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ben62670
04-09-2007, 11:19 PM
I will be using an Adcom GFA-555 for my DIY sub with a 15" Dayton Mark III, and 3 12" Polk PR's. A GFA-555 put out 850 watts clean bridged. While this may be a bit much, I also have a GFA-585 to drive 2 subs at 400 watts. We'll see what happens in the real world. First passive project besides SDA-SRS's.
Anyone do anything like this?

Any input from users of both type would be appreciated.
Thanks Ben
ben62670
04-10-2007, 11:52 AM
bump
jakelm
04-10-2007, 11:55 AM
How big is the encloser? Too small or too big of an encloser I feel will muddy the bass responce and when using 3 12" PR, the resistance has to be perfect or everything would just be "flopping" around.
heiney9
04-10-2007, 12:02 PM
Quite an ambitious project. Your enclosure has to be huge :eek: to take advantage of that much surface area. Might be overkill to have that many PR's and a 15" woofer.

H9
ben62670
04-10-2007, 12:08 PM
The woofer is 15 inches, and has 2 inches of stroke. It calls for a 6 cubic foot cabinet which is roughly 17*17*44. The passive only have about an inch of travel. I know I would have to add a little weight to tune them to 19hz to match the woofer. I was thinking of putting the 3 Pr's in front to match the phase of my SDA-SRS's PR's
PolkThug
04-10-2007, 12:11 PM
Sounds like fun! Frequency sweeps will be your friend when trying to dial that thing in.
ben62670
04-10-2007, 12:11 PM
My other Idea was to 16" sonotube at 50" with a 4" port on top which would also give me a tune of 19hz.
ben62670
04-10-2007, 12:12 PM
Sounds like fun! Frequency sweeps will be your friend when trying to dial that thing in.

Yep a lot of taking the pr's out weighting them and putting them back in.

Here is the woofer
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-420
jakelm
04-10-2007, 12:15 PM
My other Idea was to 16" sonotube at 50" with a 4" port on top which would also give me a tune of 19hz.

I think this idea will give you better responce than the Pr's

The problem I have is that every Pr encloser I have seen and delt with includes a larger Pr than the driver. I have never seen it done the other way around.
tryrrthg
04-10-2007, 12:21 PM
My other Idea was to 16" sonotube at 50" with a 4" port on top which would also give me a tune of 19hz.

You will need 6-8" of port to be able to handle the amount of air that your 15" driver is going to move.
ben62670
04-10-2007, 12:21 PM
I think this idea will give you better responce than the Pr's

The problem I have is that every Pr encloser I have seen and delt with includes a larger Pr than the driver. I have never seen it done the other way around.

Yeah I have 3 12"s already, and I used 2 10's with my SDA-SRS project, and it worked good. The thing I like about the smaller pr's is that they respond quicker. It would also look pretty cool with 3 twelves facing forward too. But I am more about performance than looks.
ben62670
04-10-2007, 12:24 PM
You will need 6-8" of port to be able to handle the amount of air that your 15" driver is going to move.

I ran WINisd, and a couple other programs, and was recommended by PE to use the 4" flared port. That is another reason I was thinking about PR's. A 4" port with woofer that "15" MKIII will sweep over 3 liters of air! " means an awful lot of port velocity.
engtaz
04-10-2007, 12:43 PM
Where did you steal the 585? LOL

engtaz
ben62670
04-10-2007, 12:57 PM
Where did you steal the 585? LOL

engtaz

Ebay
engtaz
04-10-2007, 01:00 PM
You going to buy me one???? LOL:D :D :D :p

engtaz
dudeinaroom
04-10-2007, 10:38 PM
I want one too. If you get bored with the sub project just send it to me(jump on yahoo I'll give you my address) j/k. 3 12" PR's is about right for a 15". You might be able to get away with tuning it lower, and still end up with good results. Man I wish I lived down there, I'd love to be a part of that project, and you'd have an extra hand for fixing the computers at work:)
ben62670
04-11-2007, 12:05 AM
I want one too. If you get bored with the sub project just send it to me(jump on yahoo I'll give you my address) j/k. 3 12" PR's is about right for a 15". You might be able to get away with tuning it lower, and still end up with good results. Man I wish I lived down there, I'd love to be a part of that project, and you'd have an extra hand for fixing the computers at work:)

Come on down!
dudeinaroom
04-11-2007, 12:44 AM
Not working, so there is no way I have the fundage. I've been looking since the end of January, and there is nothing. I don't have the money to move anywhere so I am kinda stuck. If I had the money I would be there in a second, I'm sick of this cold weather. oh well life goes on.