Martinelli's horns are gorgeous and he will be one of the first places I go. I like the concept of the tweeter horn and mid horn and would love to have them in wood and possibly as a stand alone. The lows will be through a BR design. Crossovers would be flexible, but I am thinking somewhere above 3.5 khz for the tweet and below 500 hz (or lower) for the woofer.

Any input on drivers, lens and woofer will be greatly appreciated and investigated. Critical appraisal of my idea is also encouraged, but probability of changing my mind is slim...

Henry

Thanks for the compliments. Here are a few things to think about. Do you want to run a compression driver in the mid horn or a cone driver. For a compression driver you will most likely need a 2" format. Sometimes the 2" parts are very pricy. For two inch compression drivers the JBL 2440, 2441 and 2445 sound great. I like the Selenium 405TI pretty well for the price too. You can run a 1" K55 down to 500hz but IMO it's really a better range for a 2" driver. Most 2" drivers will work very nicely well past 3.5khz. It's possible to cross into the tweeter from 6k to 10k driver dependant.

For a tweeter your crossing over in a very nice place. A small horn is perfect and there is now strain on the driver from a 6k-10k. Even 3.5k is high enough just about anything. My preference for 1" drivers for the tweeter are BMS4540, JBL 2425/26, PSD 2002. Altec made 1" drivers lots of guys like too.

For woofers I prefer the JBL 2226 over all others. Eminence Kilomax, Omega, and Delta, in that order are runners up. There's lots of good 15's around and if you have some parts or know of others they can all sound good. That's the stuff I use and I haven't heard anything different that would make me change. I may doing some work with Ciare Speakers and 18 Sound. I'm told they are good but I've not used them yet. The TAD 1601C and some others are also great if you are interested in pumping the Hi-Test. All of these can crossover at 500-800hz with out a problem.

Cone midrange horns are the cats meow. There isn't a lot that betters an 8" or 10" in a 14"x16" horn. (there abouts)
Your bandwidth will be more limited with this though. You'll be lucky to get 2k out of this on the top side and 500hz for the low side is a perfect place.

Let me know what your thinking of using for drivers and the crossover points will be more evident.

Bill

I really dig the Martinelli horns too. And my opinions are similar to his too; We sort of come from the same direction on this deal.

Basically, there are a lot of valid solutions. The ideal one would be to have three decade-wide subsystems, 20-200Hz LF, 200Hz-2kHz MF and 2kHz-20kHz HF. That's an ideal three-way solution as far as I'm concerned.

But actual devices tend to dictate our choices. A 20Hz woofer is pretty substantial, especially if high efficiency, so many times a decision is made to go with a 30Hz or 40Hz solution. This then often allows much higher response from the woofer, and that opens up some design possibilities.

Similarly, a 200Hz midrange is also a pretty large device, so sometimes this is shifted up an octave or even more. The trade-off is that as you move up from there, you cut more and more into the midrange band where you split between woofer and midrange. But as you move down from there, your choices of drivers become larger and more limited. A typical solution is to move the midrange crossover to 400 or 500Hz, and crossover to a large compression driver or small cone midrange.

Then we look at the tweeters. If you run a subsystem below the tweeter that runs out of steam between 1kHz and 2kHz, then that makes a 1" compression horn an attractive canidate. But if you can crossover an octave or octave and a half higher, then you can use a tweeter that performs better above 15kHz, where most 1" compression horns rolloff.

So I think you'll probably want to decide what direction you want to go. A lot of this hinges on your choices of components, and you will find some dependencies here. For example, if you find that you really like a particular modern 2" compression horn, then I'd suggest that you should probably only consider woofers and cabinets that will perform well up past 500Hz, at the least. If you are dead-set on a specific tweeter that needs crossover at 6kHz, then a cone midrange is probably not going to work for you. There are lots of good ways to do this.

Wayne

What are your thoughts on using your Four Pi-18 designs as a starting point for a three way? Looks to me that if you add a super tweeter to the 18" woofer and 2" compression, you're covered from 30Hz to 20KHz.

gar.

I think Martinelli's horns are really great too. Awesome looking and I hear they sound really good too.

I'm doing a 3-way at the moment with HF horn, midrange horn and direct radiating midbass/bass. Quick rundown the HF horn is JBL 2370 horn with P.Audio PA-D45 comp drivers, midrange horn loads an Eminence Alpha 6 driver, and the midbass/bass section is JBL 2225. Crossover point from bass section to mid horn is 300Hz and from midhorn to HF horn will be 2KHz.

Adrian

I will be asking more about your appraisal of the drivers as I spec and start designing - first off deciding what rule I will follow for horn response and bass box. The price of drivers will probably not scare me off as much as building the crossovers will...

Thanks again Bill - I'll probably FU via Email in the new year.

Henry

Thanks bunches Wayne, and one further question - what is the benefit of the decade wide aproach?

As we get in to the new year I'll be coming at you with Pi align questions as I start the speaker spec/design work.

Henry

Henry