Any DIY remedies for a BOOMY Def Tech PF15TL?

Have you looked into room placement? You might be too close to a boundary wall and could try pulling the sub away from any wall that it is close to.

I would recommend starting with a simple subwoofer crawl test to ensure you have the sub placed in a good spot.

Boom is sourced in the midbass, roughly 80 to 160Hz, and usually indicates a cab that's too small and/or a driver that has too high a Qts for the box size. But being in that octave it also probably indicates the crossover frequency is too high, so the first thing to try is reducing the crossover frequency.

Yeah, sell it. Trust me.

This was THE subwoofer that pushed me into the DIY audio world nearly 10 years ago. Built a 15" vented subwoofer with a 250w plate amp and never looked back. My DIY Adire subwoofer DESTROYED my DefTech PF15TL.

You could build an even better subwoofer than what I built to replace the PF15TL these days.

If it's sealed stuffing it may make it better. It won't work miracles. The plate amp should have a dial to adjust the low pass frequency, turn it to 50-60Hz. Also change the subwoofer crossover frequency in your receiver to 50-60Hz. If the plate amp doesn't have an adjustable low pass that's just one more indication that it's an el cheapo that might not sound good no matter what you do.

It's still going to sound boomy and crappy. I had this guy for a few years and there is not a whole lot you can do to improve it's output.

It's way undersized for a proper vented alignment. It's tuned high and it's amp cuts in with it's limiters real fast. I'd dump it and build a new better subwoofer.

Get whatever you can get for it. I paid full retail when it was new ($700) and I sold it to a friend a few years after for maybe $2-300. I don't remember exactly how much but all I know is that I used that money to fund my first DIY subwoofer and still use it to this day. It's awesome and you could build a near copy for about $300 these days.

What about plugging the port(s) effectively making it a sealed sub? Might be worth a shot just to see what it sounds like.

What about plugging the port(s) effectively making it a sealed sub? Might be worth a shot just to see what it sounds like.

In most cases plugging the port will reduce sensitivity at the lower end of the passband, which is not where boom is sourced, tilting the response curve to the upper end of the passband, where boom is sourced. 'In most cases' assumes that the cab was properly designed, and judging by the OPs problems that may not be the case.

It's a 15 year old subwoofer that really wasn't all that great when it was new. Like I keep saying, don't bother trying to mend it's poor design. Make your own GOOD subwoofer.

Trust me. You'll feel awesome.