weddie said:
Weddie, just about any 12" driver will handle that much power. This is electrical power, how much the VCs can handle. Xmas is what you want to know, as this along with the box design and available amp power will determine how much output you will get. Don't think in terms of power only, think in terms of how much output you can get. No sense getting twice the power but 3db less efficiency - the output is the same!
If $300 is your driver budget, then you can afford to consider some alternatives. If you find you are not getting enough output with your shiva, then I'd say what you want is a 15" driver with more xmax:
Acoustic Visions has some drivers you should consider
Consider:
* Stryke AV15 23mm xmax, good value, very stylish
* 15" Dayton Titanic MkIII
* 15" or 18" Blueprint - the 18" is still within your budget and probably the highest output you can get for under $300
You can't go wrong with these drivers. Another alternative is buy two Tempests and mount them push pull for lower distortion and for vibration cancellation. This does mean a big box however.
Yes Weddie,
I also think that you are touching the limits of Xmax or better
max volume displacement (cone area * Xmax)
In fact Adire has excessive speakers in this regard:
- Sadhara: 12", Xmax +/-27mm
- Tumult: 15", Xmax +/-34mm (if I remember correct)
But aside high costs the motor philosophy of both drivers
is critical in regard of damage if overpowered at lowest frequencies.
Different from most other drivers their motor pushes the cone
linear up to max. excursion until hard bottoming occurs.
Means a Sadhara will work lienear to 27mm and then the
cone will bottom with full motor force. Without proper limiter,
you must be carefull.
Most other drivers have much less linear Xmax, but bottoming will happen at excursions outside the linear drive.
Let's assume some more normal designs.
Linear Xmax=9mm
Bottoming at X=15mm
Above 8mm the force of the motor will decrease. This will require
much overproportional power to reach bottoming.
But of course you will also not reach the same sound pressure
as with Xmax=27mm....
If you are addicted to high sound pressure at low frequencies (and
your first posting indicates this
), then you will need more volume displacement.
How much?
MORE, regardless what you have or can get.
Unfortunately the sound pressure perception of human beings is logarithmic. In order to double the loudness you will need ten times the acoustic power.....
Bye
Markus
I also think that you are touching the limits of Xmax or better
max volume displacement (cone area * Xmax)
In fact Adire has excessive speakers in this regard:
- Sadhara: 12", Xmax +/-27mm
- Tumult: 15", Xmax +/-34mm (if I remember correct)
But aside high costs the motor philosophy of both drivers
is critical in regard of damage if overpowered at lowest frequencies.
Different from most other drivers their motor pushes the cone
linear up to max. excursion until hard bottoming occurs.
Means a Sadhara will work lienear to 27mm and then the
cone will bottom with full motor force. Without proper limiter,
you must be carefull.
Most other drivers have much less linear Xmax, but bottoming will happen at excursions outside the linear drive.
Let's assume some more normal designs.
Linear Xmax=9mm
Bottoming at X=15mm
Above 8mm the force of the motor will decrease. This will require
much overproportional power to reach bottoming.
But of course you will also not reach the same sound pressure
as with Xmax=27mm....
If you are addicted to high sound pressure at low frequencies (and
your first posting indicates this
), then you will need more volume displacement.How much?
MORE, regardless what you have or can get.
Unfortunately the sound pressure perception of human beings is logarithmic. In order to double the loudness you will need ten times the acoustic power.....
Bye
Markus
Nothing Wrong With The Shiva In That Box
As long as you run the Shiva in the passband-not below the tuning frequency-you should not suffer overexcursion.
The people here are confusing Xmax linear with Xmax mechanical.
The linear Xmax tells you how far you can drive a woofer without a lot of distortion. Xmax mechanical, (or Xmech), tells you how far it will go before you run the risk of damage.
The Shiva Mark I had less excursion than the new Shiva, but it had an Xmech of 22 mm.
Please note Paul Spencer's excellent graph of the Shiva with 150 watts input:
http://www.diyaudio.com/forums/attachment.php?postid=450111
He shows the excursion at 15.5 mm with 150 watts input. But the fact is, before the Shiva is in threat of mechanical damage, it has to travel to 22 mm.
