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biwired bass problem !

Discussion in 'Home Cinema Speakers' started by spk, Feb 8, 2005.

  1. spk

    spk
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    hi,

    I've just biwired my floorstanders (having run them for 150+ hrs from new) and have found something I didn't expect. Firstly the sound was much clearer and detailed using bi-wire but, there is way less bass .... to the point where some of the bass is only present in my surrounds (also 150+ hrs from new), which are not atm biwired. To check i wired one floorstander back to normal and kepted one biwired. This highlighted the lack of bass in the biwired one (and also showed the clearer detail). I then redid the auto setup and found my amp listing my floorstanders as small (while biwired) and my surrounds (not biwired) as large. I re-wired them back to normal and they came up as large :confused: .

    I check all conections, rechecked them and after a cuppa checked them again.... and found nothing wrong. I even switched the bi-wire to the other speaker and re-listened. Still the same...

    So the question is (horray !!!), is this common with bi-wireing ? (this is my first try). Or am I missing somthing ?, need better wire ?, etc.....

    floorstanders - Mordant Short 906
    surround - Mordant Short 902
    normal cable - Gale Hyperlitz
    biwire cable - Gale XL160 Biwire
    amp - Yam dspax750 (using a+b speaker selection)

    Any help, info or suggestions would be greatly appreciated as I all out of ideas and knowledge (av n00b).

    thanks

    spk

    p.s. excuse my excessive detail if it wasn't needed but, after reading other posts after a search on this topic i thought it best to include as much info as possible but did decide to stop before posting a copy of my birth certificate :laugh:
     
  2. Mason @ B&M

    Mason @ B&M
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    On the amp are the A and B channels the same power?

    Or is one for effects and one for main fronts?

    It sounds to me like a power mismatch and you're running the midbass off an effects channel.
     
  3. severnsource

    severnsource
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    I think that your problem may be related to your mention of a/b speaker outputs on the amp. I don't know the amp so I'm guessing but I would assume that the a/b outputs will be switched outputs for 2 room systems so the output will go to speaker a or speaker b.

    Your description sounds as if only the tweeters are being fed and if you were using the a ouput for the h.f and the b output for the l.f. So with the a speaker selected you will get no lf with the b speaker selected you will get no hf.

    If this isn't the case then it sounds as if you have a discontinuous wire in the cable.

    Unless you have pathologically duff equipment normal wiring and bi-wiring will sound absolutely identical.

    Bill
     
  4. Andy_t

    Andy_t
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    That's got to be the problem. Just set them back to large after auto setup and I would think they'll be back to how they're supposed to be.
     
  5. Knightshade

    Knightshade
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    Sounds daft but you have disconnected the jump wire between the speaker terminals?:)
     
  6. spk

    spk
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    many thanks for the imput guys, will try to answer some of the points....

    A B chan are same power, i first read of the capability of biwireing on my amp from a thread on another board. my amp allows me to set both chan A + B to front speaker,(tho it does not allow biamp) or, set chan B to zone 2.

    to test what kind of freq responce i was getting i ran the test tone on DVE that goes from 20 to 20k hz. speakers while biwired dont respond till around 150hz. to help confirm this i ran auto setup with just the fronts and sub and the yam set the crossover at 160hz (speakers rating is 45hz). also switched A to lf and B to hf. also tried biwireing from the same chan A conection which also showed lack of low bass.

    i have reset fronts to large after auto setup but there is no improvement and test tone still show no responce till around 160hz.

    ran the test tone on normal wire and a responce is heard from around 60hz. ran test tone of normal wiring while both A+B are selected and the front is conected to chan B, responce from around 60hz.

    the more testing i do the more confused i become but, things kinda point at the wire, will try to get a new run tomorow and re-test :suicide:

    again thanks for the imput, it all appreciated :)

    spk
     
  7. spk

    spk
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    hehe, yes i have removed the jumper, at least that was done right ;)

    spk
     
  8. spk

    spk
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    :censored: :censored: :censored: :censored: !

    same results with different wire, have to say this has totaly confused me as i cant see any reason for it to be happening at all....

    if things where ok when running the biwire from one terminal i could see the logic in the chan B theory. but as it is everything is the same as soon as i biwire in any config.

    one last thing before i throw the towel in, would changing the the ohm setting on my amp help this ?. speakers are 4-8ohm rated and yam alows me to change it some via a switch, tho cant quote the values off hand.

    again thanks for any input,

    spk.
     
