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Pioneer VSX-AX5Ai - A "pop" sound when startup

Discussion in 'AV Receivers & Amplifiers' started by felix_li, Feb 9, 2005.

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  1. felix_li

    felix_li
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    Hi Fans,

    I've a Pioneer VSX-AX5Ai which has 2 sets of speakers connected:
    1. Elac 5.1 (as speaker A)
    2. Celestion 2-channel (as speaker B)

    Everytime I switch on my amp. with speaker A as default or when I switch from speaker B to A, there will be a "pop" sound coming out from the Elac (no pop sound if I switch on with speaker B). It's quite annoying and also my worry is, in one day I will find either or both, the amp. and the speakers are burnt out.

    What I know is that these 2 speaker sets have difference in impedence, Elac is 6 ohm and Celestion is 8 ohm. I don't know what's happening :confused:

    Can anyone help? Thanks in advance.
     
  2. felix_li

    felix_li
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    Hi,

    Would anyone help me in this? Please...I'm really worrying :lease:
     
  3. The Hemulen

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    A quick way to see if it's an impedance or other Eltax speaker related issue would be to try briefly swapping them over so the Celestians are now on A and eltax on B. See if it 'pops' when switched on with B speakers now. If it does then you know it's the Eltax's it's not happy with for some reason.
    Other things to check are..
    If it does it with Eltax's on their own, ie no celestians connected?
    Is the 'pop' coming from all speakers? Just the fronts or just one of the fronts?
    Does it only do it the once after switching the amp on? Or every time you swap to and fro the speakers?
    If you have access to a digital multimeter, check to see if there is any significant DC voltage across the speaker terminals with the Eltax speakers connected, the amp on but no music being played. You can expect to see a certain amount maybe up to 100mV or so DC. If it's much more than this then there might be a prob with the amp. Try it with the Celestians and see if it's different. (reason for checking this is that if there is a DC voltage then you'll only hear it when first switched in although DC offset problems sound more like a 'click'.)
     
  4. felix_li

    felix_li
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    Hi Posh Bloke,

    Thanks for your reply. The sound is only from Elac and I have changed the impedence and seems like the "pop" sound is now turning to "click".

    I will borrow a DC meter from my fan in the next couple of days and have a check.

    A quick one, is the small DC a normal one or is a problem in amp. or a problem in amp./speaker matching?

    Anyway, thanks!!! :thumbsup:
     
  5. The Hemulen

    The Hemulen
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    100mV would be pretty high by modern amplifier standards. It should ideally be as low as possible and any remaining is due to tolerances of the components, transistor matching within the amplifier etc.
    If for some reason the speaker (and to some extent speaker cable if it's a bit exotic!) is upsetting the amp then it might be causing some instability and effecting it. With a quality amp like yours though I'd doubt it.
    If you are near to your dealer rather than an online purchase I'd give them a ring and take it round to try back at the shop with some other speakers.
     
  6. felix_li

    felix_li
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    Hi Posh Bloke,

    Thanks you very very very much!!!
     
  7. felix_li

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    Hi Fans,

    Got a digital meter and have some interesting findings...
    1. With the AC unplug and all the cables connected, there's always a constant 1.1V DC and 10mv AC across the Elac speaker posts whilst the Celestion is 0.
    2. With all the cables disconnected, there's around 500mv DC and 3mv AC across the Elac speaker post whilst the Celestion again is 0.
    Seems like the speaker itself behaves as a battery :eek: Is it something related to the magnetic shielding (or poor-design shielding)? Can anyone help?
     
  8. The Hemulen

    The Hemulen
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    ??? Something very strange going on here.. If you have the amplifier switched off then I'd assume the amp's relays to the speakers to be open..
    What is the Voltage with the amp switched on (volume at zero) and speakers selected?
    Try it again with only the speakers connected to the amp. ie remove all input connections from DVD players, CD's etc (even if they are switched off)
     
  9. felix_li

    felix_li
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    Hi Posh Bloke,

    Will try but need some time to disconnect all cables and probably come back with the result in 2-3 days.

    No wonder there's a pop sound, for sure the Elac & Pioneer connections are being offset by something.

    Anyway, thanks again for your reply :)
     
  10. felix_li

    felix_li
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    Really weired :confused: :confused: :confused:

    Let me described what's happening in these few days...
    I've disconnected all cables but the voltage differences and were still there. I'm really frustrated but suddenly a strange thought came to my mind :cool: if there's a voltage, then I can use it, e.g. lighten a bulb or something. So, I connected a 1.5v light bulb across...it really light up but then blown. I then connected a 12v computer fan across...it really rotate and then slow down. But strange things happened then...the voltages acrossed are all gone, now is only 1-2mv but they used to be 0.5, 7V and even 10V. (I'm so afraid to see 10v across and so only keep the volume as "---")

    The weired thing is that after I "discharge" the speakers, the pop sound is gone as well (I did use the amp several times and it's normal now).

    But I want to ask here...will a wrong impedence "charge up" the speakers??? Because I also have an 8ohm Celestion speakers connected. What will happen if the amp. is set to 6 ohm and the speakers are 8 ohm?

    Appreicate if someone can help.
     
  11. The Hemulen

    The Hemulen
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    There is (or perhaps now, was..) something very wrong with your amplifier. If it is still under warranty then it really is time to get it back to the dealer to be looked at.
    No speaker (8 or 6 ohm) should create the effect you have seen.

    Richard

    ps I really wouldn't mention anything to the dealer about connecting bulbs and fans to the output!! They will no doubt suggest you damaged it by doing so and invalidated the warranty.
     

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