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Author Topic: anyone built their own cabinet for 2268H subwoofers?  (Read 34317 times)

Bill Burford

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #70 on: April 13, 2010, 02:37:48 pm »

This is why I love this site!!!!

people just love to argue with you even when you are asking a question.

I said BANDS THAT USE SAMPLERS AND SUB HARMONIC SYNTHS ON THEIR BASS
ps.  max excursion probably occurs at MIN impedance
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Bill Burford

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #71 on: April 13, 2010, 02:41:53 pm »

i've also seen a lot of really big time hip-hop/r&b music myself.  In fact when I heard them on the radio, I thought it was all synth.. but their live show clearly had a real drum-kit.
and the kick always punched through the bass of whatever tracks they were playin
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Adam Schaible

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #72 on: April 13, 2010, 02:42:59 pm »

Max excursion is dependent upon the box tuning and a lot of other things.

A whole lot of drum kits are triggered.  More than you think!
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Bill Burford

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #73 on: April 13, 2010, 03:03:35 pm »

in the original QUESTION, I asked and included a disclaimer that it could be rock OR hiphop and in EITHER CASE be-it accoustic OR SYNTH which part of the mix was where max excursion occurs?
bass or kick.  to clarify my question, synth or accoustic bass or synth or accoustic kick.  


in a later post I mentioned some hip-hop/r&b.
In the cases I am thinking about, I assure you these drums are accoustic and not triggers.

if you would rather correct me I guess you don't know the answer.
I know the answer.
(sarcasm)
to find it, you can simply view recorded tracks and zoom in real close.  Inspect the peaks of the synth wave-forms and compare them to the peaks of the kick waveforms.  there, you have your answer.  (more sarcasm)
seriously is there an answer?  I know this depends on the mix.  assuming a typical good mix.  and assuming the mix is on a given box and tuning, the max excursion will still occur at some point in the mix relative to the smaller excursions at all other parts of the same mix.
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TJ (Tom) Cornish

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #74 on: April 13, 2010, 03:06:26 pm »

If you know the answer, maybe you could enlighten us, as we're all apparently failing your quiz.
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Bill Burford

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #75 on: April 13, 2010, 03:10:50 pm »

again, my question about live music.

the original post for cabinets for 2268 drivers mentioned that there were only some days with live music and other nights there were dj's..

this was really interesting to me..

so I asked where anyone thought in live music (mixed differently) than recorded music, did max-excursion occur?

I didn't state a bunch of facts.. I asked a question.

can anyone answer it? or is it slam fest for asking a question?

(  NO STUPID IT COULD HAVE BEEN A TRIGGER )
???????  what?  how does that connnect to my question?
its like people want to read into my thinking and find something wrong with it.. without attempting to even talk about the original question
yeah thanks.. do you see my point

there is more to my question as to why it is even a question.
everyone knows amps have more impulse power than continuous power.  or do they?  anyhow, considering a kick is more of an impulse than a sustained track or bass-line, in my mind, that meant that the kick had an even higher chance of creating max-excursion (as opposed to a bass line)
also, the instrumentation used to measure this for the fancy plots could be using data from the amp-- I don't do those plots so I don't know.  but could it be possible that they calculate those plots based on signal used to drive the amplifier.. however, is this the same as the actual physical motion of the driver?  or is it based on voltages?
or current drawn?
how much of that energy was converted to heat?
how much of the actual physical woofer motion mimicked the chart?

my question also has more purpose:  the answer may help the original poster decide which drivers to use in his boxes.
what if the other woofers made more excursion for a sine wave but as someone said, the excursion exceeded their specs xmax?
well, then, wouldn't this mean that physical damage could occur during a live mix?
in JBL's case, they may have a cone which is physically made to take more physical abuse than any of the electrical abuse which is ever thrown at it.. in other words, perhaps the driver is designed to operate with a max voltage, max current which will never achieve xmax on purpose-- for longevity reasons.
Also, if you over design the cone physically, you might lose some of the efficiency but they may be more capable of withstanding extended exposure to sunlight (could be helpful for anyone else reading this thread if answered).

