Crossover questions

My budget for building speakers is always based on the quality of the listening room first.
If there is another person involved, such as your girlfriend, her expectations need to be well understood.

You wrote about building a "pair of speakers" but an A/V system requires five speakers and one subwoofer. If possible, the five speakers should be identical. At the least, all three front speakers should be identical and oriented the same way (no hoizontal center speakers and vertical left and right speakers) for optimum fidelity.
The typical woofer-tweeter-woofer center speaker
sitting on top of a TV set in a horizontal orientation is a compromised (for better appearance) design placed in a less than optimum position. (The center speaker provides up to 2/3 of the sound energy in a typical film mix (excluding the subwoofer), so its design should not be compromised to make it 'look better' on top of the TV set).

Magnetic shielding will be a concern too.

To ensure your project is a success, I suggest thinking about three important subjects first:
(1) Room size and dimensions:
(For example, why waste your energy building five high quality speakers for a "low quality" small near-square room -- this type of room would also have a strong negative effect on subwoofer bass frequencies)

(2) Room acoustics:
Will you be able to treat the room so you get the less reverberant/dryer acoustics needed for A/V?
(Two channel stereo works best in a more reverberant than average room -- A/V does not).
Directional speakers (controlled dispersion) are also a plus for A/V, while wide dispersion speakers are best for two-channel stereo.

(3) What does the girlfriend REALLY want?
Women often are not as direct as men in their
conversations:
For example, is she thinking of five very small speakers and a small subwoofer hidden in a corner
or behind the couch?
- Is the appearance of the speakers more important than the sound quality?
- How flexible is the "budget"?

One question whose answer would clarify your post:
(a)When you wrote "two midranges", did you actually mean two "midrange-woofers" as in an Woofer-Tweeter-Woofer two-way design? That's what I assumed.

One comment on running woofers "flat out" (no crossover):
This is the most common arrangement in loudspeakers today (crossover = one capacitor and maybe one resistor) but almost all are cheap
speakers and don't sound very good.
-- There are a few exceptions:
I really enjoy my own EPOS ES-11 satellite speakers with no crossover at all on the small woofer. I recently enjoyed an audition of the $500/pair Triangle Titus speakers with a similar no-crossover woofer. The woofers in these speakers were especially designed to be used without crossovers. Without crossovers, MOST woofers available to DIY speaker builders would provide too much mid-range SPL relative to bass frequencies (no baffle-step compensation) and a rough frequency response at the high end of the woofer's frequency range.

I'm also not in favor of wiring woofers in series
because back-EMF from one driver will modulate the voice coil of the other driver. I don't know if this is audible -- maybe it's just an old wife's tale -- let others comment on whether this makes an audible difference.

Thanks for all the responses. Sean, I think I will contact Clayton for his expertise and opinions on series crossovers. I will probably also get in touch with Bud Fried. Herman, I will check out Gizmo's ideas. I have considered horns, but have never really fell in love with them. I do have a pair of horn speakers in my living room that my father built in the mid 1960's. They are exactly as you suggested. The sound of them is pretty good. Perhaps, I will give higher quality horns more consideration.

I am not at all interested in a 5 channel HT setup, and expressed these feelings explicitly to my girlfriend. She has no problem with this, and basically just wants to have a nice looking setup in the family room. One where we can watch tv and she can sing karaoke. Whether my woodworking skills are up to the challenge(to make something "attractive") is the question. Her reasons for wanting a good amplifier/speaker arrangement are completely to appease her boyfriend, who happens to be waaaayyy too serious about audio.

