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Old 01-29-2015, 03:33 PM   #41
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Quote:
Originally Posted by dmxtothemax View Post
For this application we do NOT want a isolation tranny We want a filter choke !

So....how do we install this filter choke?

One large filter choke in line? Appliance cord on the line side and receptacles on the load side?

Four smaller chokes installed inside the cabinets?

Rabbit ears?
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Old 01-29-2015, 06:24 PM   #42
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A filter choke is wired in series with the hot line.
Two wires
1- Hot in
2 - Hot out

No neutral involved.

It's that simple !

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Old 01-29-2015, 06:28 PM   #43
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Originally Posted by metalpats View Post
does it hum everywhere or is it just in one particular place, does it hum only when it is pluged into your mixer or if they are alone and powerede they humm ?
Well off topic !
There are no hum problems
read all the posts

now we got tangents off our tangents.

No hums
no earth lifting
no isolation required
what is required, is inductive filtering
A K A - "Filter choke"

And an isolation transformer will do that just fine.
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Old 01-29-2015, 07:01 PM   #44
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Quote:
Originally Posted by dmxtothemax View Post
A filter choke is wired in series with the hot line.
Two wires
1- Hot in
2 - Hot out

No neutral involved.

It's that simple !


Got it.

A) Large filter choke (5 plus amps to be safe) for the entire system.

B) Four small filter chokes (1 amp to be safe), one in each powered speaker.


This will 1) eliminate buzz and 2) Allow the use of a GFCI protected circuit?



Quote:
And an isolation transformer will do that just fine.
I'm back to confused. I'm just going to let it buzz and trip
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Old 01-29-2015, 07:54 PM   #45
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Connected to the mixer or not, the hum/buzz is the same. The buzz part may be the 60 cycle thing. I can't count that fast but it sounds like what I have occasionally felt.

The hum/buzz is the same when connected when plugged into the same circuit as the mixer.

Removing the ground(s) has no effect.

Both sets (mains and subs) are acting the same way when hooked up independently.

My other system (almost the same) has always had almost zero noise.

I still can't help but think the hum/buzz is connected to the GFCI tripping thing.
That leaves a few possibilities:

1: Since we know grounding is not the issue, that means the new gear is just noisier than your old gear (what makes/models are the old gear?)

2: The next biggest cause of hum/buzz in audio gear has to do with cables on the audio side. Are you using unbalanced 1/4" cables, or balanced XLR mike cables for interconnections between the mains and subs? Are they good quality cables?

(Unbalanced cables have two conductors, signal and ground with the ground also acting as the shield. Balanced cables have signal + signal - and shield, and have better immunity to noise.)

Finally, all audio cable should be routed as far as possible from AC mains cables, or if they must cross they should cross at the shortest possible path and at as close to a 90 deg angle as possible.
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Old 01-29-2015, 11:29 PM   #46
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I know it's not audio cable related. I have a handle on that stuff.

Old gear is Mackie 3 way powered amps (1530).

New gear (mains) is the basically the same MAckie 3 way powered amps (1532) with two 15's instead of one. New gear also has 18" powered subs.

All pieces have the same buzz. It's just more noticeable in the mains because of the frequency.

And, the buzz isn't horrible, it's just there. It's probably no more annoying than this thread
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Old 01-30-2015, 07:42 AM   #47
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Quote:
Originally Posted by 220/221 View Post
I know it's not audio cable related. I have a handle on that stuff.

Old gear is Mackie 3 way powered amps (1530).

New gear (mains) is the basically the same MAckie 3 way powered amps (1532) with two 15's instead of one. New gear also has 18" powered subs.

All pieces have the same buzz. It's just more noticeable in the mains because of the frequency.

And, the buzz isn't horrible, it's just there. It's probably no more annoying than this thread
Because it's buzzing with no cables attached other than power, none of the fixes mentioned will help. Did you buy these new? I would contact Mackie and see what they have to say about the GFI issue.
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Old 01-30-2015, 12:16 PM   #48
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They are not new. I demoed them when I bought them but I can't say for sure if the buzz was there.

I'd contact the dealer or Mackie if they were new but I know that it's my responsibility when I purchase something from Craigslist.

They sound freaking great but if I can find a fix, I will attempt it. I am not going to start throwing hundreds of dollars at it unless I know it will work.

I think I will open them up and poke around, like when your vehicle breaks down What's the worst that can happen
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Old 01-30-2015, 03:38 PM   #49
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They are not new. I demoed them when I bought them but I can't say for sure if the buzz was there.

I'd contact the dealer or Mackie if they were new but I know that it's my responsibility when I purchase something from Craigslist.

They sound freaking great but if I can find a fix, I will attempt it. I am not going to start throwing hundreds of dollars at it unless I know it will work.

I think I will open them up and poke around, like when your vehicle breaks down What's the worst that can happen
The fix in this case may be simple, but you have to know how to solder and work on printed circuit boards.

The odds are very good that there are bad capacitors in the amplifiers. There is a forum that deals with that: http://www.badcaps.net/forum/index.php?

An example of bad caps on a power supply board from that forum:




Note the bulging tops on the blue and brown components. Sometimes there will also be a crusty brown or yellowish "ooze" coming from the tops or bottoms of the bad caps.

Capacitors in power supplies and audio gear are used for filtering and elimination of hum, and coupling of audio signals while blocking DC currents.

Changing bad ones can be done, but it takes some practice and care to avoid causing further damage.

Too bad you are not local I could fix those for you at very little expense.

Oh, and the worst that can happen is you can get knocked on your azz..switch mode power supply caps store very high voltages and currents.
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Old 01-30-2015, 03:43 PM   #50
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Still though, I'm sure Mackie technical support could help. Ask them straight up if these models are known to trip GFI breakers. The answer will give you some direction.
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Old 02-01-2015, 09:23 PM   #51
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I agree with MX, he knows audio. Just of 📝 note in case you do it, a 480 to 240 transfomer will work fairlly well on 240 to give 120, however the kva halves in that the winding size is designed around half the current and in turn I2R losses double, so the current cant exceed what it normally would at 480 volts.

Sent from my Android Device
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Old 02-02-2015, 09:37 AM   #52
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Connected to the mixer or not, the hum/buzz is the same. The buzz part may be the 60 cycle thing. I can't count that fast but it sounds like what I have occasionally felt.

The hum/buzz is the same when connected when plugged into the same circuit as the mixer.

Removing the ground(s) has no effect.

Both sets (mains and subs) are acting the same way when hooked up independently.

My other system (almost the same) has always had almost zero noise.

I still can't help but think the hum/buzz is connected to the GFCI tripping thing.
Its sounds like you are dealing with a ground loop somewhere in your sound system. You are having AC current on the grounded shields of your sound wiring.

First, find your piece of equipment which is doing that by trying 'Ground Lift' on each instrument.

Second -- In my 30+ years of being a sound technician coupled with 45+ years of being an electrician, I have found the best way to have clean sound is to have your mixer, instruments and amps on the same circuit, or if the load is too much for 1 - 20 amp circuit, at least make sure the circuits are on the same phase. (I actually hook up a 60 amp 2 pole breaker using only one leg -- run to a 12 circuit panel with both phases hooked to this one supply to run my sound system -- no hum since it's all on the same phase and the ground loops are gone.)

Bottom line -- make sure your mixer and amps do not have AC on the shields. (There can be enough current there to trip a GFCI)
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