Speaker Design

As I understand it, there's something of a three-way tradeoff in speaker design: cabinet size, low-end frequency response, and efficiency. A good rule of thumb is that you can pick any two of these, but can't get all three.

A speaker system intended to provide deep, flat bass, will tend to be either physically large, or electrically inefficient. As Sjouke says, Bose probably leans towards "inefficient". Some of the Bose speakers (I recall the original 901) absolutely required a custom equalizer to deliver anything like a a flat bass response... the drivers and cabinets alone were far from "flat".

If you have to use an equalizer with a bass-boost circuit to get acceptable bass response, you'll certainly need more power, and (depending on the design) may suffer from increased distortion due to excessive motion of the woofer cone. A sufficiently advanced (e.g. DSP-based) equalizer might be able to compensate for the nonlinearities in the speaker's suspension, cancelling them out by "predistorting" the signal before amplification.

I doubt it. Speaker coils warm up from time to time (depending on what the music is asking them to do, and this changes the temperature and the permeability of the iron (or whatever) in the magnetic path. The non-linearities won't be the same from one moment to the next.

A synchronous linear motor drive is probably a better way of using complex electronics to combine efficiency and linearity over a long throw - you might even be able to manage to make the package more or less compact.

-- Bill Sloman, Nijmegen

Bullshit.

The speaker is stable right up to the point the coil opens from overcurrent, because you are going to do that far sooner than reaching the curie point temperature of the magnet or iron local to it.

Stop making s*it up.

Magnetic properties start changing way below the Curie point.

Look at pages three and four. It's a logical consequence of the thermodynamics, and works the same way in soft iron and hard magnetic materials, though the Curie temperatures are different.

AlwaysWrong strikes again.

-- Bill Sloman, Nijmegen

The golden-eared boys will tell you that they can detect the difference between regular speaker cables and Monster Cables with time correct technology and magnetic flux tubes.

=20 Dan

Billy snips when he is proven absurd, and he fails to refute the proof.

Case closed.

The speaker coil will fail (and assuredly smoke profusely) long before the steel or the magnet surrounding it heats up... at all.

I regularly ran 1500W low end (the audio range, not the driver quality) drivers in a live, tri-amped performance set-up and the speaker magnets and their surrounds which completed their magnetic circuit always remained cool.

These speakers had forward excursions of nearly two inches.

Ever "seen" "middle C" driven so hard the cone moves an inch out and an inch in? It *will* break wine glasses.

These were 12" drivers.

ees C.

f.

Nice to see AlwaysWrong getting it wrong again. It was Phil who avoided posting anything that might look like proof, but AlwaysWrong managed to miss that.

In AlwaysWrong's predictable opinion.

Neat trick. The coils are dissipating 1500W and the adjacent metal- work doesn't heat up at all. AlwaysWrong has either discovered a thermal superconductor, or his observations weren't all that careful.

And were horribly non-linear. Not that anybody exposed to that level of noise would have enough hearing left to notice.

an

No. On the other hand I'm not yet totally deaf.

For a rock group who liked their sound loud and distorted.

-- Bill Sloman, Nijmegen

Show me where the voice coil is connected to the "adjacent metalwork".

Now, show me where that connection is thermally conductive.

Ever heard of viscous damped and cooled voice coils?

And the coils are not dissipating 1500W, they are reacting to 1500W.

Pretty sure there isn't as much heat. Granted, they do get hot, but that is the COIL, not the magnet around it.

A mag lev train suspension magnet doesn't "heat up" either. Even after thousands of miles.

Bullshit, They were pro gear elements. Made by one of the best in the industry. Electrovoice.

Not that you would have any clue as to what a good audio transducer is.

Much less any details of its operation.

No. For the same exact application they are manufactured for.

They are what the pros use, and you have no clue what the world has to offer because you haven't gotten up off of your thumb in years.

Grind on it harder, idiot. You'll slip even further behind the curve.

Heat transfers through a vacuum by radiation, through air by conduction and convection. The gaps in in speaker voice coils are too narrow to allow much convection, but the speaker movement stirs the air, so there's some forced convection.

Sure. Ferrofluids are attractive in the application, but that just shift more heat into the adjacent metal-work.

Speakers are notoriously inefficient. Most of the 1500W is going to turn into heat.

Heat dissipates along thermal gradients. No gradient - no heat flow.

fter

Dream on. You are AlwaysWrong, as ever.

-- Bill Sloman, Nijmegen

"Mac Decman"

It is nothing like " most" but only few models "top end" and they cannot sustain those sort of levels for long enough to do the AES test in bridge mode.

... Phil

I do power testing with a Lab fp14000 in bridge mode on a 240V circuit. It will do 3000W of band limited pink noise easily. It will not do it's rated 14000W except peaking. And as I noted, it seems that the design of the 120V versions can not sustain the peak output long enough to make them useful for low frequency applications.

Other amplifier manufactuers I can't speak for because I haven't measured them. But I would imagine in the pro-audio world that they are comparable.

Mark DeArman