multiply drivers, their radiation resistance goes up too, like with a horn slightly. Not sure how much, but I did make a sweet-sixteen sub once and sealed it to the house foundation. So that makes them more efficient and cooks the voice coil less.
I hate to seem too innocent in the sophisticated company here, but I can't imagine cooking voice coils on music or even fussing over resistance changes (OK maybe the poor souls with bi-amping have to fret). Even organ music?
Seems to me the argument about amp POWER has more basis in transient peaks than the need for anything ordinarily even with sustained notes. It would take a magnifying glass to see the meter budge on my Klipschorn amp, a Kenwood Basic M1 (with Sigma Drive (cousin to motional feedback)... which seems to be helpful for my old horn.)
Klipsch used to say, "... give me just 5 clean watts."
Reinforcing the sealed box makes a lot of sense. Big forces in there (but speaker has extra forces on the face side too). But even near the mouth, are there big forces in the horn that 7/16 couldn't handle? Why don't new horns have little holes or slots for the drivers to face, not their full diameter, like the old horns?
With horns less monumental than yours, getting the box right influences response right at the lowest point and, your horn excepted, it is never low enough. I experimented with my Klipschorn stuffing the box either absorbent (I am a big fan of wool underlayer for carpets) or bricks.
Pretty clear to me a normal-size horn in a normal room gets pretty ragged at notes that are still hearable and discriminable. No way to handle that except with a super-low parametric equalizer - but such a gizmo is very helpful.
While the same gizmo logic may apply to your super horn, the world looks different at sternum shaking frequencies that are hard to tell apart by sternum or by ear. So in practice, may not add anything.
When you multiply drivers, their radiation resistance goes up too, like with a horn slightly. Not sure how much, but I did make a sweet-sixteen sub once and sealed it to the house foundation. So that makes them more efficient and cooks the voice coil less.
I hate to seem too innocent in the sophisticated company here, but I can't imagine cooking voice coils on music or even fussing over resistance changes (OK maybe the poor souls with bi-amping have to fret). Even organ music?
Seems to me the argument about amp POWER has more basis in transient peaks than the need for anything ordinarily even with sustained notes. It would take a magnifying glass to see the meter budge on my Klipschorn amp, a Kenwood Basic M1 (with Sigma Drive (cousin to motional feedback)... which seems to be helpful for my old horn.)
Klipsch used to say, "... give me just 5 clean watts."
Reinforcing the sealed box makes a lot of sense. Big forces in there (but speaker has extra forces on the face side too). But even near the mouth, are there big forces in the horn that 7/16 couldn't handle? Why don't new horns have little holes or slots for the drivers to face, not their full diameter, like the old horns?
With horns less monumental than yours, getting the box right influences response right at the lowest point and, your horn excepted, it is never low enough. I experimented with my Klipschorn stuffing the box either absorbent (I am a big fan of wool underlayer for carpets) or bricks.
Pretty clear to me a normal-size horn in a normal room gets pretty ragged at notes that are still hearable and discriminable. No way to handle that except with a super-low parametric equalizer - but such a gizmo is very helpful.
While the same gizmo logic may apply to your super horn, the world looks different at sternum shaking frequencies that are hard to tell apart by sternum or by ear. So in practice, may not add anything.
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My horn actually has very serious bracing as it is required both on the rear enclosure and right at the cone entry into the throat of the horn. The opening is the full diameter of the cone by the way. Best response that way.
Best gizmo I have ever seenis here:
Creative Sound - Product Details
This thing is very hard to better.
And yes it may help. I hope to have one coming sometime soon. But what I have always noticed about a good horn is that it couples very well with the room it is in. When made full length and not hamstrung to much a horn is very kind to low notes.
Sternum resonance is not that low by the way. 125 to 150hz in most people. It just has to be fairly loud.
I recouperating from working some crazy hours this week finishing a job in the evenings and working full time during the days. So now that I'm done I will be able to put some time into trying to get some good measurements on the subwoofer.
Mark
I have a home-brew parametric equalizer for the woofer with two control modules that run down to around 20 Hz (each with variable Q and variable gain/cut, of course). But as for that gizmo with a mic, I have never set a woofer except by ear (and luckily I have almost a dozen knobs on the EQ and e-crossover that can do all kinds of stuff to my woofer).
Thanks for sternum frequency - I was just using the term generically.
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