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post #1 of 27 Old 09-15-2011, 01:59 PM - Thread Starter
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Please help. I am in a local band that gigs twice weekly and we have blown a crossover inside one of our main speakers. I do realize that building my own would be the best way to go but I simply do not have the time and/or skill and need to replace it ASAP. Of course the company that makes these speakers does not sell replacement parts. Could someone please help me by telling me what I would need to buy to replace this crossover? Here are the specs on the speakers....

Dual 15" woofers
High compression titanium 25oz horn driver
Carpet finish
Steel corners & Heavy duty handles
Inputs: Dual 1/4" and Dual Speakon
Weight: 92lbs./ 41.7kgs.
Size: 48 (H) x 21.4 (W) x 20.4 (D)
Woofer Magnet: 650z
Driver: 250z
Frequency: 50Hz-21KHz
Max Power: 1000W
RMS Power: 500W
Warranty: 1 Year

Please let me know if you need more info!

PS - I do know that the crossover is a 2-way
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post #2 of 27 Old 09-15-2011, 02:17 PM
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The info provided is really of no help in determining anything useful about the crossover design or values. You'll need to pull the crossover to see what parts actually failed, and replace them with inductors and or caps of the same value. Depending on the age of the speakers, you may want to use this as an opportunity to replace all the caps as they can dry out over time, changing the values. Part Express or Madisound would be good sources for replacement electrical parts.
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post #3 of 27 Old 09-15-2011, 02:20 PM
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Hello Sir.

Typically we would need to know what the impedance each driver is, how they are wired and what the stock crossover point is on the existing crossover.

For an easier fix, I would look into some crossovers seen here:

http://www.parts-express.com/wizards...TOKEN=62831382
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post #4 of 27 Old 09-15-2011, 02:28 PM - Thread Starter
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Well, I really don't know anything about electronic components. All I can say is the 'bad' part is a long, square, white (ceramic?) block. I can tell by the brown color underneath it on the other side of the board. the ONLY info on the entire board is on that block and simply says '20W30RJ'

http://i1143.photobucket.com/albums/.../crossover.jpg
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post #5 of 27 Old 09-15-2011, 02:31 PM
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Your quickest bet is probably to have the existing crossover fixed.

Just search your local craigslist for electronics repair. Almost all cities have "that one guy" who fixes things for like $20 in his back room.
It probably just has a fried capacitor or something.

"The boom is dead, long live the bass"
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post #6 of 27 Old 09-15-2011, 02:31 PM - Thread Starter
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The horn is 8ohm and the drivers are both 4ohm
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post #7 of 27 Old 09-15-2011, 02:38 PM
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20W 30RJ is a 20 watt 30 ohm resistor.

You can either use 3 of these in series: http://www.parts-express.com/pe/show...tnumber=017-10

Or use one of these and expect to blow it again:
http://www.parts-express.com/pe/psho...tnumber=004-30
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post #8 of 27 Old 09-15-2011, 02:40 PM - Thread Starter
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So which of these Parts Express crossovers would work the best for this application if I just wanted to replace it?
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post #9 of 27 Old 09-15-2011, 03:20 PM
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Quote:
Originally Posted by warduke75 View Post
So which of these Parts Express crossovers would work the best for this application if I just wanted to replace it?
You don't want to do that because it'll be missing any padding to deal with driver sensitivity issues (like the blown resistor), impedance compensation aimed at getting flatter response (the resistor could be part of a Zobel network), or baffle step compensation (unlikely here).
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post #10 of 27 Old 09-15-2011, 03:30 PM - Thread Starter
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So replacement is not an option? I should just find someone to replace the resistor?
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post #11 of 27 Old 09-15-2011, 04:14 PM
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Quote:
Originally Posted by warduke75 View Post
So replacement is not an option? I should just find someone to replace the resistor?
I HIGHLY recommend this option over anything else.

Give us your location - if you're lucky, one of us may be nearby and can take a look at the crossover.

Or post high-rez pictures of the x-over and we'll see if there is an obviously blown cap or fried something.

