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Sound issues, amp to board, (Acoustic B100c).....

S

scatman

Jun 12, 2003
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#1
Hey, guys,

While at rehearsal, last night, I got serious sound issues from my acoustic B100c, going direct into the board, from the line out jack. A sound engineer was present, and indicated that, when hearing into via headphones. And even after every little adjustment, there was either a hum in the engineer's headphones, or, when I turned on the overdrive on my amp, there were, believe it, or not, radio frequencies.

But when we went from the line out connector to plain mic'ing the amp, the engineer said the sound was much better. I have another sound check, before service, on Sunday, to confirm. This time, I've been asked to bring my Ampeg direct box (I normally don't use the DI, live) to see if I can keep the line out connection. If not, I will have to keep it mic'd.

Question: Is my B100c amp a problem? Or do I have basic grounding issues? I'm now wondering if I have to change my amp.

Oh, I alternate between a '62 Reissue P and a MusicMan SUB....
 
#2
Did you try switching the ground switch on the B100c? If it is a grounding issue that could solve it. You usually identify a grounding issue because it is a hum at 60hz. You can use a tone generator or a spectrum analyzer app on your phone to check.

If it's not a grounding issue, then there's no magic answer here. Something in your rig is creating a buzzing noise and you have to eliminate one thing at a time to find what it is.
 
#3
I agree with above and try your basic stuff first like change out the xrl, change your 1/4, make sure that the ground lift isn't engaged, try a different channel, etc before assuming it your amp/equipment. Has other amps used this power outlet and have the same problem or just yours?
 
#4
A also agree with SoCal80s but I have noticed that the DI on my acoustic B100C is quite noisy with ground lifted and unlifted. Its also a pain beacuse if you just want to record or run the signal through but not have the speaker making nose, you have to have the master volume up a bit for the DI to work, it kinda defeats the point of the DI level control
 
#7
Maybe this is / was the issue, something to be careful of is some mic cables tie pin 1 to the outer shell of the XLR connector. If the XLR connector is not insulated from the equipment chassis that can cause hum and buzz issues.
I've seen that on a fair number of import Ebay special mic cables.

I actually made a plug in tester to check for on cables and wall jacks when trouble shooting buzz and noise problems.
 
#8
scatman said:
Hey, I was looking back over this thread, and didn't respond. I had to mic the amp, as opposed to a line out. That solved the problem! No hum when mic'ing! One year later response, I know. Thanks, y'all!
Click to expand...
Update #2: Started using the Ampeg D1. Better "umph" from my amp and no longer a hum. However, just recently, a new problem: the venue brought a sound engineer to "upgrade the board." (without the musicians, by the way). "Knocked me right off of the board," which means that I'm not going through the PA. Boosting the amp, though, and everyone in the venue can hear me (that's what an Amped preamp will do!). The venue will bring the sound engineer back, to fix the problem, so I can go through the PA. I'll keep you posted.
 

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