Bottlehead Forum
General Category => Technical topics => Topic started by: ttucker329 on September 08, 2013, 03:58:34 AM
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I didn't know where to post this. I have a subwoofer marketed under the klipsch brands. 800watt powered sub that is a low profile design. It worked fine for about 2 weeks then it developed this roaring sound when it received a signal. I was playing with the phase controls and also received a mild shock. I am hoping to salvage this subwoofer, but I don't really know where to start. Anyone have any ideas of what to check? Possibly just some bad wiring or a board component? I'd appreciate any input.
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Start by removing the amp from the cabinet.
Try powering the woofer from a different amp, even a $5 thrift store receiver will do. Just make sure that there aren't any odd scraping noises. Also, meausre the DC resistance between the two wires going to the woofer (should be 4-8 Ohms).
If the woofer is OK, then pop the cover open on the amplifier and look for things that are out of place. In particular, look for caps that are bulgy or leaky, as well as for resistors that are burned or completely blown out!
There's also the slight chance that there are four wires leaving the subwoofer, and that they connect to at least three very distinct places on the board. If this is the case, some additional testing will need to be done.
-PB
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Thanks for the tip. The speaker itself appears fine. I has to be something on the amp board. I didn't see anything obvious so I guess this will go on ebay as a part out.
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If you like the sub and want to keep it just look for a plate amplifier from somewhere like Parts Express. If you can't find one that fits the cabinet opening you could mount it in a Bottlehead like case (like Clark does for the Orca subs) and run speaker wire to the sub. Just a suggestion.
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Here's what I would do Tuck... Can I call you Tuck?. If you like the cabinet - It sounds like a good one. Get rid of the driver and the amp. Like others have said, get a new sub-woofer driver and an amp from Parts Express. I would stay away from the plate amps. I have gone through 2 of them. Get a Crown. Not much bucks. It will blow away anything you can buy retail. From Parts express I would recommend their Titanic Mk4. I have one.
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I never thought abouth that. I'll take a look and see what I can find
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Here's dumb question of the day:
How much effect does the "cone" have on the sound of a subwoofer? I have a Atlantic Technologies model 262PBM that I'm currently using as my sub with my orcas and stereomour. It's probably a 10 year old, 250w unit. The cone was pushed in by some ornery 2 year old. This happened a few years ago and I haven't used it prior to hooking it up to my BH.
I've been using it for a few weeks and the bass is not that crisp. It's better than no sub, but not anywhere close to great. I have no idea if it's due to the cone being pushed in, or simply because it's a very average sub. I suspect this sub was much more designed to go "boom" for movie explosions, as opposed to being designed for crisp musical bass.
I've been eyeing the new dungeoness sub to mate up with my orcas, but this thread got me to thinking: The most expensive woofer on Parts-Express is $300 or so....many are in the $200 range....and even more are priced less than that. Would it be well worth my time to do as Eric suggested for this poster's dilemma? Meaning replace the subwoofer driver with a new one? In an extreme case, I could even replace the built-in plate amp if it was not optimally designed.
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There's a big difference between a dust cap being damaged and a cone being damaged.
Typically the dust cap is the part that gets pushed in, and that's not exactly the end of the world.
If the cone is pushed in, that can have unfortunate consequences on the suspension.
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oops, sorry, not the cone. It is the dust cap "dome" in the center.
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I recommend one of these. Great for music and movies.
http://www.rythmikaudio.com/F12G.html (http://www.rythmikaudio.com/F12G.html)
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As a fan of servo technology for subs, this one looks to be even more useful with addition of a parametric EQ.
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oops, sorry, not the cone. It is the dust cap "dome" in the center.
You can cut the dust cap off with an hobby knife and glue on a new one.
If you glue on a metal one, perhaps you could connect it to the mains to keep the kids away.
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;D
one touch and he would never do it again.
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My Phoenix friend. Do NOT be afraid to HACK out that old driver and put an new one in... You will be surprised. Nothing to it. Try to get a replacement that fits it exactly, but thats not even that important. Whether it fits into the countersunk spec or not is not a biggie. My last driver is glued to the outside lip of the driver hole. Just glue it GOOD with some high power shit. Modern drivers are frickin heavy. Good performing stuff though. I think I spent $175 on my driver and about $250 on the crown amp, run in bridged mode gives me a bit over a 1KW. Kicks ass.
