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Author Topic: The O so impossible 20hz!  (Read 13615 times)

Michael Fraioli

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The O so impossible 20hz!
« on: January 24, 2006, 03:40:45 pm »

Hey everyone,

Im new here so if i posted this in the wrong spot or anythign sorry you can yell at me. anyways. I am looking to build a sub cabinet size is not to much of an issue but i dont want some more then 300lbs. I want to build a cabinet that can hit somewhere areound the 20hz range on up to maybe 100 very most anyone have any good designs or things to consider for me to do this. i realize i need a sub and an amp that will drop to that level without losing -10db so im just looking for some help and suggestions since you all are the pros here thanks anyone who can help
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Antone Atmarama Bajor

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Re: The O so impossible 20hz!
« Reply #1 on: January 24, 2006, 07:48:09 pm »

     How much are you willing to spend building the thing.
And what SPL level do you want at 20Hz (1/2 space)?

    It Cost me~ 1000$ to build two of my BS-212 subs.  A pair are capable of reproducing 20Hz @ ~117dB @ 1000W 1m.  They measure 23 5/16" Deep x 40 13/16" Tall x 24 1/4" wide.  They could be made smaller but I wanted to play with differential Driver loading to reduce even order Harmonic distortion so part of the outer dimension is caused by a recessed area in the face.

http://srforums.prosoundweb.com/index.php/m/80905/8490/?SQ=b b0e5b8a95b673c0d1fdaf63b0007716

http://srforums.prosoundweb.com/index.php/m/82403/8490/?SQ=3 21e52d2824847ab1b4342c2215b062e

    There are other good driver options that would require much larger cabinets.  The BS-212 was designed to go as low as possible but also be reasonably portable.  I haven't weighed them but I doubt they are over 200lbs.

    It would take 4 of them to come close to the output as 1 Danley soundlabs DTS-20 at 20Hz and require 2X the power.  The cost difference would probably be made up in amplifier dollars spent except it will take you a long time to build your own.

http://www.danleysoundlabs.com/DTS20.html

    What is your application?

Sealed subs using a linkwitz transform or dual integrator EQ Can go very low with relatively low distortion, but maximum SPL is limited.

    The average Horn sub would be Unmanageably large.

    The same is true for most reflex cabs and group delay gets pretty extreme around resonance the lower you try to go.

    Passive Radiators have really weird phase and group delay issues.  I don't think its very easy for the average DIYer to build an optimal passive Radiator.

    If you don't mind building some Huge 40cu ft cabs the Adire Tumults and maybe the Acoupower drivers are good but expensive options.

    I still think for convenience of cabinet size and cost the LAB12 drivers are still the best bang for the buck.

    Good luck!

Antone-
     
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Weogo Reed

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potent at 20hz
« Reply #2 on: January 24, 2006, 09:05:38 pm »

Hi Michael,

You could simply buy some Danley TH-20s :

http://www.danleysoundlabs.com/DTS20.html

Good health,  Weogo
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Antone Atmarama Bajor

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Re: potent at 20hz
« Reply #3 on: January 25, 2006, 01:24:45 pm »

     Hey I already Said that Twisted Evil!

Antone-
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Michael Fraioli

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Re: The O so impossible 20hz!
« Reply #4 on: January 27, 2006, 04:52:37 pm »

well thanks for the help the danley sub seems great and im interested in purchasing it but more then 7 feet tall damn thats a lil big. Be honest with u all i am putting this in my 14'x16'and celing is 8ft bedroom i know this is excessive yatta yatta yatta but i liek my music loud period. i looked at this subs specs and it didnt seem to require that much power 500w rms which i could use just a crown xls202 in bridge mono mode you can pick those up for $225. im not really looking for 4 subs or i would consider your design 1 or 2 subs of any size would be great im trying to keep the enclosure no more then 36"wide 36" deep and maybe 5'-6' tall any more ideas or references anyone has?
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Michael Fraioli

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Re: The O so impossible 20hz!
« Reply #5 on: January 27, 2006, 04:57:18 pm »

o and also i found this site that has a really good lookin spec wise sub but i am having a hard to believing this subs specs what does everyone think http://www.adireaudio.com/Home/TumultSeries.htm and then look at there amps that they sell. I am really looking to spend no more then 1000 for subs and amps to power them i will worry bout cost of materials if i need to build the enclosure
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John Chiara

