Hi billnchristy,
Can you explain how it does that with inductors, caps and resistors though?
I can, but then I would have to shoot you
There is no "voodoo" (using your own terminology) in the actual crossover.
The "voodoo" took place well before the crossover was designed. The voodoo was in designing the filters, Q, and phase response needed to achieve the dispersion characteristics that we were going after, what we call OPPIX -- which is a major component of the Sierra's exceptional imaging, as Tom made reference to in his review.
Once the desired response was modeled, we used digitally programmable filters to match the computer modeled response so we could test acoustically. Further tweaks were performed and the end result was that we had very precise filter specifications. From there it was a matter of designing the crossover that would come as close as to our target filters as possible, and then reducing crossover components while still coming exceptionally close to the target.
There is no "magic" in any passive (or active) filter that I know of.. The filters (crossover) are just the mechanical method of "how to get there".
In response to your question:
Can you explain how it does that with inductors, caps and resistors though?
Inductors, capacitors and resistors are the components needed to implement simple and complex filters and various other circuits required (from shallow slopes to steep slopes, impedance compensation, frequency response shaping and phase adjustments)
The real magic (or "voodoo") is knowing what to design for (and why) and then how to go about achieving this.
LEAP (as you previously mentioned) is a quick and dirty way to design standard filter topologies which can provide flat on-axis response (Linkwitz-Riley, Butterworth etc.) These often provide good results with predictable characteristics. Designing filters for which phase, off-axis dispersion, impedance and response shaping are all taken into consideration (for which specific characterstics of each are desired) is far more complex. You have to KNOW what your target is.
I am 100% for building and designing your own loudspeakers. Eventually, after much time spent and constant tweaking, you could end up with something that sounds better "to you" than a higher priced professionally engineered and designed product -- however, designing loudspeakers to appeal to tens (hundreds) of thousands of people is something else entirely.
How much free time do you have to spend modeling phase and dispersion characteristics and how they will react in various rooms? (if you had the knowledge to do so) I don't just mean a few hours a week, I am talking hundreds and hundreds of hours spent just on modeling. From there it was designing and choosing the components to *get there*
Certainly no magic in the crossover itself.... Is the "magic" in the magician's wand? The hat? The table? The Rabbit? Nope -- the magic is in putting all the non-magical parts together to achieve that seemingly magical reaction…
For anyone interested in the Sierra-1, I invite you to email me directly at davef -AT- ascendacoustics.com (I don't have enough posts to publish my email address)
Take care!!