Realistic DB capability for surrounds and mains in home theatre

[oublie]

Hi folks,

Building speakers atm and currently working through calculations in winisd and edge.

I have one problem before I make any more sawdust and thats to do with getting enough decibels for realistic movie listening.

Speakers wont be an issue i have
2 15" dvc subs for horns ( i will get them built eventually i promise)
4 15" for either open baffle or large closed box fs 30hz
64 4 inch drivers suited to closed or ported but a little low for open baffle but ok in a line array configuration.

now along with the obvious requirements of sound quality and low frequency extension (i can get 115db @ 15hz with the 2 dvc's ported according to winisd more with big tapped or folded horns)

what level should i aim for with my mains and surrounds?

The main will be line array augmented with 2 15" subs per side.

if i go open baffle with the subs i can get 110 db per pair with an f3 of 30 hz @ 107db 20hz is around the 95 to 100 db mark

the closed box with a linkwitz transform is very close to this.

Am i right in saying that i should allow a further 6db drop to allow for OB instead of closed or infinite baffle?

The mids model fairly well in closed and open baffle allowing me to get to 115db with each set of 18 in a line array open baffle and over 120db closed this is flat to 100hz

I dont plan to go anywhere near this spl.


Sorry for the verbal diarrhoea my questions are

1. what spl should i be reaching with woofer on ob for home cinema?
2 how do i convert from winisd to ob use do i take away 6 db?
3. I read somewhere that 103db at the listening position is ideal is this right and if so so i need more woofers?

I think i just need a little guidance.

PS this is my first build bar a few prototype line arrays which are working quite well.

[doug20]

Why are you not considering pro audio drivers from a company like B&C, 18sound or Eminence?

You do not need more woofers, you need the right woofers to give you the dynamics and SPL HT Demands.

How far away are you sitting?

[soho54]

Originally Posted by oublie

1. what spl should i be reaching with woofer on ob for home cinema?
2 how do i convert from winisd to ob use do i take away 6 db?
3. I read somewhere that 103db at the listening position is ideal is this right and if so so i need more woofers?

1) It depends on too many variables to come up with a simple number. See #3, and then figure out the speakers SPL needs from that.

2)Simply, you can't do that. You need to use a program that allows for OB simulation. The loss is not the same from OB to OB, as the speaker's dimensions define part of it.

3) There is no ideal. There is an industry standard though if you want something to aim for. It is 105dB at your LP.

[oublie]

Thanks Soho and doug.

Thats what i was looking for so i can design accordingly.

so ill be building the following for music

18X 4 inch mids/ full rangers in line array configuration per side to 200hz augmented down to 20 hz or so by twin 15" woofers per side this give about 110db at 1m through winisd with an f3 of 35hz 100db at 20hz is hitting xmax but i doubt if ill ever play that loud for every day music

in cinema configuration this will be augmented by 9 mids per channel for rears and centre down to 80hz once again this is 110 db through winisd and subs in llt format at 115db down to 15hz

does this sound like a fair set up?

[Pano]

Agreed, try software that allows OB sims, like BASTA, Edge or John K's software.

If you are planning a line array, you owe it to yourself to read Don Keele's papers on the CBT. It's a nice approach.