cobra93
-
Content Count
816 -
Joined
-
Last visited
-
Days Won
2
Posts posted by cobra93
-
-
Fair warning, I've not read the link on DIYMA. I clicked it, saw it was 4 pages and closed it.
I'll try to restate what I believe he's after.
I assume he means at a given frequency, say 45 hz.
If both systems are pushed to the same excursion at the same freq. and the woofers are identical. This could be a stretch, but maybe not.
If we could assume the only difference is the amount of power sent to the woofer to achieve this criteria.
Would they measure the same output on a meter?
Same excursion (and assuming same cone area, meaning same total displacement) at the same frequency in the same environment?
Yes, they would measure the same output.
See formula previously mentioned in my response to shizzon.
My original thought was that you could send quite a bit more power to the sealed system and the acceleration of the cone would be faster/quicker. I would think this would make a difference leaning in favor to the sealed system.This leads me to my next issue. Both woofers would have to receive the same clean or partially clipped signal in order to compare them.
I would have to believe that all woofers can play a 45hz freq., let's say just below clipping (an identical wave form) and the faster accelerating cone would achieve a higher (to some extent) output.
No, acceleration would be the same. It would be required to be the same by the fact they were playing the same frequency at the same level of excursion. One can't accelerate "quicker" than the other and both play the same frequency at the same excursion level. If the acceleration were different, one driver would necessarily need to either be moving faster in time (different frequency) or moving farther with each stroke (different excursion level). But acceleration would be identical for two different subs moving at the same frequency at the same excursion level.
The only difference would be the amount of power input required to achieve this condition. One subwoofer might require more power input than the other, which would mean one subwoofer had a higher sensitivity/efficiency than the other at that given frequency.....but that's it.
This was exactly the answer and explanation I was looking for.
Thanks for taking the time to break it down.
I tend to over think things sometimes and whether the acceleration of the cone would change the freq. was my hang up.
0 -
As always, a job very well done!
Very nice, very clean!
0 -
Looking good, keep it up!
0 -
I'm out for tonight, I'll be back tomorrow.
0 -
if i'm understanding this right-
This guy assumes the more a speaker moves, the louder it is and hitting xmax or xmech, whatever is it's loudest point possible...
If that's true, hahahahahahahaha.
The end.
You are right, there's not much to debate. It's a simple fact of physics that in a 2nd order alignment output is directly determined by displacement. The more displacement, the more output. In fact you can figure out the (anechoic) potential output for a given displacement at a given frequency for a subwoofer (or any driver) by the formula
SPL = 102.4dB + 20log(xmax) + 20log(Sd) + 40log(freq)
*Sd in square meters; xmax in meters, one-way
Certainly Xmax isn't the loudest possible point, as frequency needs considered also and there's no reason a driver couldn't exceed Xmax........but it's (ideally) the point of the maximum displacement the subwoofer can achieve while maintaining sufficiently low distortion.
This ofcourse excludes environmental affects such as the transfer function of the vehicle. But assuming transfer function is identical in both instances, we can ignore it and focus strictly on the drivers and alignments themselves.
No but really, in spl competitions, subs do not move no where near as much as they do when playing music but "burps" are louder than music...Maybe he should figure out why that is.
Nobody cares about SPL competitions and competive "burping" in this scenario. It's irrelevant. We are discussing 2nd order alignments, not 4th order (or higher) alignments that the majority of SPL competitors utilize. Behavior and peak output potential is different between the two. In 2nd order alignments, peak output is limited to peak displacement potentials. We could discuss 4th order (or higher) alignment behavior, excursion isn't irrelevant there either, but that's neither here nor there concerning the topic at hand. In our case, if driver A has 2x the displacement potential of driver B, and they are placed in the same environment, driver A has 6db more output potential.
If I'm reading into what you're stating correctly, then both ideal systems would produce the same output or at least a minimal difference regardless of the power applied.