If the extra excursion was linear, it would reach 22 mm around 300 watts input-about the limits of your amp. The Rhythmik 350 is 350 watts, right?
But the extra excursion is not linear. Put 300 watts into it, and the Shiva will not be anywhere near 22 mm. It will fall short of that, as it takes progressively more power to stretch that suspension once it leaves the linear area-which the Shiva did at 16 mm.
Following so far?
Please note the Dumax report for the Shiva Mark I-the earlier version of your Shiva. And your Shiva has more Smax and Xmech, (also called Xsus) than this model:
http://www.adireaudio.com/Files/DUMAX/ShivaDUMAX.jpg
So 300 or 350 watts into the Shiva, using this box, will not drive it into damage-as long as you keep the signals above the tuning frequency. Below the tuning frequency, then the damage is very possible.
If possible, I suggest you get a good, high slope low cut filter. If you can get one, then you should be able to use the Shiva in this box.
As long as you run the Shiva in the passband-not below the tuning frequency-you should not suffer overexcursion.
The people here are confusing Xmax linear with Xmax mechanical.
The linear Xmax tells you how far you can drive a woofer without a lot of distortion. Xmax mechanical, (or Xmech), tells you how far it will go before you run the risk of damage.
The Shiva Mark I had less excursion than the new Shiva, but it had an Xmech of 22 mm.
Please note Paul Spencer's excellent graph of the Shiva with 150 watts input:
http://www.diyaudio.com/forums/attachment.php?postid=450111
He shows the excursion at 15.5 mm with 150 watts input. But the fact is, before the Shiva is in threat of mechanical damage, it has to travel to 22 mm.
If the extra excursion was linear, it would reach 22 mm around 300 watts input-about the limits of your amp. The Rhythmik 350 is 350 watts, right?
But the extra excursion is not linear. Put 300 watts into it, and the Shiva will not be anywhere near 22 mm. It will fall short of that, as it takes progressively more power to stretch that suspension once it leaves the linear area-which the Shiva did at 16 mm.
Following so far?
Please note the Dumax report for the Shiva Mark I-the earlier version of your Shiva. And your Shiva has more Smax and Xmech, (also called Xsus) than this model:
http://www.adireaudio.com/Files/DUMAX/ShivaDUMAX.jpg
So 300 or 350 watts into the Shiva, using this box, will not drive it into damage-as long as you keep the signals above the tuning frequency. Below the tuning frequency, then the damage is very possible.
If possible, I suggest you get a good, high slope low cut filter. If you can get one, then you should be able to use the Shiva in this box.
Hi Weddie!
This one here may serve your purpose.
http://sound.westhost.com/project99.htm
It is 3rd order, not 4th order as I proposed earlier, but already
3rd order should help.
Good Luck
Markus
This one here may serve your purpose.
http://sound.westhost.com/project99.htm
It is 3rd order, not 4th order as I proposed earlier, but already
3rd order should help.
Good Luck
Markus
Hey Kelt,
Thanks for the explanation of Xmech vs. Xmax. That makes sense.
So while we're at it:
What good is a low cut going to do? The Unibox sim shows that
below Fb, we don't exceed Xmax again until 15 hertz or so.
How much content is there below 15 hertz?
( I know there are exceptions, but I've never heard any!)
-herm
P.S. Not arguing, just asking
Thanks for the explanation of Xmech vs. Xmax. That makes sense.
So while we're at it:
What good is a low cut going to do? The Unibox sim shows that
below Fb, we don't exceed Xmax again until 15 hertz or so.
How much content is there below 15 hertz?
( I know there are exceptions, but I've never heard any!)
-herm
P.S. Not arguing, just asking
Back in the eighties, I read a report in the Journal of the Audio Engineering Society where they compared low bass output of CD's. There were only about five CD's available with content below 16 Hz.
However, on this board there have been a few people who tell me that home theater DVD's has bass content in excess of that. And we are getting to be a long way from the eighties.
