ok i was told that at the port frequency the sub will not move at all??? i went through all the frequencies and it moved the whole time??? anyone know how exactly to tell?

thanks in advance

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1988 toyota soarer

Clarion Planet Audio Lanzar Beyond Audio

quote:

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Originally posted by bassaholic55:
ok i was told that at the port frequency the sub will not move at all

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It will still move but a lot less then at other frequencies... I can tell pretty easily by looking at my subs where its tuned to or where abouts just from playing different tones back and forth. I guess if u can't tell thats its moving less turn the volume up so the cones move more at the frequencies either side of tuning.

I read something about measuring the impedence and where its lowest is where the ported box is tuned to I think?

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Car: '90 Nissan Pintara (sedan)
Headunit: JVC KD-SX750
Fronts: TotalRecoil Carsplit.6
Frontamp: Alpine MRV-T301
Sub: 2x Alpine SWR-1240D
Subamp: Lanzar VPro 2000D
SPL: 146.4db
-1st 161 to 280sqin Bathurst Livewire 12/10/02-
"If its not quick, may aswell make it slower"

just try turning the volume down a bit, keep turning it down until one or two frquencies don't move at all.

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Car : '00 Mazda Protege

HU : ///Alpine 7852R
Front: ///Alpine DDDrive R17A Splits
Subs : ///Alpine ZR 10" x 2
Amp : ///Apline MRV-1507

PB : 142.7dB

the gains are right down so the sub doesn't move much until it is loud anyway.

about the impedance thing, do you just set multimeter on ohms and test it from the speaker terminals on amp?and where ever is lowest should be the tuning frequency.

thanks

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1988 toyota soarer

Clarion Planet Audio Lanzar Beyond Audio

"in theory" at the tuning frequency, the sub won't have to move at all, this is to my understanding... if all conditions are perfect anyways... It'll never happen though... give us ur box specs and someone will let you know what its tuned it...

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i know what it is supposed to be tuned to but was trying to check it becuase my measurements for to millimetres so it would not be perfect. the box was supposed to be 2.5 cube before displacement. the sub displaces .15(DBDON) and the port displaces .07. the port is 4inch and 21 cm long. but i don't know if my box is exactly 2.5 before or not, that is why i wanted to test it manually.

you know what i'm sayin!!!

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1988 toyota soarer

Clarion Planet Audio Lanzar Beyond Audio

Of coarse it moves at tuning frequency, otherwise it wouldn't produce any sound

Try to calculate port frequency with some free program, try WinISD
www.linearteam.dk

quote:

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Originally posted by Bodyjar:
"in theory" at the tuning frequency, the sub won't have to move at all, this is to my understanding...

---

someone may have told you a bit of BS

if the sub doesn't move, then no air will want to come out of the port (eg pause your music heheh)

at the ports resonant frequency, the air moves out of the port very easily, so the cone doesn't have to move far to move a decent amount of air out of the port

now, the reason the sub doesn't move much, is because the air moves out from the port much more easily than the cone moves

b55 - you can use a quality multimeter, but not by measuring the impedance directly

you have to measure the AC voltage in parallel, and the AC current in series and then calculate the impedance

the impedance = voltage divided by current

alternatively, you can wire up a 1000 ohm resistor in series and just measure the voltage

but to be honest, if the tuning is a little out, it won't make a significant difference anyway (Sound quality wise..)

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- A proud member of Team Gates - A proud supporter of the CAA SPL project

[Edited 1 time by Bassaholic on 16 October 2002 at 17:21]

ok thanks for that. so i will test the voltage and current from the speaker terminals at different frequencies?


thanks for explaining

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1988 toyota soarer

Clarion Planet Audio Lanzar Beyond Audio

How much are the clamp AC ampmeters worth anyways? I was looking at one for $169 today... thinking about getting one.

------------------
Car: '90 Nissan Pintara (sedan)
Headunit: JVC KD-SX750
Fronts: TotalRecoil Carsplit.6
Frontamp: Alpine MRV-T301
Sub: 2x Alpine SWR-1240D
Subamp: Lanzar VPro 2000D
SPL: 146.4db
-1st 161 to 280sqin Bathurst Livewire 12/10/02-
"If its not quick, may aswell make it slower"