What do Horns on speaker cabs do?

[KJung]

Yep, the woofers still get the full signal and the L-pad controls the tweeter only. That's what's in most typical 410 or 15 cab that has a tweeter.

The GK and most any other bi-ampable type stereo bass heads do split the signal with a real crossover so there isn't overlap.

This is not necessarily true... I find it to be about 50/50 (i.e., between a full, true passive crossover and a hi pass filter). I believe most really cheap cabs with those awful piezo tweeters don't even use any sort of crossover though (since the piezo's don't need it... they kind of 'hi pass' themselves... is that right? That's the type of cab that gives tweeters a bad name, and from what I understand, since piezo's extend so much higher than the typical phenolic or whatever tweeter, they really tend to amplify the super high hiss of the cheap amps that are usually included in those low end gear lines... not good).

I tend to prefer the high pass (like the Epifani cabs), since I love that somewhat grindy midrange coming from the top of a driver. It also allows you to turn the tweeter off and have a true one-way cab. However, cabs like Bergantino or most of the LDS cabs, the TC cabs, etc. that use a very nice 'true' passive crossover, cutting a bit of the very top of the driver off and replacing it with a tweeter crossed over a bit lower, also provide a wonderful tone... making the tweeter a touch more integrated into the sound of the cab, and resulting in a smoother tone in general.

Both approaches seem legitimate. The GK 'active crossover biamp' thing is also interesting, and eliminates the 'distortion/overdrive' issue with tweeters, since you can push the amp and add distortion and growl through the primary amp while the little tweeter amp stays totally clean. Nice design for those that really like the grit and grind, but also like a some extension up top.

I have a coax 115 cab being built by LDS at the moment, with a 'true' crossover at 1.8K. That nice low crossover with the 'time aligned/single point reference' coax tweeter results in a very natural, smoother transition from the mids to upper mid to treble, and the off axis should be quite good. I had a similar 112 built with the tweeter crossed over just a touch higher, and it sounds completely killer. To give you an idea of how good it sounds off axis, look up TBer Vision's clips (he owns that cab now) of his band on Youtube (those clips were recorded with the recorder almost completely to the side of his little 112 coax cab, and the bass sounds completely KILLLER.

Edit: I'll post that clip in the next post when I find it!

 

[KJung]

http://www.youtube.com/watch?v=nMzVBOz9xLM

Listen how beautifully integrated that tweeter is with the wonderful B&C Neo 12 (this is the LDS coax 112 I mentioned above, driven by the wonderful Markbass LMII), and also how beautiful the upper mid response is, even though the cab is at about a 45 degree angle away from the recorder. Wonderful! (Smoking playing from my buddy Jason also).

 

[SwamiRob]

This seemed to get overlooked, so I'll take a crack at it. Distortion increases the harmonic content of a signal, so a higher percentage of the amp's power lies in the region crossed over to the tweeter. This increase in power the tweeter receives is what blows the tweeters.

Would this not be solved by having a very high power handling tweeter? Or is it not that simple? I imagine that that kinda high end with an overdriven signal would be a little much but I'm interest if anything just because there's been a couple of guys that have used my right and turned the tweeter on because they liked the sound of it with their overdriven bass, mostly pretty nasty noisey modern "hardcore" bands we've had to play with ion occasion. The kinda where everythings drop tuned to buggery and the guitars put out all the bass and the bass is just a bit of a gritty midrange mushyness that you can barely here. Anyway I'd rather not have my tweeter blown, not that I use it but there are a couple of bands that we play with occasionally that do when they borrow my gear.

Also what's the deal with midrange drivers and guitar applications, are they at all viable? I really don't know much about boutique guitar stuff, in terms of stuff that integrates some decent science, not just people that will build you a valve amp out in a Japanese redwood casing with a solid gold face...

 

[billfitzmaurice]

Would this not be solved by having a very high power handling tweeter?

A heavily clipped signal can cause 10dB and more increases in the high frequency power density of the signal. So if you use a 1,000 watt tweeter or two you'll be good to go.
Where guitars are concerned you want a driver that has strong response to about 4 to 5kHz and then drops like a stone; guitar tens and twelves do just that. But they will have narrow dispersion, there's no getting around that, so the last thing you'd think guitar cab manufacturers would do is to put them into cabs that make dispersion even narrower. But they do.

 

[SwamiRob]

Bloody hell, fair enough, I assume mid drivers are susceptible to that to some extent too then and that's why they can't be used either. Are there not many companies that make 8s and 6s that go down low enough with a response in the rest of the spectrum to be usable? Obviously there's always the issue with how bloody big the heads are though obviously. Your inward firing design seems to sort out a fair few problems with the drivers, but I assume it's not your best dispersing design still given the limitations of the speakers and such.