0 -
if i'm understanding this right-
This guy assumes the more a speaker moves, the louder it is and hitting xmax or xmech, whatever is it's loudest point possible...
If that's true, hahahahahahahaha.
The end.
No but really, in spl competitions, subs do not move no where near as much as they do when playing music but "burps" are louder than music...
Maybe he should figure out why that is.
If a sub hit full excursion at the power levels that it sees during a burp it would go kablammo?
...I mean unless of course you burp at the same power you play music at.
No offense intended, however this is exactly where I didn't want this thread to go. I am not asking about being on the ragged edge and blowing woofers up.
0 -
I'm unsure if the restated question is not clear.
If two subs are paying the same tone and seeing the same excursion, it could be half of rated xmax or close to xmax, and are placed in identical environments (in front of the woofer).
Assuming the only difference is the amount of power required to achieve identical excursion from the woofers cone.
Would there be a difference in output?
I'm not asking about a sub on the edge of destruction, but would more power result in a faster accelerating cone and therefore more measurable output?
Tirefrye> Are you trying to tell me something with your response but no explanation or is this something obvious to you but not to me?
Shizzzon> No, that's not his or now my question
I'm attempting to make these two different situations as comparable as possible. Look at this as snapshot or moment in time. A broad range of frequencies doesn't matter to me as far as an answer goes.
The question I guess would be does power matter if all else is equal as it can be?
Will each in its own perfect environment deliver the same result as the other for a single tone if the only difference is power to achieve the same excursion?
I posted this here because I value the math/facts shown here to back up the statements made by some of the more knowledgeable members.
0 -
I'll try to restate what I believe he's after.
I assume he means at a given frequency, say 45 hz.
If both systems are pushed to the same excursion at the same freq. and the woofers are identical. This could be a stretch, but maybe not.
If we could assume the only difference is the amount of power sent to the woofer to achieve this criteria.
Would they measure the same output on a meter?
My original thought was that you could send quite a bit more power to the sealed system and the acceleration of the cone would be faster/quicker. I would think this would make a difference leaning in favor to the sealed system.
This leads me to my next issue. Both woofers would have to receive the same clean or partially clipped signal in order to compare them.
I would have to believe that all woofers can play a 45hz freq., let's say just below clipping (an identical wave form) and the faster accelerating cone would achieve a higher (to some extent) output.
I don't have the background/knowledge to prove this one way or the other. Which is why I was hoping for a select few , like yourself, to give an answer/ explanation as to "is there a difference and why"
I have read the sticky by Neil and believe that Force = Mass x Acceleration has to be a factor.
I don't know that this could be achieved over a freq. range and therefore wouldn't matter to me in in any of my systems, but it got me thinking.
0 -
Nobody?
0 -
This was posted on a different forum and I'd like some input from some of brainiacs on this forum.
It seemed to be a simple answer at first, but became more complicated the more I thought about it.
I don't know if more information is needed to answer this or not.
Here's the proposed question as well as a link to the thread. http://www.diymobileaudio.com/forum/general-car-audio-discussion-no-question-dumb/110780-noobish-question-but-ive-never-heard-answered-fully-sealed-vs-ib-output.html
Default Noobish question but I've never heard it answered fully. Sealed vs IB and output....I'm still not understanding why a sealed box would have more output than an IB in any frequency range. Ported is obvious so I'll leave that out.
If the same sub in both configurations can hit xmax over it's intended frequency range, how can the sealed setup offer more output? I've heard acceleration as an answer but at a given excursion at a given frequency how can acceleration be any different?
I hear the fact that IB setups can take less power than sealed thrown around as a con but if it takes less power to hit full excursion, isn't this a very good thing?
What's the big piece to the puzzle that I'm missing or is this one of those myths like a small sub is quicker and large is slower? If two identical subs are moving the same distance, how can one be louder than the other?
0 -
Without any pics of the condition of the paint we're all going to be guessing.
