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Help. Channel imbalance

Discussion in 'audio' started by Chris, Nov 10, 2019.

  1. Chris

    Chris pfm Member

    Any para psychologists out there ?
    Used to assume this was caused by my room. Now no idea. Symptoms :My amp has 2 volume controls, one for each channel.with left hand ser volume, when I turn up right hand volume only I hear the sound basically centred between speakers in other words predominantly to the left of my right hand speaker and I am sonically unaware of right speaker’s presence unless I get up really, really close to it. It quite literally seems to disappear and the sound seems to be generated from inside my rather hefty bureau situated between the 2 speakers. rather as if a balance control had been turned to the left but of course a) my amp has no balance control and b) the left hand speaker has zero volume so the word balance is not applicable. My left hand speaker seems perfectly normal , indeed predominant in the bass.
    So I proceed to swap l and r input from deck to my phono amp. Disconnect left input. Hello buzz on right hand channel with no left connected. When I connect left, buzz disappears and all is well ( apart from the original imbalance ). Swap inputs and buzz changes sides.
    So, one channel would seem to have an earth buzz when the other rca is not connected. Buzz disappears when other rca is connected. No hassle, presumably easy to sort. But my question is : when using one earth for both channels can this cause as if it were a suck out of highs andmids in the earth less channel enough to affect lateral lobing enough to simulate a central image ? I can’t believe I have written that.
     
  2. Julf

    Julf Evil brother of Mark V Shaney

    Sounds like you have a cold solder joint or contact problems with one of the input connectors or ground.
     
  3. Chris

    Chris pfm Member

    Thanks Julf. yes I am sure you are right. My question is “what effects can such a short have in the speaker’s performance.
     
  4. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Blown tweeter on right channel?
     
  5. Chris

    Chris pfm Member

    Hi Jez
    If that were the case, heavenforbid cos it’s a Millennium, , might that explain the apparent shift to the left of, presumably the mids of the right hand mid woofer
     
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    It's something to check anyway... if you blow a tweeter the good speaker can sound a lot more prominent sometimes even though the majority of the sound power is coming from the woofers. Our ears are most sensitive to directional information at higher frequencies in the presence region, just where the "crack!" of a twig breaking, leaves rustling etc from an approaching predator would be... evolution and all that stuff:)
     
  7. Michael J

    Michael J pfm Member

    Does your turntable use a separate chassis ground lead? If not, it is quite normal to ground through the left hand channel only, via the phono cable outer braid, thus preventing ground loops.
     
  8. Chris

    Chris pfm Member

    Yes, it’s an lp12 with Ittok
     
  9. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Is it the same with all sources?
     
  10. Chris

    Chris pfm Member

    Dunno. I only use vinyl
     
  11. Rug Doc

    Rug Doc pfm Member

    Don’t worry about the grounding issue for now, that’s pretty standard as both L&R are usually connected...

    You didn’t mention when swapping the RCAs from deck to amp if the speaker with the lower volume output swaps sides??
     
  12. mjw

    mjw pfm Member

    Have you got any foo interconnects? I once had an amp on demo that was sent with a fancy American interconnect that included magnets. I called the dealer to report a possible fault (volume imbalance) and he asked me to clean the interconnect RCAs with blu-tak. Removing metal particles that were shorting the signal path (apparently) sorted it.
     
  13. Chris

    Chris pfm Member

    No, I don’ think it does. The left hand speaker has always been predominant. Hence my fitting dual volume controls to my Sugden A21SE to provide a balance control.
     
  14. Bjork67

    Bjork67 pfm Member

    I had similar and it turns out I'm hard of hearing in my left ear, various folks told me there was no imbalance between my speakers. I thought I was going mad wondering why the right speaker seemed prominent.
     
    Suffolk Tony likes this.
  15. Chris

    Chris pfm Member

    I could live with that but I don’t notice it through cans
     
  16. poco a poco

    poco a poco pfm Member

    Yes it would. I had a tweeter on one of my pair of speakers die about 10 years ago (ferrofluid dried out). Suddenly was getting the an out of balance problem, that seemed worst on some records. Did the usual left right swaps, but at first I was still not sure of the cause. Putting my ear close to each drive unit on each speaker showed that one had hardly any output on one tweeter. The easiest way to be sure is with a test record (as you only use vinyl) and play some white or pink noise through the speakers while listening to each speaker driver.

    I had the tweeter replaced and both crossovers checked for balance. Problem solved.
     
  17. Chris

    Chris pfm Member

    Thanks Bit by Bit,
    I suspect it might only be "a bit" dead ´cos I can feel vibration but that could be the mids through the woofer I guess. Anyway I´ll start by digging out my HFN test record although dunno if I´ll be able to distinguish a lower level. Pity my amp hasn´t got a mono switch. Could I perhaps record a frequency sweep with my ipad ? Is there an app or do I need a mic and PC ?
     
  18. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    Just play a record and stick yer lug holes near the tweeters and it should be obvious!
     
  19. poco a poco

    poco a poco pfm Member

    As Arkless says it should be obvious with a comparison with wth an ear close to each tweeter. It will probably be working or completely dead unless a ferrofluid tweeter problem.
     
  20. Chris

    Chris pfm Member

    If there are no half measures in being dead or not, then I pronounce it undead. There is deffo something coming out but I don´t seem to hear splashing cymbals. The plot thickens. I don´t think the Seas Millenniums do ferrofluid.
     

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