Chev2... Anyone? need help understanding HT Xovers!

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04-20-2004, 06:57 AM

Thunderous Contender

500 Watt CAFz'r

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Join Date: Sep 2002

Posts: 679

Hey guys, I noticed something today with my 3 way home speakers. All three of the drivers are 8 ohm, yet the final impedance is 8 ohm. How are they wired or crossed over to cause this? I thought three 8 ohm loads would yield a 2.66 ohm load? I'm going to be building my own 2 way speakers and I'm trying to understand how to wire and cross them over. I will be building 4 large bookshelfs for highs and mids, my sub can handle 80 and below. I want my speakers to handle everything else. thanks guys...

04-20-2004, 07:28 AM

chev2

Join Date: Apr 2000

Posts: 1,220

There is a number of possible ways..

If its a 2 1/2 way system, the 2 mids could be in parallel or series, then series or parallel to the tweet...

Further, they could be using resistors, etc, etc, in the passive to get it to work.. R&D at large companys is a good thing.. [img]smile.gif[/img]

If your planning on building your own speakers, i highly recommend you choose some of the pre-engineered and tested designs.. Rather then design completely from scratch.

A few to look at:
scanspeak and vifa designs on www.scanspeak.com
Adire audio
GR Research
Audax
Seas designs

to name a few

[ April 20, 2004, 08:29 AM: Message edited by: chev2 ]

04-20-2004, 07:34 AM

Thunderous Contender

500 Watt CAFz'r

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Join Date: Sep 2002

Posts: 679

Thanks Chev, what I was thinking of doing is pretty much just using a 1" tweet and 6 1/2 mid to play from 80 to 20k and above. I wanted to use resistors to cross them over. My 3 ways are using resistors and it seems like the easiest way. I'll check out those links. I was hoping to use Tangband drivers and map out a box using bassbox and winISD.

04-20-2004, 07:56 AM

chev2

Join Date: Apr 2000

Posts: 1,220

In passives resistors dont really act as the xover.. Capacitors and inductors are what creates the filters.

In my experence its very hard to get a decent sounding speaker, designing it on your own. With out a lot of trial and error and being very familar with xover design.

04-20-2004, 07:56 AM

Shaughn Murley

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The other way to think of this, is you have a 3 way setup, all crossed over, and all three of your drivers are 8ohm yet you have a final impedence of 8 ohm, each driver is only playing a specific band of frequencies at it's 8 ohm impedence, so theoretically, over the entire audio spectrum, the impedence is 8 ohm, thanks to those wonderful crossovers.

04-20-2004, 07:59 AM

chev2

Join Date: Apr 2000

Posts: 1,220

I would suggest looking at something like the impuls sheilded, or Premium 11 on the www. scanspeak.com site, in the vifa area.

Im not sure if the premium 11 can be done sheilded..

Or the GR research stuff..

[ April 20, 2004, 09:00 AM: Message edited by: chev2 ]