
	Where results make sense

Topic: Mains hum

Related Topics

Rattle and Hum

Venus Hum

The Humming Bird

Hums of the Lovin Spoonful

Humming Bird Soft

om mani padme hum

Van der Hum

Hummingbirds Venus Hum

Switched on Christmas Venus Hum

Humming Bird Records

Ho Hum

In the News (Fri 1 Jan 10)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Mains hum - Wikipedia, the free encyclopedia
		Spectrum of mains hum at 60 Hz Electric hum, mains hum, or power line hum is an audible oscillation at the frequency of the mains alternating current, which is usually 50 or 60 hertz depending on the local electric utility configuration (see Mains electricity).
		This hum is generated by oscillating electric currents induced in sensitive (high gain) audio circuitry by the alternating electromagnetic fields emanating from nearby mains-powered devices like power transformers.
		This hum is usually at the second harmonic of the power line frequency (100 Hz or 120 Hz), since the heavy ground currents are from AC to DC converters that rectify the mains waveform.
	en.wikipedia.org /wiki/Mains_hum (478 words)

	Pickup (Site not responding. Last check: 2007-10-21)
		For a scene which is filmed after the main production of a film has finished and which will be edited into the rest (commonly called a "pickup"), see film theory.
		Mains hum consists of a fundamental signal at a nominal 50 or 60 Hz, depending on where you are in the world, and usually some harmonic content.
		The changing magnetic flux caused by the mains current links with the windings of the pickup, inducing a voltage by transformer action.
	bopedia.com /en/wikipedia/p/pi/pickup.html (463 words)

	Pickup
		Mains hum consists of a fundamental signal at a nominal 50 or 60 Hz, depending on where you are in the world, and often some harmonic content.
		Thus, any hum or other extraneous noise that is picked up is immediately cancelled out, while the musical signal is reinforced.
		A pickup is a scene which is filmed after the main production of a film has finished and which will be edited into the rest.
	www.ebroadcast.com.au /lookup/encyclopedia/pi/Pickups.html (263 words)

	[No title]
		Mains cables and adapters cause noise hum/noise when they are too close to audio cables, or even audio units, such as wah wahs.
		If mains and audio cables have to cross, make sure they do this at a 90 degree angle.
		Paying extra attention to the correct phase of your mains cables is something not many people do, simply because they don't know or don't believe.
	www.tubefreak.com /humnoise.htm (876 words)

	Repair Briefs 2
		Hum for only about a third of full range of vol control,when present it is constant volume regardless of vol setting.
		Technics SU V5 amp Dead unit The mains fuse next to the voltage selector switch was blown.Access this pcb by removing the single screw on the base of the amp and sliding the pcb off the pins of the mains transformer.Fuse knocked out because one of the two 8200uF,56V smoothing caps was s/c.
		The mains transformer for the logic is pcb mount type so shock loading had snapped one of the primary wires near the mounting pin.This equipment failed earth-bond safety test.
	www.divdev.fsnet.co.uk /repair2.htm (17606 words)

	Guitar - Wikipedia, the free encyclopedia
		The strings may be plucked using either fingers or a plectrum (Guitar pick).The sound of the guitar is achieved either mechanically or electronically, forming two main categories of guitar: acoustic (mechanical amplification) and electric (electronic amplification).
		Some guitars need a battery to power their pickups and/or pre-amp; these guitars are referred to as having "active electronics", as opposed to the typical "passive" circuits.
		The main purpose of the bridge on an acoustic guitar is to transfer the vibration from the strings to the soundboard, which vibrates the air inside of the guitar, thereby amplifying the sound produced by the strings.
	en.wikipedia.org /wiki/Guitar (7181 words)

	Master Plan Audio Diary
		Mains hum could also be useful as it is relatively stable over periods, but the absolute change in pitch is smaller than at line frequency so differences are more difficult to detect.
		The main audio was then fed through the signal path of the compressor and post-filtered to remove the mains hum.
		Notch filters were employed to remove scan whine and mains hum where necessary, some roll off at each end of the frequency spectrum helped with hiss and rumble, and a general eq curve closer matched the sound to the original recording.
	www.purpleville.pwp.blueyonder.co.uk /rtwebsite/masterplan.htm (11526 words)

	PLL Hum Cancellation Circuit
		Normally this is useful for DHT amplifiers with AC operated filaments, as even with a hum balancing potentiometer, there is a residual hum component at twice the line frequency that is unavoidable, even with perfectly filtered HT voltage.
		I've reported a hum cancellation circuit (here) that provided improvement in hum performance of many DHT circuits.
		A main level control and a set of 8 amplitude-phase controls is used for the channel.
	members.aol.com /sbench/humbal2.html (767 words)

