D.I.Y. cab attenuator question

etherealme · #1 05-01-2010, 10:03 PM

Spent quite some time doing research here and there. Before I bite the bullet (no pun intended, ha!) I'd like to get some feedback on weather this is the proper application, i.e. an acceptably good idea. Any feedback is welcome!

So, I have a few plywood cabs about 23"x 18" x 36" which have worked well for me with 15" woofers in 'em.
I've been upgrading one and thought about adding a crossover with hi freq attenuator.

I'll be using this exclusively with Genz Benz 750 which is rated 400w @ 8 ohm. I've been looking at these eminence cabinet ready crossovers which are rated precisely at 400w rms and 8ohm.

http://www.usspeaker.com/px-ii5k0-1.htm

and coupled with the appropriate tweeter http://www.usspeaker.com/SUPERTWEETERS-1.htm combo I should be up and running no problem, yes?

Here's a relevant thread : DIY Advice needed: jackplate/attenuator?

My questions are: Am I interpreting these specs correctly to assume I can run 400w from the amp with the 8ohm woofer I'm using and the 8ohm tweeter of choice and be fine?

I'm assuming the crossover makes the pairing of tweeter with woofer a cinch? Is this application that straight forward? Hook up tweeter and speaker to appropriate crossover connections and bam?

The woofer is rated at 600w, but that'll just give me more headroom, correct?

Thanks!

AlexanderB · #2 05-02-2010, 02:16 AM

Many builders do not use a crossover for the woofer but just let it receive the full input. Most 10"-15" woofers in bass cabinets have very little natural output in the range the tweeter is working anyway. However, using a real lo/high crossover will certainly not be a disadvanage in any way.

The Eminence super tweeter is anything but "eminent"... It is actually one of the worst HF units I have heard, but it will still add some high end sizzle to a non tweeter cab. (I bought two compete APT-200 units to get the biradial horn that is not sold separately. I removed the APT driver to use some good HF drivers in the horns and it works really well.)
Picking an "drop in" crossover will only get you so far and the sound will also be very different depending on which horn you select.
But as I said, there will be sound and it will not burn up if properly hooked up and powered.

/Alexander

billfitzmaurice · #3 05-02-2010, 09:25 AM

Don't use a tweeter, use a midrange driver. Tweeters leave an octave wide hole between where the woofer leaves off and the tweeter starts, and midranges go as high as you need to go. See the fEarful threads on how it should be done.

etherealme · #4 05-02-2010, 12:31 PM

Thanks for the input, guys. I really appreciate it. I have looked and read up through a lot of the fEarful threads but it's nice to get direct advice for my particular set of circumstances.

I have used these cabs with great success allowing the full input to go to the speaker, but this time around I suppose I was just interested in trying something new. More hi-fi.. like my bass sounds through the yamaha pa. I figured I could always tweak the high end down either onboard, with the amp eq, or with the attenuator; it'd be nice to have the option up top for certain scenarios.

Alexander: I wasn't actually considering the eminence tweeters at the top of that page but the beyma cp22 http://www.usspeaker.com/beyma%20CP22-1.htm
or the B&C ce35 actually. http://www.usspeaker.com/B&C-DE35-1.htm
I suppose if their tweeters are lacking then you're not recommending the eminence crossover either, correct?

The Radian 324/215 sounds pretty awesome. Being that there's no picture or detailed desciption, i'm not completely sure what's included with it. Does it have a cabinet ready plate with input jacks, or do I use my own? I'm thinking it must if it has " Attenuation & Equalization". Not sure it's just the circuit board and components of the crossover with wire, etc. ???

And thanks, Bill. This is a concern I actually left out of my OP but I was curious about. I did notice the frequency gap when looking at the response specs of both the speaker and the tweeter.
Ok. I suppose I was looking at the ease of dropping in a bullet tweeter without having to design/install a baffle between where the midrange driver would go. Will I need to separate air space between the mid and the 15"? Obviuosly, it'd be better in doing so, but could I get away with having the mid in the same air space, so to speak?

AlexanderB · #5 05-02-2010, 01:42 PM

OK - that´s a different story!

Funny enough, the drivers that I use with my Eminence APT-200 horns are actually Beyma drivers! They sound very good.

Bill has a point in adding a mid instead of a horn, but I can imagine you wanting to try something else. It is your application we are talking about, right?

A dedicated mid can not share the same volume as you have for the woofer. There are mid range speakers with a sealed design, with a back plate that is isolating the cone. Those can be dropped into any existing sealed or bass reflex cabinet as long as there is room in the baffle.

The bullet tweeter will not work too well, I guess. Recommended cross over is 5kHz. Up there you will not find much signal from a bass guitar. However, a large format PA horn with a good 1" driver can be crossed over at 1,5-2 kHz and work very well with a 15" woofer. It will be both a mid and tweeter in your application.

Good luck!

billfitzmaurice · #6 05-02-2010, 04:00 PM

Quote:

Originally Posted by etherealme

Will I need to separate air space between the mid and the 15"? Obviuosly, it'd be better in doing so, but could I get away with having the mid in the same air space, so to speak?

You can with a sealed back mid, like the Alpha 8MR or the Alphalite 6 CBMR. Otherwise a separate sub-enclosure is a necessity.
BTW, the 'hole in the mids' you saw looking at the axial charts is misleading. Off-axis, where most of the audience is, the useful output of a fifteen drops off on average an octave lower than on-axis.

I wouldn't run a fifteen in a direct radiating alignment higher than 1kHz.

etherealme · #7 05-02-2010, 05:41 PM

Ok. I'm sold on the mid driver angle. Don't mind installing an enclosure for the mid or using the sealed back design either. That side is covered for now (in concept). And I suppose if I'm mainly concerned with with 500Hz to 5kHz (or 7-8kHz even)
the closed back driver should be (more than) adequate, yes?

Any thoughts on the other crossovers available and how they're intended to be installed? In other words is the Radian 324/215 just a board, components and wires coming out to hook to the speakon jack, then woofer and mid driver. i don't mind contacting a rep to find out more about the product but seeing as any of y'all may have experience with these particular units, I'm asking here first.

Quote:

Being that there's no picture or detailed desciption, i'm not completely sure what's included with it. Does it have a cabinet ready plate with input jacks, or do I use my own? I'm thinking it must if it has " Attenuation & Equalization". Not sure it's just the circuit board and components of the crossover with wire, etc. ???

Once again - thanks!!!!