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Yea, these Subs are more for explosions than music.
Eric makes a great point of replacing the driver. rip the old one out and measure the inside of the box, best you can and if it has ports or not. Maybe we can suggest a different driver to try, something less output, more musical...John
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It is tempting....It would be cool to upgrade this on my own.
I removed all screws from the driver, but it's also clearly glued. Not sure what to do to pry it off. The amp plate removes easily in back. I decided to leave it alone, unpowered, until morning to avoid electrocution risk. 8)
I suppose I'll try a gentle putty knife maneuver around the edge of the driver in the a.m. to see if that pops it loose. If it will come off, it should be a very simple replacement.
BTW, I mistyped earlier....the amp is 150w, not 250.
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Your plate amp is solid state. Speaking of a "standard" power supply, not a switching power supply, few of them have high voltage in the power supplies. Look at the voltage rating of the power supply capacitors. If they are 60V or lower, jump in.
A putty knife or a big flat bladed screwdriver would be good tools to gently pry the sub loose.
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well, that was simple. Driver popped right out.
Sub box is un-ported/vented.
14.25" tall,
19.625" wide
13" deep.
These are outside dimensions. Wood is .75" thick. Fiberglass-type insulation inside.
The subwoofer driver measures 12.0625" wide, outside edge. It drops into a hole cut-out measuring 10.875". Eight screw holes on the driver.
The specs on the amp and crossover show a working frequency range from 20Hz to low pass filter setting up to 125Hz
It has a continuously adjustable low-pass filter from 60Hz to 125Hz. The only impedance number I can find is 10ohms....?
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So far so good, 10 ohms would not be an unusual number. My math GUESS is that cabinet is a little over 1 cubic foot. Now I'm thinking that a suitable driver would have the needed parameters to work in this size enclosure. I usually just go to the Theil/Small specs of the driver, where a useable sized enclosure may be given. So far, you have an idea of the impedance,driver size, enclosure size,frequency parameters(not necc frequency response) and power handling of the old driver. Using just that much will get you a good start down the right path. Spelling might be off, but Madisound sound has a number of possibilities that will also help you narrow down your choices. Then of course the price limits will further dictate the rest.
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I'm curious, did it have two or four wires going to the woofer? If four it has a servo circuit.
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Greg; thanks I'll check it out! Thanks!
Grainger, just two wires.
Thanks guys.
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Yep.. like Granger says .. some voice coils are wired in such a way that you can power them with a 2 channel amp. 2 - 4ohm voice coils. Easier on the amp than a 2 ohm load. Its good to buy the amp and driver together to maximize the compatibility. I dont have a dual voice coil driver. Its something to consider though.
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I get 1.5 cf, that is a little big for the driver I was thinking of.
I bet if you call PE or Madisound, Hey I got this box with this amp, looking for music, explosions, not so much. they will hook you right up
they're tech guys, they live for this :)...John
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I'll be making some calls tomorrow. Thanks!
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I'm just sayin...
dust cap (http://www.parts-express.com/pe/showdetl.cfm?partnumber=260-379)
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I had no idea that you could buy them.
Interesting!
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It is certainly easier to reduce the volume of the box than to increase it.
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I'm just sayin...
dust cap (http://www.parts-express.com/pe/showdetl.cfm?partnumber=260-379)
gosh, $1.68? that's far too cheap and easy. ::)
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I'm not sure if this makes a difference, but I have seen some dust caps that allow air flow, while others don't. It probably has something to do with a vented pole piece, point being replace like with like.
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Cool thing about PE drivers - they give specs on each driver on cabinet size, ported/sealed or both, etc. Frequency response, efficiency, power handling etc. What was iinteresting for me, was that my HSU 12" sub that I bought many years ago (a round one) had a very efficient 12" that produced low bass (down to 20hz) very well, but broke up and got muddy in the 30hz range. I still use the same cabinet today, have cycled through several woofers in there. What I have 'settled' on is a good high power handling driver that goes 'low'. I havent measured it, but prob rolls off in the low 20's, but has good punch in the 30's for those transients that we all like. It wont rattle the window with pipe organ stuff.