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Discussion Starter #1
I have a definitive tech 15tl+. The plus signifies it has the upgraded 500 watt amp. The internal airspace is aprox. 16x16x16 (2.3 cu. ft?) and it has a slot port on the back bottom that is 15.5"x12"x3/4". I could use the same port, put in a different port, or seal it. I will check the ohm rating on the driver to make sure but i heard that it is 3.9ohm. It currently has a 15" paper treated cone and it is older. By looking at it I would guess it has around a 13mm xmax. Would I get noticeable performance out of it if I changed out the driver and kept the amp? I am very open to suggestion on driver selection if you could recommend. I was looking at the RE SE15 but there may be a much better fit??

here are the RE specs:
15"
Electrical Q Value -Qes: 0.55
Mechanical Q Value -Qms: 4.3
Total Speaker Q Value -Qts: 0.49
Free Air Resonance -Fs: 22 Hz
Equivalent Compliance -Vas: 209 liters
One-Way, Linear Excursion -Xmax: 18 mm
Efficiency -SPL 1W/1m: 88 dB SPL
Effective Piston Area -Sd: 810 cm^2
DC Resistance -Re: 2.8 ohm
Nominal Impedance -Znom: Dual 2/4 ohm
Thermal Power Handling -Pe: 600 W
Force Factor -Bl: 17.7

Thank you
 

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Elite Shackster
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Any given driver works best in a particular sized enclosure, and can handle a specific amount of power. By keeping the cabinet and amp, but swapping the driver, the chances are any driver you would put in there wouldnt work at its best in that enclosure. For that you would need a driver with similar TSP's which kind of makes swapping a bit pointless. I dont know about that amp specifically, but most sub amps have had something done to them to tweak their design and output a bit, and chances are that one works best with that driver in an enclosure of the size you have.

The amp is probably still very useable, but if your changing driver, then you need to model it to see what performance your likely to expect. Chances are you can do even better by building another cabinet for use with a different. You current driver is stated as having 18mm xmax, are you looking for something with more?

Its possible you could get a little more performance by re jigging things a little, but it depends what your looking for, is there something in particular your unhappy with?
 

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Discussion Starter #3
This current sub has a lot of distortion when you turn it up past half. I use it for strictly HT. it just seems like the driver in it is so obsolete. I am looking for more output but cleaner.
 

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If it's audibly distorting I bet it's the amp and not the driver.
 

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Elite Shackster
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Do you have another amp lying around, or one you could borrow to test that its not the amp causing the issue. Preferably one with more power?

I did this with an old sub that died ( the amp died ) and the little Kef was surprisingly lively. An amp change can be surprisingly easy to do.
 

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Discussion Starter #7
good point. I will see what i could find. If i end up keeping the cabinet later and getting a new driver and amp, what driver would you recommend? i will buy the amp according to the driver.

thank you
 

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Elite Shackster
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I think people will hold from putting forward driver options till you know its got nothing to offer. No point replacing it if you can get more out of it with a better amp. There are companies out there charging thousands of dollars for subs with $80 drivers in them, purely becuase they get amazing results from them.
 

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Discussion Starter #9
I think i figured out my problem...
the slot port opening is way too small. It is 3/4 tall by 15.5 inches wide by 12 inches deep. In researching I believe I need to get a 4" round port and seal up the slot.
Also on the inside, does the port just hang in there near the bottom as I am porting in the rear (no room in the front) or should I get it close to the bottom so it will rest on the bottom?

Thank you
 

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What makes you think the port opening is too small? With the dimensions you've given, the port tunes the enclosure at approximately 30Hz. To answer your question about installing a round port, you need to keep the opening at least 1/2 diameter away from the inner walls for best performance. A 4" round port is just a bit larger than the 15.5X0.75 slot you now have, by the way, and to achieve the same 30Hz tuning would have to ba approx. 13.5" long. What tuning frequency are you trying for?
 

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Discussion Starter #11
thank you. i figured out the same tuning. I have been told by several different people that due to the small port i am hearing chuffing or port noise at higher volumes which is also taking down the performance. This makes sense as I thought it sounded like distortion but it is probably also port noise. Do you think differently? Also i will be tuning it the same.
 

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Yes, it is possible you are hearing chuffing since the tuning frequency is in the audible band although chuffing does not sound like distortion. If it is literally distorting I still think your amp might be over-driven.

Have you already purchased that woofer? With the RE SE15 in a 2.3 cuft enclosure tuned to 30Hz, you're going to end up with a car-audio style boombox system. It will have a large peak at about 55Hz that could present problems in a home theater environment. I'd recommend lowering your target tuning frequency to around 18.5 Hz and building a new larger enclosure of around 3.5 cuft if you need to use that woofer. You'd have a much more satisfying result in my opinion.

If you haven't purchased the woofer yet, consider a woofer like the Dayton HF-15" from Parts Express. In a 2.3 cuft enclosure you can achieve a very nice looking output if you simply seal up the existing port and operate as an acoustic suspension system.

Best luck!
 

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Discussion Starter #13
thank you for all your help.
i have scrubbed the idea of the RE. I will look at the dayton.
I am going to try the round port idea for fun. I will most likely end up building another enclosure later though. What other drivers might work well in that space with 500-1000 watts rms sealed?

Thank you
 
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