Need help sorting a Speaker balance problem...

Discussion in 'Hi-Fi and General Audio' started by Deaf Cat, Dec 21, 2008.

  1. Deaf Cat

    Deaf Cat

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    Hiya,

    Just wondered if you may be able to help?

    I've shifted the stereo gear to the opposite side of the room, and think I may have discovered a fault...:eek:

    The speakers, before moving, were approx. 1.3m apart and I always thought there may have been a slight inbalance one being slightly louder than the other but nothing too much to worry about, singers were just slightly off center.

    Now the speakers are approx. 2.2m apart and the singers are pretty close to the RH speaker and I've had to tweak up the LH balance about 4.5dB to bring the singers to center stage.

    While sat listening, things seem ok, but get up and move around and the LH speaker does not seem to have the same low end, and therefore the RH speaker seems to have more welly
    :confused:

    I've swapped the speaker cables at the power amp output and the actual LH speaker still seems the same - So I'm thinking the LH speaker it's self is at fault?

    The speakers are floorstanding and have two 6" drivers and a tweeter each. From listening I'm thinking the lower freq's come from the bottom 6" cone which seem to blend to mids listening to the upper 6" cone, hi freq's from the tweeter.

    The LH speaker still has a lower volume coming out its lower cone (once trimed with +4.5dB) as far as I can tell, when compared to the RH speaker.

    I would love any pointers as to how I may test this further to find the problem and hopefully rectify the inbalance.

    (Oh, I have listened facing away from the speakers just to count out my ears ;))

    Very much look forward to hearing from you.

    Many thanks:)

    DC
     
    Deaf Cat, Dec 21, 2008
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  2. Deaf Cat

    bottleneck talks a load of rubbish

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    Hi DC

    If I was a gambler I'd say that you're suffering from a change in the speaker positioning rather than a technical fault - I'm supposing you've put them back where they were to see if the problem goes away?

    If you have/prepared to buy the tools/learn to use them I'd be running test tones through the speakers with an SPL meter up close to the cones. If that checks out ok, then I'd use a software program like CARA to study the speaker position in-room.

    If that sounds like hard work, you could PM 'Tenson' who would probably turn up if you paid him with all of that equipment in tow and do the work for you.

    It's a truism in hifi (IME) that people are more prepared to spend money and time on boxes, leads and stands than time and effort on learning acoustics and room treatment products, or paying for their implementation.

    All just my 2p
     
    bottleneck, Dec 21, 2008
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  3. Deaf Cat

    Deaf Cat

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    Cheers BN

    I had not thought of putting them back as a test, because the tv and all its gubbins is now where one was, and the Christmas tree is where the other one was :-(

    Ah-ha, but I could swap left to right yes? Then if its the room the LH position will be as is, and if its the speaker its now the RH speaker that is at the lower level ;) I'll try that tomorrow :)

    Yes your right, the test tone reader pc thing sounds way way too techie for me, I've just thought, on more basic lines, like swap two lower drivers....if the test above shows speaker rather than room - I hope its the room - fingers crossed!

    Thinking about it, having the rear of a rear ported speaker closer to a surface would increase the lo freq output....?
    (thinking of the louder RH speaker)
    But then again the LH position is much more in the corner of the room, which increases lo freq.........

    OMG
    :eek:
    :confused:

    one thing at a time a!
    :)
     
    Deaf Cat, Dec 21, 2008
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  4. Deaf Cat

    Dev Moderator

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    I'd swap speakers over. I.e. move the left to the right and vice versa. I had exactly the same issue and thought that I had a faulty right speaker. It turned out to be an issue with the room (I think), because it didn't matter which speaker was on the left or which amp or CD channel fed it, the left one was always louder. I played with speaker positions and found a compromise by moving them into the room and toeing in the left one and keeping the right firing straight down. It looks odd but sounds OK (to me).
     
    Dev, Dec 21, 2008
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  5. Deaf Cat

    Deaf Cat

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    :D
    Cool to know your experience!

    Will have a swap / play tomorrow.

    Many thanks
     
    Deaf Cat, Dec 21, 2008
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  6. Deaf Cat

    spica

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    To try another amp, and if all is then well, it's the amp, another pair of speakers, and all is well, it's the speakers--speaker.
    If your just using Vinyl...problem could be *connected* to the arm...etc etc.

    So would try different components to narrow down the problem.

    Good Luck.. :)
     
    spica, Dec 21, 2008
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  7. Deaf Cat

    Coda II getting there slowly

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    My experience sounds exactly the same as Dev's - right was always louder through changes of pretty much every component - including speakers. Mono recordings can be useful in trying to sort things out.
    From discussions elsewhere it seemed that distance to speaker was theoretically the best way of addressing the imbalance ie have one slightly closer; in practice I found a combination of distance and toe in to be most effective.
     
    Coda II, Dec 22, 2008
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  8. Deaf Cat

    D Louth 77

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    Help ?

    Hi Deaf Cat

    While what the guys says sounds possible, and I have heard room acoustics cause slight shifts in image position (say you have a solid wall on one side and a plaster board wall on the other, or a wider/deeper alcove) it sounds more to me like one of the following.

    Are all your cables correctly in phase ? If not you can end up with both image shift and one speaker sounding louder as there is a different quality of bass coming out of it ( the speaker is sucking rather than blowing ,crude I know but that is the best terms I can explain it in). The other issue is that you may have a bad solder joint in the speaker and the signal is being reduced. It is also possible that one of the bass or mid drive units is faulty. These speakers wouldn't be Mission's ? If they are and they date from about 4/5 years ago Mission had a quality control issue with drivers. They would either fail, sound lower in output or crackle. This massive problem (and as I was in the trade then I can well recall the number of drive units I had to replace. And once Mission had gone out of business too. Before the Iag new ownership). Have you noticed any dampness/beads of fluid around the dust cap/center of driver. Some of these Mission Drive units had started to do this. I don't know how or why as I thought only tweeters had cooling fluid in them.

