Best pa subwoofer. (Technically)

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Perhaps I can help?

<flies in with cape and colorful tights>

In order to answer your questions, you need to *define* what you want to do in technical terms. Otherwise there are no answers, or limitations as to what can be done.

If you want something that you will "like" I would suggest cruising around project threads here, and look at pictures on the web and here until you find something that looks like it is what you might want. Then work backwards from those technical specs to see if it is anywhere near what you may need or want.

Either way you can either just build or buy something more or less at random. For best results follow a successful design, proven, and use the exact speakers used and follow the plans.

_-_-

PS. for bass speakers, tapped horns are not large...
 
My taste in music is a bit random to be of use, think reggae, metal, occasionally drum & bass and dub step (not the new dub step noise like skrilex though!) punk, rock, and any variation in between, in terms of my likes in speakers, I like a good thump when the time calls for it, clear vocals at all times, a
Serious rumble when the time comes and of totally
Necessary mid and highs.
So pretty much need Multi purposes. I like the look
Of scoops and folded horns but whatever will be the
Most versatile.
When I have decided in the speakers I will source amps to match
And signal
Source
Could be anything from decks
To my phone.
 
Well a 3 foot tall cab is a bit big! House party at most, as I said this is for me.
I know realistically not going to hit 30hz but as near as can get whilst staying out of the realms of fantasy. I'm looking for best can get under 1kw ideally and without breaking the bank or my back carrying. Tall order I know but no harm in trying
 
I may know a lot about making amps, but I am a relative rookie in the speaker design world. I made a lot of speakers back in the early 70's, and some of them actually fulfilled their intended purpose....big bass, loud bass, not necessarily good tight bass, but this was pre-disco Latin boom - boom music. My formula was one or more Eminence 15's in a BIG sealed box and lotsawatts! Solid state watts.

I have recently started randomly tinkering with a bunch of cheap Ebay drivers and random plywood boxes, and realized that it's relatively easy to make loud bass that sounds GROSS! So I decided to start reading and learning. I discovered the magic key....software. Get a program that models woofer and box response and spend a few days....or weeks, playing before buying ANY speakers.

You can make a graph of SPL VS frequency and tweak the box size, type, port size, and power input level for a given driver once you enter its parameters. From this exercise you will find out about Xmax and why "it depends." You will also see that it is possible to make big bass with nearly any speaker in a BIG sealed box. Porting a speaker box can extract maybe an extra octave of bass from a given speaker by carefully balancing box size and port tuning while keeping a careful eye on cone excursion. Yes it's possible to rip a speaker apart at well below its power rating with the wrong box and tuning.

If you decide to explore the software route, start by simulating several published designs to observe the trade-offs that were made in their designs.

I have some PA design requirements that aren't too different from yours. I want a system that I can use for playing my guitar, bass, or keyboard at neighbor irritating volume. I also want to play music at LOUD volumes, and small outdoor gigs are likely. It all must be portable enough so that this 60 year old guy can break it all down and stuff it all into a Honda Element. Speaker system cost should be what most people would call cheap! Maybe $500 for a stereo full range system. The amplification system MUST be all TUBE (see my user name) bi-amped, or tri-amped, I haven't decided yet. 1KW total power is the limitation imposed by a US electrical outlet, 120 volts, 15 amp, 1800 watts max input. The amp stuff is not hard for me.

Since a bass guitar, keyboard or loud techno and dubstep are design criteria, as is portability, I have set 40 Hz as the lower 3db point, with a 40 pound weight limit per cabinet, and two (or more) cabinets per channel to make portability easier.

After playing with the simulator, I have come up with a way to make the bass. Granted 40 Hz is not "subwoofer" territory, there is a reality factor here, I'm not going to build something that can make 120+ db SPL at 20 Hz for cheap and be able to carry it up some stairs! I have done a "paper" design, but haven't purchased anything yet, and aren't going to right away, but, this woofer:

Dayton Audio PA380-8 15" Pro Woofer 295-034

Costs $75, and claims to eat 500 watts. The simulator "Winspeakerz" (cheap download) claims that it will make 122 db SPL at 50 Hz at Xmax with 350 watts with a 3 cu foot box tuned to 45 Hz. 3db down is 40 Hz (only 119 db SPL). So, getting this speaker in the UK is likely to be expensive, but I'm sure that there is something equivalent.

