Crazy 8 tweeter replacement

rippingglass

rippingglass

Mar 4, 2006
10
1
4,551
Portland, OR
www.blacktangerinemusic.com
#1
I have blown my tweeter on my Crazy 8. I purchased this used so I am not sure of the original source. I need to replace the tweeter and the mounting bracket (it's cracker). Does anyone know what type of tweeter this is and where I can find a replacement? (See attached pictures)
IMG_8721.jpg
IMG_8722.jpg


I have also found that pulling the 8" speaker out to get to the tweeter is very difficult. It's built super tight and I am afraid of breaking something pulling it out so any recommendation is appreciated.

Thanks!
 
#3
Note that I don't think you should need to get the woofer out, in order to access the tweeter. I'd see if the tweeter pulls out far enough to access the connections without disturbing the woofer. Don't lose track of plus and minus when you disconnect the wiring.

You can also sometimes get in via the jack plate, at least to see what's going on in there and decide how to proceed with the repair.

I've had situations where a woofer seems like it's stuck, because the gasket has bonded itself to the woofer and box. It can sometimes take a little bit of persuasion to get a woofer out, and of course it has to be done with extreme caution in order to avoid warping the frame or sending a tool through the cone. So it would be preferable to leave it alone if possible.
 
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#4
DukeLeJeune said:
Looks to me like an Eminence APT-80. I think that is the standard tweeter for Crazy 8 and Crazy 88.

http://www.eminence.com/pdf/APT80.pdf

I don't think you'll have much trouble finding one online.
Click to expand...
How would you cross it over? Just curious. I have a DIY cab with that woofer, not as well engineered as the Crazy 8, but quite handy for jazz combo gigs.
 
#5
I do think, as you say: " the gasket has bonded itself to the woofer and box"

The tweeter hole is so small it looks like the tweeter was inserted from the back and the bracket was inserted from the front and attached together with a pipe clamp. Once I get the tweeter I will look at is closer and see if there is some way to get the tweeter through that darn hole at some angle. Thanks for the feedback, I hope I don't need to pull that woofer.
 
#6
You could try the Greenboy forum. There are some authorized builders here, but you'd be going to the source if you asked the question there. You may even get a response from the builder of your exact cab.
 
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#7
fdeck said:
How would you cross it over? Just curious. I have a DIY cab with that woofer, not as well engineered as the Crazy 8, but quite handy for jazz combo gigs.
Click to expand...

I'm not a fan of the APT-50 (the compression driver in the APT-80 driver/horn combination unit) nor of the sharp-edged "lip" of the APT-80S (the conical horn in the APT-80).

Unfortunately I am no good at armchair-quarterbacking highpass filters for compression driver and horns. At a minimum, I would use a second-order highpass filter; a first order filter will fail miserably to adequately suppress the compression driver's output at resonance, causing coloration and poor power handling. Assuming you decide to trial-and-error it, remember to try both polarities for the compression driver, as it's hard to reliably predict from a distance which polarity will actually end up being "in phase" with the woofer in the crossover region. It's a lot easier to trial-and-error a second-order filter versus a third-order filter. If you get peaking from the compression driver in the crossover region, try reducing the value of the series capacitor and/or add a damping resistor (a few ohms) in series with the shunt inductor.

A damping resistor in series with the shunt inductor will help minimize the impedance dip that the amplifier sees in the event of "blowing" the compression driver. I use them all the time for that reason even if they're not "needed", but then I have a fancy modeling program that does a pretty good job of calculating the predicted response so I can "trial and error" a lot faster using the program.
 
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#9
The Eminence APT80 is a decent, cost effective part, and quite a step up from piezo tweeters. The Apt 80 performs well provided that it is used within its bandwidth and power handling limits (http://www.eminence.com/pdf/APT80.pdf). Thanks to its phenolic diaphragm, it avoids the harshness and metallic edge typical of cheap titanium drivers. It's principal limitation is low end extension. The horn loads the driver effectively to about 1.6 kHz, so it needs to be crossed over an octave higher: 3-3.5 kHz. Eminence recommends a 12 db/oct high pass filter at 3.5 kHz (http://www.eminence.com/pdf/Eminence_HornFlares.pdf). For most bass drivers there will be a hole in response between woofer and tweeter. This is not likely the case in a Crazy 8 or 88.

In this case, a replacement diaphragm, or a complete new unit could be installed. There is not much difference in cost. The crossover in this cab has been designed specifically for the two drivers being used. Replacing the APT80 with something else would require a new crossover design, unless optimum results were not desired.
 
#10
Looks like an early one of mine. Indeed it is the apt80. The woofer likely has a bit of a bond with the speakers gasket. To get it out---you have to be careful. I think that it's a composite cab. Take out all of the screws. Then use a very small flat screwdriver ( 1/8") and go in each hole and pry up a bit. While the cab is composite, there is a ring of 1/4" baltic birch that it attaches to. You won't hurt the birch by prying this way. Can't remember the crossover--it's been a while. I hate that tweeter. It sounds ok, but is heavy and is prone to breakage where the driver screws on. I've built a few 88's (didn't call them that!) where I used the Ciare tweet that I'm fond of. Sounds better and the cab lost a pound. The APT80's are cheap at Parts Express.
 
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