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BOBALOO
04-06-2004, 08:10 PM
Does having a ported enclosure necessitate having a subsonic filter? i had a problem blowing subs (Cerwin Vega Accurate Image 12") in my ported box last summer and found out that my sub might have been trying to play sounds lower than the port frequency.
I had a PPI A600 art series driving one sub, and a PPI crossover dividing the signals.
The new setup is dual Kicker Comp VR 12"s in a large ported enclosure. The PPI crossover remains but I added a Hifonics BXD1500 with subsonic filter and remote bass adjustment.
Question;
Does the PPI have a subsonic filter?
Is a filter necessary or just a good idea?
I know that I am running more power than I should but that is the way of life:D

rivercrazy
04-06-2004, 08:24 PM
Not sure if that PPI has a subsonic filter. Is it a mono class D amp?
You really do need SSF to eliminate those frequencies below the tuning frequency of the ported box.

BOBALOO
04-06-2004, 09:38 PM
No the PPI amp is a stereo amp, and I am 99%sure the PPI crossover has no SSF.
I hope the new setup lasts longer than the last. I only got 5 1/2 hours of loud listening time out of it last weekend with all three amps hot as hell.
That is with 2 Trojan t-105's 6-v, and I am adding 2 more. :D
the less powerful amp setup with 3 Interstate 27's lasted only 2 hrs
Plus I'm adding an onboard charger.:D

BOBALOO
04-06-2004, 09:39 PM
I think I have a problem

ROZ
04-07-2004, 12:19 AM
What's your problem?
What did they tune the port to?

BOBALOO
04-07-2004, 04:48 AM
Too much stereo junk = Problem:D
Do they have a stereos Anonymous ? (sp)
Roz, what is your take on having a SSF? In how I understand they work it is a neccesity for ported but does it need/help in sealed boxes?
Chime in INTERNET STEREO PROFESSIONALS:D

Havasu Hangin'
04-07-2004, 05:38 AM
Originally posted by BOBALOO
Roz, what is your take on having a SSF? In how I understand they work it is a neccesity for ported but does it need/help in sealed boxes?
I'm not Roz...but I'll take a shot.
A subsonic filter is not needed in a sealed box, because the sealed airspace creates a stiffer suspension. As the sub tries to reproduce the low frequencies (that humans can't hear), it attempts to travel beyond it's excursion design limits...
...but the sealed air suspension holds it back.
In a ported box, there is nothing to hold it back because the air moves freely through the port (and you can't hear the overexcursion until it's too late).

ROZ
04-07-2004, 09:50 AM
Originally posted by Havasu Hangin'
I'm not Roz...but I'll take a shot.
A subsonic filter is not needed in a sealed box, because the sealed airspace creates a stiffer suspension. As the sub tries to reproduce the low frequencies (that humans can't hear), it attempts to travel beyond it's excursion design limits...
...but the sealed air suspension holds it back.
In a ported box, there is nothing to hold it back because the air moves freely through the port (and you can't hear the overexcursion until it's too late).
Adding to HH's post...
The parameters of the speaker will determine if a speaker is suited for large, small, sealed, ported, infinite baffle, or bandpass enclosures.
The calculations for your ported enclosure are not only to find the measurements for the correct tuning of the port for a specific frequence, but are to calculate enough airspace inside the enclosure to help provide some suspension for the driver. This is why you need to know the size of your box and port in order to recommend a subwoofer. Unless you decide to replace the box....

ROZ
04-07-2004, 09:54 AM
Originally posted by rivercrazy
You really do need SSF to eliminate those frequencies below the tuning frequency of the ported box. Especially at high volume...

BOBALOO
04-07-2004, 03:16 PM
Thanks guys, for the very good explanation. I used the design volumes from kicker for the new sub box and have a SSF on the hifonics.
How far under the tuning freq should I cut off the low frequencies.
Or how should I go about setting it?

