Passive Crossover and tweeter recommendation

[Deny]

Hello,

I am building myself a compact stereo FRFR monitor for using with amp modelers + FX in general (eg POD, Digitech RP1000 etc). The amp itself is a 150W + 150W generic MOSFET board I've got cheap from eBay, supposedly has a somewhat flat response, we'll see.

Now I was initially planning on using just a pair of 8 ohm 10" speakers for this project but from my latest testing in similar systems I think it may lack a little high end, so my question is: given the speaker data below, what kind of passive crossover should I get and which model of tweeter? Is there any crossover models in which I can adjust the amount of high end? I fear the amp ends up sounding harsh and fizzy.

[Steve Conner]

If you want a flat, "hi-fi" response then you probably want to cross that speaker over below its presence peak. But for a guitar application you may find it sounds better with the presence peak. I used to have a couple of Peavey bass cabinets, and I preferred the sound with the woofer part of the crossover bypassed, so the woofers got full range.

You can buy generic horn tweeters from various different makers, Fostex is one that comes to mind. You can also get crossovers for them. A horn tweeter has a resonant frequency and you have to cross over above that to avoid lots of distortion.

My favourite sounding horn tweeter was the one in a Hartke VX215 bass cab I used to have. You hardly noticed it was there. In fact, when the cab arrived it wasn't there! The driver had broken free from its horn and was rattling around the cabinet, and I had to mend the horn with a hose clip. It was some Chinese thing custom made for Hartke.

Maybe a small cone midrange unit would sound less harsh than a horn. Hi-fi dome tweeters might be worth looking at too, but I fear they wouldn't go loud enough, because they have lower efficiency than horns. They might just burn out.

It should be easy to get a crossover with a "L-pad" attenuator, or add one.

Speaker and crossover availability varies by country. I see your datasheet is in Portuguese, I have no idea what is available there, but Eminence make some nice 8" coaxial drivers: a woofer with a tweeter horn integrated into the middle. I think these would be great for a modelling amp "PA".

[Deny]

Wow thanks for the detailed reply Steve!

I'm thinking about getting the ST400 model from the webpage below (I'm in Brazil):
SELENIUM

And possibly a 1st order 2-way crossover tuned at 4.4kHz, what do you think? It's not an audiophile cabinet so maybe I'm allowed a few design liberties that would otherwise be considered heresy

My goal is to make the amp as lightweigth and compact as possible so the 10" speakers, tweeters and air duct (it'll have just one) are gonna be very close to each other. I'm thinking about including a switch that turns all crossover networks and tweeters off so I can have it sounding more like a regular guitar cabinet too.

[Steve Conner]

Ah, OK, Selenium should be able to supply a crossover for that.

But in the manual they spec it with an 8kHz, second-order crossover, and that's probably what they'll supply. If you go down to 4.4kHz and use only a first-order filter, that's a whole lot more midrange energy you're asking it to handle. Your 150 watt amp may be able to burn it out. I'd use 5kHz, second order, or more.

That ST400 is really more of a supertweeter. If you want a 4kHz crossover, you might be better using the DT150. http://www.selenium.com.br/site/asse..._pdfManual.pdf

[MWJB]

Another alternative might be the dual cone speaker approach, though I think you'll find you have a better choice once you start looking at 12" drivers, the Beyma 12GA50 claims to handle 18kHz, the Fane Sovereign 12 200LT claims to handle 10kHz. Be aware that speakers often reproduce "adequately" somewhat beyond their rated specs.

The Eminence CX speakers are recommended for use with a crossover...taking into account what I just wrote above.

[Deny]

The DT150 looks like a good match, and it even has a 4kHz (2nd order) suggested crossover transition point, which seems to go perfectly in balance with my ESX310 (a very nice speaker that resembles an Electro-Voice BTW). Unfortunately 12" speakers are not an option, I've already purchased the speakers for my little project. Thanks for the replies!