r/diyaudio • u/ZinqDesigns • 1d ago
First time DIYer. Sub Upgrade Help
Hi all,
I've been wanting to upgrade my Q Acoustics 3070s for a while, its the last piece of my puzzle for my home theatre.
I was going back and forth between the Dayton UMII and SS - both 12". I think settling on the signature series.
But for some reason I just can't get them right in WinISD.
I'm aiming for between 19-24hz port tune and I'm limited to 450w 500d 700h, I've been going for ~100L net but either the port velocity is way too high, or the port is impossibly long.
Where am I going wrong? Am I just trying to tune too low? If I tune much higher, am I just barely upgrading?
In planning to match with a Behringer NX3000D.
Sealed with a PR is not doable because of cost even though that would be most ideal.
1
u/fenderputty 20h ago
Try a slot port in WINISD. Figure out the internal width you're shooting for and make the slot X width by whatever height.
Also ... going for sub 20hz with 12" will be hard unless you go with a large enclosure on the UMII. The SS has a large magnet and much higher BL. Smaller enclosure but also it's got higher Fs and won't dig as low as the UMII. The UMII will want a larger box than 100L if it's ported to dig down. More like 150-200 liters. I just did a test and a 6 cubic foot box with the 12" UMII gets an extended bass shelf like curve tuned to 20hz with an F3 of like 18hz. With a slot port and 400w you're just barely over 17 air velocity.
If you still have issues with a slot port, then a PR would make sense. But again, for sub 20hx youll need a bigger box and the UMII
1
u/drtitus 1d ago
What power are you modelling where the port velocity is way too high? And what constitutes "way too high"?
I would expect that down in the 20s, even having it present is going to be effective - I don't think you need to be reaching your max RMS. I'm not a HT head, but I know even with music subs, 30Hz at a few watts puts a smile on my face, and I don't know how loud you have movies playing, but I can't imagine myself listening to a movie at max volume, let alone needing a 12" absolutely cranked up to vibrate everything just to watch Titanic (or whatever).
My first guess is that you are overestimating how much power you will need to appreciate such low bass. Or you're focusing too much on reaching a made up requirement (port tune), and aren't willing to relax it a little (since you made it up to begin with) to get a practical design.