Pa Buzz

DBTOYS · #1 07-20-2011, 10:19 PM

Have a gig comming up and i have been setting up the pa
but when i plug my ampeg direct out it makes one hell of a Buzz
so i ran it through a mic. i don't think that is proper how can i get rid of the buzz??? I have a ampeg svt 4 pro

used to have a sound guy. But now i am learning to do it

seanm · #2 07-20-2011, 10:57 PM

If there is a ground switch on the DI, try changing it.

DBTOYS · #3 07-20-2011, 11:11 PM

Quote:

Originally Posted by seanm

If there is a ground switch on the DI, try changing it.

None on the amp! or the mixer

AndreyR · #4 07-21-2011, 12:28 PM

This might not be the case, but what if its the cable that you use to connect the amp to the pa is giving the buzz?

KeithAlanK · #5 07-21-2011, 08:48 PM

Double-check the XLR cable you're using--if the wire on either pin 2 or 3 is broken, you'll still get some signal but it won't be balanced any longer, resulting in buzz.

If that checks out, plug your amp into the same AC circuit as the mixing board.

fokof · #6 07-21-2011, 10:03 PM

Try your bass in a DI , and try to remove the ground lift switch on the DI.

basey · #7 07-21-2011, 10:18 PM

I do sound quite a bit and I've noticed that this is a common problem with svt4s. I will usually get a direct signal from the bass itself from a direct box when they buzz. I don't know what causes it tho.

allexcosta · #8 07-22-2011, 05:28 AM

Your location could be playing some role on this...

DBTOYS · #9 07-22-2011, 09:19 AM

Quote:

Originally Posted by basey

I do sound quite a bit and I've noticed that this is a common problem with svt4s. I will usually get a direct signal from the bass itself from a direct box when they buzz. I don't know what causes it tho.

I have had 9 diffrent bass amps and they all seem to do it when you go direct out to the board. do the make a cable that is wired for di to pa??

fokof · #10 07-22-2011, 09:47 AM

Try a 'pin 1 lift'

Pro Co GLX XLR-F to XLR-M Ground Lifter | Full Compass

Do you have an Older board ?

Some older boards are pin 3 hot

DBTOYS · #11 07-22-2011, 09:16 PM

Quote:

Originally Posted by fokof

Try a 'pin 1 lift'

Pro Co GLX XLR-F to XLR-M Ground Lifter | Full Compass

Do you have an Older board ?

Some older boards are pin 3 hot

No its a Yamaha mg 32/14

DBTOYS · #12 07-31-2011, 11:19 PM

I have a sans amp tech 21 nyc could this work and how would i set it up with my current setup

Keithwah · #13 08-02-2011, 10:02 PM

Also this is caused most commonly due to a ground loop being present. You are drawing power from circuits that are not on the same electrical phase and/or the circuit you are plugged into could also be wired in conjunction with a ceiling fan, fluorescent dimming, etc). Now I realize many of you with "direct outs" on your amps are pretty successful very often just running the cable out of the head. Some of those heads even do have ground lifts. If that makes you 100% noise free plugged into a PA, you are now finished reading this. If it doesn't, it's because of the ground loops. Always plug you stage into the same phase as your PA. Lighting should never be on the same circuit as sound gear. No matter what, never. I suggest using a DI before your amp or after your effects chain, but unless the direct out is pre-eq, the sound guys are not getting that great a sound compared to getting the instrument before it hit the amp. What you are hearing from your rig is not really what you're sending the house using a post-eq direct out.
So yes the answer is, get a direct box.

testing1two · #14 08-02-2011, 10:22 PM

Quote:

Originally Posted by DBTOYS

I have a sans amp tech 21 nyc could this work and how would i set it up with my current setup

Yes, if you have a SansAmp BassDriver then that will do the trick. Take a 1/4" cable from the line output of your SVT4 to the input of your SansAmp and use the XLR output of the SansAmp to the PA. Make sure the "Phantom & Ground Connect" switch is off.

http://www.tech21nyc.com/support/man...Driver-OM1.pdf

TimmyP · #15 08-02-2011, 10:56 PM

The problem is a potential difference between the grounds. Being on the same phase should have no bearing on it.

Bob Lee (QSC) · #16 08-06-2011, 09:05 PM

Quote:

Originally Posted by fokof

Some older boards are pin 3 hot

There is no "pin 2 hot" or "pin 3 hot" on anything with balanced inputs and outputs. It's irrelevent to hum and buzz problems, anyway.

Use a DI and lift the ground on it.

fokof · #17 08-06-2011, 09:28 PM

Quote:

Originally Posted by Bob Lee (QSC)

There is no "pin 2 hot" or "pin 3 hot" on anything with balanced inputs and outputs.

I understand that this is irrelevent to PA buzz but what do mean by that ?

(I have hardware at home that IS pin 3 positive)

Tunaman · #18 05-19-2012, 08:37 PM

BUMP for an old thread but I had these problems today!!!

Amp on or off, instrument plugged in or not... buzz like a bastard! In fact I could plug in my rackmount tuner & get more buzz. Changing outlets changed the level of buzz from horrible to fair. Tried GND lift, different XLR cables, mute. Its not the bass PROMISE. All connections grounded with proper grounded cables & outlet tester

I ended up going direct out my wireless which was quiet... but then I would go 1/4 to my amp out of the wireless & the hum was in my cab. So it seems like grounding loop issues... voltage just trying to find a ground on different electrical circuits from PA to where I was plugged in. NOTHING I could do about it.

After reading this I feel better. I have a Sansamp & I'll ALWAYS have that from now on. Its nice to know I also have the option to eliminate it through the wireless as well. Knowing what the problem was is better as well, its not the amp. The thing NEVER EVER buzzes.

IS THERE ANY WAY TO GROUND SOMETHING LIKE THIS I"M MISSING ??