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Opinions please (fosgate woofer with 15'' PR design)

3K views 24 replies 4 participants last post by  Endesereth 
#1 ·
Attached is the Winisd file. What do you guys think about this sort of setup? Intended use for house parties and small DJ gigs.
 

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#7 ·
Oh yeah I already have the subs. The active driver is the fosgate rfp3812 and the other is a 15 inch nexxtech driverfrom RadioShack. Right now what i have as a potential amplifier is the plate amp from an old logitech z2300, which if it's enough to make this system perform decently well, it would work because this needs to be a 2.1 channel setup. I only have eough money to burn on the materials for the box for now, i won't be able to spend anything until January, and even if I did, i didn't seem to find any plate amps or power amps that do the 2.1 channel configuration.
 
#9 ·
So far I am looking at the graphs and if you do a ported design you'll get more output compared to the Passive Radiator, I am assuming though you are building another box right?
Also I was on logitechs site looking at the plate amp, It doesn't tell the high pass cutoff on the subwoofer so sorry.
On the Graphs theirs is always gonna be a huge...curve at the end, and I dont think that you can get rid of it.
 

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#10 ·
that's cool, i can always do a ported design with the fosgate, though your graphs came out much nicer than mine did. I was really just looking for an excuse to use both speakers in a design seeing as i spent only about 20 dollars for the nexxtech driver and i didn't want it to continue collecting dust in its wrapping. Do you think that the 120 watt amplifier is good enough for the fosgate? I really don't' have the cash to redesign this system in order to allow a more powerful sub plate amp, but if i'm compromising too much by using this amp then i'll have to start saving up.
 
#11 ·
The RFP3812 is a 8 ohm sub. The Z 2300 is listed as 200 watts. Assuming the Z 2300 is an 8 ohm amp, assuming it has a 30 hz Hi-Pass filter, and assuming the PR can take 200 grams of added mass,(lots of assumptions here!) here is the following modeling.

Pink is with the PR with 200 grams of added mass. Shown with 40 watts input power as that is the amount of power the PR can take before it starts to bottom out.

Yellow is with one 4" port 10.5" long. Input power is 200 watts and the sub is nowhere near its limits.

You really should try and find out the specs of the Z 2300 amp from Logitech. Also keep in mind it was never designed for this application and be prepared for it to fail.

I'm not sure what applications the Nexxtech PR would do well in but this isn't one of them.

Text Oscilloscope Technology Line Font
 
#12 ·
The z2300 is an 8ohm amp and it does have a 30hz hi-pass filter because it doesnt' recreate any frequency under 30hz. I did enough full-spectrum tests on it to know this one. The logitech amp also pushes 120w into the woofer channel, the rest go to the left and right channels.

Seeing as the Fosgate power rating rests at 200w RMS at 8ohm, I don't see how the 120w amp would fail if it powers a speaker that's at a higher power rating. Isn't this usually how you prevent blowing your driver? I know that if you push an amplifier too hard it could clip and distort, causing damage on both sides, but I've never had that issue with the Logitech amp. I'm pretty sure they have it set in the volume knob to be impossible to push it hard enough to clip or something, because I never succeeded in doing it.

I have no problem forgetting about the nexxtech driver. Maybe i'll build a box for it just to sell it to someone.
 
#14 ·
yes i am, i have a pair of floorstanding 2-ways that sound way better than the one way 3.5 inchers that come with the z2300. The idea is to have a powerful yet decently portable system to take with me to small DJ gigs if they don't have a system already, like house parties and the like.
 
#16 ·
Well i'm new at the whole DJ-ing thing but a recent party I was at the DJs didn't show so I ended up doing it for them. Everyone at the party loved my mix and it wasa learning experience, I found out about a talent I didn't know I had. Mainly Electronica and Hip-Hop is what I want to start out mixing but I plan on mixing all genres once I get really good at it. I'm also a musician so this would help me to hopefully get a foot in the door for some gigs.
 
#19 ·
Fosgates are a good brand, Exodus audio(also here on the shack) is very good too, I am going to order their new midwoofer soon. One rap song I have Hero by Nas goes I think below 35 hz tho and it sounds awesome on my system.
I do suggest if your going to go pro on dj I say get louder speakers, or if your a bass head then get a better subwoofer lol, what kind of mixers are you going to use
 
#20 ·
well i have my eye on the Hercules E2 DJ controller which has pretty much everything i need and then some as far as an all-in-one piece of equipment, so i won't be needing any dedicated mixers just yet, but if i do, i have a discontinued 8-channel behringer eurorack i can take with me to events.

When i start making some cash off of this i'll definately go grab an exodus and a good amp for it, but this is kind of a system to start me out cause i'm a very broke student at the moment :)

As long as you fine professionals think that my setup will do a decent enough job then i'm happy. I just figured it wouldn't hurt to get a professional opinion.
 
#22 ·
What do you think Mike meant when he told me to expect the Logitech amplifier to fail? I think that's the only thing i heard against my idea to use the fosgate with the 2.1 plate amp from Logitech. From what I know, as long as the amp pushes less than the woofer can handle in RMS watts, you should be safe...
 
#23 ·
as long as the amp pushes less than the woofer can handle in RMS watts, you should be safe...
As long as you keep the amp turned down a bit and not at its maximum output all the time you should be OK. I've has 3 Logitech computer subs over the years and all 3 failed. Go easy on the amp and hopefully you won't have a problem. From personal experience I have no faith in Logitech audio products.
 
#24 ·
ah alright i will definately do so. at 50% the amp seems to kick pretty hard anyway so I doubt i need to turn it up too much. As long as this baby will make me some cash so I can upgrade to something worthy of the shack then i'm happy. Thanks for the advice everyone.
 
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