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Re: The O so impossible 20hz!
« Reply #6 on: January 27, 2006, 05:16:52 pm »

Michael Fraioli wrote on Fri, 27 January 2006 16:52

well thanks for the help the danley sub seems great and im interested in purchasing it but more then 7 feet tall damn thats a lil big. Be honest with u all i am putting this in my 14'x16'and celing is 8ft bedroom i know this is excessive yatta yatta yatta but i liek my music loud period. i looked at this subs specs and it didnt seem to require that much power 500w rms which i could use just a crown xls202 in bridge mono mode you can pick those up for $225. im not really looking for 4 subs or i would consider your design 1 or 2 subs of any size would be great im trying to keep the enclosure no more then 36"wide 36" deep and maybe 5'-6' tall any more ideas or references anyone has?


You can lay the DTS 20 on its side.

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Antone Atmarama Bajor

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Re: The O so impossible 20hz!
« Reply #7 on: January 27, 2006, 05:53:48 pm »

Plenty of output???  1 Lab driver @ 20Hz in a vented cab can only produce about 107dB.  Room gain not included.

    If you want to achieve full scale cinema LFE headroom to 20Hz (-3 to 6dB @ 30Hz normally).  You would need banded pink noise at about 95dB at listening position (in the LFE range with 20dB of headroom).  If you wanted to reproduce 20Hz -3dB from full scale you would need 112dB at 20Hz at listening position available.  Listening position maybe only 1 meter from the sub and room gain may give added sensitivity in the sub octaves.

    A pair of Labs in a vented cab may just get you there if you are sitting 1 meter from them.  Most people won't be doing that.                                    

    The mains center and surrounds need to be 85dB banded pink with 20dB headroom at listening position.  But how many people listen to movies full scale at home in their bedroom?

 I'm getting ready to build my friend a Dual lab Sealed sub using a likwitz transform  I should be able to get 104dB @ 20Hz,  1/4 space loaded into his cinder-block wall I should get ~110dB @ 20Hz.  A pair 1/4 space loaded should get 116dB @ 20Hz

    1 driver aiming forward and one aiming at the floor mounted in the box differentially.  The primary enclosure needs to be a well stuffed 14.78" Cube (internal dimensions)  I'm making it 24" tall to get the Magnet of the backwards down firing woofer off the floor.

     Cost of the 2 drivers ~300$ 3/4 or 1" MDF ~ 30$.  You would need either a linkwitz transform circuit made for it www.linkwitzlab.com (He has a spreadsheet for designing the appropriate circuit),  or play with some parametric filters, or get or make a Dual integrator ELF type circuit (This will limit your Flat response upper end to whatever the cabs box resonance is so not really appropriate for an LFE application)

    If you just want your setup for music I don't think you'll find much source material with significant recorded energy bellow the upper 30's of Hz.  Especially older recordings.

    Good luck whatever you plan on doing.

Antone-  

   
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Ivan Beaver

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Re: The O so impossible 20hz!
« Reply #8 on: January 27, 2006, 09:39:43 pm »

If you look at their site and the tech library and max output you will see that the infrasub 18 has a max continous output of only 98dB at 20Hz.  Is that loud enough for you?  Yes they will get fairly low-but not very loud at those freq.
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Antone Atmarama Bajor

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Re: The O so impossible 20hz!
« Reply #9 on: January 29, 2006, 03:25:15 pm »

Yah the infra sub (No longer ELF since Ron Wickersham had a falling out with Bag end) is an interesting approach but you need an awful lot of them to get loud.

    I think a pair or more of lab 12s in a sealed enclosure would be much more cost effective an a lot smaller you could build a dual integrator circuit for them really easily.  In fact I think the guy who runs the ESP audio website has a schematic for one there.

    I think the main concept behind the Infra/Elf system is that they want to operate the driver bellow box resonance so that it doesn't color the sound and THD is supposedly low.  And the Dual integrator is supposed to exhibit only a mild phase shift Vs. using other types of filters.

    Does anyone here know how different the phase shift between and integrator and a linkwitz transform circuit is???

Antone-
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