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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: Antone Atmarama Bajor on October 13, 2005, 02:09:07 am

Title: My first Sub Design.
Post by: Antone Atmarama Bajor on October 13, 2005, 02:09:07 am
     Finally popped my cherry.
Here's my First cab ever.  God What hard work.


I'm Calling it the BS-212.  Partly because BS can be interpreted as many different things.  But It really stands for Bajor/Steckling.  

    I researched and designed the cab, (assisted by Harris Tech Bass Box Pro) around the Lab 12 Subwoofer.  Jerry Steckling gave me some construction and configuration suggestions, and graciously provided the facilities to do the work in.

    As far as I can tell I'm -4dB around 25Hz with roll off starting around 50Hz.  Though I haven't gone outdoors with the TEF to see what's really happening.

    I'm planning on using these for a bass rig, and possibly reference subs when playing with Some DAW mastering.

    Just wanted to Share.

    I will post all of the outdoor TEF sweeps once I get these out to the field with some test gear.



Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on October 13, 2005, 02:11:47 am
Heres a rear end shot

Title: LAB12 heat exchanger
Post by: Wayne Parham on October 13, 2005, 02:50:22 am

Since you're using the LAB12, I encourage you to look at the work I've done on improving thermal performance.

Title: Re: LAB12 heat exchanger
Post by: Antone Atmarama Bajor on October 13, 2005, 07:06:56 am
Hmm Don't know if I want it sticking out in front of this cab with the Differential setup.  I don't think I'd be able to get a grill cloth in front.

   Is it just aluminum pipe with some heat sink compound attached to an aluminum plate?  Would Copper pipe work well also?

Title: Close TEF Measures
Post by: Antone Atmarama Bajor on October 13, 2005, 10:51:49 pm
Here are some close measures I took of the driver an inch or so away overlayed with measures from in front of the port (Almost in).

Title: 5 String Bass rig!!!
Post by: Antone Atmarama Bajor on October 14, 2005, 03:30:24 pm
      Wow these things are fun.
I felt sick to my stomach from sub bass for the first time playing a 20Hz Tone.  I also experience the same voice modulation phenom' that Michael E.  Was talking about experiencing with his dual 2245 CABS.

    Here is a shot of the Boxes with my TL606's on top for mid bass to nice Breakup mode upper mid 80-3kHz.   Its nice to finally have some authority in the sub range.  I can really Rock the house with my LOW A string (maybe I should buy some of the .150 gauge strings and tune to low F# Muahh Hahhh Hahhh).

And its actually reasonably portable LFE for a bass rig if you got a big enough vehicle.    

Title: Re: My first Sub Design.
Post by: Evan Kirkendall on October 14, 2005, 03:39:07 pm
Sound guys are gonna hate you.   Twisted Evil

Sound guy: "I can hear the damn band over your bass rig. Im clipping 2 JBL SRX725's with PLX2402's bridged trying to get to vocals on top."

Audience memeber: "My head feels like its gonna explode when you are playing!"

Have fun... Smile

Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on October 14, 2005, 05:30:56 pm
     Awe Come on I'll just be able to compete with the Marshall Stack players.  Only like 123dB at 27.5Hz with 1600Watts.

    You know its actually amazing how intelligible everything is with these cabs since the Diff configuration cuts down on Harmonic distortion.  I can really over hype the Sub Region but the vocals are still really intelligible.

    Now its really a chore trying to fight for intelligibility over saturated guitar, especially when you can't convince some overzealous guitarist that its in everyones best interest for him to keep his stage levels down.  Talk about spectral clutter.

    I love the guitarists that like to play so loud that you don't need to add them to the mix and your standing 75' or more away from him at mix position (even better playing that loud in a little dive bar).  "But dude I can't get my tone if I don't play like that."  But dude your ears are probably so fried that you need to play it that loud to hear any tone.

    I should just announce to the audience that I have come to make them sick.

Title: Re: My first Sub Design.
Post by: [x] on October 15, 2005, 01:51:54 am
Actually, to be brutally honest, the LAB12s make a lousy direct-radiating pro subwoofer because they require a cab that is so big to get lots of low. You could have easily fit a pair of 15" in the same space, possibly even a pair of 18".

Wayne, have you measured the T/S parameters of the Lab12 with your heat exchanger contraption stuck up the Lab12's hole? Some important things, like Qes, could change. Loudspeaker motors are designed for a certain amount of flux saturation.
Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on October 15, 2005, 03:29:59 am
     Yes I could have used a couple of 15's Rory Or an 18.  But my goal was extra LFE in a reasonably sized package.  

