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Discussion Starter · #1 ·
So I was wondering if I could modify my existing PA-120 by changing the woofer and amp with better components from say parts-express and get a much better sub.


The PA has a 2.5 cubic feet enclosure with a 3.5" rear port and a 9" tube.


If yes, would I have to modify anything else? Also, if yes, what well known sub would this set-up equal in terms of output and extension?


Thanks!
 

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An answer to the idea posed in section 1...


Yes, you can.


To answer your first question...

Probably not.


To answer the second question...

Depends what you buy


Do you buy a paper woofer?

Do you buy a plastic woofer?

Do you buy a plasticized paper woofer?

Do you buy an aluminum woofer?

Do you buy an aluminum covered plastic woofer?

Do you buy an aluminum covered plasticized paper woofer?

Do you buy an aluminum covered paper woofer?

Do you buy a fiberglass woofer?

Do you buy an aluminum covered fiberglass woofer?


As far as amp...

Do you buy a 125 watt 150 watt peak amp?

Do you buy a 125 watt 200 peak amp?

Do you buy a 150 watt 250 peak amp?

Do you buy a 200 watt 400 peak amp?

Do you buy a 600 watt 1000 peak amp?

Do you buy a 10,000 watt 100,000,000,000,000,000,000 peak amp?
 

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The biggest challenge is going to be finding a sub that matches the existing box volume and port tuning frequency. You'll need the port length as well as the above info.


If you do it, I'd also consider adding bracing, or at least see if it needs it, while youre at it.
 

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I have a Polk PSW10; a very cheap sub; and by just replacing the driver I get a lot better sound!!....


I have also a BIC PL200 and I am going to do exactly what you have in mind for the PL200. The PL200 enclosure is pretty nice; and have a 250W Bash Amp. It sounds pretty good for movies; and just Ok for Music. But I will do this upgrade to replace my sub at bedroom (the Polk PSW10).


As for my living room I am doing a DIY Sub. Elemental Designs are going to make the Sealed Enclosure with Skeletal Bracing and Flush Mount. Amplifier will be the new Inuke 3000 DSP or EP4000 and driver will be a custom PSI Platform 1 - 15" driver: 1000W RMS - 2000W Peak, D2 Cooper Coils.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by tuxedocivic /forum/post/20822200


The biggest challenge is going to be finding a sub that matches the existing box volume and port tuning frequency. You'll need the port length as well as the above info.


If you do it, I'd also consider adding bracing, or at least see if it needs it, while youre at it.

Matches existing volume?


Port tuning frequency?


I have no idea what you mean, all this is new to me. I know the sub will do 25hz...??


I'm obviously looking at going lower than that with stronger impact through the range (crossover is at 80hz).
 

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1. Making sure the efficiency of the driver you are buying is at least as efficient as the one you are replacing(the db at 1 watt rating)


2. Port tuning is figuring out what frequency the existing port is tuned for...and making sure the woofer you are buying is "compatible" with the frequency the port is designed for (like if the port is tuned for 32hz, you don't buy a driver that shows a frequency drop at 32hz)


Call Parts Express* after you take out the driver and amp and they will be able to tell you which drivers they have for sale that are at least as efficient. Then it is up to you to search amongst those drivers(possibly purchasing 2-3) and trying them out to see which you like best. Then return the other 2 while acknowledging you might have to eat a re-stock charge.


*Parts Express

Madisound


There are many DIY speaker sources.
 

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That box is tuned to 30hz. The Dayton RSS315HO-4 would have a 2db peak at 30hz in this enclosure. You would need to have a high pass set at 30hz in order to protect the driver below that point, this would also remove the peak and give you flat response. You could feed the driver its entire 700 watt rated power and never reach 10mm xmax with this setup.


I would leave the old amp in place, drill and install binding posts to connect the woofer, and run a pro amp like this Behringer EP2000 in bridged mode. The amp has a 30hz high pass setting also
 

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I am sure it will not be that difficult to either lengthen or shorten the port.


Download WinISD. Enter the enclosure volume and port size and enter in different driver parameters and see what you come up with.
 

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Whether you'll perceive this as a "big improvement" depends... "Sounds better" means different things to different people.


When someone designs a ported subwoofer they do it around the mechanical and electrical characteristics of that particular driver (what your'e calling a woofer). You try to get a response that doesn't vary a lot in loudness over the range of frequencies you're interested in. So you adjust the length of the port, the volume of the box and the amplifier's filter for the following:


= Even response over a large frequency range

= Keeps the "woofer" from bottoming out (possible damage) on very low frequency passages

= Doesn't produce audible airflow noises out of the port (chuffing)


So it's very unlikely that you can just plop a driver and amp into the box and meet these criteria. However if the driver and amp are better quality you may hear less distortion. You'd be taking a chance that the new driver might bottom out on low passages if you push it and it may be that the new driver won't let your system play as loud at lower frequencies as the old one did.


However you might not be sensitive to variations in loudness over the frequencies or getting the lowest response possible and may be more sensitive to hearing distortion. So you may think it sounds better.


If you're serious about it model it in WinIsd, and look at several drivers and be ready to adjust the port length.


Otherwise it might work out and it might not.
 

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To make it easier to wrap your head around...if you have tools(or just spare cash), play around with car audio first.


IF you have an old stereo shelf system(that still works for at least radio), go buy a pair of 6 1/2 inch round car stereo speakers and a couple of "pre made" boxes that you can "cut/chop/glue" and not care about. That way you'll get an idea of what you are doing before you hit the subwoofer.


Call a plumbing supply house(or a local plumber) and ask if you can buy some scrap PVC in various sizes.
 
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