So if it was for music, I would say that he probably does not need the high slope low cut filter. For home theater, apparently all bets are off.
However, on this board there have been a few people who tell me that home theater DVD's has bass content in excess of that. And we are getting to be a long way from the eighties.
So if it was for music, I would say that he probably does not need the high slope low cut filter. For home theater, apparently all bets are off.
Chocoholic:
That low cut filter you suggested is even better than you thought. Remember the markings are 20 dB. It appears to go from -6 dB, (excursion cut in half) at 15 Hz down to -30 dB at 7.5 Hz. So that's about a 24 octave slope, starting at 15 Hz.
Oops, no, it's minus 25 at 7.5. Anyway, it still looks pretty good.
If we don't find another, perhaps we can start another thread. I would like to know myself. Frankly, I just thought it was a case of cascading 6 dB or 12 dB filters made with opamps.
That low cut filter you suggested is even better than you thought. Remember the markings are 20 dB. It appears to go from -6 dB, (excursion cut in half) at 15 Hz down to -30 dB at 7.5 Hz. So that's about a 24 octave slope, starting at 15 Hz.
Oops, no, it's minus 25 at 7.5. Anyway, it still looks pretty good.
If we don't find another, perhaps we can start another thread. I would like to know myself. Frankly, I just thought it was a case of cascading 6 dB or 12 dB filters made with opamps.
I just did a simulation of the Shiva driven to 360 watts on Subwoofer Simulator.
Without Chocoholic's filter, the excursion is 50 mm at 13 Hz.
With Chocoholic's filter, the excursion is 10 dB down from that. So if -6 dB is half the excursion, -3 dB is 25% less excursion, then your excursion should be less than 20 mm. The Xmech of the Shiva III is somewhat in excess of 22 mm. So the filter should fit the bill, at least down to 13 Hz.
Without Chocoholic's filter, the excursion is 50 mm at 13 Hz.
With Chocoholic's filter, the excursion is 10 dB down from that. So if -6 dB is half the excursion, -3 dB is 25% less excursion, then your excursion should be less than 20 mm. The Xmech of the Shiva III is somewhat in excess of 22 mm. So the filter should fit the bill, at least down to 13 Hz.
Just for the heck of it, I ran Subwoofer Simulator at 19 volts, which will give excursion readings half as much as at 38 volts, which is full power for the Rhythmik 350 amp.
At 19 volts, at 10 Hz, the excursion is 36 mm. That means at 38 volts-full power-the excursion will be 72 mm.
But the chart shows that Chocoholic's filter will be 17 dB down at 10 Hz.
Since excursion gets cut in half every time you go down 6 dB, at 10 Hz the excursion will be about 1/8 of 72 mm.
That will be 9 mm. So Chocoholic's filter will get it done for the Shiva in a 142 liter box tuned to 18 Hz.. I would recommend it.
At 19 volts, at 10 Hz, the excursion is 36 mm. That means at 38 volts-full power-the excursion will be 72 mm.
But the chart shows that Chocoholic's filter will be 17 dB down at 10 Hz.
Since excursion gets cut in half every time you go down 6 dB, at 10 Hz the excursion will be about 1/8 of 72 mm.
That will be 9 mm. So Chocoholic's filter will get it done for the Shiva in a 142 liter box tuned to 18 Hz.. I would recommend it.
How bout either one of these products...
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-246
or
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-248
The crossover design mention before looks pretty intimadating, so maybe i could buy the 30hz one cuz its only a 2nd order. By the way, the sub was blown with a moive, i've had it much higher with music and it worked perfectly fine. Does anyone have any other sugestions. Thanks
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-246
or
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-248
The crossover design mention before looks pretty intimadating, so maybe i could buy the 30hz one cuz its only a 2nd order. By the way, the sub was blown with a moive, i've had it much higher with music and it worked perfectly fine. Does anyone have any other sugestions. Thanks
weddie said:
They look nice. However, you can get the method on how to do the same thing from your moderator's, Planet 10's, website right here. Custom design your own, and for a lot cheaper:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
weddie said:
Fine with music but not home theater? More indication that suggests that it was blown by overexcursion trying to reproduce frequencies below Fb, (18 Hz).