    Even So the only drivers that come anywhere close to the LF extension are TAD 1603's and 1801's  But they cant handle the same amount of power and would require a cab of similar size.  The TAD 18 would require ~10Cu' port not considered.  A 4Lab cab would need to be 12cu' But I can split it into two 6cu' cabs making it much easier to move.  I have a little lower Cut off and a bit more output (with about 8X the power as a trade off).

    There are other more efficient drivers out there for anything above 30-40Hz range but the range where the labs win in efficiency below that range.  

    Even the Seismic does not have the same level of extension.  In a not so optimally sized box for the Seismic (10Cu Ft.)  Theoretically I can get 115dB @ 20Hz with 1000Watts Port tuned 25Hz.  With the 4Labs In 12CuFt I can get 117.5dB @ 20Hz with 1000Watts Port tuned 22.13Hz.

If I push the Seismic's box up to 12cu' I can get 118.1dB @ 20Hz Port tuned to 23Hz.  But again I dont want too have to move 1 12Cu' box for a bass rig I'd rather move 2 6cu' boxes.  The seismic really wants a 2.3cu' box with a foot wide 61" long port tuning it to 44Hz ("High Fidelity Tuning").  

    Another Driver I was considering is the Sonicraft SC-12SC-.
I could have more low extension greater xmax but in a significantly larger cab with less power handling.

    So the Lab 12 may not be much of a low to midbass motor but In the low 30's to twenties Watt For watt Is a much stronger subwoofer than a majority of other direct radiators available.  
Title: Re: My first Sub Design.
Post by: [x] on October 15, 2005, 10:12:54 am
Eminence Omega Pro 18's give you 25 Hz extension but you have to build exactly the right box, with the tuning actually at the resonant frequency to control the driver's tendency to overexcursion at the highest drive levels. The thing is, the Lab12s make such lousy direct-firing pro subs because they are, by themselves, woefully inefficient. They follow a model similar to today's hi-fi subwoofers where they use a really heavy cone and a really heavy voice coil and a long-throw suspension that has a lot of damping in it. They work well in the horn because the horn is hyper-optimized to get lots and lots of output from them, because they are strong drivers. It takes a large amount of pressure to counteract the motor's action. But efficiency is the key for a direct-radiating box. With both those drivers, you're probably only getting a net 91dB 1w/1m sensitivity. With the Kilomax 18, you would be getting 98dB 1w/1m sensitivity with higher power handling as well. And for a pair of 12's, that is not a reasonably sized package. Boxes look well-made, though.
Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on October 15, 2005, 01:58:27 pm
     The kilomax 18.  Models really Hot at 30Hz and 117.4dB at 20Hz  1000 Watts in a 16Cuft' Cab.  Not very linear in its band pass though very bumpy.  And the Cone is about 6mm past xmax @ 38Hz.

    That seems to be a major problem with most of the drivers I've been modeling.  They all look good initially until you look at the cone displacement they over excurd within their rated power bandwidth.   This is not true of the LAB12 I can put 1600Watts into the 4 of them and never exceed XMAX until I hit about 18Hz.  I'm not using them bellow 20 So I should be doing very well.

    I personally think that there needs to be disclaimers on Cabs and drivers saying  Cone Excursion Will be linear across X-Powerbandwidth.
Power bandwidth will be reduced above X-Watts RMS.

    I think that is the big lie in a lot of driver specs.  I was really irritated when my EVM15-B's Voice Coils started smacking the keeper plate driven at RMS.  Now I have them Crossed over around 80Hz and they are very happy with me.

    I would never try to use these boxes for a large PA but I think for a smaller club these things will really kick ass and the fidelity is very good.  By the way Two Boxes are 93.4dB Not exceptionally efficient but from the 40-150Hz Range I can put out about 125dB.  Great for onstage bass, studios etc.  But then I can use my BT7's for some of that too but I don't wanna lug em around.

    I'm glad you like the cab build though.  That was some hard work my hands still hurt.  Since it was a proto I used 3/4 Marine ply instead of some nice 13ply birch.

    Anyhow I will hopefully run some good outdoor measures on them soon.



Title: Successful gig.
Post by: Antone Atmarama Bajor on October 16, 2005, 03:12:06 pm
     I just took my BS-212's out on a gig.  The sax player and Violinist officially Hate them.  They didn't like being rumbled by the extra LF they were standing only 6' away.  I personally enjoyed the Organ Massage.  

    I don't think I've ever played with so much fundamental except when I played through My BT7's.  Now our band leader can stop complaining about not being able to feel my bass the way he wants.

Title: Re: My first Sub Design.
Post by: Tim Duffin on October 17, 2005, 07:46:35 pm
In that case---"not enough xmax at 20Hz" a car audio driver would win out over pretty much all pro audio drivers, but sacrifice upper bass performance and efficiency.  Just for fun, have a look at Massive audio's DMX stage 2 12" driver.  At
I think that for your application, even the lab12 isnt quite good enough.

