Proposed home cinema project + questions.

[Dannyball]

Brill, perfect not quite as good as range as parts express but i think they have what i want.

Does anyone have any idea what the sub cross over frequency is for the sony a/v reciever (link above)?

Will the simple vented box be alright or should i be thinking of more complex designs?

[Timn8ter]

Does anyone have any idea what the sub cross over frequency is for the sony a/v reciever (link above)?

Not sure but most have settings at 80, 100, and 120Hz. That's a valid question and the only way to know for sure is to read the manual or find somebody that has one already. It's a little aggrevating that retailers will post the frequency range of the AM and FM bands (which are pretty standard AFAIK) but not something useful like the sub XO setting choices.

Considering your price range and goals a BR box should work well.

[RobWells]

Ok Dannyball that makes it a bit easier

If you can make a sealed box with a f-3 that matches the amps xo then you'd do well. AV receivers generally roll of the main speakers at 12dB/octave, and the sub at 24dB/octave. Sealed boxes roll of around 12dB octave and added to the receivers roll off would produce a 24dB slope to match the sub.

Hope that makes sense.

Good luck with your project btw.

Try maplins or bkelectronics for some more driver choice:

www.maplin.co.uk

http://www.bkelec.com/new/

I take it you found wilmslow aswell:

http://www.wilmslow-audio.co.uk/

Cheers,

Rob

EDIT: maybe a pro 10" driver plus tweet would work well for this app ? - or even a 10" full range in a sealed box....

[Timn8ter]

If you can make a sealed box with a f-3 that matches the amps xo then you'd do well.

That could help you cope with power issues as a sealed box will give you higher power handling.

[Dannyball]

I'm trying to keep the boxes as small as poosible as my room is not all that big. Will a 6" do in a sealed enclosure plus a tweeter.

This is what i had in mind:

http://www.maplin.co.uk/Module.aspx?...ldID=6&doy=7m1

[Timn8ter]

This is a quick sim of the Alpha 6 in WinISD just to give you a comparison.

[Dannyball]

Sorry, i feel a bit stupid asking this but what is the graph showing?

[Mutley666]

I am also currently looking to build some speakers for my home cinema system, and being based inthe UK have found that drivers are alot more expensive than they are in the US.

Have you had a look at the Alcone units available from www.bkelec.com? (UK based)

The prices are very reasonable, the AC 5.25 HE is just £25.00 and the AC 6.5 He is £32.00.

For and example of what you can acheive with these take a look at this web page; http://www.lautsprechershop.de/hifi/index_en.htm, it maybe in german but you can get a good idea!

[RobWells]

Hey Tim,

Maybe if you ported the alpha 6 @40Hz-ish the curve would resemble a sealed roll off with a lower f3 ?

A bit like an ebs curve.

Cheers,

Rob


The graphs are showing simulated output in dB against frequency of your alpha 6 in a sealed box and a ported box.

Do a search for winISD and download it and play with it if you haven't got it already.

Have a look at this site too:

http://ldsg.snippets.org/idx.php3

[Timn8ter]

Originally posted by RobWells
Hey Tim,

Maybe if you ported the alpha 6 @40Hz-ish the curve would resemble a sealed roll off with a lower f3 ?

A bit like an ebs curve.

Cheers,

Rob


The graphs are showing simulated output in dB against frequency of your alpha 6 in a sealed box and a ported box.

Do a search for winISD and download it and play with it if you haven't got it already.

Have a look at this site too:

http://ldsg.snippets.org/idx.php3

Rob,
Good call. My post is just a teaser for the Dball man.

Dannyball,
WinISD Alpha is a good place to start playing around with T/S parameters and frequency response sims. It is not comprehensive but it can get you going in the right direction, especially with cabinet size and ported vs. sealed. Crossover design is another animal completely. There are freeware programs for that too but the only way to do it correctly is to perform reasonably accurate measurements with programs like JustMLS or Praxis, then import those measurements into a crossover simulation program like LspCAD. Even then you may need to tweak the XO to get it right.