[won ton on]

Gee and i thought big white vans sold stolen speakers. I've had someone try to sell me some years ago.At the time i had Martin-Logans and wasn't going to fall for that scam of empty wooded box's

[James Lehman]

Huh!

If a speaker is designed well around inexpensive drivers, the box might easily be the most costly element of the whole thing.

Might as well put some speakers in there!

I guess that's one of the weird things about speakers. A box full of nothing but air is a BIG part of the design. Usually, bigger is better. Large boxes of nothing take up a lot of space.

James. 

[*Scotty*]

A Chebyshev alignment can shrink the box size of a vented design somewhat.
Scotty

[James Lehman]

There are lots of neat tricks but if you put every variation of woofer system on a chart you would see an overwhelming trend.

Size matters!

The current popular idea is to use a woofer with a lot of cone mass and a stiff suspension and a huge magnet in a small box. The problem with that is the efficiency is horrible. That's why these tiny, self-powered systems are so heavy and get so hot. They take 3000 watts to drive a 5 inch woofer!

If you want large cone area, low distortion, low -3dB response and high efficiency, you need a big box.

That's why I like dual isobaric 8" woofers. Yes. It's a bit of a trick. But it works well.

[*Scotty*]

The current thinking is power is cheap, operate the sub below resonance and damn the torpedoes.
Scotty

[James Lehman]

In a vented system there is no such thing as below resonance. Below the tuning freq of the box, the vent works out of phase of the woofer cone.

Power is cheap, but so is lots of distortion that comes with a system that is way out of whack.

James. 

[FullRangeMan]

There are lots of neat tricks but if you put every variation of woofer system on a chart you would see an overwhelming trend.

Size matters!

The current popular idea is to use a woofer with a lot of cone mass and a stiff suspension and a huge magnet in a small box. The problem with that is the efficiency is horrible. That's why these tiny, self-powered systems are so heavy and get so hot. They take 3000 watts to drive a 5 inch woofer!

If you want large cone area, low distortion, low -3dB response and high efficiency, you need a big box.

That's why I like dual isobaric 8" woofers. Yes. It's a bit of a trick. But it works well.

Well said. This is why Eminence woofer are so popular among DIYers, they are big, had hi sensitivity and are low priced.

They take 3000 watts to drive a 5 inch woofer!
Not strangely this favor the big amps manufacturers that thanks this ''market trend''.

[James Lehman]

If you consider speaker designers as those who are separate from driver designers, then we can say that the hardest part of speaker design is the woofer box. The rest of the system is just a matter of choosing the right stuff to match the woofer system.

Then take into consideration that all speaker systems are horribly inefficient! A decent woofer system can do about 90dB @ 1W @1M. A 100% efficient system would do 120dB. So that's a loss of 30dB. That's 1000 to 1 loss! That means that 90dB SPL is 0.1% efficient! 99.9% of the electrical signal in goes straight to heat!

All the math applies to cone area, mass, spring and the strength of the motor.

So no matter where you start with any kind of conventional cone type woofer design, you are already WAY out of the sweat spot and into the rough edges of a proper alignment, because a strong motor pushing a small piston is a lousy match for coupling with the large air mass of a room.

That's why some folks like horns so much. But the physics of size will really get you there!

[*Scotty*]

I thought your "small box" comment referred to the proliferation of small enclosure sealed subwoofers that are designed to be operated below resonance and have VERY large power amplifiers. I was not referring to vented enclosures.
Scotty

[James Lehman]

I can dig it. And you are right. Those are out there.

It's really hard to talk about this stuff without coloring comments with personal opinion.

The sealed enclosures you speak of have very gradual roll-offs and rely heavily on psycho-acoustics. They don't really have the low end you *think* you hear.

A well tuned ported woofer box can produce well over 100dB at 20Hz in a large room.

I think that's the one thing that most music listeners don't get...... The First Octave!

James. 

[JLM]

Bass done right in a residently sized room requires 3 or 4 subs placed separately from the main speakers.  As most mega priced speakers have woofers in them, they fail by default.  Better to spend $2-3000 on such a sub package and add quality standmounts.  And the best standmount setup uses 6 speakers for stereo (2 per channel plus a fill-in center channel with $1500 processor).

So the total is 10 speakers to do stereo right with processor, sub amp, and 3 stands:

http://www.audiocircle.com/index.php?topic=107770.0
http://www.audiokinesis.com/
http://jamesromeyn.com/home-audio-gear/
http://www.ampzilla2000.com/trinaural.html

[James Lehman]

OK. But now you are walking away from the idea of a stereo pair of speakers and into some hybrid arrangement.

The rest of the world hasn't thrown away the idea of a stereo pair.

There must be some life left in the concept.

And.... No Matter What..... Physics is Physics!

Math works the same for everyone!

PS. It's kinda' neat to see the MCM adds on this site featuring the 55-1190 8" woofer!

[*Scotty*]

There is plenty of life in the concept as virtually every "Mega Speaker" I have ever seen has consisted of a stereo pair of some kind.
In my opinion once you have crossed over into mega speaker territory you should have gone the rest of the way into multiple subs and gotten the bass right as well as the rest of the spectrum. In my book most companies have "missed it by that much" .
Scotty

[James Lehman]

Well...... I happen to like multi-amping and multi-boxing myself!

Once I stepped away from passive crossovers and went active with multiple power amps, I never went back.

Although I still love the sound of Metal, which is a three way passive crossover with an added active sub.

http://akrobiz.com/speakers/metal_index.html

Note the 10 cu. ft. sub enclosure..... and it's still only about 87dB SPL! But, what the heck. It's -3dB @14Hz!   

The biggest problem I ran into when trying to design multi-way passive crossover systems is the point between the woofer and the mid. The coils in the crossover become very massive and high in DC resistance if you try to cross over at lower freqs. To get the best performance out of a woofer and keep the mids clean, you need to cross over well below 300Hz.

James. 

[srb]

Although I still love the sound of Metal, which is a three way passive crossover with an added active sub.

That's the second time you've linked to your website where you offer them for sale.  I think a better venue for that might be the Industry Ads circle.
 
Steve

[James Lehman]

Don't worry. If I have something to sell, I'll go there. I have some real experience with what this thread is about.

[JerryM]

Don't worry. If I have something to sell, I'll go there. I have some real experience with what this thread is about.

Noted. You should read this, though. 

[Letitroll98]

That's the second time you've linked to your website where you offer them for sale.  I think a better venue for that might be the Industry Ads circle.
 
Steve

Don't worry. If I have something to sell, I'll go there. I have some real experience with what this thread is about.

Well, that's exactly the problem here.  Please reference this thread.  http://www.audiocircle.com/index.php?topic=110569.0

Perhaps James will be willing the read the industry participants guidelines and modify his posts by removing the offending link.  Other than being highly opinionated, I think he has a lot of experience to offer.  And let's be honest, there's a lot of us that are highly opinionated around here.   

Signed,
Your friendly neighborhood facilitator

[doug s.]

i don't mind so much that james linked something to sell in his post.  but, i do think that his moniker should identify that he is an industry participant.  whilst reading his posts, i sorta assumed he was a mfr, but i wasn't sure until i clicked on the link...

doug s.

[James Lehman]

Wow.