"The boom is dead, long live the bass"
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post #12 of 27 Old 09-15-2011, 04:15 PM
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Awhile back I had a lighting system that wasn't working right.

I posted about it in the "help wanted" section of my local craigslist and got a couple offers overnight from local electronics techs offering to fix it for little to no $$$.
Your mileage may vary - not every tech is capable.
But I lucked out and got mine fixed by a really cool old school guy for $20.
Got to listen to some crazy Aerosmith stories from when he was their tech.

"The boom is dead, long live the bass"
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post #13 of 27 Old 09-15-2011, 04:33 PM - Thread Starter
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You can see the obvious burns around the resistor. From all of the pictures I have seen of crossovers this one looks very... should I say... 'basic'?

http://i1143.photobucket.com/albums/...1/100_3597.jpg
http://i1143.photobucket.com/albums/...1/100_3596.jpg
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post #14 of 27 Old 09-15-2011, 05:01 PM
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Hmm, can't really make it out. Does your camera have a "macro" button? That's what you enable to take close-up pics. The macro button usually has a picture/symbol of a "flower" on it.

Post up the numbers on the resistor.

Here are the Dayton resistors so you can match it up to buy one.
http://www.parts-express.com/dayton-...-resistors.cfm

While you're at the website, buy this $15 soldering kit:
http://www.parts-express.com/pe/show...number=374-100

Then watch this video that shows you how to replace a resistor.
http://www.youtube.com/watch?v=rfps0kfKWK4

"The boom is dead, long live the bass"
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post #15 of 27 Old 09-15-2011, 05:14 PM - Thread Starter
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20W 30RJ
which jzoz1 said 'is a 20 watt 30 ohm resistor'
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post #16 of 27 Old 09-15-2011, 05:16 PM - Thread Starter
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I don't see 20W 30 ohm on their site tho. Can it be replaced with something different? Like a slightly higher wattage?
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post #17 of 27 Old 09-15-2011, 05:28 PM
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Quote:
Originally Posted by warduke75 View Post
I don't see 20W 30 ohm on their site tho. Can it be replaced with something different? Like a slightly higher wattage?
30 ohm / 10 watt here:

http://www.parts-express.com/pe/show...tnumber=004-30

Unless someone else says otherwise, this is what I'd go with. I think the worst that would happen is it may not last as long as a 20W resistor.
Madisound doesn't have anything.
Digikey probably would though.

"The boom is dead, long live the bass"
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post #18 of 27 Old 09-15-2011, 05:43 PM - Thread Starter
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How about 3 - 10 Ohm 25W in series?
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post #19 of 27 Old 09-15-2011, 06:26 PM
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the math supports that, but i hope that you can see the problem...even 3 x 25 resistors is but 75 watts.

Listen. It's All Good.
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post #20 of 27 Old 09-15-2011, 06:37 PM - Thread Starter
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Haha, like I said. I'm an electronics idiot. Just looking for the best and quickest option w/o spending $250 for a new main speaker. Got 2 gigs this weekend and my little 200w peavey aint gonna work sitting next to my other 1000w main
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post #21 of 27 Old 09-15-2011, 07:27 PM - Thread Starter
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So confused now... some people say, replace the crossover, some say DON't do that. Some say run 3 resistors in series, some say DON't. Some say use a lesser wattage resistor, some say DON't. Just looking for the best course of action here guys. Again, I REALLY appreciate all the help. I'm a bass player, that prolly explains why I don't know anything about electronics....
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post #22 of 27 Old 09-15-2011, 07:37 PM
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Quote:
Originally Posted by LTD02 View Post

the math supports that, but i hope that you can see the problem...even 3 x 25 resistors is but 75 watts.

Hmm. My EE degree is over 20 years old...but I'm pretty sure that if a single 30 Ohm resistor that could handle 20W was sufficient in the circuit then three resistors that each could handle 25W would be more than sufficient. (The design max current flow through the 30 Ohm resistor would be < 1A if 20W was acceptable...so each of the 10 Ohm resistors will never have more than 10W of power across/through them...)

