Newbie crossover questions

[kirknelson]

As I read through the various build threads and look over the crossovers it seems most people use a single resistor or cap to fullfill designs parameters. However, I have read elsewhere (zaphaudio.com) that one should double up on resistors to increase the power handleing (if the design requires a 2 ohm, you would use 2 4 ohms in parallel).

I see most resistors are rated a 10 watts and I've heard that many people use in the range of 20-30 watts to achieve reference level playback. This of course varies on the sensitivity of the speaker, seating distance, etc.

My questions are:
Is this really necessary?
If so why do most people use a single resistor?
Does the possibility of exceeding the limits of the resistor exist?
Why or why not?
Will it result in better sound?
What about for caps (would multiple smaller caps be better than a single large cap)?

On a side note, I plan to build the RS TMWWs & WTMWs. I like the looks of Jonmarsh's center XO but am unable to find his tower version. Does it exist? I suppose I could make three WTMWs but would really prefer towers for both looks and dispersion characteristics. If someone could help me out with a link I'd really appreciate it. ops:

[ThomasW]

Yes it's better to use multiples of resistors to up the power handing. Most don't do this in effort to keep costs down.

The use of multiple small caps lowers the ESR, and in most cases drives the price pretty high.

There's no tower for Jon's designs. It's unnecessary unless you have a huge room or want very high SPL. If that's the case the MTM design can be placed on a bass bins containing a couple 10"s using an active crossover.

[kirknelson]

Thanks Thomas,

So multiple resistors is good, multiple caps is bad. :P

What do you mean by saying the towers are unnecessary? I would certainly want matching speakers across the front instead of using a three way center and MTMs for L&R.

Do you mean that the horizontal dispersion characteristics of the WTMW are good enough to make no difference over a design with vertically alligned drivers? I have never known this to be the case in a horizontally oriented speaker. Usually that orientation compromises the off axis response but is accepted as a necessary evil to allow the speaker to be placed near the screen.

...or did you meant that no changes were necessary in the crossover design when changing to a tower configuration?

I see that Jon's design was done awhile ago, did he have any plans to make a tower version of the XO?

[ThomasW]

Thanks Thomas,

So multiple resistors is good, multiple caps is bad.

No, multiple caps are expen$ive with no obvious advantage other than lower ESR.

What do you mean by saying the towers are unnecessary?

There's enough bass out from the MTM to match up with a sub.

I would certainly want matching speakers across the front instead of using a three way center and MTMs for L&R.

Fine then built the TMWW, or the MTMWW

...or did you meant that no changes were necessary in the crossover design when changing to a tower configuration?

Using an outboard active crossover would be mandatory if you went this direction as opposed to buliding one of the existing tower designs.

I see that Jon's design was done awhile ago, did he have any plans to make a tower version of the XO?

Nope that's why bass bins were invented.