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Speaker Noise!

Discussion in 'AV Receivers & Amplifiers' started by scaramanga, Aug 7, 2001.

  1. scaramanga

    scaramanga
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    Since i bought my Yamaha DSP-A592 (Dolby Pro-Logic AV amp with 6-ch input), I've noticed a noise coming from the centre and surround speakers, which can be heard when the system is at low volume (and even when the source is not playing). The noise is similar to the hissing/buzzing noise which you'd hear when the speakers are turned to full volume without a source actually playing (the front Left and Right channels are fine).

    I've tried using different cables, and recently upgraded my speakers but it makes no difference. I'm using the 6-ch input from my dvd player now, but the noise just refuses to go away. I had taken it back to the shop that sold it to me, and they sent it away to be tested but they couldnt find any problems with it.

    Has anyone else had a similar problem, or know how to fix it?
     
  2. bayfjord

    bayfjord
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    I have a sony strdb-930 that hum's from the speakers when the display is turned on but does'nt when off I too sent it to a sony repairer and found no problems with it,my manual states in the troublshooting not to have connecting cords within 5 metres of a tv screen is your amp near a motor,transformer or tv screen???, if you have any answers let me know and i'll do the same....
     
  3. Rob

    Rob
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    I have exactly the same problem. Since purchasing a Kef TDM23c centre.This happens as soon as I turn on my Quadscan, so the PSU is the culprit, in my case anyway. I've been told to try mains purifiers (?) As yet I haven't had a chance. If I have any luck, I'll post my findings <img src="confused.gif" border="0">

    Regards Rob.
     
  4. Guest

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    Gents, here are a few thoughts/views to your problems.<br />Mr. Scaramanga.<br />This sort of thing is quite common particularly when processors are added to two channel amps. I presume that this noise is present regardless of input status, (t.v analogue Pro-Logic and 6 channel input sources) this being the case it is most likely the simply the amp's low s/n abilities and lower spec devices on the center/surround channels if i recall correctly doesn't that Yamaha hark back to a time of reduced output for the extra channels with the bulk of the output being placed on the main stereo channels? Also bear in mind that just because Yamaha said there was no "fault" present doesn't necessarily mean that the hum shouldn't be there it just means that the unit is performing within expected operating tolerances. Given that the main channels are "better" at all times this would indicate the amp itself rather than any cable capacitance problems/ground loop noise or impedance mis-matches.<br />Bayfjord.<br />Can't really help you too much on this one it does however sound like an internal screening problem of which there is little you could do about. On your other note i use a stack of power amps which i first positioned racked up right next to the t.v the result was a huge phasing type hum (rather than the more common monotone-like 50hz hum) which i simply put down to an R.F interference inducesd into the transformers of the power amps, an integrated with alot of low level signal stuff flying around may/would suffer to at least the same/more extent. Re-sititng the racks to the other side of the room completely eleviated the problem.<br />Rob.<br />Assuming you are not simply suffering a ground loop problem (all equipment plugged into the same sockets/all equipment removed from earth or the TDM or it's cable being close or in parallel to the Quadscan/supply or output leads and all other "obvious stuff") i too suffered a similar problem in so much as i use three sub's and one (which we will equate to your TDM (is it power amp fed?) would hum as soon as 1 (a mk1, all others being mk2 etc) of the four power amps was in circuit (which we will equate to your Quadscan).<br />I will try to be brief, inherently there will be capacitance between the primary and secondary windings of a transformer, this is particularly so with toroidals, in some circumstances (especially noticable when used in conjunction/connection with other transformer driven audio equipment) this capacitance will suffer a phase shift and produce a non-linearity in capacitance phase, the up-shot of this being hum. One method of trying to reduce this (it will not or is unlikely to remove the problem entirely but may reduce the angle of phase error) is too open up the offending unit (the Quadscan in your case) and reverse the polarity of the supply side of the transformer.<br />W A R N I N G!!!!!!!!!!!!!!!!!.<br />This is possible with power amps (and was effective in my case) given they are simple devices. Speak to Quadscan technical about this first as in all honestly it is most likely that there are polarity dependant devices within the secondary winding fed side (I know nothing of Quadscans or even what they are but understand "hum-bucking") and you may cause irrepairable dammage to pc boards and the like.<br />Always reverse polarity on the transformer and not the plug top or your main switches/fuses/control circuits will be neutral switched!!<br />Mains conditioners/rectifiers - Very nice - Very big - Very Very expensive (££££'s) if you wish to rectify kilowatts to supply amps and stuff. They are still £££'s just for low power rectification 50/100 watts for dvd/processor's and other negligible current using equipment.
     
  5. saggu1

    saggu1
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    I too am experiencing noise from my subwoofer.

    I can hear a radio station from my subwoofer which is placed near my amp (not receiver) and hi-fi separates.

    Please advise on how to get rid of this sound.

    Could the solution be to move the sub away from the hi-fi??
     
  6. saggu1

    saggu1
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    soome help!!!

    <img src="eek.gif" border="0"> <img src="rolleyes.gif" border="0"> <img src="eek.gif" border="0"> <img src="eek.gif" border="0"> <img src="rolleyes.gif" border="0"> <img src="eek.gif" border="0"> <img src="rolleyes.gif" border="0">
     

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