Title: Done my homework.
Post by: Antone Atmarama Bajor on October 18, 2005, 01:50:17 pm
The Lab 12 is basically a "car subwoofer".

    The Massive Audio Competition and Reference subs are more than half the sensitivity of the LAB and and needs 1 Cu ft. larger optimized cabinet than 1 lab sub in an optimized cab.

    The 4 Voice Coil Monstrosity doesn't have close to the output of 1 LAB 12 At 20Hz both in optimized cabs Even with 2500 Watts behind it.  And what is the Street price of a DMX12????  Looks like a waste of money to me( well I guess the guys who buy them are only interested in a wicked 808 Kick drum sound).

    I wonder how much better the chrome plating on the Subwoofer Makes them sound!!!  I bet if you put some diamonds and gold on them The laws of physics would be circumvented and Bass reproduction would be increased to imesurable numbers.

    I think too many people are biased by brands that they have taken a liking to.
    The Lab 12 was not my first choice of drivers but the more I've modeled and compared the more I find it to be a superior motor down below 40Hz.  My original choice was the Sonicraft
SC12 NRT.  Another Fun one would be an NHT 1259 but Its sensitivity isn't very good, I don't really want to built 20 and 40 Cu' Optimized cabs for four of these things.  And the Lab is much friendlier on the wallet for its performance.

    If someone can actually find me a better performing woofer than the lab in the 30Hz and bellow range I want it!!!  I'm serious!    

Title: Scary Bass, Good.
Post by: Antone Atmarama Bajor on November 16, 2005, 03:20:13 pm
     Hey I just discovered a good LF Rich movie that will push the lower limits of ones subs.  The Atomic Bomb Movie Trinity and Beyond (Narrated by William Shatner).  I haven't gone through the whole film yet but the first Atomic blast from the Trinity test has a really nice percussive Shock wave that really gives you that sick to your stomach feeling!  Video quality is not very special but it has a really nice soundtrack.  

    I'm doubting that this is the original recorded sound from the military test film.  They probably sexed it up a bit but its pretty freaky.

    Do any of you have any suggestions of source material with significant sub bass down to the 20's.  I know some of the Standards are movies like Pearl (Necklace) Harbor, Jurassic Park and some silly U boat movie.  How about some music that has some actual recorded sub bass.

Title: Re: Scary Bass, Good.
Post by: Ivan Beaver on November 16, 2005, 07:28:04 pm
The Incredibles has some pretty heavy stuff at 10-15Hz!

Spiderman also has some great stuff.
Title: Re: My first Sub Design.
Post by: MARK PAVLETICH on December 04, 2005, 11:00:39 pm
Let me get this right........You want a 25Hz extension box on bass guitar. What for ? The only time there is likely to be any energy in that frequency is when you thump the bass guitar with your fist.With a rig like this in any room short of Madison Square Gardens, that will happen just before the soundman or other band members thump you with theirs!!!!!!
Title: Re: My first Sub Design.
Post by: Dave Rickard on December 05, 2005, 12:36:37 am
MARK PAVLETICH wrote on Sun, 04 December 2005 21:00

Let me get this right........You want a 25Hz extension box on bass guitar. What for ?

So you can detune your low B down to an even low(er) G!   Shocked

(Great for the bluegrass banjo tunes in G)

Not seriously,
Title: Re: My first Sub Design.
Post by: [x] on December 05, 2005, 01:32:24 am
I agree. For lots of sub discussion pertaining to home theater, go here:

But for subwoofer discussion pertaining to pro audio apps, I recommend this page: 625415114ecdaafee31982cd98e

Honestly, pro audio guys aren't concerned with 25 Hz and below unless they can get a lot of it loudly, efficiently, and cheaply. Which is almost impossible to do without big bass-horn arrays.
Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on December 05, 2005, 05:16:06 am
     Ok Mark,
My intention for building this cab is personal application as a bass rig.

    My original criteria was to have as much output in the 30Hz and bellow range as possible in a conventional direct radiating cabinet roughly around 10cu'.

    I play a 5 string bass.  Fundamental of Low B is 30Hz I drop tune 1 whole step to Low a 27.5Hz.  Almost no commercially available Bass Guitar cab has much significant output bellow 40Hz let alone bellow 50Hz even worse once power bandwidth is taken into consideration.

    After much cabinet and driver modeling I came up with a 12cu' cab that utilizes 4 12" Lab 12 Drivers (TS params specified by Tom Danley for the LAB subwoofer project so I feel it is somewhat appropriate that I post about it here).