Re: Nothing Wrong With The Shiva In That Box
It doesn't seem to me that it's likely the Shiva would be damaged in this box with that amp very easily. Sounds like a case of bad luck.
Interesting point. It would be interesting to see how much difference there is between the simulated and measured excursion.
The slope is actually more than that. From the site:
"It is essentially a pair of cascaded 18dB/octave filters, giving an ultimate rolloff of 36dB/octave. The -3dB frequency is about 17Hz with the values shown."
Of course you haven't heard any exceptions, they would be felt rather than heard, however, in most cases the output is probably not enough for you to notice it. There is a surprising amount of low frequency energy even in music, quite often not intended, and usually not content that adds anything worthwhile. I have often watched my TL speakers wobble to produce sounds I can't hear (sub 20 Hz content down down to 2 Hz). I may in fact put a rumble filter even on these speakers.
No, there isn't, but we are concerned with peak demand here. Basically it's about getting rid of occasional extreme peak demand for excursion. Without it, you will occasionally get ridiculous excursion demands placed on the driver that will bottom it and cause you to run over and turn it down while you are trying to enjoy a movie! If you want to safely operate the driver at anything approaching its limits, you need a rumble filter.
This applies to a vented box below tuning. In a sealed box, it's different.
An added bonus of rumble filters is that it reduces vent turbulence as you get more turbulence as you go lower with a vent.
It doesn't seem to me that it's likely the Shiva would be damaged in this box with that amp very easily. Sounds like a case of bad luck.
kelticwizard said:
Interesting point. It would be interesting to see how much difference there is between the simulated and measured excursion.
ChocoHolic said:
The slope is actually more than that. From the site:
"It is essentially a pair of cascaded 18dB/octave filters, giving an ultimate rolloff of 36dB/octave. The -3dB frequency is about 17Hz with the values shown."
herm said:
Of course you haven't heard any exceptions, they would be felt rather than heard, however, in most cases the output is probably not enough for you to notice it. There is a surprising amount of low frequency energy even in music, quite often not intended, and usually not content that adds anything worthwhile. I have often watched my TL speakers wobble to produce sounds I can't hear (sub 20 Hz content down down to 2 Hz). I may in fact put a rumble filter even on these speakers.
herm said:
No, there isn't, but we are concerned with peak demand here. Basically it's about getting rid of occasional extreme peak demand for excursion. Without it, you will occasionally get ridiculous excursion demands placed on the driver that will bottom it and cause you to run over and turn it down while you are trying to enjoy a movie! If you want to safely operate the driver at anything approaching its limits, you need a rumble filter.
This applies to a vented box below tuning. In a sealed box, it's different.
An added bonus of rumble filters is that it reduces vent turbulence as you get more turbulence as you go lower with a vent.
Re: Re: Nothing Wrong With The Shiva In That Box
I believe I already did that.
Here is the link again. I think the graph on the right is a force vs dispacement graph for the Shiva, though I cannot tell you waht K means. But clearly you see displacement in mm listed on the bottom, K must be some unit of force.
I redid the dispalcement line in red to make it clearer, and posted it below.
First, I can see that there is minimal amount of "oilcanning", or center shifting, for the Shiva under high power. As you can see, in the minus direction it requires 6 units of force to move the cone 15mm, but in the plus direction it takes only about 2.5 units of force.
Still, these are extreme excursions, and you can see that between -10 mm and +17 mm, it is pretty smooth sailing. Between 2 and 2.5 units of force to throughout that range. Nice and linear.
If this is as bad as that "oilcanning" or center shifting gets, I sure wouldn't worry about it. A lot of woofers would get worse than that. The Shiva has an extended pole piece to prevent it from getting out of hand. As you can see, it controls the phenomenon pretty well.
