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Speaker Problem


John Tweed

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I have a Behringer K3000FX amp and recently the 15 inch speaker in it has started cutting out intermittently, while the high frequency horn continues to work. Generally it seems to misbehave for about 5 minutes when I turn it on, but then work flawlessly for the rest of the gig. I've checked the wiring for loose connections and they all appear fine, so I strongly suspect the speaker. However I can't personally recall one behaving this way - usually they sound horrible or just stop working altogether. I don't want to replace the speaker just to find out that it was something else - the crossover maybe.

 

Has anyone experienced speaker failure like this?

 

 

 

Legend Soul 261, Leslie 251, Yamaha UX1, CP4, CK61, Hammond SK1, Ventilator, Privia PX3, Behringer 2600, Korg Triton LE, VB3M, B3X, various guitars and woodwinds, drum kits …

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The fact that after some time it stops misbehaving makes me suspect the amp. I would be it's biamped and that the low frequency amp is the culprit.

 

Another possibility if it IS the speaker is the wires that go from the speaker termials to the cone. These get a lot of abuse and can intermittently open - typical fail point is at one end or the other. Send a test tone to the speaker then wiggle the wires with your finger and see if it cuts out. I've had this happen to a few speakers and have had mixed results fixing it. But again, if this were the cause, cutting out would be completely random and not only when first fired up.

Dan

 

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.

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This keyboard amp isn't biamped.

 

Here is the manual: KLONK

 

Check the speaker terminals for a loose-fitting connection.

 

If everything looks tight, then connect a spare speaker to the output wires from the crossover. It doesn't have to be a 15" woofer, you can use just about any speaker if you don't play it too loudly. Try it. If it doesn't stop working, chances are that you have an open circuit within the voice coil of your 15" woofer.

 

However, if it does stop working, there may be a loose connection or solder joint in the crossover. Usually, the crossover circuits in these amps aren't very complex. You should be able to trace the problem with a volt/ohm meter.

 

Good luck!

 

Tom

 

 

 

 

 

"Music expresses that which cannot be put into words and that which cannot remain silent." - Victor Hugo
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This happened to my keyboard amp about 15 years ago. Sometimes it would go out during the middle of the gig and other times on startup for about 10 minutes then "kick in". It turned out to be the connection to the speaker (the attaching female clip of the wire that attaches to the speaker's male connector). Although it appeared to be firmly connected it wasn't. I took a pliers and crimped the wire clip onto the speaker connector very tightly then soldered it for good measure. Never happened again after that. Since the horn was a piezo tweeter that was "tapped" from the same connector it caused both the 15 and the piezo to go out.

57 Hammond B3; 69 Hammond L100P; 68 Leslie 122; Kurzweil Forte7 & PC3; M-Audio Code 61; Voce V5+; Neo Vent; EV ELX112P; GSI Gemini & Burn

Delaware Dave

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Good post, Tom.

 

Might be a cold-solder joint: one that looks good, but where the solder isn't actually bonded to one of the conductors -- just pushing against it. These will be intermittent, and are often temperature sensitive (thus working fine once it warms up).

 

After doing what Tom suggested, if you haven't found the problem, try using a can of compressed air or canned coolant and directing that at different solder joints while the speaker is playing (not loud), and/or press gently on each solder joint with a small screwdriver or probe.

 

If it's the voice coil, some voice coils are removable/replaceable. Sometimes the coil filament is broken between the coil and the connector, in which case you can sometimes remove one wrap and resolder it. But usually in that case it's not intermittent.

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Thanks for the suggestions, everyone. I haven't been able to identify which component is failing - moving the amp around or wiggling the wires while listening to a test tone, tapping the crossover and connection points, tapping the amp. It has continued to misbehave even more than before, but still not failing completely.

 

I was really hoping to be able to pin it down to the speaker, in which case I'm confident about replacing it myself. Anything more complicated and it'll have to go to the tech, and there's no point in sending it there until it has stopped working altogether.

 

In the meantime I need to get an alternative. I've been planning to get a powered speaker, QSC K10 or similar, mainly to cut down on the weight. It's overdue really, since I've spent the last couple of years selling off or decommissioning extraneous speakers and amps to the point where I no longer have a spare. QSCs seems to get a lot of love hereabouts, but my budget is closer to Behringer, so I have some research to do.

 

John

 

 

Legend Soul 261, Leslie 251, Yamaha UX1, CP4, CK61, Hammond SK1, Ventilator, Privia PX3, Behringer 2600, Korg Triton LE, VB3M, B3X, various guitars and woodwinds, drum kits …

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Thanks for the suggestions, everyone. I haven't been able to identify which component is failing - moving the amp around or wiggling the wires while listening to a test tone, tapping the crossover and connection points, tapping the amp. It has continued to misbehave even more than before, but still not failing completely.

 

Did you try our suggestions?

 

My bet is that it is either an open circuit within the voice coil of the woofer, or a cold solder joint in the crossover or wiring to the woofer.

 

Moving the amp around, wiggling the wires while listening to a test tone, tapping the crossover and connection points, and tapping the amp are not the same tests.

 

 

"Music expresses that which cannot be put into words and that which cannot remain silent." - Victor Hugo
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Not all as yet as I'm away for a few days. I have a JBL D140 speaker which i'm on the verge of selling, and which would be suitable for the test as suggested by Tom. Alternatively i'll just swap it in and see how it goes. My only concern is that the JBL is 8 ohms and the Bugera is 4. I figure that should be ok unless it somehow causes problems for the crossover.

 

As i have a gig next weekend where i'm playing keyboard bass, i need to be sure i have a reliable amp, so i'm going to buy/borrow/hire something else in any case. Normally i don't carry a backup amp - i carry spare cables and always two keys - as i figure in the event of the amp going down on the gig i'd just go thru the PA. However that wouldn't work too well for the bass.

 

John

 

 

Legend Soul 261, Leslie 251, Yamaha UX1, CP4, CK61, Hammond SK1, Ventilator, Privia PX3, Behringer 2600, Korg Triton LE, VB3M, B3X, various guitars and woodwinds, drum kits …

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  • 2 weeks later...

Update: looks like it must have been the speaker after all - I swapped my old JBL D140 in and the amp didn't miss a beat on the two gigs I did on the weekend. With the 8 ohm speaker instead of the original 4 it semed to need to be turned up a bit more, and went into distortion a bit more easily, which is as I would have expected, given the power available would be less. I was almost at the point of selling the JBL off - good thing I didn't.

 

John

Legend Soul 261, Leslie 251, Yamaha UX1, CP4, CK61, Hammond SK1, Ventilator, Privia PX3, Behringer 2600, Korg Triton LE, VB3M, B3X, various guitars and woodwinds, drum kits …

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