    What I came up with was a pair of 6cu' cabs using two 12" drivers each (think of them as one cab its just easier to move that way).  I am able ot achieve 124dB at 30Hz 1 meter with very low harmonic distortion.  More than enough headroom to play at reasonable stage volumes at those levels.  I also have the added bonus of significant usable low distortion extension down to and below 20Hz.

    I don't think that they are the best option for Large PA sub.  I think We would all do a lot better with one or more of Tom Danleys Towers if extension down to 20Hz is desired.  Although if that level of undistorted extension to 20Hz was required my BS-212 would do better than 90% of anything considered a PA sub.  But It would take a lot of them and a lot of amplifiers to get proportional SPL.

    I do think that they would lend themselves well to studio, and home theater applications.  I think I actually exceed the Genelec 4X12 sub as far as distortion, extension and SPL.

    I have never experienced anything else like them.  Playing my 5 string bass guitar in front of the thing makes me feel like I've lost my land legs.  Playing a 20Hz sinewave through them makes me feel ill, and modulates my voice.

    I am not trying to sell the thing to anybody, and I plan on making the cad drawings available to anyone that is interested I just haven't cleaned them up and labeled them enough to be very useful to anyone.

Sweeps: b1ac9f6e1e07f049ef86293c162ec0c

    This as I said is a project of personal interest and my first speaker cabinet.  There is nothing extraordinary about it.  It was born out of my discontent with BS subwoofer/speaker specs and wanting to have something with superior performance and much less cost.

      Can they be used in pro audio.  Sure why not, are they practical, that really depends on the situation now doesn't it.  I think this design is borderline in where it is applicable and doesn't need to be pigeonholed.

Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on December 05, 2005, 05:29:10 am
     Another thought,
    Isn't it normally better to have bigger rigs in smaller venues.  An smaller rigs in large venues since keeping stage levels down to keep the FOH clean is important.

 Where in a smaller club/bar like venue the PA is normally used for vocals only.

Title: Re: My first Sub Design.
Post by: MARK PAVLETICH on December 05, 2005, 06:27:59 am
Have you ever done a scope reading of the actual output of the low B string on your bass guitar? If so, can you answer the following questions
How much fundamantal was present on the lowest note produced by the low B string ?
IMHO the only instrument that I have encountered that produce significant fundamentals at those very low frequencies are based on electronic oscillators. How much 30 hertz fundamantal do you think a 34 inch scale 125 thou thick bass guitar string is producing ? You might be hearing something but I very much doubt it is much 30 hz fundamental.
Far be it from me to question the artistic validity of making people sick with very low frequency sound, but the science of doing it needs to be addressed.
Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on December 05, 2005, 03:30:14 pm
     No I've done better I've done a spectral analysis.

    I know all about electromagnetic pickup placement and roll off issues.

    The roll off has a bit to do with practicality of placement and also not hitting a null for any of the fretted note fundamentals.

    Right now All I have is a clunky Graphic EQ to compensate for roll off.  But I am probably going to use a simple high passed integrator summed with a highpass filter to give me a 6dB per ocatave boost to counteract the 6dB per octave roll off.

    The Zero dB point is determined by Instrument scale (mine is 35") and pickup distance from bridge and tunning of the string.  So the integrator has to be optimized for the particular instrument.  I also have the option to run my pickups in stereo so I can have one EQ per pickup since both have different 0dB points.

    There sure are a lot of people that are agitated about the prospect of me even trying to attempt to reproduce the fundamental of my bass.

    I agree that normally only synthesisers and oscillators can easily reproduce significant LF sinewaves.  So what.  Have you ever banged on an orchestral Bass Drum?  It doesn't generate a pure sinewave but it has a very low fundamental pitch.  Does any non electronic instrument produce a pure sinewave.  Ever play with a quartz urn (the ones used to grow silicon ingots in) those things can shake the walls of a house.

    Ok Mark what is your personal experience with Sub Bass.  I consider myself a novice.  I feel lucky enough to know what a 20Hz sinewave at 116-118dB is like.  I also own 8 BT7's so I know what a sinewave at 30Hz in excess of 136dB is like.  Its not a very big club have you ever been experienced.

    I would venture to say that nay sayers have not.  Or they have weak stomachs.


Title: Re: My first Sub Design.
Post by: MARK PAVLETICH on December 06, 2005, 04:23:29 pm
Where did I say sine wave in my post ? The lowest PITCHED low frequency sound that I have ever experienced from a non electronic instrument was from a very large pipe organ. If you want real low frequency non electronic sonic information, I would suggest 155mm artillery, I have only felt the outgoing side of it. I imagine it is even more impressive at the incoming end !!!!
Title: Re: My first Sub Design.
Post by: Antone Atmarama Bajor on December 06, 2005, 05:33:31 pm
Dont make me play a solo on my Electric Shirt Colar!

I'm afraid of the report from a 155mm cannon.