Anyway, in either direction, once the excursion hits -10 or +17, it zooms right up. Even in the plus direction, to reach 22 mm requires 5 units of force-about twice what it requires in it's linear range from -10 to +17 mm. Assuming these units of force translate into power, in this box the Shiva would be hitting 22 mm with 300 watts input only if the excursion was linear up to 22 mm. As we can see, it is not linear after 17mm. So I think a fair assumption, (anyone who knows for sure, please jump in), would be that it would require 600 watts from the amp to drive this Shiva to it's Xmech of 22 mm.
Also remember that Weddie has the new Shiva, which has more linear Xmax-and I presume more Xmech as well. The larger one gets, the larger the other tends to.
In summary, I believe the chart posted below proves that in this box with this tuning, about 600 watts of power would be required to drive this Shiva up to it's Xmech.
paulspencer said:
I believe I already did that.
Here is the link again. I think the graph on the right is a force vs dispacement graph for the Shiva, though I cannot tell you waht K means. But clearly you see displacement in mm listed on the bottom, K must be some unit of force.
I redid the dispalcement line in red to make it clearer, and posted it below.
First, I can see that there is minimal amount of "oilcanning", or center shifting, for the Shiva under high power. As you can see, in the minus direction it requires 6 units of force to move the cone 15mm, but in the plus direction it takes only about 2.5 units of force.
Still, these are extreme excursions, and you can see that between -10 mm and +17 mm, it is pretty smooth sailing. Between 2 and 2.5 units of force to throughout that range. Nice and linear.
If this is as bad as that "oilcanning" or center shifting gets, I sure wouldn't worry about it. A lot of woofers would get worse than that. The Shiva has an extended pole piece to prevent it from getting out of hand. As you can see, it controls the phenomenon pretty well.
Anyway, in either direction, once the excursion hits -10 or +17, it zooms right up. Even in the plus direction, to reach 22 mm requires 5 units of force-about twice what it requires in it's linear range from -10 to +17 mm. Assuming these units of force translate into power, in this box the Shiva would be hitting 22 mm with 300 watts input only if the excursion was linear up to 22 mm. As we can see, it is not linear after 17mm. So I think a fair assumption, (anyone who knows for sure, please jump in), would be that it would require 600 watts from the amp to drive this Shiva to it's Xmech of 22 mm.
Also remember that Weddie has the new Shiva, which has more linear Xmax-and I presume more Xmech as well. The larger one gets, the larger the other tends to.
In summary, I believe the chart posted below proves that in this box with this tuning, about 600 watts of power would be required to drive this Shiva up to it's Xmech.
Attachments
@Paulspencer:
..you are right. The proposed filter is 6th order, quite steep.
Sorry for messing up
Over the last years there seem to come up more and more subsonic signals not only on DVD, also on music CD.
In fact I like it. You do not really hear it... just some deep perception.. powerfull.... impressive...
But the required volume displacement is endless if listening at high levels.
IMHO for subsonic signal sealed designs are better than vented.
A vented design cannot generate sound pressure below its fb.
Well, it can. But SPL is droping with 4th order, while the cone excursion becomes crazy.
A sealed design drops SPL with 2nd order only and cone excursion
is always nicely related to the generated SPL/f^2.
Some linkwitz transform or ACE electronic or cone motion control can extend the -3db corner down to any requirement.
Of course at frequencies around fb and above the vented design
has the advantages on it's side....
Bye
Markus
Bye
Markus
..you are right. The proposed filter is 6th order, quite steep.
Sorry for messing up
Over the last years there seem to come up more and more subsonic signals not only on DVD, also on music CD.
In fact I like it. You do not really hear it... just some deep perception.. powerfull.... impressive...
But the required volume displacement is endless if listening at high levels.
IMHO for subsonic signal sealed designs are better than vented.
A vented design cannot generate sound pressure below its fb.
Well, it can. But SPL is droping with 4th order, while the cone excursion becomes crazy.
A sealed design drops SPL with 2nd order only and cone excursion
is always nicely related to the generated SPL/f^2.
Some linkwitz transform or ACE electronic or cone motion control can extend the -3db corner down to any requirement.
Of course at frequencies around fb and above the vented design
has the advantages on it's side....
Bye
Markus
Bye
Markus
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.