Bandpass, Was fun when worked well, but now....

Topic: Bandpass, Was fun when worked well, but now.... (Read 2517 times) previous topic - next topic

Bandpass, Was fun when worked well, but now....

January 11, 2007, 03:33:34 PM

Hi, some of you guys saw my other thread some months ago about building a system. I was (well, im still glad) for the performance of the system.

I have a Bandpass box, of two 10`s rockford fosgate punch. It worked well, bla bla bla, until 3 days ago. I was driving with the music loud enough when a mechanical noise started to hear. I pulled and checked the box, all was well and tight, but when the woofershiznit the loudest notes, the speakers made an awful mechanical noise. I disconnected one to see which woofer was failing, but when they work alone both woofers worked ok, at the same song with the same volume. I reconnected both woofers and the mechanical noise happened again.

Well, my bandpass box has 4 air ports. I put a can of soda, restricting the air outcoming of the one of the chambers, and the noise reduced significantly. I put another can of soda in another port and the noise gone.....but many performance gone, too.

I checked the behavior of the woofers when i was doing this. Covering two of the four ports, one for each chamber, reduced the excursion of the woofer, and the performance. Im well used to hear this sound system so i knew this instantly. Now, with the 4 ports uncovered, the woofers felt powerful as ever, and the excursion of the woofer was significantly much more (and producing that bad noise in the loudest notes).

i dont know, even, i doubt, im having over excursion with my woofers. Those are rated at 150 rms, 300 max, and im powering with a sony amp rated at 80 rms max per woofer. I am thinking if my box is faulty of design/measurements, ill go again with the sealed box.

Any help would be appreciated....thanks...

EDIT: this is the box what im talking about...

Bandpass, Was fun when worked well, but now....

Reply #1 – January 15, 2007, 10:46:40 PM

Sucks to here about the problem. Have you checked the front of the woofers to see if the dust cap came loose? That would make and very nasty noise when pushed hard. Also denpending on hown have the speakers wired that could have someting to do withthem not traveling as far when one is disconected. Also it could be that with the lower power amp that you pushed them hard a few times to many without the corect power that could cause the voice coil to get someburned spots then casueing the wofers to stick or sorta short out.

Bandpass, Was fun when worked well, but now....

Reply #2 – January 16, 2007, 05:02:09 PM

You could have easily pushed your sub beyond excursion while underpowering it, considering you switched to a bandpass box from a sealed. Where did you get this bandpass box from? Did you build/design it, or did somebody else?

Bandpass, Was fun when worked well, but now....

Reply #3 – January 18, 2007, 02:19:00 PM

shhhhhhssss, it was my fault. I removed the woofers from the box to inspect them and one had the cone broken. I guess i can fix it with loctite.

Thanks for all the replys. My brother designed the bandpass box,i guess, according to the manual of the woofers. Im going to try with another set of 10`s.

How i can set the gain of my sub amps ? its very hard to hear clipping in a subwoofer !

Bandpass, Was fun when worked well, but now....

Reply #4 – January 18, 2007, 02:48:33 PM

Well you run it in regular mode with it running some mids/tweets and set. Then turn the crossoever back on and hook the woofers back up. There you go. Also you could use an oscillascope to do it but they cost $$$$. Also it isn't to hard to hear the clipping in a woffer that is in a sealed and ported box.

Bandpass, Was fun when worked well, but now....

Reply #5 – February 10, 2007, 02:24:31 AM

oscope... $109.00 plus shipping here: http://www.fullnet.com/~tomg/tek.htm#0

Not too hatefull. If you buy, tell them I sent you.

note: I do not work, represent, or am I affilated with fullnet.com

Bandpass, Was fun when worked well, but now....

Reply #6 – February 10, 2007, 02:34:00 AM

A volt ohm millammeter, capacitor tester, and oscilloscope are right up there with a feeler guage, timing light, and hand tools when working on anything technical today. Especially auto...:)

Bandpass, Was fun when worked well, but now....

Reply #7 – February 10, 2007, 06:59:38 PM

I just use a multimeter set to AC 250v. With volume turned up ~3/4 on your deck, all sound processing off (EQ, loudness, etc) and speakers disconnected, you probe the + and - to get the desired voltage (depends on amp). My amp is supposed to be putting out 12.3v into a single channel or 24.6 bridged. After they're all set, you turn DOWN any channels to adjust the sound, not turn any up. Gives some overlap in case you have some quiet recordings, but not really anything that can harm the amp.

I haven't touched the gain from the original 12.3v settings and everything in my car sounds about perfect volume wise. I could use a tad more from my door speakers, but they're running in parallel with my 6x9's. Subs blend in perfectly, but a little powerful on any bass heavy songs.

Bandpass, Was fun when worked well, but now....

Reply #8 – February 11, 2007, 03:47:49 PM

I had that exact same setup, I had P1's, Plug up a port on each side, it greatly affects the sound. I just used wadded up dish towels, and they sounded alot better. I plugged the opposite ports. Left side top, right side bottom ports.