posted
That will get some respoce I know it. Well I finished with the girlfriends’ car and I am not sold on ports. A quick over view…. I have 8 Vega tens in a .8cu.ft. Sealed enclosure and two 500aII to power them. She has 4 Vega tens in a 1.5cu.ft. Ported box with ports 3”x10.27” and a 500aII to power it. So same power per sub woofer. The big difference might be I have some AudioControl stuff and she has none. I have the EQ-X, Epicenter, and ESP-2. Now the disc I compare the two systems with is the DB-Jams Vol.2 I know a lot of you have this so you know the first track has a sweep at the beginning. At the end of this sweep my subs (sealed) are hitting hard and loud. Hers are snap crackle and popping. I never knew if I have clipped a sud before but this might be it. Also when the voice that comes on after the sweep says Welcome to the………. Her subs are going nuts. Witch what looks like the full exsturtion. Or X-max. Not only in this sweep but other low tones on the disk the subs do the Kellogg’s Rice crispy thing too. So Dukk you will have to do some of you best work to try and sell me that ported is the way to go. One possible thing that I might have done wrong and I can and plan to fix is the port location. Using them 45 PVC pipe elbows to get the mouth of the port away from the wall. At the same time this will only bring me noise not this problem right? I do have them at an angle to each other to from the side looks like this….and from the front like that.… X=port O=sub (the subs are offset. about ¼ of the driver overlap as seen on bottom) _______ [ ]x [_____/o [ \o [______]x
posted
Anytime you play a ported box at a freq below the tuning frequency there isn't anything to control the speakers movement which means it will bottom out and do nasty things real quick. In a high power ported box system you should run a subsonic filter to remove some of the damaging frequencies. Ported boxes have benefits but like anything there are trade-off.
posted
I agree. If the end of that sweep drops below tuning (which it most likely does) then it can be real hard on the woofers. Vocals an be nasty on them too if there is a lot of resonance in the voice.
I thought I read a post where you said that the 4 blew your 8 away????
------------------
And that's the bottom line, cuz: LORD DUKK SAYS SO!
The Big Show The Dukk says: Know your bass: PORT your damn box!! Have HoleSaw, Will Travel!
posted
t jc2 said about playing below tunning freq. is right.
Also don't forget that your system is going to be about 3 Db louder than her setup. You are not expecting them to be the same are you ? You have twice the power...
------------------ ******************* Founder: Street Sounds Car Audio Club ******************* If It Don't Read 150+ it Ain't Loud......
Posts: 289 | From: Howell, MI | Registered: May 1999
|
"when overloaded, the vega driver sounded like big red knocking down charlies with a big machine gun"
not exact words, but to that effect (10th anniversary issue, titled Perfect Tens)
Did you build the box correctly? Did you apply a subsonic crossover? You should, you know it will lower the excursion below the tuning freq and assure yourself that you don't kill the subs...
Also.. Does the "welcome to" on db jams have bass underneath the voice-over? If not, you might be lowpassing your subs at the wrong freq, or not at all. (I've done this a couple times by putting an Xcard in wrong.)
And it could just be somebody left a bowl of rice krispies next to the port and they got sucked it.
ShadowStar
------------------
Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
|
posted
Dukk it was in one of my past threads there was talk that her 4 ported Vegas will blow out my 8 sealed. It has yet to be put to the mic. at the window yet. That will be this July 18th. I kind-da though it might have something to do with the tuning point and playing below it. Sub sonic filter. Remember I'm new at ported I have always and I mean always used sealed boxes. I lied. I once built for a good friend of mine a band pass box. Do I build a subsonic filter? How? With that in mind Audiocontol has this built in to some of their stuff right? I don’t remember. If so that dose explain why my subs have no movement at the end of the sweep. I watched closely and see nothing. I set up the x-over on the amps the same way on both setups. I do believe 80hz and down. Punch ba$$ at 0 and gains around 1/2. I might have time and long enough RCA's to plug in my AudioControl stuff to hers and see what that dose. Then I just might have to run out and get her a EQ-X too.
Some pieces do come with a subsonic filter. You can cross them over with your audiocontrol at a low pass, and then use cards in your X card to attain a highpass.. Make it's X-point be @ the tuning frequency of the box. You will find that this should eliminate problems.
ShadowStar
------------------
Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
|
posted
Harrison Labs sell the some RCA filters called F-Mods. They sell for about $30 and don't bother the amps output. I have used them and they do the job quite well.
------------------ Carlos Alexis DDS of Puerto Rico
Posts: 246 | From: Bayamon PR USA | Registered: May 1999
|
posted
I have the same problem with my 2 10's. I made a set of test tones and put it in. Anything below 40hz just makes the subs flop around at high volumes. Anyway there is a link to harris-labs on the homepage of this page. "upper right corner of screen "Home"
posted
I found the Harris Labs page. Now the question is what F Mod to use 20Hz or teh 30Hz high pass. My box is tuned to about 35Hz. I'm leaning to 30Hz high pass.
posted
I found the Harris Labs page. Now the question is what F Mod to use 20Hz or teh 30Hz high pass. My box is tuned to about 35Hz. I'm leaning to 30Hz high pass.
posted
A subsonic is a must. I always incorporate one and always forget to remind others to do so as well. The FMODs work ok. 30Hz may be a little high but it's only 12 db. Your AC stuff is 18db at 27Hz. Drop the EQX into her car just to test....
------------------
And that's the bottom line, cuz: LORD DUKK SAYS SO!
The Big Show The Dukk says: Know your bass: PORT your damn box!! Have HoleSaw, Will Travel!
posted
Just a FYI, www.crutchfield.com sells the Fmods. They dont list the subsonic on there site but I called and they have them. For $19.95 a pair. I use a set of the 20hz subsonic on my 10's just in case. Never had a problem yet.
Printer-friendly view of this topic