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Old 24th January 2007, 04:58 PM   #1
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Default Looking for extreme low loud bass...el pipo, horns,...

Hi, subject says it all.

I am just finishing to rebuild a freaking power amp, and fallen into my hands a nice sub for very cheap.

The sub i have is a car subwoofer, SWX 1242D capable of 1000wrms, 3000 peak, 12 inches, dual 4 ohm voice coil.
The amp is a QSC usa 900 clone, sligtly modified to pump around 1000wrms at 8 ohm in bridged mode.

I also have a "down converter" which takes the fundamental frequency down low and divide it by two and put it back into the music...it remembers me the so called "Epicenter" from Audio control, for car system applications. It realy makes the difference !!!

So, i have also a 12 inch concrete tube...it just lends me to build a EL PIPO.
(COPY/PASTE FROM THE WRONG FORUM, SORRY)
sub spec

I am also thinking about a front loaded horn, but i am totaly lost as to where to start picking up info for this. I searched a bit on this site, i returned me either super specific info with complicated calculations, or elusive info.

Can i have some help my friends ??

I have enough space, i am using my home basement for the project.

Is there any calculators tha i can download and enter my sub specs and "fo" wanted, then it returns most of the dimensions to build the horn ??

Id like to get pictures of finished projects similar to mine.

thanks !!
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Old 24th January 2007, 06:24 PM   #2
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Default Hey Pat.....

if their are any "Transmission Line Subwoofer" calculators out there, I'd sure like to find one !

I'm fixing to start experimenting with TL setups myself. I have searched unsuccessfully, for some type of calculator. So now I think I have decided to just get me a nice big sonotube (probably a 16" or 18") x 14ft or so. Then attach a couple of 15" Dayton Titanics to one end of it {in a push-pull configuartion}, and start playing around with this and a frequency meter. Too low... cut off some pipe. Too high.... add some stuffing.

On the one hand, a calculator would be great..... But on the other hand, personally speaking, I think I might take a little more pride and satifaction in the project if I did it myself, and it then especially if it came out bombastic :-)

Peace,
Fish

PS, This guy is using two 10"s in each of these tubes. http://www.teresaudio.com/haven/subs/subs.html

This setup seems kind of modest to me.... but then this guy was not trying to rock the house down either. He was just shooting for the "nicest sounding bass" he could get, and claims he has found it with this setup.
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Old 24th January 2007, 06:39 PM   #3
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I know how you feel

I made few test last years with my actual sonotube.

12 feet long, 12inches diameter. I was using a 12inch subwoofer that i was already having, not good quality.

I made some sound test with a frequency generator. The tube was horizontal. I read somewhere that it MUST be vertical...

Anyway, i got some noise going out of it, but was a bit disapointed about the SPL. There was something like 100w in play.

Its been 2 hours now that i am searching this forum...

there is a lot of simple questions unanswered, and there is far more bla bla bla (no offence to anyone plz) rather than real buildups or physical tests.

simple question like:

1-what kind of "system" makes the most SPL
2-what is the easiest one to build
3-what is doable and what is not

practicaly speaking, a system that makes terrific spl, but within a very narrow bandwidht is out of equation...
My quest is to build "something" that can makes music sound like music, from anything in between 0hz and 100hz, where most of the "normal on the shelf" speakers literally stop to play...
AND/OR something that makes the house going off of its foundations...

i wonder what 0hz sounds like...anyway...

I played a lot in the past in car audio, i made a lot of good "kit" with many subs, the better one was with 4 12 inches in a minivan. It was quite loud and very disturbing
i played with...bandpass, double bandpass, compound, ported, sealed,...
i know how good bass feel, and id like to make it in my house

I have big thought about a front or rear loaded horn. The fact that it can extend the fo of the sub 1/2 is tempting, but seems a lot complicated to build and calculate.
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Old 24th January 2007, 08:23 PM   #4
freddi is offline freddi  United States
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the late Bob Bullock's free DOS t-line boxmodel program might (?) work - someone here may have a feel for specifying stuffing density so could ~correlate to MJK's work (?)

http://www.hal-pc.org/~bwhitejr/
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Old 24th January 2007, 11:58 PM   #5
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Ive made a few sonotube pipes subs and all I can say is that they are worth the effort.

one was made with a 12" 8ft length of pipe and a 12" kenwood car stereo driver siliconed into place. pipe is filled with polyester

the other uses a 4" voice coiled 18" (industrial 98 db@1w, 1m) in a 10ft pipe, 18" diameter, siliconed into place. filled with fiberglass

I have used them both vertically and horizontally with no noticable difference.

The first system lives in my living room, The second lives in a 250 seat cinema.

awesome is a common comment at the cinema!
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Old 26th January 2007, 09:14 AM   #6
AndrewT is offline AndrewT  Scotland
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Hi Pat,
Quote:
I am also thinking about a front loaded horn, but i am totaly lost as to where to start picking up info for this. I searched a bit on this site, i returned me either super specific info with complicated calculations, or elusive info.
most of the information on this site and the references quoted in it are consistent. There are anomalies but often they are more to do with the amount of truncation of the true horn and the sound (depth and quality/response variation) that results from that truncation (cutting off the horn before it reaches it's required length/mouth area).

The facts are.
1. the mouth circumference >= wavelength of the lowest frequncy to be reproduced.
2. the flare rate, controlling the length, is related to the lowest frequency to be reproduced.
3. the horn length >=either a quarter or a half wavelength of the lowest frequency to be reproduced.
4. the throat area should be related to the cone area, usually equal to or down to one third Sd area.
5. the frequency range from a horn loaded driver cannot approach the ten octaves in normal music. Usually it is divided into two or three octave segments and each is designed for appropriately.
6. the room loading on the horn can usefully reduce the mouth area required for good sound reproduction. This is usually only applied to the bass frequencies, mid and treble frequency horns are usually designed for operating into free space.

The result of all this is that as the required bass frequency goes down the bigger the horn becomes, in volume, length and width.
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Old 26th January 2007, 09:18 AM   #7
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by Cameron Glendin
Ive made a few sonotube pipes subs and all I can say is that they are worth the effort.................the other uses a 4" voice coiled 18" (industrial 98 db@1w, 1m) in a 10ft pipe, 18" diameter, ............The second lives in a 250 seat cinema.

awesome is a common comment at the cinema!
I have aquired a pair of 18inch drivers but with a low Xmax. would these be suitable for Sonotube loading?
How much power does one need for a Sonotube to give effective bass and sub-bass?

How far below Fs does a Sonotube go and still be effective?
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Old 26th January 2007, 02:38 PM   #8
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Default Thanks guys....

Hey Cameron G, each successful TL subwoofer pipe I hear of, gives me that much more confidence.

I notice you said they work fine horizontal.... as I originally suspected.... Although I think I have figured out at least one reason this is not rcommended > The stuffing needs to be spread evenly, and given some time and use, if layed on its side, the stuffing might tend to squash down to the bottom side. Maybe if one could find a stuffing with more body... like maybe furniture batting ?

Peace,
Fish
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Old 26th January 2007, 04:06 PM   #9
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Fish,

You might want to try basalt insulation. Sold as Rock Wool among other names. Not likely to compress over time.
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Old 26th January 2007, 04:11 PM   #10
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Default All about the numbers

The idea of standing vertical invloves boundary loading..... ie Allison technique... turning 4 pi space into 2 pi space.

With a long enough tube, ya gets the woofer loading into the floor and the vent at the ceiling.

Cyclotronguy
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