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12" cab, high power handling recommendations

#81
agedhorse said:
I'm afraid that's just simply not true. I'm very much into driver design (from the engineering side of things), design the operational parameters for the cabinets, and I do have a good grasp of the math involved as well. I spent a good deal of time designing for the pro audio world as well, so I am aware of the advanced technologies well beyond what the MI market typically uses. With all of that, some (high quality) stock designs are within 0.5dB of the best available performance of any driver, assuming that they fit the appropriate parameters.

My issue in general with the MI speaker industry, is that there are widespread claims being made that just don't hold up when the actual numbers are worked out. The tradeoff between excursion, LF extension, enclosure size, sensitivity and midrange voicing is something that every transducer engineer struggles with in order to achieve the best tradeoffs for each particular application. Were you aware that the most common speaker rating method only requires that the driver survive for 2 hours? How useful is this? When the time is extended to a lifespan of 200 hours, the power rating decreases by ~25-30%. Which is the more realistic power rating?

How many folks have actually measured power compression transition curves versus frequency? I have, and design around these limits because that's the point where the non-linearity knee becomes significant. IME (and I have measured a lot of speakers in my day) 800 watts into any 12" driver will be far into power compression, and well past the point of linear operation. That's the point where mechanical damage becomes an issue

The system I used is the IASYS, which includes a non-destructive algorithm for creating an SPL linearity transfer function, by comparing input linearity with output linearity. This really shows what's happening under mechanical system limits.

And for clarity, I am not claiming that any of my designs exceed the real world limits of performance, I am held to the same rules of physics and math that everybody else is. I am just asking that we are all playing by the same math and the same physics.
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Agedhorse, with all your graphs and charts you sometimes don't realize you are talking about something real that you may have not touched with you hands. Now tell me that you bought a big baby 2 and did your measurements and tests, as well as listening sessions. If not, please stop saying that a contender's product suffer from bad advertising, it's not fair or intellectually correct, if not potentially illegal. Skepticism does not belong to the domain of science. If you actually found that Alex Claber is lying when he says 600 watts continuous and 800 watts peak for the bb2, then stop arguing about planetary systems and spit the truth out. We want to know.
 
#82
I am generalizing when claims are made that simply can not be realized no matter how good the intention, but violate the laws of physics. It is simply not possible to take the combination of variables available to come to that conclusion, to do so would require a motor strength that is not possible while maintaining sufficient gap depth. In fact, in order for JBL to get beyond the limits of motor strength in a deep gap, they were forced to develop the differential drive system using 2 motors with one inverted and driven with opposite polarity.

It's like inventors claiming their 4000 lb car gets 100 miles per gallon... just not possible even though it would be great.

So is the BB2 an 800 watt speaker or a 600 watt speaker or a 500 (or 400) watt speaker and what units of measure? The metrics were not at all clear based on what I saw on the website. Sratas, you say 800 watts peak, so if you do a units calculation back to "RMS" then that would be 400 watts RMS, and if measured or calculated in 1/2 space, it's a reasonable number for a high quality speaker. If it's 800 watts "RMS", then there's not enough magnet strength in the world to get that kind of sensitivity and LF excursion (with acceptable midrange voicing) and power handling without tearing itself apart. Since "RMS" was clarified in the post before Plutonium stated 800 watts, the. perhaps this was inaccurate? The website states maximum recommended amplifier size of 800 watts but a thermal power rating of 500 watts (which would be by definition "RMS")

It's all in the details my friend, perhaps an essential detail is incorrect? That's what it looks like to me, as it appears the website is more accurate than what's being claimed by others in this thread.

Now it doesn't matter what the speaker is, or who makes it. I am not being critical of the actual sound, the performance, the cosmetics, or anything except the claim make by the OP. I have absolutely nothing against the product itself I hope that's crystal clear.
 
