4 Way High Power Active Speaker

[bob123]

Hi,

I intend to design and build a pair of largish active speakers. I currently have a couple of Eminence Delta 15LFs that can be used as the side facing subs. I then plan on using a bass, mid and treble driver facing forward in a sort of floor stander manner.

Looking around a bit has revealed that Chinese clones of the Naim Nap 140 amplifier can be picked up pretty cheaply. I feel that these could be good for driving the bass, mid and treble with the sub being driven by a more substantial, cheaper and possibly class D amplifier.

There are a few things that I feel I need to explore before settling on a design.

1. As these speakers are supposed to be loud but also pretty good quality, would it be better to isolate the smaller drivers from the Delta 15's to prevent them being over driven or put into a non-linear region?

2. I intend to design the active X-over myself. The system will be Bi or Tri amped. Either with the delta's running and everything else or only the mid and treble on the same amp. Should phase shift be a concern on this system as some people seem to think it make the sound unclear and muddled? Has anyone got a good resource for designing active X-overs in this situation?

3. Are there any particularly good drivers that could be used for bass, mid and treble? Im thinking of using either 6-8 inch for bass.

3. What do people think of the idea in general?

[otto88]

What are your goals, eg max dB, bass - 3 dB point; and budget?

[cbdb]

1. As these speakers are supposed to be loud but also pretty good quality, would it be better to isolate the smaller drivers from the Delta 15's to prevent them being over driven or put into a non-linear region?

Yes that seems to be how the better speakers are built now (each driver in its own enclosure (the tweeter usauly already done)). Makes sense to acoustically isolate the different drivers (all of them) even in a ported design.

[otto88]

Though as a compromise you might have the bass in one box, and the rest in another.

6-8 inch for bass would generally be in a three way

[chris661]

Bob,

1 - yes, isolating the other driver from the others will be required.

2 - Some links for you on active crossovers in general... Woofer crossover & offset
Active Filters

3 - there are many drivers out there. If you wanted to avoid importing from the USA (gets expensive, believe me), try here... Europe Audio - Home page

3 (MkII) - potentially a good idea, though you might be over complicating things by going 4 way, when you could get away with a 3-way design. I think I'd look a little further into amps than buying something cheap. There's a lot of kits out there that will probably sound better, for slightly more money. Still, all depends on what you're after...

I also quickly modelled the Eminence driver. Ported, the cabinet is large (0.65 cubic metre), tuned low (25Hz), and has group delay past 50ms.
Sealed, you get an f3 of 50Hz, f10 of 29Hz, and the cabinet is now a mere 0.42 cubic metres.

Chris

[Henry8]

I'm almost finished my fully active 3/3.5 way system
The xover, power amps and speakers are fully diy.
You need to look at all three parts separately and decide what features/design elements you wish to have/not have, and then integrate them together.
Overall, you need to be able to carry out frequency response testing (and impedance tests will help) to build such a setup.