JL Audio Subs

[Spiffyfast]

Finally some people that are smart enough to understand that a DIY sub can compete with a manufactured sub, its about time more people spoke up.

 

[MacManNM]

Volume wise, so instead of having a sub that outputs 97db at 400 watts it will output 100db at 800 watts, that will be a huge increase in overall volume as compared to a 3db increase from 90db to 93db.



Good or decent, not some $300 PA amp.

You are clueless.

 

[Privateer]

You are clueless.

Have you ever looked at a db graph? It is not a straight line buddy.

 

[MacManNM]

Have you ever looked at a db graph? It is not a straight line buddy.

It's a log function. Add 3db and it is twice as loud. No matter where you are in the spectrum.

Again, clueless.

 

[Buckeyefan 1]

Also, magnet size and weight really mean nothing about a subwoofer. It is all in the design of the parts as a system.

The more coil you have, the more heat the coil can take. This allows for (and demands) a larger magnet, which yields more control over the movement, and thus greater power handling. A larger magnet will also reradiate more heat than a smaller magnet (not its intended purpose, but an added benefit).

 

[annunaki]

The more coil you have, the more heat the coil can take. This allows for (and demands) a larger magnet, which yields more control over the movement, and thus greater power handling. A larger magnet will also reradiate more heat than a smaller magnet (not its intended purpose, but an added benefit).

I guess that renders patented cooling systems and the like useless? If one can generate enough airflow over the coil and other motor parts a "heat sinking" magnet is not neccessary. Typically the reason larger/thicker magnets are somtimes used is to generate more motor force or lengthen the gap (higher excursion needs) while keeping the cost down. Neodymium motors can be stronger yet can be less than half the size. Unfortunately they cost much more than strontium ferrite or ferrite ceramic.

Your statement is partially true though. Especially for cheaply developed sub drivers.

 

[annunaki]

It's a log function. Add 3db and it is twice as loud. No matter where you are in the spectrum.

Again, clueless.

3db requires twice the power. 10db is generally accepted as twice as loud, for most people.

 

[MacManNM]

Also, magnet size and weight really mean nothing about a subwoofer. It is all in the design of the parts as a system.

So I guess as long as we designed the hell out of a cabinet, crossover and amp, we could use a 12" driver with a 6oz magnet from rat shack, and it would sound awesome.

Magnets and coils create fields, the stronger the field, the more accurate the movement of the motor, the more accurate, the better sounding.

Plus huge magnets really look cool.

 

[MacManNM]

3db requires twice the power. 10db is generally accepted as twice as loud, for most people.

I am speaking in terms of electronic measurement. An increase of 3 db in the world of engeneering a factor of 2. Im not talking about what one thinks one hears. 10db is an order of magnitude. 20 db is 2 orders of magnitude.

 

[annunaki]

I am speaking in terms of electronic measurement. An increase of 3 db in the world of engeneering a factor of 2. Im not talking about what one thinks one hears. 10db is an order of magnitude. 20 db is 2 orders of magnitude.

That is completely correct then.

 

[annunaki]

So I guess as long as we designed the hell out of a cabinet, crossover and amp, we could use a 12" driver with a 6oz magnet from rat shack, and it would sound awesome.

Magnets and coils create fields, the stronger the field, the more accurate the movement of the motor, the more accurate, the better sounding.

Plus huge magnets really look cool.

I agree that big magnets look cool. What I was simply stating that just because a woofer has a big magnet does not mean it will be good. The same holds true for small motors but in reverse. A small magnet woofer with high motor linearity will probably perform better than a woofer with a large magnet and a very parabolic bl and kms curve.

I also never said that the quality of the woofer didn't matter, which is what this seems to reference:

we could use a 12" driver with a 6oz magnet from rat shack, and it would sound awesome.

What I should have stated was a woofer that has a small motor structure does not necessarily have lower performance than a speaker with a large one.

Magnets and coils create fields, the stronger the field, the more accurate the movement of the motor, the more accurate, the better sounding.

None of that means that the magnet HAS to big.

 

[MacManNM]

I agree that big magnets look cool. What I was simply stating that just because a woofer has a big magnet does not mean it will be good. The same holds true for small motors but in reverse. A small magnet woofer with high motor linearity will probably perform better than a woofer with a large magnet and a very parabolic bl and kms curve.

I also never said that the quality of the woofer didn't matter, which is what this seems to reference:

What I should have stated was a woofer that has a small motor structure does not necessarily have lower performance than a speaker with a large one.

None of that means that the magnet HAS to big.

All true, I took what you said originally as a blanket statement.

 

[WmAx]

Magnets and coils create fields, the stronger the field, the more accurate the movement of the motor, the more accurate, the better sounding.

Plus huge magnets really look cool.

As with everything, this is a dynamic situation. It would not be prudent to target the highest motor strength achievable in a given woofer design unless the specific application that is intended, calls for this feature. Example: If one uses a dipole or IB alignment, a motor that was very highly damped(maximum motor strength and low QTS) would be a sub-optimal choice. The response of such a woofer in that situation would have very little low frequency output compared to a higher Qts version, unless the low frequency response was E.Q.ed(in which case the woofer has to operate at much greater excursion/incursion, thus reducing headroom, reducing maximum SPL and increasing distortion proportionately). But for example, in a 4th order(such as a vented box) alignment, such a woofer would be an excellent choice.

-Chris