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#83
agedhorse said:
Frankly, I don't know of any 12" drivers that are suitable to bass guitar (with acceptable bass guitar mid voicing) that will be able to safely handle 550 watts (RMS) with any kind of reasonable lifespan. With a compact cabinet, and the expectation of good low frequency performance, you will find that you will exceed the mechanical power handling, and in order to increase the mechanical power handling (driver design adjustments) you will lose almost all of that increased power handling with a corresponding decrease in sensitivity... ie. crossing the point of diminishing returns, because you will be so far into power compression that any gains from power handling are offset by losses in sensitivity (including static sensitivity plus power compression losses)

Driving any 12" cabinets with that kind of power will require good common sense and judgement, along with a steep HPF set around 40Hz (or higher), seems like a lot of effort to gain a "net nothing" from your speakers (whatever they might end up being) with big potential for damage.

And, before anybody dogs on me for disparaging other speakers, I am talking in general about all known drivers that I have worked with, including drivers that I have designed. I know there is a lot of bragging about how this or that cabinet can "take the power", but if you were to actually measure the net gain, (via a large signal model) you would find that it's not even close to what the "small signal" model would predict... and everybody uses the small signal model to extrapolate the large signal performance (which is VERY misleading IMO)
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This is something I've been meaning to ask, but is "small signal" a reference to Small, of Thiele/Small fame?
 
#84
pie_man_25 said:
This is something I've been meaning to ask, but is "small signal" a reference to Small, of Thiele/Small fame?
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Good question, and something almost universally ignored when discussing speaker performance specs.

A small signal model is what is also called the linear model. It applies to all physical dynamic processes like acoustics, electronics, hydraulics & pneumatics. Put one unit into the system and one equivalent unit comes out. Nonlinearities are small enough that they can be ignored.

As the signals become larger, non-linearities begin to make a significant impact on the 1:1 transfer function, put 1 unit in and you might only get .8 units out. These nonlinearities are included in the large signal model because they have now become important factors and can no longer be ignored.

Maximum SPL and maximum power handling are 2 specs that are usually measured at small signal levels (like 1 watt) but are then calculated out to hundreds of watts, where huge large signal nonlinearities really should be subtracted from the small signal based calculations to be accurate. Numbers can differ by 6dB easily.
 
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#85
agedhorse said:
Good question, and something almost universally ignored when discussing speaker performance specs.

A small signal model is what is also called the linear model. It applies to all physical dynamic processes like acoustics, electronics, hydraulics & pneumatics. Put one unit into the system and one equivalent unit comes out. Nonlinearities are small enough that they can be ignored.

As the signals become larger, non-linearities begin to make a significant impact on the 1:1 transfer function, put 1 unit in and you might only get .8 units out. These nonlinearities are included in the large signal model because they have now become important factors and can no longer be ignored.

Maximum SPL and maximum power handling are 2 specs that are usually measured at small signal levels (like 1 watt) but are then calculated out to hundreds of watts, where huge large signal nonlinearities really should be subtracted from the small signal based calculations to be accurate. Numbers can differ by 6dB easily.
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Okay, thank you very much for the answer. I'll try to read through the thread in the morning, I'm a bit worn out right now, but I do appreciate when people go to lengths to answer a question, and I'm striving to get back on the learning train right now.
 
#88
Another vote for Barefaced cabs. They probably own the best weight-to-power record for now. Physics is good, okay but in some cases you have to try the thing yourself to prove it works. In case with Barefaced cabs you'll never believe it until you try. I've got One10 recently and was shocked by the volume and low end this little boy spits out. Crazy thing, looks miracle and probably it is ;)
 
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#90
SteveHeissner said:
There's no replacement for displacement. One 12 inch driver, even a Barefaced, has limitations. Two 12 inch drivers are less limited, four even less and so on...
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True, but if the displacement of a barefaced twelve is the same as the displacement of two of a competitors twelves then the Barefaced 112 could go as loud as the competitors 212. It's too bad that none of the competition reveal their displacement numbers. Barefaced does, so the question is why doesn't everyone? Especially competition that talks Barefaced down. As the old saying goes, put up or shut up.
 
