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Old 14th November 2011, 07:06 PM   #11
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Location: Toronto, ON, Canada
Quote:
Originally Posted by just a guy View Post
And one more note before I let this go.

I realize that this list is ONLY concerned with displacement, but more displacement doesn't always = more bass. At least a cursory glance should be given to the driver specs to determine how it is likely to be used. Sure, the Alpha15 has decent displacement/$$$ but it's almost completely useless in anything besides OB, and on OB it really won't have much bass at all. You could get more bass out of a regular 10 inch driver (and certainly a whole lot more from a low priced Beta15) in a ported box.

Anyway, I don't mean to be nitpicky, I still like lists like this but there are so many other things to consider than manufacturer rated displacement.
The fact is, SPL is dependent on frequency and displacement only. Even if a woofer doesn't want to be a sub, you can still EQ the heck out of it and get your bass back.
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Old 14th November 2011, 07:18 PM   #12
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Quote:
Originally Posted by 454Casull View Post
The fact is, SPL is dependent on frequency and displacement only. Even if a woofer doesn't want to be a sub, you can still EQ the heck out of it and get your bass back.
Are you sure?

In other words, if you take 2 of any given driver and put 1 in a massive horn and 1 in a small baffle OB, you think they would make the same SPL at xmax at any frequency below 120 hz?

Your statement is only true at higher frequencies, down low the enclosure is everything.

Last edited by just a guy; 14th November 2011 at 07:28 PM.
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Old 15th November 2011, 04:50 AM   #13
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Quote:
Originally Posted by just a guy View Post
I think Danley said the Lab12 driver (rated at 400 watts) should be able to handle close to 2000 watts each (assuming a stack of 8 horns or more in 2pi space.)
I'm not sure what I was thinking when I wrote this, but there's multiple errors, sorry.

It was Seaton that said it, I believe, and it was 2000 watts or more per sub, in other words at least 1000 watts per driver (not 2000 per driver) and he was referring specifically to a stack of as little as 4 Labhorns.

Wow, 3 errors and 1 omission in 1 sentence. Not sure where my head is today.
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Old 15th November 2011, 11:20 AM   #14
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To paraphrase just a guy's statement above I might wonder if Patrick's list has any significance at all.

Given that absolute displacement is the crucial factor, displacement/dollar might perhaps be used as some effeciency measure between speakers displacing (nearly) the same amount of air. But just then.

Comparisons of this kind also rest on an implicit 'ceteris paribus' clause - that is 'all other things equal' which of course is not the case in any of the comparisons here.

/Erling
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Old 15th November 2011, 11:28 AM   #15
sreten is offline sreten  United Kingdom
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Hi,

Its quite easy to find much "better" based on that simple criterion, e.g. :

MCM Audio Select 15" Woofer with Poly Cone and Rubber Surround 200W RMS at 8ohm | 55-2974 (552974) | MCM Audio Select

$27 for a 15" with 6mm Xmax works out $53 per litre.

You get what you pay for though ..... but more usable than an Alpha A :

Sensitivity: 92dB (W/M)
Impedance: 8ohm
Re: 7.2ohm
Le: 1.522mH
Frequency response: 50Hz~3KHz
Fs: 32.5Hz
Qts: 0.47
Qes: 0.56
Qms: 3.08
Vas: 322.23 liters
Xmax: 6mm
Overall frame diameter: 15.08"
Required cutout: 13.82"
Mounting depth: 5.63"

rgds, sreten.
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Last edited by sreten; 15th November 2011 at 11:44 AM.
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Old 15th November 2011, 01:19 PM   #16
tb46 is offline tb46  United States
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Hi Y'all,

And all that is assuming, that the data provided is accurate.

Regards,
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Oliver
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Old 15th November 2011, 04:39 PM   #17
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Quote:
Originally Posted by just a guy View Post
I'm not sure what I was thinking when I wrote this, but there's multiple errors, sorry.

It was Seaton that said it, I believe, and it was 2000 watts or more per sub, in other words at least 1000 watts per driver (not 2000 per driver) and he was referring specifically to a stack of as little as 4 Labhorns.

