The box measures 9"x20"x22" for 1.6 ft3 or 45.311l. It has a 2" port. I made the first port 3 3/8" long which according to this site(http://www.bcae1.com/spboxnew2.htm) tuned to 34 Htz.. In testing the port wistled badly below 40 Htz.

Speaker Specs:
I have made another port at 5 1/4" and I think it works better. It is tuned(by software) to 29.5 Htz. I does wistle but not till down at 28 Htz.

Any body know what the disadvantages of tuning lower are??

http://www.blaupunktusa.com/NR/rdonlyres/A836F9A4-C803-41C0-8957-0905208B025C/5710/ProComponentSubwooferSpecs.pdf

• Response curves of closed vs. vented systems

I would suggest either adding a second port, or replacing the 2" port with a larger diameter port, or going with a flared port. Of course if you change diameters you'll have to recalculate the length.

Precision Ports' flared models have smoother airflow at the ends and so can play louder than a non-flared port of the same diameter before becoming noisy. I like them and use them. Switching to a 3" diameter flared port should help quite a bit. There's an online port length caluclator at their site which should help.

Getting back to your original quesiton, lowering the tuning as you have done will change the shape of the bass response, raising the -3 dB point but lowering the -6 dB point (by how much is hard to say from here). Depending on your room, this may or may not be an improvement.

Duke

• high quality flared ports

The minimum length for a 2" diameter flared Precision Port is 5" long due to the length of the flared sections, and that would tune your box to 31 Hz. This would probably be the lowest noise route, but of course it's also the most expensive.

Duke