	Drawmer - 1961 Manual
		The mains fuse should be a class 3, 250 Volt, Time delay type, with a body size of 20mm x 5mm, at the correct rating for the mains input voltage.
		In addition to tube circuitry being used in each of the four main equaliser bands, a further tube amplifier is included in the output stage which may be deliberately overdriven to achieve the warm, detailed sound of vintage classic tube designs.
		Mains hum in the UK and Europe has a fundamental frequency at 50Hz and harmonics at 50Hz intervals stretching up throughout the audio spectrum.
	www.drawmer.com /op1961.html (3354 words)

	Power Supply Wiring Guidelines
		The safest is an IEC mains connector with integral fuse holder, as it is impossible to access the fuse while the lead is inserted.
		The ideal mains switch is a double pole switch, to ensure that both active and neutral leads are disconnected when the power is off.
		The mains safety earth must be connected to a separate bolt, whose sole purpose is to provide a solid earth connection to the equipment chassis.
	sound.westhost.com /psu-wiring.htm (2417 words)

	Colors of noise - Wikipedia, the free encyclopedia
		This fl noise is like the so-called fl light with frequencies too high to be sensed, but still capable of affecting the environment.
		AC-powered appliances can give off a characteristic hum at multiples of the frequency of AC power that they use.
		It is very different from all the other examples on this page, in that it has a very specific spectrum: 50 or 60 Hz (depending on the local power frequency) plus harmonics.
	en.wikipedia.org /wiki/Colors_of_noise (1356 words)

	HTGuide Forum - HT_ADDICT: How long ago did you buy your RMB-1095?
		Some people have reported a grounding problem with the 1095 that causes a hum that can't be resolved using the tradional techniques which points to the grounding topology used in the 1095 being somewhat more sensetive to the ground.
		NB: The easy test for mains noise vs. ground loop is to disconnect the RCA or Balanced inputs from the 1095 (or 1090 or 1080), leave it plugged in to the mains and the speakers.
		If you still get a hum into your speakers even when you remove the RCA inputs from the RMB-1095 and it is only connected to the speakers - then you probably have mains noise related hum (which will be fixed for many people through the latest updated ground plane on the amplifiers).
	www.htguide.com /forum/printthread.php4?t=1726 (2775 words)

	HS-2 Hum-Stop Hum Eliminator
		The HS-2 Hum-Stop is a custom-wound "hum-bucking" coil intended to reduce the level of mains hum acquired by video cables linking areas or buildings with differing earth potentials, and in any situation where long video cables (over 5 metres) pick up induced mains hum.
		It is a passive device which eliminates up to 15 volts of superimposed or induced hum, yet it is virtually transparent to the video signal.
		The small size and robust packaging make the HS-2 suitable for studio and OB applications, and a rack adapter is available for rear-of-rack mounting of up to 4 coils.
	www.vtx.co.uk /video/hs2.htm (98 words)

	Alternating current (Site not responding. Last check: 2007-10-21)
		However high voltages also have disadvantages, the main ones being the increased danger to anyone who comes into contact with them, the extra insulation required, and generally increased difficulty in their safe handling.
		From a three-phase main board both single and three-phase circuits may lead off (and in some cases also circuits with two phases (not to be confused with two-phase) and a neutral are led off).
		To illustrate these concepts, consider the 240 V AC mains used in the UK (it should be noted that the UK is now officially 230 V +10% −6% but in reality voltages are still closer to 240 V than 230 V in most cases).
	alternating-current.iqnaut.net (1968 words)

	Camcorder advice from Spalding Camcorder Club
		Any interfering signal such as mains hum will affect both wires (the ground and the signal wire) equally, but of course the ground is fixed to, err, ground, so it can't carry a signal.
		Loudspeaker cables will pick up hum (as will any cable) but the voltages driving the speaker are far higher than the hum so it will not heard.
		Of course the two signal cores will still pick up mains hum and other interference, but because the hum will appear as two signals in phase, (I.e., they are both going positive at the same time - Hey Presto, they cancel each other out in the differential amplifier.
	www.lance.co.uk /scc/balanced.htm (996 words)

	DHT Filament Hum Cancellation
		Directy heated triodes (a.k.a DHT) with AC-fed filaments are prone to generate unfiltered residual 120Hz (in counties with 60Hz mains) hum, as sjown in [].
		The hum is most troublesome in in low-power single-ended triode (a.k.a SET) amplifiers working with high-eeficiency speakers.
		If 120Hz hums is a property of Directy Heated Triodes (DHT), how about cancelling the noise of one with the noise of another.
	www.geocities.com /dmitrynizh/dht-filament-hum-cancel.htm (573 words)

	HTGuide Forum - Calling RB1080 owners
		The humming is most likely due to your cable TV connection (try disconnecting to see if the humming stops) and there are many good ground loop isolators available to cure the humming problem without running any risks.
		This is particularly evident as a possibility given the strange hum / hiss behaviours as various elements of your HT equipment are plugged in or earthed / not earthed.
		A mains leak on your earth wire (can be from within your house or even a neighbours house since you share a common mains earth!) Currents here of a few volts can do bad things for hum and his and I have seen up to 220V in some cases!.
	www.htguide.com /forum/printthread.php4?t=169 (2721 words)

