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SWR Goliath with Crackly noise at F sharp

neuro512

neuro512

Jun 20, 2008
29
12
Seattle, WA
#1
I just bought a used Ampeg SVT II Pro (which I love) but am now having problems with my SWR Goliath III. With my old amp (Ashdown Mag 600), the Goliath sounds like butter; with the SVT II, it sounds great except when I hit an F# (all of them ??!!??).
I went to an amp guy I trust and we could not find any loose connections or microphonic tubes. I plugged my rig into another cabinet and it does not make the same noise.
The speakers on the Goliath don't sound blown, and they sound great except on F# Anyone have any ideas? A loose connection in a speaker?
I searched but could not find anything like this.
Thanks!!
 
#2
Interesting.

If possible isolate the source of the noise with a mechanic's stethoscope or a vacuum cleaner hose (or some other ingenious method of your own choice) while someone else plays the offending note. Once you find that, you will be on your way to an explanation. It may be in such a weird place that, once found, the cure will be obvious.

It may be one driver or something in the cab itself, or ???
 
#5
Two other thoughts, these have happened to me in the past and drove me nuts til found. 1) A lead wire to one or the other of the speakers has slipped and is touching the back of the driver. Sometimes they vibrate around, and simulate the effect of a blown speaker. 2) A screw is loose on the driver, and a small amount of air escapes, causing an effect similar to blowing over a bottle. The resonant frequency may be F#. Can't say what for certain, but these two tiny issues have had me tearin down more than one cab, and once found what they were, felt pretty dumb. 'Course, I see myself that way a lot. Heh. Try tightening the speaker screws, evenly but not too tight, with the cab on its back. Make sure it is seated in the hole evenly, and tighten screws like you would the lug nuts on a car's wheel. This may cure.
 
#6
The Nameless said:
Can't say what for certain, but these two tiny issues have had me tearin down more than one cab, and once found what they were, felt pretty dumb.
Click to expand...
If you found them, you're not dumb. :hmm:

I got a GII from a guy who had driven himself nuts and replaced two perfectly good drivers just because he had a damaged 1/4" input jack (which is still there, BTW...I use the banana plugs).

You'd be amazed at the stuff that will cause freak noises in a simple bass cabinet -- all the ones previously mentioned and a few dozen more.
 
#7
Thanks for those words, Bongolation. I felt dumb, but you right. And, since you mention jacks, here's another idea. You mention the quarter in. jacks, I've had an issue with other cabs that the jack not bein used will fart, or let air from the cab slip through, similar to the air around the loose speaker screw. I put tape over all my unused jacks now, or plug them wit a blank 1/4" plug. Stopped all the farting. And, I got this tip from a big time pro, so know not the only one wit that problem. Thanks again, and hope all this helps.
 
#8
So it is the tweeter- tweeter all the way down, noise disappears, tweeter all the way up, noise is worse. Still only with F sharp... Should I replace it or get it reconed?? I live near OC speaker, do you recommend them or send it to SWR? Thanks for all your help.
 
#9
That it makes noise only on one note still has me puzzled, and questoning whether it's blown. I'd take it in to be checked first, if horn needs replaced, do it however is cheapest and fastest. If you just send it off, without gettin both horn AND x-over checked, you may find the new one wit same issue. Let an experieenced tech checkout the x-over and horn, and then proceed wit what's best for you. Call SWR as well. They may be able to help, and at least get you specs on what horn to buy. Then go to OC, and give them that info. See who can do work wit the least hassle on you. That my opinion.
 
#10
M'kay. Try this: turn your amp on(no bass connected), tweeter all the way up, and start cranking the volume and treble on the amp. Do you hear a hiss from the tweeter? If so it's fine. Probably a loose connection at the tweeter. F# causes the cab to vibrate in such a way as to rattle the wire, I'd guess. Remove the tweeter and check connections- I bet one is loose.
 
#11
I had a problem like this with my old SWR Goliath SR. I noticed it only started happening after I adjusted the tweeter for the first time in months. It turned out to be a dirty tweeter attenuator. I sprayed tuner pot cleaner into the attenuator (through the slight gap where the attenuator post sticks out of the cab) and turned it back and forth for a minute or so. The problem was then gone. You can buy the stuff at radioshack. I used to use it to clean dirty pots in guitars when I worked at a music store in Boston. So not sure if this is really your problem but it is useful to keep a can of this stuff around anyways.

Later,
Mike
 
#12
So I wanted to give an update. Thanks to everyone for their advice. I tried you suggestions and the tweeter does seem to work. We thought it was my G&L L2000, but when I plugged in my P bass, it did the same thiing. I contacted SWR who were prompt but recommended I take into OC speaker. Finally, I was able to reproduce the same crackle with the Ampeg SVT 2 pro on another cab (without a tweeter).
So I took it back to the amp guy, who again, could not get it to make the same noise (on top of an Ampeg 8 x 10). Maybe I was just hearing things??!!??, but my wife, the professional violinist, also heard it. He suggested starting to replace the tubes.
So I traded in the Ampeg for a Traynor Dynabass 800H, which I really like. I wish I could say that the story ends here. Last night, at practice I blew one of the SWRs 10 inch speakers. I was using my P bass and the amp settings were about the same as when I practice at home. I was singing through a PA in the practice space that was facing us. There was some feedback then that big, bad noise.....I have been playing, on and off since college (many years ago) and have never blown a speaker.
I had the distortion on slightly on the amp and the limiter and compression were off...which I won't do again. Besides telling me I am an idiot (which I already know), what can I do to avoid this? Any advice on settings, or how to set up the PA? I'm planning on getting the speaker reconed.
 
#15
Yeah, thanks. Low mid was too high, while the rest were flat. No bass boost, but a scoop control. Does a scoop control just cut mids, or does it also boost low?

Finally, which is better for the speakers: gain high with a lower volume or lower gain and a high volume?
 

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