Driver size and frequency range

[conguiño]

Ive never seen a qualitative analysis of the different driver size-assigned frequency range combinations. Such an analysis of course is much more relevant in the context of multi-way speaker enclosures. My curiosity arose when I checked out two different 3-way speakers on Mackies site: the SA1232 and Fussion 3000.

 

Mackie SA1232

Mackie Fussion 3000

 

The SA1232 has a 6 driver assigned to 700Hz-3000Hz. The Fussion 3000 has an 8er covering 500Hz-2500Hz. Each also has a different approach to high and mid frequency reproduction. These frequencies were supposedly chosen to prevent from placing crossovers at certain key frequencies.

 

My initial question was about how the low-mids would differ between the two cabs. Upon reflection some more general, fundamental questions became obvious.

 

How do different driver size-frequency range combinations sound?

How is this knowledge used when combining drivers in a multi-way speaker?

 

And getting back to the matter which inspired this post (first sentence):

 

What would your custom made cab be like?

What size drivers would you assign to what frequencies?

How would your choices help you achieve your desired sound?

 

I must admit Tom's Signature Bass thread helped with the last 3 questions.

 

These should be useful.

 

Acme Cabs

Accugroove Cabs

 

And for those of you who missed all those great threads from when Greenboy was around

 

A Rig for All Seasons

Crossovers, biampingand multi-way cabs

3-way speaker designs

[_Sweet Willie_]

My custom cab would weigh less than 40 lbs., be smaller than a 18"x18"x18" cube, and effectively cover the freq. range of 35 Hz thru 20 kHz. It would handle 1000W RMS at 8 ohms.

 

My second choice would be an all metal, downward firing 30" woofer attached directly to my one-string broomstick bass, w/out an amp in between that would color the "true" sound of my bass. I would expect this rig to be particularly effective in acoustic situations. It would be nice if the woofer could also double as a beer cooler when filled with ice at a summer barbeque.

 

Honestly, I don't think I'm up to or interested in designing my own custom cab. I think there are other folks doing that already. Although the idea of a biamped rig w/ a meaty subwoofer and quality full-rangish cab on top is appealing to me, I'd rather have a single "full-range" cab that's not too big, but has a big, full sound. Although I haven't played one yet, I think that the AccuGroove Tri-112 would do well for me (maybe the EA 1x12 or their upcoming NL210 w/ two neodymium 10-inchers). If my needs grew, I would consider biamping w/ the Tri-112 on top and an AccuGroove sub on the bottom (maybe the Dickens' 2x12 sub, or the 1x18...).

 

Peace.

[GeorgeR]

Good topic!

 

I've always been curious about speakers and cabinets.

 

I've seen some speakers that have nice 15" woofers and have absolutely no audible bottom end, and I've seen other speakers (Audiophile gear) with tiny 4" or 5" drivers and have tremendous bottom end and a smooth mid range.

 

Based on these observations I no longer believe in placing a low frequency limit on a loudspeaker. A high frequency limit makes sense because it becomes a matter of inertia, available energy from the "motor" (voice coil) and a point of diminishing returns.

 

But think of it this way...you can put DC on a speaker and the cone will move! Ok, so that literally sets the low frequency limit on any dynamic loudspeaker at zero Hz!

 

If the cone doesn't leak air, the displaced air will be proportional to the DC excitement, to a limit of course. But the experiment proves a speaker will operate at zero Hz.

 

We can't hear it that well, so at that point it becomes a matter of optimizing the acoustics of the cabinet so that small amount of air movement from a cone X inches in diameter will be able to overcome the human ear's insensitivity to low frequencies.

 

This is the only reason why low frequency speakers have traditionally been huge, because the amount of air needed to be moved and overcome our ear's insensibility at an average listening distance has been a very large volume by comparison to mid frequencies.

 

Traditional formulas rely on speaker volume, Q, resonant frequency and cabinet volume. Why? To use resonance to optimize response.

 

Some day I'd like to think of a way to evolve an air pump/speaker which does not rely upon resonance at all but is a pure linear air mover, functioning independent of operating frequency.

[conguiño]

I have no idea if it's possible since I decided to major in Industrial Engineering instead of Applied Physics like i really wanted, but I always thought a full range speaker should be one big driver.

 

Only the necessary area of the driver would move according to the frequency it was reproducing. It would kind of be like having infinitesimal, fractional drivers in it, so if 9,25in. of it would reproduce a certain frequency best only that much would move. I assume a separate HF driver would be necessary and that their would be an issue of variable tension on the cone. I wonder if a speaker like this could reproduce several frequencies simultaneously (chords)?

 

I imagined this based one stuff I've heard on the forum and from speaker manufacturers websites, so if it this sounds stupid, it's out of pure ignorance. Feel free to tell me if that's the case. I'm assuming I managed to explain my idea correctly in the first place, so I guess that's another factor.

 

Hope I wasn't that off .