As far as the excellent speaker questions that were raised, here are my rapid fire answers(sorry for my lack of clarity in the initial statements)... I was stating that the midranges(or mid/woofers) be run flat out(no caps, coils, or resistors), and wired in series in an overall parallel crossover network. Wiring the entire loudspeaker in series would preclude me from keeping components out of the path of the midrange drivers. Rgreene2, Triangle(glad you mentioned them) is one of the speakers(along with Eggleston and personal experience) which have proven to me the benefits of running the midrange or midwoofer with no crossover components in the circuit. In my parallel crossover approach, the tweeter would have a film and foil capacitor wired on its positive leg, and a resistor(if needed). As far as woofers(in the strict sense of the word) go, I am still undecided. They suck a good deal of current. I may just build these speakers with nothing larger than 6.5" drivers. If I later decided that I really needed to have that last octave, I could go with a pair of subwoofers.
Still have a lot of thinking to do... Things like do I use a REALLY dead cabinet, or more loosely damped(that everything old is new again thing)? I'll decide that after I figure out the crossover, but have always felt a dead cabinet was the way to go. Double thick walls(featuring MDF and plywood), with a layer of something between them(Swedak, viscoelastic, or other polymer), corner braced internally, and BlackHole 5 on the inside walls.

Joe, apply your "deader than a door nail" speaker cabinet theory to the horns / horn bodies on your dad's speakers. Keep in mind that some horns have some type of screen / mesh "diffusor" in the throat near the driver. If that is the case with those specific speakers, remove them. Most of the glare / ringing that you hear from horns can be directly attributed to the resonance of the two culprits i just mentioned.

As to using "Black Hole" (which is quite expensive in large quantities) for damping / deadening / mass loading, try using "damping sheets" from Parts Express. MUCH, MUCH cheaper and it will do at least 80% of what you're looking for. I'll snag a part number later should you or anyone else need it. Sean
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Thank you Sean! I will think about horns in a more thorough light. The cabinets of my father's speakers(horns with cone woofer), while excellent for their day, can be improved in several ways. Also, the quality of the passive parts(coils, caps, resistors, and wire) have improved quantum levels since those speakers were built. I will also take your advice about the "diffusors" to heart.

You are quite correct about the cost of BlackHole 5. I once made a few "sound boxes" at my previous company. We manufactured EL(electroluminescent lamps), for use in cell phones, pagers, night lights, etc. The whole technology is simply a capacitor that lights up when supplied with AC voltage. There was a lot of noise generated via the AC voltage(coming from the inverter)/lamp. My job was to get rid of it. I looked into anything I could. The sound boxes were just basically speaker cabinets we built(minus the speakers, but with a window to view an inserted SPL meter), which insulated the lamp/meter from the ambient noise of the plant. Got lots of wonderful experience with sound insulation materials. Things like acoustic foil, SoundCoat, foams of every sort, viscoelastics, rubbers, silicones, polymer formulations I developed(applied via screen or pad printing). In the end, the best solution was to simply screen print a third electrode(using my carbon resistor paste) which served as a "shield".

The experience of building those boxes and insulating them(with foams, SoundCoat, foils, BlackHole Pad, BlackHole 5, Swedak, etc.) was invaluable in teaching me about quieting down a box. Materials were free(either sample or out of the company's money), and I was being paid. BlackHole 5 proved to be an excellent product(I like the viscoelastic/multiple foams combination), and we did end up buying a bunch.

To be honest, I can(and probably should) build that BlackHole 5(or better) using viscoelastic sound panels(probably the same as the sheets you are getting from PartsExpress), and two kinds of foam(from Foamex or whoever) for a fraction of what Orca's retailers charge for it. Even incorporate some acoustical foil(very effective stuff) in the my homebrewed insulation.

Now I get to use all of that information! Speakerbuilding is an immense subject, and no one has all the angles covered, but it sure is fun to play this game. If you are going to be undertaking a similar project in the future, it would be great to bounce a lot of ideas off each other. Again, thanks for your help.

Sean by the way, I just came across a thread on Tweaker's Asylum from 'Clayton Oxendine' regarding a series crossover question(via web search on "series crossover"). So, I now have found at least one person in the world who has knowledge of this mostly forgotten technology. Again, thanks for your help in steering me toward this person!