Power Line Pollution & Ferrite Beads

[rjb]

I really should know the answer to this, but I'm a dummy:

Say a solid state amp and an Ott lamp are plugged into the same electrical outlet or power strip.

Say that turning the lamp on causes the amp to buzz,
regardless of the distance or orientation between the amp and the lamp,
and regardless of whether an instrument is plugged into the amp's grounded input.

Might using a "ferrite beaded" line cord, or installing a super-duper line filter in the amp, tame the buzz?

Thanks,
-rb

[soundguruman]

Palomar Engineers | RFI Kit
It depends on the frequency of the interference...the kit contains several different beads, and a manual about how to use them.

Basically if the components in the amp (such as ceramic disk capacitors) are in the 60 cycle field, the frequency will enter the audio path, and then will be amplified... so the components in the pre-amp may have to be upgraded, like changing ceramic disk to silver mica.
A power filter does nothing to prevent that scenario, only modifying the components.

Also as far as the guitar, humbucking pickups are the only solution.

[doctor]

I really should know the answer to this, but I'm a dummy:

Say a solid state amp and an Ott lamp are plugged into the same electrical outlet or power strip.

Say that turning the lamp on causes the amp to buzz,
regardless of the distance or orientation between the amp and the lamp,
and regardless of whether an instrument is plugged into the amp's grounded input.

Might using a "ferrite beaded" line cord, or installing a super-duper line filter in the amp, tame the buzz?

Thanks,
-rb

I do not know what the Ott lamp is, but if it is a fluorescent lamp, it is a source of the problem.

This lamp itself together with build-in power supply is the source of two types of interferences: radiated emission and conducted emission.

The first type represents electromagnetic waves traveling through space. It depends on the orientation. The second type represents parasitic currents traveling through mains wires and this is your case.

Any officially manufactured consumer electronics must pass special EMC tests and has certificate confirming that their emissions level does not exceed limit allowed by the standard.

Your lamp generates interfierences above this limit. It may be just out of order. It may be manufactured by irresponsible manufacturer or home-made without needed preventive measures.

What is the solution after all these explanations?

The best way is to replace this lamp with another one from well known manufacturer. There is high probability that new device passed all needed EMC tests. In this case you eliminate the source of interfierences and all peripheral devices (not only amplifier) will work properly.

If it is impossible, use isolation transformer and/or special line filter before amplifier’s line transformer.

[rjb]

I do not know what the Ott lamp is, but if it is a fluorescent lamp, it is a source of the problem....
The best way is to replace this lamp with another one from well known manufacturer....

I meant to say "OttLite". FWIW, OttLite is a well-known manufacturer of over-priced "full spectrum" florescents.
My local community college uses them in their electronics labs.

I don't need to run the amp and the lamp on the same circuit; I was thinking in terms of "If I can bullet-proof the amp against line noise at home, then I'm less likely to run into problems when I don't have control over the environment." If I could do that by, say, cannibalizing a power cord from a computer monitor, it might be worth the effort.

However, my GF just took the lamp for her new office. Since I'm not going to buy another OttLite just to use as a noise generator, it's all become a moot point.

Oh well,
-rb

[soundguruman]

I have read complaints about these lamps before. They seem to have a solid state ballast that generates a lot of hash noise.
I think all of these lamps do the same thing, noise wise.

[doctor]

I have read complaints about these lamps before. They seem to have a solid state ballast that generates a lot of hash noise.
I think all of these lamps do the same thing, noise wise.

If you, rjb, are thinking that "If I can bullet-proof the amp against line noise at home, then I'm less likely to run into problems when I don't have control over the environment", you’re wrong.

You don’t know environmental conditions and for this reason it is impossible to make preventive measures against interferences of unknown nature, level and frequencies.
You will need struggle with interferences on the spot.

This is exactly why the standard exists. Equipment complying with EMC standard generates interference below allowable limit and has immunity against interferences sufficient up to this limit.

BTW, ferrite beads can help you, only if you know frequency of the interference. Physical mechanism of the ferrite bead filtration is based on the resonance absorbtion at the material spin precession frequency. Clearly that the band of this action is very narrow. In order to expand frequency range manufacturers of ferrite beads use mixture of different materials, but even in this case in order to choose an appropriate ferrite you need to know approximately frequency of the interference.

[soundguruman]

I think what the Doc is saying, that the filters work at "only" some frequency.
If the filter is the wrong frequency it won't be working for you.

And what I was trying to say is that electrical fields around the amp can penetrate right into the audio wiring.
"then" you hear the buzzzzzzzz

So, some of this comes from the electricity, some of it travels through the air, like radio.

[rjb]

I think what the Doc is saying,...
And what I was trying to say is ....

Thanks for breaking it down into "electronics for dummies" language. ;^)
Thanks to your input, I think I'll just leave the amp as is for now.
-rb