I actually dont know the answer.. I'm just thinking about it.  I'd like to know.  but I'm thinking in practical terms, if I knew the answer to where maximum excursion occured, I could use that information to decide if they actually had made the cone more durable than necessary.  this could encourage me to buy more of them or not.. or it could help me decide how maybe a friends drivers were actually damaged or if someone asks me.. 'hey, do you think this setup is ok?'  it may help me give them advice of what to watch out for.. say someone asks.. where do I put my limiter on this amp which is more powerful than the spec.. all kinds of reasons for asking this question.
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Seth Hochberg

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #76 on: April 13, 2010, 03:15:42 pm »

Bill, I think the inherent issue here is that you've asked a question for which the best answer, like so many other things in audio, is "it depends". There will never be any sort of constant where maximum excursion will occur - it (excursion) is a factor of the power being fed to the speaker, the frequency content of the signal, the driver itself, the box the driver is placed in, etc, etc, etc.

If you have driver x placed in a box tuned at 50hz and I have driver x in a box tuned to 30hz, even when fed the same signal from the same amplifiers to the same speaker, we will each receive dramatically different results for our particular setup's peak excursion.
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Evan Kirkendall

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #77 on: April 13, 2010, 03:18:47 pm »

Bill Burford wrote on Tue, 13 April 2010 14:37

This is why I love this site!!!!

people just love to argue with you even when you are asking a question.

I said BANDS THAT USE SAMPLERS AND SUB HARMONIC SYNTHS ON THEIR BASS



Bill,
There's no arguing going on here. Just stating facts. If you can't figure out that a kick drum is an impulse that creates a good amount of cone movement, then you probably should consider a new hobby. Wink

Here's an easy excursion test: At your next sound check, have somebody hit the kick drum. Push the fader up until you hear the subs bottom out. Now do the same with the bass guitar. I bet you'll get a lot more volume out of it. However, that bass guitar is going to create a lot more heat then the impulse of the kick drum.


Bill Burford wrote on Tue, 13 April 2010 14:37


ps.  max excursion probably occurs at MIN impedance


Actually, that's completely wrong. Maximum excursion occurs where the impedance is the highest. As the voice coil cuts through the magnetic field, the impedance rises.

Here's an example:


index.php/fa/29438/0/
(Pulled from EV's website, the QRX218S)

You see that big impedance bump at 70hz? That's where the cone is hitting hard. It's a bit above the tuning of the cabinet, and within the operating range of the cab. If you were to run a sine sweep from 100-40hz, you'd see the most cone movement at 70hz.



Evan
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Bill Burford

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #78 on: April 13, 2010, 03:38:43 pm »

I'm not 100% sure about this, but I don't think max-spl is the same as excursion.

I would bet that the max excursion occurs at around 35Hz on that cab.

the reason why is it has the lowest impedence.. this causes the most current throught the coil which causes the greatest EMF against the magnets which will move it the farthest.  

again, I could be wrong but I'd bet if you are going to invert that driver, putting a high-powered 35Hz signal into it is the best way to get the coil to hang up on the basket.

either way, you are telling me to get a new hobby.  for me the hobby years were 7, 8 years ago.. well beyond hobby.  that is like a personal attack dont you think?

where have I gotten personal in here?  I am more than happy to take challenges and even admit if I'm wrong without ever attacking someone personally.  bands don't like that too well.
I don't take it personally at all.  I've already said I could be wrong about this.. but you've definitely got my attention on the impedence curve for a driver.  I'd like to hear from a JBL engineer on this one.  I will happily admit my error.  I'm a mixer and don't really do this kind of study myself.  I have no need to.. I operate well within the spec sheets.
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Bill Burford

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Re: anyone built their own cabinet for 2268H subwoofers?
« Reply #79 on: April 13, 2010, 03:46:31 pm »

YES!

Knowledge!!!!!!!!!
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