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req
06-10-2005, 04:40 PM
So all you genious builders (jmac if you are reading :blush: )

i have a question that i still have yet to fully understand. i would like a good discussion, and some links if you guys are up for it.

when designing a box, say winisd for simplicity - its ok for getting rough estimates on the port tuning and keeping params handy. but it dosnt give accurate graphs when it comes to most everything else.

so then comes all the little details about box building, how big, port area, bla bla bla. what about the 'alignemnt', or 'Q' of the box? say i bult a random box for a random speaker, how do you figure out what the Q is? and why is there always talk of ".707"? what are the advantages\drawbacks of different alignments?

and what other kinds of factors matter other than volume\tuning (not including bracing and stuff like box placement and the likes) - i mean, things that people usually WONT think about when designing a box, like impedance rise, power compression and stuff like that?

id just really like to read some information that matters to apply to what i currently know about designing loudspeaker boxes (sealed and ported for now, TL, FH, and BP boxes will come later :laugh: ).

if anyone has good info to contribute to those (including myself) who like building boxes and expierementing with different equipment, please do. any links to discussions that have been previously gone over are welcome.

i do know there is no endall beall of enclosure design, but what to aim for in many kinds of applications, and why.

i think thats all. i cant quite think of anything else :p:

thanks for reading.

JimJ
06-10-2005, 05:01 PM
what about the 'alignemnt', or 'Q' of the box?

Advanced? N00b. That isn't advanced, it's fundamental ;)

"System Q" is a term thrown around in a lot of fields in electronics (in RF, for example, it's the ratio of reactance to resistance in a series circuit like a loaded antenna)...but in acoustic terms, it's related to the enclosure volume, transient response, and frequency.

http://www.geocities.com/kreskovs/Box-Q.html

That page could explain it quicker than I can.

JimJ
06-10-2005, 05:03 PM
theroy


:rolleyes:

req
06-10-2005, 05:07 PM
thanks :)

i forgot to spellcheck :laugh:

and by the way. i have not looked into this stuff at all really. i never got around to it. so yea. dont flame too bad :)

squeak9798
06-10-2005, 05:14 PM
Jeez req....I just went over this less than a week ago :p:

http://forums.caraudio.com/vb/showthread.php?t=101057

EDIT: Well....seems like less than a week ago, after looking at the date it's been a few weeks now. But, regardless....search n00b :p:

JimJ
06-10-2005, 05:14 PM
dont flame too bad

I'll supress the overwhelming desire to ;) At least, mostly :)

http://www.diysubwoofers.org/sld/sealed2.htm

That's how Q is related to frequency response for a sealed system.

req
06-10-2005, 06:36 PM
thats all i wanted.

sorry for being a newb at some things, but i could venture to guess you guys have never fiberglassed ;)

lol, i just never looked into it is all :laugh:

req
06-10-2005, 06:46 PM
wow.

this file is awesome

http://www.diysubwoofers.org/sld/sealed.zip

squeak9798
06-10-2005, 06:47 PM
I didn't click the link....but if that's what I think it is (box program setup in Excel), then it, in all likelyhood, is more accurate than WinISD

dbornotdb
06-10-2005, 09:05 PM
Well those links are what I was thinking of when I was reading your post req.

And winISD has the Q rating on there. I, myself prefer to do a 1 - 1.5 Q. I find that is actually the sound most peiople are looking for. I say most, not all.

ngsm13
06-10-2005, 11:38 PM
thats all i wanted.

sorry for being a newb at some things, but i could venture to guess you guys have never fiberglassed ;)

lol, i just never looked into it is all :laugh:

noob....now what are you going to say to me? ;)

read up, as I'm sure you have done on most of the links in this thread. It's solid information, great links Frosty and Squeak...btw...

NG

Nikuk
06-14-2005, 09:59 AM
thats all i wanted.

sorry for being a newb at some things, but i could venture to guess you guys have never fiberglassed ;)

lol, i just never looked into it is all :laugh:

Anyone else see a problem here....?

Nikuk
06-14-2005, 10:00 AM
BTW *** cheebah, have You used CF and epox in a vaccum bag yet? Or acutally seen kevlar matt? **** fiberglass cloth & tape, go big or go home.

Don't ****ing think that You are gods gift to composites.. jerkoff.

-Nick

chubby
06-14-2005, 01:33 PM
lol

DBfan187
06-18-2005, 07:34 PM
BTW *** cheebah, have You used CF and epox in a vaccum bag yet? Or acutally seen kevlar matt? **** fiberglass cloth & tape, go big or go home.

Don't ****ing think that You are gods gift to composites.. jerkoff.

-Nick

:hilariou:

XOXOXOXOXOXOXO

theCybe
06-19-2005, 11:29 AM
on topic:

http://www.physicsforums.com/archive/t-9215_Why_is_the_frequency_cut-off_0.707_in_filters.html

.707 is the square root of half.

Rawr-DQ
06-19-2005, 01:12 PM
Anyone else see a problem here....?

Actually, after reading it over a few times, you get what he is trying to say. He could have said it better, but he's a spelling god after all :rolleyes:

Nikuk
06-19-2005, 05:57 PM
Actually, after reading it over a few times, you get what he is trying to say. He could have said it better, but he's a spelling god after all :rolleyes:


I think that You've missed the implied point... Sorry. :)