Need help with a sub/driver question please.

[conchyjoe7]

Hi guys:
While I have been here for a while and have good all around knowledge, I am lacking in subwoofer terms. I have 2 Definitive Technology 1500TL+ subs. They each have 15" drivers and 500 w/rms amps and a beautiful piano black lacquer finish which I love and are decent all around subs, but NOT up to the rest of my system. My question is: Does anyone know if I can merely change the drivers and keep the rest of the subs? In addition, if I can indeed do this, what drivers would you recommend. I get usable measured response right now down to about 25-28hz, but as all you bass freaks know...THAT AIN'T LOW ENOUGH!!!
Any and all info and opinions would be much appreciated.
Cheers,
Konky.

[mdrake]

Sell them and DIY an LLT.

[Mike P.]

It will depend on the internal volume of the cabinets that you have. It would help if you could tell us the inside measurements, if there is any internal bracing, and how thick the cabinet material is. Once the volume is known a recommendation can be made, if it's possible.

[eyekode]

Judging from the enclosure dimensions the maximum internal volume (not subtracting volume of driver or amp) is 2.8cu. This is also assuming .5" walls.

I don't know of any 15" that will play really low in such a small enclosure. They claim 14hz output from this sub. Guess that was all marketing. I would assume though that they have some sort of LT circuit or EQ/bass boost built into the amp, otherwise the claim of 14hz is really silly. It would take some experimenting to see how a different driver copes with the EQ.

I don't see how changing the driver will give you much gain. Sell those pretty box and build a sonotube .

[mayhem13]

I'd keep them the way they are. I'm sure lots of engineering went into them to match the amp,freq response and driver. If they have high level in/outs why not use them with your front mains to extend lower. Set the subs xover to 100hz and send the rest to the mains in effect giving your mains a little more breathing room. Add a DIY ported sub to your LFE and set the processor x-over to 60 hz and keep all the really low stuff where it belongs. An RLP-15 from soundsplinter would easily get you down to 16hz in a reasonable size box. Cost could be kept well below commercial offerings and you could build it into a piece of furniture to add function to the room. I'm currently building 2 matching end tables 170 liters each with dual downfiring drivers to flank my HT seats. Cost was less than $1k for both and when done, you won't even know they're subs. Hope this helps

[conchyjoe7]

Thanks to everyone so far for the replies. I do need to explain a couple of things. First, I'm pretty severely disabled with both heart and diabetes problems which severely limits my ability to even walk much less think about building something, or even as basic as sitting on the floor. Now, I know given what I just said I will get logical suggestions to have someone build them for me. I tried that on this forum and others and got zero replies...no, I wasn't asking anyone to do it for free, just for reasonable. Discussions as to what is reasonable never got underway as again, nobody responded or showed any interest in doing it...so much for the alleged recessive job market I guess.
Yes, for those reading DefTech claims of 14hz response are just that: baseless claims. I guess at this point, since they really are "decent" subs; I'll keep them as is...they do pressurize my listening/HT room and within their response range are tight and musical and play LOUD! As far as using them to extend the reach of my front mains...they barely go as deep as my mains (Aerial 10Ts) which are -3db @ 24hz. I also have the power to drive my mains without strain as I use a Parasound HCA-2200 mkII amp which outputs 220wpc into 8 ohms and 385wpc into 4ohms and that is both channels driven 20hz - 20khz, and all the while capable of 90ampere peak current outputs per channel. At the moment I have my eye on 2 Hsu VTF3 mk 3 w/turbocharger or HO, but that starts to get pricey. Anyone interested in the local Atlanta area in buying my 2 DefTechs; please contact me...They're in great cosmetic and functional condition and I am the original owner with original packing etc.
Other than that, please let the thoughts keep coming...I may be naive here, but I really do/did believe a driver change would do the trick (at least to some extent), although it now appears that after the cost of buying upgraded drivers etc. I might as well go for the sale of what I have and the purchase of the 2 Hsus'...yes?
Cheers,
Konky.

[bobgpsr]

If you are not willing to DIY entirely new enclosures, then I would reccomend buying a couple of SVS PB13-Ultra's to replace your Def Tech subs. With two PB13's you can plug two ports in each sub to configure to 10Hz mode and get excellent ultra low bass.

Would not think that doing a driver change in the Def Tech subs will make much performance difference. Except by going to a huge Xmax driver with external pro amp and a Linkwitz transform circuit add-on. Or you could consider using a couple of Rythmik DS1500 Direct Servo (sealed version) subwoofer kits to retrofit your 15" sealed subs.

[eyekode]

Looking at Rythmik's sub designs they are larger then 2.8cu for the 15" drivers. It might work, and I hear they have great support so you can probably ask them. But I think you would be better off selling your existing very nice looking boxes and buying something beefier .