Wow, 3 errors and 1 omission in 1 sentence. Not sure where my head is today.
The Lab 12 can handle 2000 watt peaks, but will burn up given little more than 400 watts continuous sine wave, whether in a ported, sealed or horn loaded enclosure. I have been demonstrating my ported Lab 12s with just over 1000 watts (peak) per speaker, I have no doubt that 2000 watt peaks per driver could be sustained above Fc in a proper horn cabinet.

Fc will lower in a large array of horns, but that change won’t affect power handling, other than the small change in the impedance curve.
Fs lowers in multiple driver bass reflex cabinets too, for what it is worth.

A horn loaded cabinet may raise average impedance, which can result in less average power than another alignment given the same voltage.

The enclosure is important as far as bass output, but given the same enclosure, a driver with greater Xmax capability simply can put out more peak SPL than one with less.

As has been repeated in the thread, that statement assumes that the Xmax figures are correct.
Having tested lots of different Eminence drivers, I know their figures are correct, I’d pay a bit more per displacement for a driver from a company that has stood the test of time.

Then again, there are drivers like sreten suggests in post #15, $27 for a 15" with 6 mm Xmax, that are probably worth taking a chance on if the goal is mainly moving some air.

Art Welter
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Old 15th November 2011, 04:55 PM   #18
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Quote:
Originally Posted by just a guy View Post
Are you sure?

In other words, if you take 2 of any given driver and put 1 in a massive horn and 1 in a small baffle OB, you think they would make the same SPL at xmax at any frequency below 120 hz?

Your statement is only true at higher frequencies, down low the enclosure is everything.
I thought that you would see the implicit assumption that I was talking about apples, not apples and oranges. Regardless of the type of enclosure, more displacement means more SPL, period. Yes, one driver in an OB is likely to produce less SPL than a driver in a regular monopolar box, which will produce less than the same driver in an ideal horn... but neither of us are idiots. I hope. Are you sure?
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Old 15th November 2011, 07:27 PM   #19
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Ok, so you are saying that if you have 2 drivers in the same type of enclosure and the drivers are identical but one has more xmax, that the one with more displacement will win?

Ok, I fully agree, that much is almost too obvious to be stated. But it doesn't have anything to do with the statement you quoted from me. I was trying to point out that the drivers on the list WILL NOT work in the same type of alignments at all so they are in fact apples and oranges. The Alpha will ONLY work well on OB while the other drivers listed work best in other alignments, so rating them based on displacment alone has limited usefulness.

Last edited by just a guy; 15th November 2011 at 07:29 PM.
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Old 15th November 2011, 07:35 PM   #20
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Quote:
Originally Posted by weltersys View Post
Fc will lower in a large array of horns, but that change won’t affect power handling, other than the small change in the impedance curve.
Actually the change in the impedance curve looks pretty dramatic when you compare 1 cab vs 8. I have no experience with the driver itself and certainly no experience with stacks of horn subs so I don't know how much difference the change in impedance makes in real world power handling.

Anyway, here's the original quote.

Quote:
On the topic of power handling, please read through Tom's last post. Each driver
itself would normally be rated for about 400W of thermal power. Within Tom's post are
some things which should be noted. First, the real power to the system is related to
the efficiency of the system. This stems from a direct change in actual impedance with
this efficiency change. Likewise, these gains are only in the range where the horn is
loading the driver. Below the cutoff of the given block of LAB bass horns, the power
handling reduces down to that of the driver on its own. So bandwidth matters.

Examining what Tom said in the last post we also find that 6 boxes ground stacked will
have higher power handling per box than 2 boxes ground stacked. So, the fewer boxes
being used, and the fewer boundaries you can take advantage of, the lower the power
handling. The same is true of our BassTech 7, so this is nothing unique to the driver,
just the nature of a bass horn. In general it would be safe to say that 1000W per box
shouldn't fry drivers, and when using 4 or more boxes coupled, 2000W per box should
not be a problem, WITHIN THE BOX'S PASSBAND. Depending on distortion and frequency,
even higher available power may be justified for those going for large amplifier
headroom. The thing to keep in mind is that it appears that this should be a power
limited subwoofer, not necessarily a distortion limited subwoofer, which is much more
common.
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