Crossover and Impedence

[whenley68]

I'm a musician and am designing a cabinet. So here is a question for a savvy electronics person.

Fact:: Minimum load is 4 ohms.

Crossover is 4 or 8 ohm.

I am thinking....

1 18" 4 ohm woofer

2 10" 8 ohm speakers wired in series?? to get to a 4 ohm load

1 horn tweeter, which is 8 ohms.

1. Is this how is should be done?

2. I don't want to overload the tweeter with to much power, is there something I would put between the tweeter crossover and the tweeter driver that would limit the amount of watts going to it?

3. Was looking at this Dayton Audio XO3W-375/3K 3-Way Crossover 375/3,000 Hz.

4. Is there a comprehensive book on all this that is practical and not on an academic level, I mean, I don't want to go buy and oscilloscope or anything.

5. Every bass enclosure I have ever owned, like my current Gallien Krueger, were all ported, so continue with the same?

6. I've read the word "throw"????

thanks up front for any guidance, I don't want to spend money on all the wrong things and end up with a less than good sound.

Will

[Sydney]

2 10" 8 ohm speakers wired in series?? to get to a 4 ohm load No. Series resistance is additive, so (2) 8 ohm speakers in series is 16 ohms.
Parallel wiring of (2) 8 ohm speakers creates a 4 ohm load.

[whenley68]

Yes, I kinda forgot which was which. LOL

[Sydney]

. I don't want to overload the tweeter with to much power, is there something I would put between the tweeter crossover and the tweeter driver that would limit the amount of watts going to it?
Some resort to one of these:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=071-254

[Sydney]

I've read the word "throw"????
That refers to directivity.
http://www.mcsquared.com/speakers1.htm

[whenley68]

I understand the concept of directional movement, venue size and area and how the movement of sound is important now. Thanks for that link.

[Sydney]

4. Is there a comprehensive book on all this that is practical and not on an academic level, I mean, I don't want to go buy and oscilloscope or anything.
The Loudspeaker Design Cookbook is a good start.

5. Every bass enclosure I have ever owned, like my current Gallien Krueger, were all ported, so continue with the same?
To get the bass extension you probably desire, stay with ported.

[Chris Roemer]

I'm a musician and am designing a cabinet. So here is a question for a savvy electronics person.

Fact:: Minimum load is 4 ohms.

Crossover is 4 or 8 ohm.

I am thinking....

1 18" 4 ohm woofer

2 10" 8 ohm speakers wired in series?? to get to a 4 ohm load

1 horn tweeter, which is 8 ohms.

1. Is this how is should be done?

2. I don't want to overload the tweeter with to much power, is there something I would put between the tweeter crossover and the tweeter driver that would limit the amount of watts going to it?

3. Was looking at this Dayton Audio XO3W-375/3K 3-Way Crossover 375/3,000 Hz.

4. Is there a comprehensive book on all this that is practical and not on an academic level, I mean, I don't want to go buy and oscilloscope or anything.

5. Every bass enclosure I have ever owned, like my current Gallien Krueger, were all ported, so continue with the same?

6. I've read the word "throw"????

thanks up front for any guidance, I don't want to spend money on all the wrong things and end up with a less than good sound.

Will

6. "Throw" is also (more commonly?) used for how far a cone moves in and out, a.k.a. excursion, measured/spec'd as "Xmax".

5. It depends on a drivers T/S parameters (especially Qts and Fs) and what you're trying to accomplish. Venting a woofer with a Qts much above 0.55 or so can be a real challenge.

4. "Speakerbuilding 201" is a much easier read than Vance's LDC, more modern with internet links you can use, more design examples.

3. A "pre-made" XO almost NEVER works well (99% of the time), and the odds of one working OK are a lot higher for a 2-way than a 3-way.

2. Generally, no.

1. Even for "pro" audio (is that what this is for?), that's an odd driver combo. How many 18" woofers are really out there to pick from? Horn tweeters ARE efficient, but generally not "hi-fi", even for "pro" use - I'd think an 8" or 6" mid would work better than a 10". A properly designed XO does all the work of "impedance matching". Since the biggest woofer gets the most power, its nominal impedance will ultimately set the systems nominal impedance.

Chris

[rogoll]

Some resort to one of these:
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=071-254

Take a look at the devices offered by Erse ---> http://www.erseaudio.com/Products/ProtectionDevices

[Sydney]

6. "Throw" is also (more commonly?) used for how far a cone moves in and out, a.k.a. excursion, measured/spec'd as "Xmax"...
In Pro Sound "Throw" is euphemistically a dispersion vs distance thang'
http://www.onesystems.com/pdf/education/Loudspeakers_and_Throw.pdf
Audio engineering for sound reinforcement By John Eargle, Chris Foreman
p 137
And since whenley68 is a musician...