tuning frequency

I am looking for build some HT speakers and sub and some separate speakers for the computer (music and games). I have a few questions:

1. What's the BEST frequency for a home theater sub?
2. What's the BEST frequency for a sub for music/games?

I am looking to build the lowest frequency producing sub design. Can anyone help me with that? I have decided it will either me a tempest or 15" Dayton. I have a guide from Adire Audio for a box design using a tempest tuned to 15.8hz requiring 380L box (24x24x44). That's kinda huge and if made from MDF it'll be unmoveable. So I am thinking about moving towards sonotubes since you only need a sonotube and 2 end caps.

Well basically the real question is how low can I go using these two subs? (leaning more towards the 15" Dayton becuase I can't find the tempest for sale anywhere). I want to build one for HT using the best tuning frequency and another for music, since I heard playing music on a low tuned box sounds kinda crappy.

Your question is much to vague? Do you mean crossover cutoff frequency? vent frequency?

And why would the Hz be different for music/games and home theatre? Does home theatre mean movies? They shouldn't be different if you are going for nice clean sound and the enclose is tuned good.

It just depends on how low you want it to go, if you tune for say 22Hz it'll hit below 20 no problem and you don't need it to go far below that. I would reccomend visiting http://www.avsforum.com/ for real expert advice, a lot of people rave about the daytons over there. The lower you tune it the less flat the upper levels will be (ie. 40-30Hz), I would say 20-18Hz tuning is fine for all purposes but you may want it a touch higher for music. Below 20Hz you won't really be hearing it anyways, it just shakes the walls and your chest (provided the dB are high enough). Seems to me you would rather have a flatter response at frequencies that are actually audible but the people at AVS would know better what you can tune the dayton to without losing dB where you need it.

I didn't want to build my own so I bought an SVS sub (their cheapest PB10-ISD, $429 US) and love it, it will hit about 18Hz or so before it drops off too much (tuned for 22Hz IIRC). For $699 you can get the PB12-ISD/V which has 3 ports that you can plug to change the tuning level (20Hz, 16Hz or 12Hz) although it is a lot more then the cost of a dayton and some MDF it ,of course, is powered, CNC machined and looks nice. The HSUs are also highly reccomended if you don't want to build your own.

EDIT: I just googled the frequency response for a 15" dayton sub and it only goes to 20Hz... wouldn't want to tune it too low but again I reccomend AVS they can answer any questions you have a lot more accuratly then I can.

For most HT applications a ~20 Hz tune point is good. It's low enough to avoid unloading the driver on the rare movie with some 20 Hz or lower content. In most cases you wont suffer much in the upper bass ranges by tuning lower. Maybe a dB or two but it really shouldnt be noticable.

Personally I have my tempest tuned to 16.5 Hz. I run it like that for movies and plug the port for music. Playing music on a ported sub in general wont be as clean as sealed (depending on the alignment of course). But you would be supprised how clean the upper bass ranges are with the ported sub when its tuned low.

One of the biggest problems with ported subs is their group delay near the tuning point. It can make the sub sound a bit muddy or slow. But when you tune low (20 Hz or lower) that group delay spike is much lower so it doesnt effect the higher bass frequncies as much. Theres still some people that think its bad to use a low tuned sub for music but in general its OK and much better than the other ported subs i used (Titanic with 28 Hz and 31 Hz tuning points).

If your gonna buy two dayton 15"ers I would seriaously think about making them sealed. You are looking at some insane SPL levels fro mtwo of those drivers and I think you might be fine with them sealed. Either that or port both and tune low. I dont really see the point in running two different designs. Its pretty easy to just stuff some foam in the port and make it sealed if you want the flexibility of the two different designs .


Ryan