I've noticed there's been a trend going on. Everyone
wants a High Xmax woofer.
Thats fine, and, all providing you have the power
to use it to its full potential.
But, if your using these high Xmax woofers
with low power, why bother?
The higher the Xmax, the lower the efficiency. So,
are we really making a wise choice going for these
larger than life Xmax drivers, when we don't have
the power to drive them to their full capacity?
What are your thoughts..................
wants a High Xmax woofer.
Thats fine, and, all providing you have the power
to use it to its full potential.
But, if your using these high Xmax woofers
with low power, why bother?
The higher the Xmax, the lower the efficiency. So,
are we really making a wise choice going for these
larger than life Xmax drivers, when we don't have
the power to drive them to their full capacity?
What are your thoughts..................
I do not believe that extremely high excursion woofers are necessary at all......
Theres an interesting post going on at the diysubwoofers.org discussion forum at the moment regarding high excursion woofers, see:
http://www.diysubwoofers.org/talkshop/messages/30880.htm and
http://www.diysubwoofers.org/talkshop/messages/30882.htm for the main argument.
Adrian
Theres an interesting post going on at the diysubwoofers.org discussion forum at the moment regarding high excursion woofers, see:
http://www.diysubwoofers.org/talkshop/messages/30880.htm and
http://www.diysubwoofers.org/talkshop/messages/30882.htm for the main argument.
Adrian
Xmax is just but one parameter, one has to consider all the parameters when picking out a suitable driver (for your needs).
Both xmax and efficiency can be high. It just so happens that a majority of off-the-shelf high excursion drivers were designed for very small enclosures -- making them inefficient (or power hangry).
Both xmax and efficiency can be high. It just so happens that a majority of off-the-shelf high excursion drivers were designed for very small enclosures -- making them inefficient (or power hangry).
F4ier is absolutely right.
It is not the high x-max that makes a woofer ineffective. If you keep the BL product the same by using a larger magnet then the efficiency stays the same.
It is just because people want small sexy subwoofers which go low - that those special subwoofer drivers (with low Vas) were introduced which offer high excursion at the cost of efficiency.
There is also a trend of introducing program material with more low-frequency content than before.
Nowadays even P.A. speakers are going lower at the cost of efficiency and it isn't a bad thing at all. At least I don't want ghetto-blaster bass at a live concert; i.e. such with a lot of punch at 100 Hz but nothing below 50 Hz. Apart from that: high-power amplifiers are simply using much less truckspace than high-efficiency speakers.
Regards
Charles
It is not the high x-max that makes a woofer ineffective. If you keep the BL product the same by using a larger magnet then the efficiency stays the same.
It is just because people want small sexy subwoofers which go low - that those special subwoofer drivers (with low Vas) were introduced which offer high excursion at the cost of efficiency.
There is also a trend of introducing program material with more low-frequency content than before.
Nowadays even P.A. speakers are going lower at the cost of efficiency and it isn't a bad thing at all. At least I don't want ghetto-blaster bass at a live concert; i.e. such with a lot of punch at 100 Hz but nothing below 50 Hz. Apart from that: high-power amplifiers are simply using much less truckspace than high-efficiency speakers.
Regards
Charles
f4ier said:
Both xmax and efficiency can be high. It just so happens that a majority of off-the-shelf high excursion drivers were designed for very small enclosures -- making them inefficient (or power hangry).
Please show me a high xmax speaker (over 15 mm) with a
high efficiency. I haven't found any.
Dave Bullet said:
Depends watt power level you call low? (excuse the pun
A Shiva (moderate xmax?) will reach excursion in a 5^3 ft box tuned to 22Hz @ about 32Hz with *only* 250 watts.
Dave.
Please Explain. Are you saying that your driving the Shiva
at its full potential (Xmax linear) with as little 250 watts?
phase_accurate said:
Are you sure about that? Oversized magnets are used
on plenty of woofers with high xmax, and, still have
low efficiency.
Many large x-max woofers are designed with subbass reproduction in mind. I.e. they are having low Vas and low fs in order to produce low frequencies in small cabinets.
