System design

[Wstanton]

Hi, just wanted to run my ideas past the old guard, get it picked apart etc.. !

So I have been challenged to get a sound / PA system going for a climbing wall, the floor area is ~ 600sq M and it will rarely expect more than 150 people.
As with most things I tackle I'm rather unwilling to just buy something OTP, I'd rather make my own, also my budget is somewhat prohibitive. £800 all in.

So my idea is thus;

I think I will have ~ 5 inputs, so I will take these into a small stereo line mixer or pre amp. I only need this to switch between inputs, however I believe it will also offer me some frequency control depending on what I get.

I have purchased a QSC RMX 2450 amp, I purchased this amplifier after doing a bit of reading, it will run 450W into 8, and it's good to run at 4 ohms without any heating issues to 650W.

I was planning to build a 2 of these speakers;
http://www.fane-acoustics.com/downlo...closure_12.pdf

I just had a couple of questions! ....

The horn that is suggested (FH 305) is no longer available, would I be ok to use another horn with similar dimensions? or will this have a large detriment to the sound quality ?

My only other question is how can that speaker enclosure contain two 8 ohm drivers and still have a total impedance of 8 ohms, do you think this is a mistake in the FANE pdf file?

Unless anyone has any other ideas for the set up?! I've read around a bit and I'm happy to make the enclosures etc... But I haven't got the time to learn how to design and tweak filters, hence I quite like this design from Fane.

[Loren42]

If they are not in any hurry at all to get this system, go for it!

However, designing and building your own speaker (and doing a half decent job at it) requires a lot of work and knowledge.

You can learn all of this, but the learning curve is steep. You will also need equipment (software and hardware) to test your final product. The software can be had for free, but the mics and USB sound cards are something you need to buy. This will eat into your budget and require more time to master (testing has its own demons). You still need to learn what you are doing, so buying some books like Vance Dickason's Loudspeaker Design Cookbook is a good start in addition to listening to advice here.

While I would not want to discourage you from learning all of these things (it is a fun and addictive hobby), doing your first build as a commercial sale is not a good idea at all.

I would recommend considering buying a finished product and install that. Even after doing that you still have to setup and test the system, which is a good bit of a learning experience in itself.

However, buying COTS (Commercial Off the Shelf) speakers will give you a much better chance of satisfying your customer's needs and less opportunity for things to go wrong.

[Nanook]

check the dimensions of the horn. Make one yourself or buy a similar one. Most manufacturers provide specifications for particular drivers, so if the 305 isn't available maybe a "315" or similar is for the exact same driver. Or perhaps JBL or similar have a pre-made one.