BOBALOO
04-07-2004, 03:23 PM
Sorry for the poor pic, but this is what I made.
The box is behind the seat back and the ports go under the seat.
I didn't make the carpet go back far enough on the port but it is fixed now.
And if I put grilles on the subs the seat would stick out even more
http://www.***boat.com/image_center/data/520/129sub_box-med.jpg

ROZ
04-07-2004, 10:53 PM
Originally posted by RiverDave
How does that work? I would think that at the "tuned" frequency of the port the speaker would be more likely to over extend itself, then on an off frequency? At the tuned frequency there is reverberation at that frequency which is literally pushing the speaker in n out, further then it would've if it was just sitting in free air.. ???
RD Read my addition to his post .... I also want to note the the driver in this effecient application moves very little when compared to a sealed enclosure at the same db output at a specific frequency...

SCUBA STEVE
04-10-2004, 07:04 AM
Originally posted by BOBALOO
No the PPI amp is a stereo amp, and I am 99%sure the PPI crossover has no SSF.
I hope the new setup lasts longer than the last. I only got 5 1/2 hours of loud listening time out of it last weekend with all three amps hot as hell.
That is with 2 Trojan t-105's 6-v, and I am adding 2 more. :D
the less powerful amp setup with 3 Interstate 27's lasted only 2 hrs
Plus I'm adding an onboard charger.:D
My interstates havent let me down yet. (only 2) But I dont have as much wattage as you do.
I will be adding more batteries this summer though.
I thought you were against the on board charger? :confused:
I'll probably see you before I read through this again, good luck. :cool:

Cheap Thrills
05-05-2004, 11:25 AM
just my thoughts on the SSF . I wouldnt run my system without one. reason being subsonic freqs are just that subsonic .
why send subsonic frequencies to your amp ? it creats a higher load on the amp and speakers . properly set up a system with an active crossover and a subsonic filter will play more effeciently than a system without .
Passive crossovers are another NO in my book while good for the speakers, why subject your amp to reproduce freqs. that are going to be literally choked from the signal source ?
it's like this if you send a full range signal to the amp thats just driving the subs and youre using a passive crossover the amp is still having to work to reproduce freqs that the speakers arent going to play resulting in wasted power (Heat)
use a good active crossover it'll make your amps and the speakers happy .
Just my .02
C.T. :wink:

ROZ
05-05-2004, 01:57 PM
Originally posted by Cheap Thrills
just my thoughts on the SSF . I wouldnt run my system without one. reason being subsonic freqs are just that subsonic .
why send subsonic frequencies to your amp ? it creats a higher load on the amp and speakers . properly set up a system with an active crossover and a subsonic filter will play more effeciently than a system without .
Passive crossovers are another NO in my book while good for the speakers, why subject your amp to reproduce freqs. that are going to be literally choked from the signal source ?
it's like this if you send a full range signal to the amp thats just driving the subs and youre using a passive crossover the amp is still having to work to reproduce freqs that the speakers arent going to play resulting in wasted power (Heat)
use a good active crossover it'll make your amps and the speakers happy .
Just my .02
C.T. :wink:
Audiocontrol is your friend ;)

Cheap Thrills
05-05-2004, 02:13 PM
Originally posted by ROZ
Audiocontrol is your friend ;)
:wink: Epicenter :D
I use to use SSF on my home systems back in the vinyl days to cut turntable rumble .
I remember back in the mid 80s when Audio controll was just getting started with the Epicenter it was awesome then as it still is today properly set up that is . a little too much of the darn thing sounds "mechanical " and un natural . but when set up right woooohooosie :D
C.T. :wink:

ROZ
05-05-2004, 02:23 PM
Originally posted by Cheap Thrills
:wink: Epicenter :D
C.T. :wink:
Ahh, the Epicenter... I had one of those back in the 80's. Especially on a 15 in a 4ft^3 ported enclosure :D Cool piece. :)
I just ordered an EQS to integrate my factory headunit to my worked over 5channel JL amp :D Can't wait to get it...

Cheap Thrills
05-05-2004, 02:46 PM
It's been forever and a day since I updated myself on AudioControl's products, they have alot more to offer than I could have imagined . wow how time has changed things .
I purchased my first Epicenter back in 1990 and it's still going today .
the EQS looks like a nice piece too .
for those interested in what we're referring to .
http://www.audiocontrol.com/MobileAudio/Products/index.html
C.T. :wink: