Band Pass vs. Bass reflex vs. other

[Mr. RF62]

Looking to get some opinions on the different Subwoofer enclosures. What do you guys think???

S

[TNRabbit]

Sealed is the most musically accurate, but generally the least efficient. Bandpass just plain sux because it generally pounds a very limited frequency range. Bass reflex is most efficient but again can get very flappy/breathy at high excursions.

[mas]

A tuned bandpass enclousre doesn't 'suck' at all! In fact, for a maximum 2 octave response before exhibiting excessive passband ripple, it is one of the most accurate loadings.

And a reflex loading is totally undamped at the point where its tuned resonance approaches the free air resonance of the driver. So much for accurate bass if misapplied. Which begs the question of those who maintain that the electromechanical damping of an amp is of minimal value (assuming a passive crossover is not used - in which case all hope is lost...as the amp's damping capacity is rendered moot.)

So please don't hold what so many car audio 'enthusiasts' (...a term only implying excitement and not knowledge!) have done to the tuned bandpass against it! [:S]

A particular loading only 'sucks' if you misapply it. And then it is not the topologiy's fault, but that of the operator.

A Porsche 'sucks at towing a large boat, as does a TEREX truck at Watkins Glen.

If you misapply the technology you are responsible for the results.

[DrWho]

A Porsche 'sucks at towing a large boat, as does a TEREX truck at Watkins Glen.

If you misapply the technology you are responsible for the results.

lol, great analogy [Y]

I would argue though that band pass is probably one of the harder alignments to get right, and as a result there are more bad examples than good examples on the market.

As far as ported versus sealed, you actually get less distortion with a ported system than you do with a sealed system achieving the same bandwidth. I don't think it's very fair to compare two systems that don't cover the same frequency range (which is often the case with ported versus sealed comparisons).

I might question what spurs this question about different topologies. Is the goal to make a selection based on product available on the market, or is the goal to persue DIY? If the former, I would recommend choosing other criteria to make the purchase. If the latter, then I would recommend learning more about the different topologies, and then choosing the one that seems to be the best tool for the job.

[mas]

What Doc said...

[Mr. RF62]

Actually, I am a Disc Jockey, and my Subs consist of Band-pass enclosures, and mains are Bass-reflex, I wanted your thoughts as I received up above and am pleased with your comments. I use pro audio equipment and wondered what your thoughts were to the different enclosures.

Thanks mas & Dr. Who (not in that particular order) for your opinions, I know you guys are really knowledgable(no offence to others on here) and value your opinions. If any others please continue.

Thanks...62

[Professor Thump]

Maybe I am old school because when I use to DJ and do Live Sound I would feel naked if I didn't have (8) 18" EVX 180 woofers for subs horns. Brad G DJ's also and brings 2 iPods a computer and 1 powered sub if at all. Maybe I was playing bigger rooms, or I had the advantage of getting woofers cheap, but it is hard ignore cone area and horns if you want the efficiency and have the room. I had K Horns that would tilt back and were 48" high so the Mid/Hi box would fit nicely on it to get the HF horn over peoples heads.

[DrWho]

Yea, surface area is everything when it comes to bass in large rooms. The more your drivers move, the more they distort. Increasing surface area means they don't need to move as much for the same SPL.

Ports also have issues with chuffing and getting overloaded. There is a maximum SPL that can come out of a port, which is a big deal in bandpass systems since all of your output is coming through the ports. If you're talking high SPL, then chances are the bandpass systems aren't the best approach...especially considering they sound kinda nasty when you start reaching their limits. You'll reach the limits of your ports in a normal bass reflex too, but at least the higher frequencies still come through...only the frequencies near the tuning point get affected.

One free thing you could do is run your subs mono center-packed. In other words, feed the subwoofer amp a mono feed from the active crossover (most units have a summing feature for the subs) and then run your subwoofer amp bridged mono. And then instead of having the subs underneathe the mains which are usually on either side of the stage, stack your subs up front in the middle and wire them in parallel. This will give you 6dB more output and make the bass more consistent throughout the room (which is a big deal for DJ'ing).

Here's an article that talks about the power alley (with some pretty cool measurements):
http://www.prosoundweb.com/live/articles/jbrusi/pa.php

[Mr. RF62]

Thanks Dr. Who for the link, nice read, I usually do put my subs in the middle, right under the table where it'll move the cloth covering the table. Sounded awesome on the weekend.

Thanks guys.

[TheEAR]

For home use and restricted budgets BAND PASS subs you can purchase and that are compact are of low quality.This is not tey are BAND PASS,it is the design trade off made. As you have subs for the pro world that are BAND PASS and are of the highest quality both build and sound.

Ported with the classic port is the most efficient economical way.Ports cost next to nothing and reinforce the output,plus you can apply a sharp filter below tuning freq. to prevent over excursion. Sound quality as with all wel implemented designs can be tops.(Epik,SVS,Aerial being great examples)

Another ported design is using PASSIVE RADIATORS,these are weighted membranes that replace the classic port. Here the gain is no port chuffing,the cabinet size can be reduced greatly. (Klipsch RSW series,TC Sounds designs like THE BEAST)

Sealed,here you sacrifice efficiency. You need a mighty woofer and amp but can have descent output from a very small cabinet. Extension can be nearly astounding given the dimensions. Sound quality again varries,at its best its five star (JL Audio being a showcase).

You have IB, simply equal pressure on both size of the piston. Here you use the drivers mounted on a reinforced wall or celling,can be mounted under the floor. Uses a complete room or attic...basement as INFINITE enclosure so to speak.Compression being so low it almost does not affect the driver.Best sounding if implemented correctly,as logic dictates the driver(motor) works least hard (no back pressure of significance).You need to use large drivers in multiples to really know what a great IB sub is all about.

And you have horns,horn subs are not for home use as to reach in the single numbers you would have to use HUGE horns.The mouth would be freaking large.Here the piston moves least ,this being ideal to get the purest signal reproduction pissible.

My two and a half cents

[BLSamuel]

I remember reading years ago about fanatics who would bury the driver and beginnings of their bass horns in the yard and would then terminate in the wall of the room - maybe the whole wall being the horn mouth?

Wonder how such a monster sounded...

[michael hurd]

Pretty poor, unless there was delay added to the other drivers. ( tweeter, midrange device, full range woofer ) [:^)]

Maybe someone else can crunch numbers, but I imagine a 100 foot path length difference is going to be a HUGE difference. ( and mere milliseconds are audible when comparing from one device to another )

[DrWho]

It's about one millisecond per foot (closer to 1.1mS, but who's counting?)

[TheEAR]

Who is counting...Dr Who of course. []

WOW after a leave from the Klipsch forum I am still a top 10 contributor ! Some are slacking []

[CECAA850]

TheEAR is back, all is right with the world[Y]

[TheEAR]

Back with a shop full of new power tools to make toolmongers drool. DIY is a serious addiction,makes you buy motor powered devices.

Even seen a lunatic wandering in a Home Depot picking five drills in one shot? Bosch,DeWalt,Hilti, Makita,Ridgid ...18 to 36V drills. The orange aprons were asking if I have a construction company...I said NO JUST FOR LIGHT DIY ! LOL

[Shodrewken]

What projects you working on now TheEAR?

[TheEAR]

Dual 8" and dual 10" Dayton Titanic 3 sealed. Not much just colecting tools as an excuse to build two huge,seriously huge subs one sealed around four LMS-5400 18" drivera nd the other dual ported 18" from Sound Splinter.

Too busy to start anything before June -July next year. So smallish DIY subs are good to keep me busy a few hours each second week.