Remember that efficiency is only proportional to BxL and proportional to Vas put it is also proportional to fs^3 !!!
So it is still impossible (and it will always stay that way forever !) to have a box that is at the same time - small, going low and having high efficiency.
So for P.A. works you usually design for economy, i.e. reasonably sized boxes that allow high SPLs at the cost of subbass performance.
Regards
Charles
/not caring too much about efficiency with his 90 dB/Watt 8" woofers having an x-max of +- 11 mm
phase_accurate said:
I agree. However, using 4, 2, or 1 ohm dual Voice coils
are not giving you high efficency. Its just pulling more
wattage out of the amp.
Thats their trick of achieving High Efficency. Ever notice
that these enormous Xmax woofers are never designed
at 8 ohms?
There's a reason...............
There are plenty of people that would use these High
Xmax drivers for other use, than cars, but, can't with
these low impedance rating.
You mean to tell me this hasn't crossed any of these manufactures heads????
I don't remember saying that they have high efficiency. I even mentioned the contrary (remember fs^3 !).
The reason why they have low impedances is because they NEED high power, which is usually delivered more easily into lower impedances (up to some extent), which is specially valid for car audio applications. I do of course know that some manufacturers use this for "cheating".
Regards
Charles
/whose 8" 90 dB/Watt +- 11 mm x-max woofers are having an impedance of 8 Ohms (and a max excursion before damage of +- 18 mm)
The reason why they have low impedances is because they NEED high power, which is usually delivered more easily into lower impedances (up to some extent), which is specially valid for car audio applications. I do of course know that some manufacturers use this for "cheating".
Regards
Charles
/whose 8" 90 dB/Watt +- 11 mm x-max woofers are having an impedance of 8 Ohms (and a max excursion before damage of +- 18 mm)
This one: http://www.diyaudio.com/forums/showthread.php?postid=96330#post96330
Maximum Excursion Before Damage (P-P) 36mm
Maximum Linear Peak Excursion (O-P) (Xmax) 8mm
15" / 8Ohm
Sound pressure level: 97dB/W (1m)
Relative Efficiency 2.00%
http://www.pioneerelectronics.com/P...ndustrialTADProductDetails/0,1445,873,00.html
(Edit: In addition to what has already been said... )
It would not be right to say there aren't high xmax, high efficiency, drivers around. You can be sure there are some out there... Perhaps just not available (and known) to the average builder. The reality is customers want small enclosures -- sacrificing efficiency down low -- requiring large Xmax with which to compensate, which in turn would require more power (in such a small enclosure).
But notice using larger boxes such as a reasonably-sized EBS box, it takes very little power to move a woofer [even high-excursion woofers] past its Xmax -- especially if the box size approaches that of IB or freeair. A Shiva in an EBS vented-box, at 10Hz, would reach 16mm of one way cone excursion using as little as (roughly... not taking into consideration suspension nonlinearties...) less than 10Watts.
Yes, but since a sub, when made to have half the impedance, is 6dB more efficient, you can lower the power and still be just as efficient as the higher impedance version of the same driver.
High excursion drivers (designed for small boxes) are usually made to have lower impedance so that the components required for a suitable amp wouldn't need to be expensive. If one would signifantly restrict a high impedance woofer with a really small enclosure, an amp with higher voltage output is required just to provide enough current (for enough cone movement). Remember that electrodynamic drivers are current devices. Higher operational voltages means higher rated passive/active devices -- can be expensive
Bottom line is, basing one's opinion on one parameter alone isn't enough.
It would not be right to say there aren't high xmax, high efficiency, drivers around. You can be sure there are some out there... Perhaps just not available (and known) to the average builder. The reality is customers want small enclosures -- sacrificing efficiency down low -- requiring large Xmax with which to compensate, which in turn would require more power (in such a small enclosure).