    If you want to check out drive units place a large book or cushion over each drive unit (NB not the tweeter as you would crush it). Have volume set to normal and balance centered and listen to sound, if you hear an imbalance then issue is with that drive unit. You could get a friend to hold the book/cushion and use a digital or analogue meter. Set to C weighted and about 75 db. This will detect a drop in out put too. However to do this you will need to unplug the opposite speaker to the one you are testing, to avoid the Meter picking it up as well. You must also test each speaker to gauge what normal reading are. So test good speaker first and write reading down.

    One other thing you should check. Are your speakers exactly the same distances from whee you sit. If one was a lot closer it would sound louder, not by much but you would hear it as a shift in image/volume.

    Your speakers should be set up to have same distances. Back of speaker to wall , side to wall( but not same measurement as back of speaker. You will avoid bass boom) and be level( use spirit level) on top and unable to rock, perfectly stable. If you have to use a bit of toe in to get the best image remember to have it the same for both speakers. Don't be to frustrated if it is not exact as the walls in your house are unlikely to be true. If they are badly out of line, then measurement to where you sit. This more vital as long as other measurements are not massively out.

    Bit of time will sort this out . If its a drive unit the dealers who sell the speakers will be able to help. If its a Mission speaker I am not sure if the new owners will be helpful in regard to the previous owners problems. I would ask you never know.

    Regards D Louth 77 :)
     
    D Louth 77, Dec 22, 2008
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  9. Deaf Cat

    Deaf Cat

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    Cheers Spica and Coda for your comments :)
    And many thanks D Louth for you rather decent explanations of various problems. (They are Ditton AV3's, thankfully not missions however, I'm told they sound like Missions)

    An update, that I would appreciate comments on as to if I'm thinking along the right lines:

    Before I switching the speakers L to R to test for room/speaker positioning causing the inbalance, I tried the following with the pre/dac balance set as 0 on L and 0 on R:

    lhs speaker quiet, rhs speaker loud
    swap speaker cables at power amp
    lhs speaker loud rhs speaker quiet

    different from yesterdays test....:confused:

    but going by above
    - not speakers at fault
    - not speaker cable at fault
    - not room/speaker position at fault

    next

    lhs quiet, rhs loud
    swap rca L & R into power amp
    lhs loud, rhs quiet
    swap rca L & R out of pre/dac
    lhs quiet, rhs loud

    - not power amp at fault
    - not IC rca's at fault

    next

    lhs quiet, rhs loud
    change digi coax source input on pre/dac from CD input to DVD input
    lhs quiet, rhs loud

    - possibly internal dac/pre faulty
    - possibly source faulty

    Going by its the first time I've used the pre/dac, I'm somewhat concerned its that which is buggered.

    Other things I should try...?
    Another digital source (is the source at fault)
    Another digital coax....? (could these cause a channel inbalance?)
    An analogue source, to bypass the dac in the pre/dac.

    :( it may be my new second hand pre/dac, do you think I'm on the right lines?

    Cheers for any further thoughts,

    DC
     
    Deaf Cat, Dec 22, 2008
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  10. Deaf Cat

    Jimbo

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    As others say it could be the room. Its surprising how much shift there is by moving your head an inch or so too. Another thing which i suffered a lot from was wax build up in one of my ears.
     
    Jimbo, Dec 23, 2008
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  11. Deaf Cat

    bottleneck talks a load of rubbish

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    Hi DC

    My head is buzzing from that - like one of those magician tricks where they move a piece around under 3 paper cups until you can't see it.

    It sounds like (correct me if I'm wrong) - you have one loud channel from the amplifier, one quiet channel from the amplifier ?

    In which case - it sounds like it's the amp.

    you say 'not power amps fault' ... why?

    Sorry, I may be missing the obvious here..?
     
    bottleneck, Dec 23, 2008
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  12. Deaf Cat

    Deaf Cat

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    Almost there I think..

    Oh Boy, glad I'm not the only one having trouble understanding what I'm doing:cool:

    Not the power amp as........errr..... well I did know why, however, the next test may narrow thing down and hopefully easier to follow:


    Ok, I have two speakers and that's it.

    Processor is listened to in stereo mode, using only main fronts L & R outputs. No balance adjustments applied rhs is louder than lhs by roughly 4.5db (found by boosting lhs untill vocals are central)

    No balance adjustments applied.
    I tried using the rear suround outputs from the processor into the power amp in DD Prologic, it sounded terrible:eek: drop outs maybe every second or beat:confused: - is this right?

    But, the balance left to right was spot on.

    Back to the main front speaker outputs, drop outs as with the rears, sounded dreadful, and, the right was once again louder than the left.

    Leading me to believe something with the front two channels within the processor is a bit out of balance, well, from what I can work out about 4.5dB out.

    Thanks to everyone for helping!!

    I found placing a board behind the lhs speaker, roughly giving the same distance from rear ports as the rhs, seems to bring the lo freq's from the lower driver pretty much in line with the rhs once the 4.5dB boost is applied to the lhs channel :)

    Therefore very basic room and speaker adjustment with a bit of a boost on balance seems to have brought things much more in line with how they should be:D


    Hope above is clear:( and your thinking same as me:eek:


    Just a bit of a worry on the internals of the processor, do you know of anyone that may beable to fix the balance thing in the processor, or at least check out what I think is wrong?

    Many thanks again :)

    DC

    PS will hopefully confirm listening is pretty near normal with some more music tomorrow:)
     
    Deaf Cat, Dec 23, 2008
    #12
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