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#92
Stepping back, it really does seem unreal we are talking about doing actual gigs with single speaker cabs as small as 12", and even 10". Guitarists routinely bring two 12 amps, often four 12s, and we want to compete with a paltry single 12. Sometimes we can, which I find breathtakingly miraculous. And am grateful.
 
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#95
This is what agedhorse wrote:
agedhorse said:
Frankly, I don't know of any 12" drivers that are suitable to bass guitar (with acceptable bass guitar mid voicing) that will be able to safely handle 550 watts (RMS) with any kind of reasonable lifespan.
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This is Invalid Link Removed about their 12-inch woofer:
Thermal power handling 500W
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No conflicting accounts so far, from anyone.
As for the 600W and 800W figures, I can't make heads nor tails of that, but maybe yous will:
Invalid Link Removed
It does talk about "recommended amplifier power" and "continuous system output", not thermal power handling.
As far as I understand (which may turn out to be not much), throw 750 watts' worth of pink noise at any single 12" voiced for bass and it'll roast in a very short time. It would be prudent, for people who recommend them, to stop calling their single 12" cabs "800-watt cabs".
 
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#97
We have to get past this 'more power get's you louder' argument. Especially into a single speaker cab. More speakers will get you louder. Putting 800+watts into a speaker with an honest thermal rating of 400w is nuts. Why? It's not going to get any louder. Are your bands that frikkin' loud on stage? No PA support? What happened to finding efficient speaker cabs that will kill with 500w?I frequently do R&B gigs using a GK MB200 into a 4ohm Eden 212 cab. Plenty loud with bands that keep stage volume nominal.

Soapbox moment over. Carry on.
 
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#98
The BB2, and Greenboy designs blur that line between FOH cabs. There are plenty more FOH that can fill the needs. JBL, Turbosound, EV and so on. Head over to the FOH section of the store and try some out. The BB2 has an advantage that it is designed like a high performance sports car chassis. Highly engineered it's lightweight with carefully placed bracing and attention to strength and weight. It lacks the full set of measurements and charts that JBL and other FOH release for their cabs. Very useful information, and EASE data. Mackie has even come out with a line of coax drivers making the form factor more box like, but they don't have the full lightweight of the bb2.

More powered cabs and coming out on the FOH side. Built in DSP, and they communicate to each other. Bass amp makers should get on the ball and focus on some pre-amps that can exploit a powered cab, or a power amp. I can hope TC comes out with one that keeps the signal digital all the way up to the cab.
 
#99
sratas said:
Agedhorse, with all your graphs and charts you sometimes don't realize you are talking about something real that you may have not touched with you hands. Now tell me that you bought a big baby 2 and did your measurements and tests, as well as listening sessions. If not, please stop saying that a contender's product suffer from bad advertising, it's not fair or intellectually correct, if not potentially illegal. Skepticism does not belong to the domain of science. If you actually found that Alex Claber is lying when he says 600 watts continuous and 800 watts peak for the bb2, then stop arguing about planetary systems and spit the truth out. We want to know.
Click to expand...
All of this watts, SPL, displacement, yadda yadda yadda, is a lot like gas mileage claims for vehicles. You have to know all of the parameters involved in the test, horsepower, wind drag, weight and so on. You must have repeatable exact conditions to make comparisons. You can't say a Ford Zippy gets better mileage than a Chevy Chimp just by driving them around. Both cars must be subject to identical conditions, same gas, same route, same driver, same weather and much more. Nor can you compare one speaker/cab owned by Jack and played at gig A, to one played by Jill at gig B. To make a fair comparison, both cabs must be operated under identical conditions at the same time.
Subjective comparisons are just that, subject to the preferences of the person using it and the conditions of its use. As many have said before, and just like with cars, your mileage may vary.

And for the record, skepticism is the very foundation upon which science is built.
Scientist, engineers and technicians understand that.
If you are not of those disciplines it can seem to be a strange concept.
 
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