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Help me finish my polystyrene cab build

#221
Crater said:
When the speaker cone moves out, the cabinet will flex inward, so you'll have weird phase cancellations. The speaker driver and cabinet will actually work against each other.
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I play a tea chest bass (UK version of a washtub bass). From where my ears are (directly above the top) it is not very loud, probably because of complex cancellations, but it can hang quite well with a few acoustic guitars and rattle any lose panelling in the room (only for a very short period of time as the note decay is very quick).

I would think that a bode plot of it would be interesting (and not too dissimilar to your cab if it was laid on it's back with the speaker facing upward).
 
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#225
Roxbororob said:
This..."then by all means prove us wrong but don't let confirmation bias get in the way of the data/results."

Neal, I respect your outside of the box initiative and your efforts but now is the time for objectivity. You were asking earlier how to test and the very best way to do that is by benchmarking against a known control. You need to do this with an open mind and be ready to accept that your experiment (in its current configuration) might not actually be an improvement or a viable alternative to the status quo. A negative does not invalidate the experiment.
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as I said before, I don't have any amps or combos that are "known quantities." I don't know if anyone in this thread in the is in the Boston area and willing to lend me such a combo or rig. I am pretty good at graphs from school and will at a minimum take several sine wave sweeps (near a wall, middle of the room, other rooms, maybe a few on the sides of the cab?) and their IR with a pair of phones with a signal gen app and a audio spectrum/db level measurement app (conveniently I already have both and they are free). I am also reviewing the documents posted to the thread regarding audio testing to see what else I can come up with. I would love to overlay the output atop the driver specs from eminence, but I don't have their quantized data and can't think of how to obtain it easily from my phone apps either.

I will also record some sound clips with my basses.

My physics midterm is this Friday, but I don't expect to get to all this till my spring break ( march 9-17).
 
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#227
agedhorse said:
You will also find that the air frame power and avionics industries never color outside the lines, they very carefully expand the lines based on tremendous research, knowledge and experience.
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Don’t tell that to Burt Rutan or the engineers at Scaled Composites!
 
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#228
popgadget said:
Don’t tell that to Burt Rutan or the engineers at Scaled Composites!
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IMO, they did exactly as I suggested. They moved the lines based on knowledge and research.

Kaman Aerospace, the parent company of KMC (owner's of the brand I worked for) was probably the leader in composites for A&P. They too moved the lines based on research when they developed the power system for the K-Max high lift helicopter. It wasn't coloring outside the lines, there was a lot of work, testing and regulations to conform to in order to bring a safe and revolutionary product to market.
 
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#229
neal sanger said:
as I said before, I don't have any amps or combos that are "known quantities." I don't know if anyone in this thread in the is in the Boston area and willing to lend me such a combo or rig. I am pretty good at graphs from school and will at a minimum take several sine wave sweeps (near a wall, middle of the room, other rooms, maybe a few on the sides of the cab?) and their IR with a pair of phones with a signal gen app and a audio spectrum/db level measurement app (conveniently I already have both and they are free). I am also reviewing the documents posted to the thread regarding audio testing to see what else I can come up with. I would love to overlay the output atop the driver specs from eminence, but I don't have their quantized data and can't think of how to obtain it easily from my phone apps either.

I will also record some sound clips with my basses.

My physics midterm is this Friday, but I don't expect to get to all this till my spring break ( march 9-17).
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Ask “ Staindbass”. Yepp
Bass player for Staind is on TB

Seems very friendly and wouldn’t hurt to ask ? He’s invited folks in Mass to visit and try his rigs so ... Give him a shout !
 
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#231
d626197a8978ab7ed006ca99921b5756.0.png
 
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#236
Respectfully, in my entire career I have never seen a woofer that flat is any measurement environment expect a very high quality driver measured in an anechoic chamber. Nobody is that lucky on a first build, measuring in a room with real world boundaries. That's smoother than most raw drivers used for bass guitar (by a long shot). There are some very low sensitivity foam or butyl rubber surrounds that are quite flat but they have no high end bandwidth.

What kind of averaging and smoothing algorithms does your measurement device use? By any chance does this have any eq correction applied? What tweeter are you using?

Your yellow line looks more realistic, complete with EM measurement artifact.
 

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