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What is this and what does it do to prevent hum/buzz/noise?

Chinese finger torture - It's for torture, obviously.
- 1 (5.3%)
Stops electrical system noise from getting into your power amp
- 4 (21.1%)
Stops electrical noise inside your amp from getting out into the electrcial system
- 2 (10.5%)
Stops Triplen Harmonic Current Buildup in 3-phase electrical systems
- 2 (10.5%)
Prevents radio signals from getting into your sound system
- 10 (52.6%)

Total Members Voted: 19

Voting closed: September 30, 2013, 01:31:36 pm


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Author Topic: Name that gadget  (Read 10014 times)

Mike Sokol

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Name that gadget
« on: September 23, 2013, 01:31:36 pm »

Take a look at this handy gadget. They only cost a buck or two, but can not only help improve your sound system, it can also help prevent an entire building's electrical system from burning up.



So what is it and what does it do? There's actually two correct answers (maybe three) but one of them is its most important function (IMHO).

I'll post the answer next Monday.
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John Roberts {JR}

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Re: Name that gadget
« Reply #1 on: September 23, 2013, 01:49:29 pm »

I've never seen one that big.. But I don't work with that kind of stuff.


JR
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Corey Scogin

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Re: Name that gadget
« Reply #2 on: September 23, 2013, 01:52:20 pm »

They help attenuate noise that may be carried through the cable to which they attach.  That noise may be from a device, the electrical system, or noise picked up from the environment where the cable is acting like an antenna.  I'm guessing they are most effective at attenuating higher frequencies...outside the power 50/60 hz range or the audible range of < 20 kHz ?
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Greg_Cameron

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Re: Name that gadget
« Reply #3 on: September 23, 2013, 01:55:30 pm »

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gary makovsky

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Re: Name that gadget
« Reply #4 on: September 23, 2013, 01:55:44 pm »

Take a look at this handy gadget. They only cost a buck or two, but can not only help improve your sound system, it can also help prevent an entire building's electrical system from burning up.



So what is it and what does it do? There's actually two correct answers (maybe three) but one of them is its most important function (IMHO).

I'll post the answer next Monday.

AC line Ferrite filter for blocking noise on incoming power. Usually a last minute fix required to prevent EMI for FCC or UL compliance.  As far as preventing a building system from burning up ???? Not sure how RF energy put back on a AC line could do that.
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Mike Sokol

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Re: Name that gadget
« Reply #5 on: September 23, 2013, 04:21:24 pm »

As far as preventing a building system from burning up ???? Not sure how RF energy put back on a AC line could do that.

I know this is true because it happened to me where I worked in the 70's. This was in a million square foot warehouse with a 100,000 square foot production floor. Took out the entire electrical system, and the plant was was down for days with hundreds of exploded bulbs, ballasts, and electrical controls. 

Hmmmm..... How could this happen???  ;D

The little gadget shown above might have made a difference.

I'll give you all a hint: Triplen Harmonics....  ::)
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Greg_Cameron

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Re: Name that gadget
« Reply #6 on: September 23, 2013, 07:08:31 pm »

I know this is true because it happened to me where I worked in the 70's. This was in a million square foot warehouse with a 100,000 square foot production floor. Took out the entire electrical system, and the plant was was down for days with hundreds of exploded bulbs, ballasts, and electrical controls. 

Hmmmm..... How could this happen???  ;D

The little gadget shown above might have made a difference.

I'll give you all a hint: Triplen Harmonics....  ::)

Triplen harmonic frequencies are well below the RF range in 3 phase power systems, . I don't see any evidence that ferrite beads of a conventional nature are able to operate anywhere near there. And the most problematic harmonics are the lower frequency harmonics closest to the fundamental.
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Mike Sokol

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Re: Name that gadget
« Reply #7 on: September 24, 2013, 04:38:58 pm »

Triplen harmonic frequencies are well below the RF range in 3 phase power systems, . I don't see any evidence that ferrite beads of a conventional nature are able to operate anywhere near there. And the most problematic harmonics are the lower frequency harmonics closest to the fundamental.


That's true, but I have one report of an office building full of desktop computers with switching power supplies that burned up the neutral bus via Triplen harmonics. It's not just 3rd order harmonics, but also 5th, 7th, 9th, 11th, 15th, 19th, 21st etc... I don't think there's a top end to it.

Some of these harmonics are created primarily by variable speed motor controllers, some by Thyristor light dimmers, and some by inverter power supplies in computers. I've just begun to think about modern power amplifiers with switching supplies. All of these odd-order harmonics can be additive on the neutral of a 3-phase power system rather than subtractive and can cause trouble with neutral overheating. 
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TJ (Tom) Cornish

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Re: Name that gadget
« Reply #8 on: September 24, 2013, 05:16:47 pm »



That's true, but I have one report of an office building full of desktop computers with switching power supplies that burned up the neutral bus via Triplen harmonics. It's not just 3rd order harmonics, but also 5th, 7th, 9th, 11th, 15th, 19th, 21st etc... I don't think there's a top end to it.

Some of these harmonics are created primarily by variable speed motor controllers, some by Thyristor light dimmers, and some by inverter power supplies in computers. I've just begun to think about modern power amplifiers with switching supplies. All of these odd-order harmonics can be additive on the neutral of a 3-phase power system rather than subtractive and can cause trouble with neutral overheating.
According to this: http://www.csgnetwork.com/harmonicscalc.html the 15th harmonic of 60Hz is only 960Hz.  I find it hard to believe there's substantial power at harmonics much past the first few cycles.

I spent some time chasing down the 1500KHz radio station in some signal wiring of my house.  It took several turns on a ferrite with the lowest operating frequency I could find to knock it out.  Pretty sure the attenuation of my ferrite beads would be very close to 0 at 1KHz or less.

PFC power supplies make a difference as they make the load appear to be closer to linear, reducing the potential for triplen issues.  All of the servers at my company have PFC supplies, and most of our desktops do too.  I don't think there's been much progress on dimmers - sinewave dimmers are still rare and expensive.
« Last Edit: September 24, 2013, 05:28:30 pm by TJ (Tom) Cornish »
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Greg_Cameron

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Re: Name that gadget
« Reply #9 on: September 24, 2013, 05:52:01 pm »

Also, the triplen harmonics generated by switch mode supplies have rapid energy drop off as you go up in harmonic order/frequency. The following is a typical graph:

.

So even if you could get a ferrite bead that would get down into the upper end of the audible band, it's not going to do much good unless it can work down to a pretty low frequency.
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Cameron Pro Audio

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Re: Name that gadget
« Reply #9 on: September 24, 2013, 05:52:01 pm »


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