But notice using larger boxes such as a reasonably-sized EBS box, it takes very little power to move a woofer [even high-excursion woofers] past its Xmax -- especially if the box size approaches that of IB or freeair. A Shiva in an EBS vented-box, at 10Hz, would reach 16mm of one way cone excursion using as little as (roughly... not taking into consideration suspension nonlinearties...) less than 10Watts.
Yes, but since a sub, when made to have half the impedance, is 6dB more efficient, you can lower the power and still be just as efficient as the higher impedance version of the same driver.
High excursion drivers (designed for small boxes) are usually made to have lower impedance so that the components required for a suitable amp wouldn't need to be expensive. If one would signifantly restrict a high impedance woofer with a really small enclosure, an amp with higher voltage output is required just to provide enough current (for enough cone movement). Remember that electrodynamic drivers are current devices. Higher operational voltages means higher rated passive/active devices -- can be expensive
Bottom line is, basing one's opinion on one parameter alone isn't enough.
Maybe i missunderstood what you meant. But xmax can´t be be linear, else there would be no suspension. And xmax in my example is > 15mm what you asked for. So you did not express exactly what you meant. btw: what the hell should that be? imagine this 15" at 97dB/W with the double excursion? You can´t use that indoors anymore. I don´t make use of 4mm x with the TL1601 and it gets loud enough - belive me.
f4ier, I hear what your saying coming from a user thats fond
of small enclosures/high xmax woofer combination.
However, I was looking more at the wider side of the
spectrum. Car, Home, and PA.
I guess it is unfair to ask such a question, comsidering
the majority of the users are DIY home builders.
Regards,
of small enclosures/high xmax woofer combination.
However, I was looking more at the wider side of the
spectrum. Car, Home, and PA.
I guess it is unfair to ask such a question, comsidering
the majority of the users are DIY home builders.
Regards,
http://www.stryke.com/store/shop.cgi/page=preorder.html/SID=PUT_SID_HERE
stryke AV15
xmax 23mm one way
Fs: 19.7 Hz
Qms: 4.71
Qes: .399
Qts: .368
Vas: 228 L
Re: 2.97 ohm
Z: 4 ohm
BL: 15.5 Tm
Cms: .25 mm/N
Mms: 260 g
Pe: 500W
1W/1m: 88.5dB
2.83V: 92.5dB
Xmax: 23 mm
Xsus: 30 mm
Sd: 802 sq cm
Vd: 3.8 L
these are amazing subs...
bottomline, if you want volume you need to move the air. this means you need area, and you need excursion.
when looking at subs, checking their eff is prolly the least important parameter. most often it is not accurate at all and it changed anyway by the installation or enclosure it is put into. as far as making subs 8ohms??? why.. the lower impedence the better, get more power out of your amps---and i hope no one talks about damping
stryke AV15
xmax 23mm one way
Fs: 19.7 Hz
Qms: 4.71
Qes: .399
Qts: .368
Vas: 228 L
Re: 2.97 ohm
Z: 4 ohm
BL: 15.5 Tm
Cms: .25 mm/N
Mms: 260 g
Pe: 500W
1W/1m: 88.5dB
2.83V: 92.5dB
Xmax: 23 mm
Xsus: 30 mm
Sd: 802 sq cm
Vd: 3.8 L
these are amazing subs...
bottomline, if you want volume you need to move the air. this means you need area, and you need excursion.
when looking at subs, checking their eff is prolly the least important parameter. most often it is not accurate at all and it changed anyway by the installation or enclosure it is put into. as far as making subs 8ohms??? why.. the lower impedence the better, get more power out of your amps---and i hope no one talks about damping
till said:
Till. I think we both had a sudden misfortune of
communication, for I never said what size driver.
You could've gave me any size (15, 18, 21, 24, 32)
providing it had a high efficiency, and, beyond
15 mm xmax.
I hear what your saying about not making use
with the full xmax of the TL 1601. (Oh, by the
way.Thanks for those xmax measurements. I
needed that) I can feed 2000 watts (at clip)
on two 15's that have 4.5 mm xmax, and,
can do some major damage in a apartment.
Best Regards,
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