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Pacifica Pre noise/hum - Grounding issue? Condenser Microphones
Old 12th September 2007
  #1
Gear Addict
 

Question Pacifica Pre noise/hum - Grounding issue?

I've had a pacifica pre (great pre) for not too long and sometimes I get some nasty noise and hum that slowly builds up until it becomes extremely loud.

I'm sure many of you have had this problem at some point yet I can't find the right thread dealing with this issue. I've had this problem before and it would go away by turning the power on/off on all my units. I think that plugging the pre to a different outlet also helped. Now that I moved to a new place I can't get rid of it.

I'm using the API Lunchbox Power Supply for the Pacifica Pre. I wonder if this could be part of the problem since all the other slots are empty. Also, I have one of those power supplies that keep your computer running when the power goes off. If this is pertinent I'll let you know which one I have and how much power.

I believe this is a common grounding issue. If this question has been asked several times before let me know where I can find the answer.

Thanks guys
Old 12th September 2007
  #2
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daillman's Avatar
i own the pacifica and have not had this issue(yet)but i know the guys at ad do answer the phone and are very helpful
Old 12th September 2007
  #3
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Quote:
Originally Posted by DreamSound View Post
I've had a pacifica pre (great pre) for not too long and sometimes I get some nasty noise and hum that slowly builds up until it becomes extremely loud.

I'm sure many of you have had this problem at some point yet I can't find the right thread dealing with this issue. I've had this problem before and it would go away by turning the power on/off on all my units. I think that plugging the pre to a different outlet also helped. Now that I moved to a new place I can't get rid of it.

I'm using the API Lunchbox Power Supply for the Pacifica Pre. I wonder if this could be part of the problem since all the other slots are empty. Also, I have one of those power supplies that keep your computer running when the power goes off. If this is pertinent I'll let you know which one I have and how much power.

I believe this is a common grounding issue. If this question has been asked several times before let me know where I can find the answer.

Thanks guys



Dear DreamSound,

Quick but maybe a stupid question.......why would you use an API Lunch Box to power the Pacifica?

Peter
Old 12th September 2007
  #4
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e-cue's Avatar
 

I assume you mean the P1. I suspect dirty power. Have you used any other modules in the api rack? Tried a ground lift? Checked your studio power?
Old 12th September 2007
  #5
Gear Addict
 

Question

Peter, first I love your company, I'm a lifetime customer. Second that was not a stupid question. I actually started a thread about comparing the API Lunchbox to the A-Designs 500 Pwr Supply a while ago:

Why pick A-Designs A500 pwr. supply over API Lunchbox??

I chose the API because of the extra slots that will hopefully be filled in one year with all of your products.

Apparently (after all), the issue is not just with the Pacifica Pre but it started today for a few seconds when I was doing vox takes with the console's pres.

I do have a APC Back-UPS with Surge Protection. This may also be 'caused by the M-Audio Sputnik Mic I'm using (which has its own power supply)

e-cue, I don't have other modules on the API but at this point it is not related to the module or the Pacifica.

How can I do a ground lift? How does grounding works? What am I looking for when doing a power check on my studio?

Thanks again
Old 12th September 2007
  #6
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e-cue's Avatar
 

OT, I suggest you list your generalized location. If you were local, I'd offer to let you drop by my studio and plug into my API rack to see if the problem persists.

Quote:
Originally Posted by DreamSound View Post
How can I do a ground lift?
Put this 50¢ guy on your 3 prong ac cable.

These are also sometimes called "Earth lifts".

Quote:
Originally Posted by DreamSound View Post
How does grounding works? What am I looking for when doing a power check on my studio?

Thanks again
This is a bucket of worms.

Basically, a buzz has more harmonics than a hum, and those harmonics extend to a higher audible frequency. A hum is usually a 60 cycle funk (in the US) that contains harmonics in the 120 Hertz., 180 Hertz, 240 Hertz and Hertz rental cars. Sometimes you can call your local power company and they can figure out if the problem is your wiring (most likely) or them (highly probable if you live in the Lost Angeles area). I'd start with a ground lift. Try different ac outlets. Then try a barrel audio isolation transformer or "hum removal" device for starters. If that still doesn't help, switch cables with ones you know are good.

I'm sure some electricians could shed way more light on this than I could dream of. Speaking of, do you happen to have light dimmers in your control room?
Old 12th September 2007
  #7
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nosebleedaudio's Avatar
 

Don't lift the AC ground, lift or cut the sheild on pin 1 on the output, the male XLR, if that's what your using to get out of the pre.
Unless you have REAL AC problems I would never use a UPS to drive gear.
Seen too many have problems and most don't have CLEAN AC out.
This is why I have a ground lift on the pres I build...
Is it only on the Pacifica?
I thought the Pacifica ran on +-28Volts.
The Lunch box is +-16volts.
Old 12th September 2007
  #8
Gear Maniac
 

Quote:
Originally Posted by Peter Montessi View Post
Dear DreamSound,

Quick but maybe a stupid question.......why would you use an API Lunch Box to power the Pacifica?

Peter
Uhhh Is it becuase has the P1 pre which is a 500 series style that works specifically with an API lunchbox?

There's even a pic of it in an API lunchbox on the A design site.

http://www.adesignsaudio.com/p-1_emseries.htm

scroll down.
Old 12th September 2007
  #9
Registered User
 
Rick Sutton's Avatar
 

Quote:
Originally Posted by stickers View Post
Uhhh Is it becuase has the P1 pre which is a 500 series style that works specifically with an API lunchbox?

There's even a pic of it in an API lunchbox on the A design site.

http://www.adesignsaudio.com/p-1_emseries.htm

scroll down.
I think Peter may have been saying "You are powering the rackmount Pacifica preamp with a lunchbox?". The Pacifica and P1 are related but not the same and sometimes people do try to do some pretty strange things.
NOT "Why are you using another companies product to power mine"
Old 12th September 2007
  #10
Gear Maniac
 

Yeah but come on, it's pretty obvious he's talking about the P1. The Pacifica 2 channel pre has a built in power supply.
Old 12th September 2007
  #11
Gear Addict
 

Yes, it is the P1 and I think what Peter meant was why having an API Lunchbox if I'm only using one slot. Again, I'm hoping my lunchbox will look like that pic soon: A-Designs Audio: Quality without Compromise. For the finest in all tube microphone pramplifiers (mic pre), direct boxes, passive line level control, tube EQ and more!

... but have to fix the grounding issue first.

OT and nosebleedaudio thanks for the options, I'll start trying those as soon as I install my new Dual-Quad Xeon Sonica PC I got today

I feel so sluty... heh
Old 13th September 2007
  #12
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ulysses's Avatar
My money's on a bad capacitor in the API power supply. The best way to find out would be to try other modules in the same lunchbox.
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