Boy will I be interested to hear what happens here...but I strongly recommend finding someone local who's worked on power electronics and letting them investigate and fix this. Keep in mind that the failure of that one resistor doesn't mean that all other components of the crossover were unaffected by the failure transients...it's possible that grabbing three 10 Ohm 25W resistors and soldering them in place in series will work, but what if it doesn't? At that point you'll be trying to find someone to help troubleshoot the crossover--I'd start by finding that person and getting them involved now.

Finding a random speaker crossover off the street, and putting it in an existing speaker, does not sound to me like a plan likely to succeed unless you have better documentation on the characteristics (-3 dB frequency point of low-pass filter, other filtering, etc.) of the existing one--and I don't think you're there. It's a much better bet to try to fix what you've got, since you can't buy a plug-and-play replacement. Good luck.
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post #23 of 27 Old 09-15-2011, 07:50 PM
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After looking at what's out there for resistors that really would be high enough quality for this, if you're not going to find an electronics guy and you really want a DIY solution I'd consider three of these (Mills 10 Ohm 12 W, possibly OOS until 9/16) in series. They're less than $5 each, they're designed for high-quality audio applications, and they'd provide a little additional headroom on the power handling (less likely to leave more scorch marks).

Good luck...
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post #24 of 27 Old 09-15-2011, 11:27 PM
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Quote:
Originally Posted by CZ Eddie View Post

Here are the Dayton resistors so you can match it up to buy one.
http://www.parts-express.com/dayton-...-resistors.cfm

While you're at the website, buy this $15 soldering kit:
http://www.parts-express.com/pe/show...number=374-100

Then watch this video that shows you how to replace a resistor.
http://www.youtube.com/watch?v=rfps0kfKWK4

Do this ^^

I would get three of these non-inductive 10ohm resistors and wire them in series:
http://www.parts-express.com/pe/psho...tnumber=004-10

The three resistors in series will act like a single 30 ohm, 30W resistor. In other words, it will have more capacity than the burnt resistor you are replacing. The behavior of the speaker will be the same. It will just be less likely to burn up.

I attached a before and after picture below to show how you can wire the resistors in series and place them on the board. Note that two of the connections just connect one resistor to another and do not connect to the circuit board at all. I drew them as half-circles, but you can just twist the wires from the resistors together and apply solder. Trim the excess wire and position them so that they won't touch anything metal. The other two connections (that end in a dot) connect to the circuit board just like the original resistor did.

To keep them from moving around, glue the resistors to the circuit board. This, or something like it, would work just fine:
http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053

Soldering is not hard. And the kind you need to do is as easy as it gets. You can do it. There are lots of videos you can watch to learn, but generally you just get the parts/wires in place, heat them up with the soldering iron, melt some solder on them, and then let it cool before you try to move the parts. This:
http://www.youtube.com/watch?v=1ZjdiRxr0OM

You'll need solder, too. This will work, or you can get some at Home Depot:
http://www.parts-express.com/pe/show...number=370-050

If you don't feel comfortable doing this, I bet that a friend or someone else in the band would be willing to try if you show them this thread. A first-timer can definitely do this work. It won't be hard, and you'll end up with fixed speakers and a new skill. Go for it!

-Max
LL
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post #25 of 27 Old 09-15-2011, 11:38 PM
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I just looked at the picture of the crossover again. My original layout won't fit on the board. Here's a new pic with two separate options for how you could put the three resistors in series on the board. In the second one, the three resistors are stacked on top of each other.
LL
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post #26 of 27 Old 09-15-2011, 11:58 PM
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Excellent.

"The boom is dead, long live the bass"
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post #27 of 27 Old 09-20-2011, 01:04 PM - Thread Starter
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maxcooper - Thank you so much! Going to be ordering the parts ASAP (as soon as the parts-express website comes back online).
I'm going to go ahead and order 6 for when the other main fries! I'll letcha know how it works out! Thanks again to you and everyone else!
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