I'm planning to use an active crossover at about 1500 Hz and a separate amp to drive a second small box with a pair of mids and tweeters.
 
I think you can't do it.

The best you can manage is going to be a sealed box, put in a corner, with EQ and a LF highpass to get the subsonics out. You'll need a high Xmax woofer and it's best to aim for a low VAS if you can find it.

Run a simulation program, that will show you what you can expect from the native response of the sealed box + driver (T/S parameters inputted) before you apply EQ.

Look up Bob Cordell's EBS alignment as a guide.

IF you own the house there are other options, depending on the local WAF or lack thereof.

_-_-
 
I think I may have a play with some software and see wht happens, can anyone recommend any good free software and any that can do horns etc
Hornresp, great free software, can design horns, bass reflex and combinations.

It helped me design this cabinet:

http://www.diyaudio.com/forums/subwoofers/185588-keystone-sub-using-18-15-12-inch-speakers.html

Too big for your taste though;).

It also makes it easy to understand that a driver with double the Xmax can produce 6 dB more output.

And Hoffman's Iron Law: Loud, Low or Small- pick any two.

Have fun!
 
I think given you need this setup to be used in peoples houses, i.e. compact, you need to be looking at car and hifi drivers not PA as they want a big box.

Bear in mind for this kind of application you don't want to be going down ultra low as it will sound overblown and destroy things. 40 Hz is fine.

I would suggest a ported box and 12 or 15 inch driver. Two of.

What amps do you have available as the sub crossover could be a problem on both cost and performance grounds if you go passive.
 
not enough Xmax
thats how much its able to move
and still keeping the voice coil inside the magnet gap
also called linear Xmax
in this case it appears to be +/-2.5mm
which is the same as 5mm P-P(peak to peak)

literally it means the woofer can move 2.5mm in and 2.5mm out

if it moves more it will result loss of cone control, and distortion

I've just looked at the spec. It looks like one of these products that will deliver what it says, but not for long!
Take the Crown Xls 1,000 amp. That might deliver 500 watts per channel, but it soon gets over temperature and switches off.
At least with the amp, you can switch it on again later and it will work, but speakers fry.
I would only use that at half of it's rated power. That should prolong a useful working life.
Back in 1968, I remember a friend of mine buying some low priced Richard Allen 12" speakers, I think they lasted a week.
 
Back in the '70s and '80s, the Community Extended Leviathan (2x15" driving a gigantic horn) was the way to go. Visually impressive and efficient. But they couldn't reproduce sub-bass by today's standards. Back then, getting down to 60Hz for a large PA system was considered doing pretty good.

Around 1990, when I was completely out of the touring sound business, a Chicago-area company produced some subs that used a rotary motor that looked like what you might find turning a large fan or elevator, and attached it to large cones by a system of cranks, belts and other connectors to convert rotary motion to linear. Despite the bizarre design, these enjoyed some reasonable success IIRC. Can't remember the name, and the last time I drove by where their offices were, someone else was there.

Right now I'm very impressed by the McCauley Sound M421. This is a large 4x21" ported box that specs to 143dB between 20Hz and 100Hz. Each driver can be independently driven, or they can be wired in parallel to one of the modern PA amps that hit peak efficiency at 2 Ohms or less. ~15k US$.

For PA use I can't picture 12" drivers giving you true subwoofer response. For home use, sure, but most 12" PA systems just can't make the bass extension and the SPL at the same time. It sounds like your needs are more for home use though.

If you can find a nice pair of 12" high compliance drivers, why not try an acoustic suspension design? The problem with ported systems is that you get a few Hertz of extended response, and then response drops off a cliff. A well-tempered AS box with enough amplifier power (which comes cheap these days) and some judicious EQ can give you great all-around performance.
 
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