The age and color of the paint do matter.
Do you have ant experience with a buffer? Not an orbital.
If you do some Meguiars #2 with a waffle pad will remove the oxidized paint, but be careful around edges, trim and things like the antenna.
#2 will break down as it's being worked and should leave minimal swirl marks (tiger striping).
If you don't get some imperial hand glaze and go to work.
Follow this up with some type of wax, Meguiars #6 or #26. It's cheap and decent.
If someone were to wetsand the paint and breaks through the clear you're going to be out time and money. I don't think it's worth it.
Whatever you do stay away from anything with silicone in it, it won't last.
Also don't use any silicone products on the tires, weatherstripping or anything else for that matter if you're going to have the car painted.
If you do, it'll be fish-eye city and some pissed off people.
0 -
I hope he can't have any kids.
How the hell does he get in the car?
I wonder if everything is hooked up to one amp. HA HA, Do the maf on that for me.
0 -
a little thank you to sefugi for doing back to back projects for me, I have been working alot this summer and time off has been scarce. Thanks for letting me tie up your garage for the past 9 months or so. You really are the best!!!! A big round of applause for sefugi, this guy rocks!!! Next project has got to be for you, enough other peoples dreams time to tackle a project for you~~~Im sure it will be a show stopper;)
Too bad Sefugi isn't my neighbor.
0 -
Time to start laying plans for the old work trucks interior, gettin some new buckets soon!!! then custom center console time !
on the new bucket seats!! Who you gonna get to build that center console??Hmm, I wonder who that will be.
0 -
Definitely have my attention.
0 -
Glad you got your issues sorted out.
So have you caused any quakes in your state yet?
0 -
Every time I see a shot of your box I keep thinking your DD subs are 10 inchers because the amp is freaking massive.
BTW I liked how you stated "It's just violent when I turn it up". That's awesome.
0 -
Awesome build!!
Great ideas and craftsmanship!! Make your place of employment work for you!!
Finally someone that knows how to take a video. I hate it when most people keep whipping the camera around and you can't see anything without pausing the video a million times.
I'd love to know what you like/dislike about the horn enclosure versus a ported enclosure.
How well, over how big of a freq. range, does the horn loaded enclosure control excursion versus a ported enclosure?
Last but not least, how about some action vids. We want to see some wangin.
0 -
It sound like Shizzzzon has confirmed my thoughts.
I had the same issue with 4 SA-8's.
From 50 hertz to 30 they were monsters, but above that, nothing.
I was allot happier with around .25 C.F. per sub than the .8 C.F. that was in the middle of what was recommended for the subs.
The were peaky.
My dash bouncing up and down would agree.
0 -
I looked at this on BBP6 and with The recommended minimum port, 14" in diameter and 51" long, it is has a very flat response.
However, if I add cabin gain starting at 50 hertz with a 3 DB rise, you wind up with an 11 DB peak at 25 hertz.
You are only 3 DB up at 50 hertz.
This doesn't mean much in your vehicle, but could be part of the problem you have described, if this is a lack of output.
If it has plenty of output but sounds bad, it could be something else.
0 -
Pics won't help, but they're nice to look at.
What is your net volume, port dimensions, overall (gross) volume and thickness of the walls?
0 -
If you take off some volume inside the box, and keep the same port, it should lower your tuning. If I understood it correctly.
Try to put some wood, or anything, to take some room off the box and test, test, test it !
No Sir.
The smaller the net volume, assuming the port dimensions are unchanged, the higher the box tuning.
0 -
They look like cd changers.
0 -
Lookin good, Sefugi.
So you happy with you're router?
0
Sealed vs. IB and output
in Subwoofers / Speakers
Posted
Thanks for you input and for pointing out that in the real world it may be far form what is expected.
I've come to realize that most of the time "It's not that simple" applies to most everything in (especially) in the harsh/reflective environment of our cars since I joined this forum.