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View Full Version : This sound ok for ports/volume/velocity?



Savant
03-19-2003, 11:31 PM
K.. using win isd.. on the specs for a Pioneer Premier 1241dvc..


3 cubes
26.9 Hz freq
1 port at 6" x 30.56"
Max port velocity of 15.5 m/s at 25 Hz (but I have a sub-sonic filter on set at 20 and the design is set for 30 Hz to be at 0dB, 25 Hz is at -3.5 dB)..

It's a 500 rms sub, but I have the wattage set to 350 to stay in the mechanical excursion (but since < 40 Hz is now at 0dB gain versus being at ~-5 and the SPL is only 1 dB under where it would be at 500 watts.....)..

3 cubes is a LOT bigger than I wanted, but that's the only way I can keep the port lengths reasonable (not sure I can find a 6" flexable tube either *sigh*) and still be near 30 Hz as the 'base' of the top of the response curve...

Does that look ok? Anyone know where I can get 6" flexable tubing? Is PVC flexable under heat (I thought it was, but now I don't recall .. been years since I've messed with PVC)...

TIA

Gauntlet
03-20-2003, 01:29 AM
I used WinISD and got the same numbers...

As far as the PVC - there is flexible and non-flexible PVC. There is 6" Flexible PVC, but all I found was this http://www.absoluteponds.com/pump-tubing.htm , and the only offer it in 50 foot rolls. Maybe you can call them and see if they can sell just what you need - if not, call up a local plumber and see if you can get some. I also found this website - http://www.minadek.it/inglese/tubi.htm - looks pretty promising, you could contact them and see what they can do.

And if you do heat PVC, be very careful....I think that at 300 degrees farenheit (not sure of the number) it releases toxic fumes and hydrochloric acid gas. Not a good thing. ;)

Savant
03-20-2003, 01:48 AM
Originally posted by Gauntlet
I used WinISD and got the same numbers...

As far as the PVC - there is flexible and non-flexible PVC. There is 6" Flexible PVC, but all I found was this http://www.absoluteponds.com/pump-tubing.htm , and the only offer it in 50 foot rolls. Maybe you can call them and see if they can sell just what you need - if not, call up a local plumber and see if you can get some. I also found this website - http://www.minadek.it/inglese/tubi.htm - looks pretty promising, you could contact them and see what they can do.

And if you do heat PVC, be very careful....I think that at 300 degrees farenheit (not sure of the number) it releases toxic fumes and hydrochloric acid gas. Not a good thing. ;)

Yeah, that flex stuff is $800 for 50 ft.. that aint happenin' :D

If I heat PVC I'll have to make sure I have a good fan blowing.. and maybe a mask of some kind .. or see if I can get it bent for me..

Oh, just noticed.. I had (on the 'box' tab), the advanced.. Qa set to 10 (stuffing in the box, that Pollyfill?) and it was a flatter curve.. If I knew the resonance freq of my truck I'd know if I want to stuff or not..

EDIT: OH.. Thanks for the reply :)

Gauntlet
03-20-2003, 01:52 AM
The stuffing in the box would be polyfill.....and you really shouldn't use it in ported boxes. It's made as a last ditch effort for sealed boxes that need to be a little bigger, and when building a new box isn't an option. Polyfill would throw off the volume of a ported box, and thus have an adverse effect on your output.

I would try to get the PVC bent professionally before taking any risks yourself. I would just call a plumber or a contractor who specializes in those man-made ponds rich people get in their backyards. Tell them what you need, and if they can't do it they should be able to direct you to someone who can.

Good luck, btw.