	4QD-TEC: Touch operated switches
		Not as reliable as mains hum since skin resistance varies wildly from person to person and also depends on the person's age and emotional state, as well as on the atmospheric humidity.
		Main problem is the time delay as heat flows from a finger to the semiconductor, so more of an interesting idea than a practical solution.
		The main problem is the time it takes for a finger to warm up the diode.
	www.4qdtec.com /tchsw.html (923 words)

	Signal Detecting Auto Power-On Unit
		Use an approved mains outlet if the unit is to be used as a peripheral device to existing equipment.
		The terminal marked "A" is the active or hot mains lead, and as seen goes to the transformer (via the fuse) and to the normally open switching contacts on the relay.
		The neutral lead is connected to the transformer, and to the outlet (lower three connections on the left of the diagram).
	sound.westhost.com /project38.htm (1630 words)

	Using Spectrum Lab for reception of natural radio
		If the frequency deviation of the mains frequency (from the "nominal" value) may be larger in your country, try to increase the frequency range passed to the peak_f function.
		Another alternative is to activate a second hum filter in the second DSP flbox in a signal processing branch (the one close to the output, near "L4" in the circuit window).
		After removing hum and other kinds of unwanted signals, the "remaining" effective voltage is usually much less than the total signal at the input.
	www.qsl.net /dl4yhf/speclab/natradio.htm (2469 words)

	SARL Council Advisory Forum - Interesting Receiver Problem (and solution)
		But there's a high-pass filter with a cutoff frequency of 6 MHz between the T/R switch and the receiver, which should have clobbered any mains hum that came from the antenna side.
		The transmitted signal was inaudible as it was at precisely the same frequency as the receiver was tuned to (zero beat).
		However the driver and final run directly from the 13.8 volt supply, without an onboard regulator, and the output signal was being amplitiude modulated by mains hum on the supply lead.
	www.sarl.org.za /forum/topic.asp?ARCHIVE=true&TOPIC_ID=244 (536 words)

	Turntable To Amp Set-Up For Low Hum And Noise
		That is exactly what causes hum if you place a turntable too close to something containing a transformer - like an amplifier for example, and even worse, one of those open frame valve amplifiers that offer a big fat zero when it comes to electro-magnetic screening.
		Most hum problems are fixed in seconds by the skilled installer simply pinching in the outer contacts of the phono plugs.
		And since the customer will usually hear hum for the first time when the phono preamp is connected, it will then be blamed as the culprit.
	www.gspaudio.co.uk /faqs/noiselessphono.htm (2466 words)

	duplexnoise (Site not responding. Last check: 2007-10-21)
		Mains hum is the curse of audio engineering.
		A fluorescent tube is a column of gas which is being ionized by the 50Hz mains supply, thus it flashes 100 times a second.
		The end result is that at some points in space we find 'hum spots', similar to 'null' spots caused by multipath.
	www.mwc.co.uk /duplexno.htm (392 words)

	Suggested enhancements for the Teac DVB300 - DTV Forum Australia
		Also, what about them fixing what sounds like mains hum, when the unit is powered down (but still connected to a powered up amplifier etc.).
		Poor earthing can cause hum, but it typically arises when there is a difference in the earth potentials (impedance difference) between the two points that the equipment is plugged into.
		I'd be interested to know if powering the unit down causes a mains relay to drop out, such that it somehow disconnects the earth (dunno why this would be done though, normally the active, and sometimes the neutral too, is disconnected).
	www.dtvforum.info /index.php?showtopic=3384 (1174 words)

	The ModularEEG Design
		Because it is faint, the signal can very easily drown in noise, particularily 50/60Hz hum from the mains which is transmitted capacitively (i.e by an electric field) from the wiring in your house.
		This ensures that a large percentage of the mains hum never enters the system, because the level of the mains hum on those two locations is essentially the same.
		The purpose of the DRL is to reduce common-mode signals such as 50/60Hz mains hum, by cancelling them out.
	openeeg.sourceforge.net /doc/modeeg/modeeg_design.html (3432 words)

	Q: How can I stop mains noise in my studio once and for all?
		If there's still more hum than you expect, it might be due to a nearby 'line-lump' power supply, in which case, you should move this as far as possible from audio cables, and at the very least try rotating it to find the 'quietest' position.
		If there is, it's generally because you've just created an earth loop — the amp/speakers are already earthed via their mains cable, and the mixer is earthed in exactly the same way, so when you connect the two with an audio cable its screen connection completes the loop, causing unwanted earth currents to flow.
		However, if your mains power is 'generally dodgy' it may pay you to have an electrician check your house wiring, and contact the local electricity board to have your incoming mains checked for quality.
	www.soundonsound.com /sos/jul05/articles/qa0705_1.htm (1574 words)

Try your search on: Qwika (all wikis)