  9. belgrade

    belgrade
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    Spk,

    I think Bill has found your problem above.
    If I am understanding you correctly, you have biwired your front speakers , sending one set of wires to the Speaker A output on your amp, as you would normally, and then sending the other set of wires to the Speaker B output on your amp.

    I also have MS Avant floorstanders (904s) and Yamaha amp (dspax640). This is not how I have biwired my fronts. Both sets of wires coming from my speaker are connected to the Speaker A outputs on my amp. I have left the Speaker B connections alone.

    Why not give this a try. This way works fine for me. As I understand it, Speaker B connections are only to be used for speakers in a different room.

    Hope this helps. :)
     
  10. dj001k4727

    dj001k4727
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    HI, my friend had this problem with bi - wire, your problem may be a bit more simple.
    You mention A and B out puts, you have probably wired each speaker in stereo .
    That is each speaker is being fed both left and right channels, so you will have no stereo sound stage.This is why it sounds poor.This is your fix:

    Use only speaker output A . " leave out put B well alone"
    You have in Total 8 runs of wire for the front speakers.
    At the amp end twist together both of the positive,red or + together of the LEFT speaker run. Then do the same with the negative, black or - of the LEFT speaker run.

    Now insert these into the positive LEFT and negative LEFT on speaker out put "A"....

    Now do the same with the RIGHT hand run inserting it into positive RIGHT and negative RIGHT on speaker output "A".....

    Now the speakers: You will have 4 terminals on the back of your speaker.2negative and 2positive.
    With the left run you will have 4 wires ,,,,2negative and 2positive ...
    Insert 1 negative into one negative terminal. And the other negative into the remaining negative terminal.
    Repeate this with the left positive

    Then again do this now with your RIGHTcable run to your right speaker......

    You sound like you have allready done this to your speakers so concentrate at the amp end..remember use only out put "A" never use two outputs for bi-wire.

    Also some speakers sound better not bi-wired. But i will show my back side from the roof tops if this is not your problem...........
     
  11. spk

    spk
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    you'd better get some ladders ready :rotfl: ....

    i've done what has been suggested (wireing to just terminal A) and when using biwire i get the same result as using both A+B or, just B. anything/ everthing other then normal wireing results in a lack of bass responce.

    it's confusing, no matter how i rig biwire i get the same results. this leads to the mega confusion and why i posted. i truely cant think of anything i've over looked or possibly missed and is why i posted here to draw on other peoples knowledge/ experience.

    i just cant understand (on my limited knowledge) why adding the extra wire should lead to bass loss. if things where all ok when using only chan A or chan B, with biwire, i would see some sence in it. but as it doesn't it just leads to more and more confusion....

    maybe it's just time to go back to normal wireing and leave it at that :) .

    again thanks for everyones input, it made me look at things i maybe over looked in my adventure to track down the missing bass :thumbsup:

    spk
     
  12. wookie

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    Sorry if any of the following is of insult but I just had to say something as this is mad :eek: Doing my head in now!

    Have you tried swaping electrical phase on the LF set of terminals?

    Are your cables + & - the same at both ends?

    Might be an idea to pick Tons of Funs brains here.....
     
  13. Docta teef

    Docta teef
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    I had the same problem last week ( with a pair of 906's ) i had set up the same as you and had terrible responce from the bass driver but i found it was corrected by connecting to the A terminals alone. I know thats no help to you at this stage but it would appear that the other guys should be right
     
  14. wookie

    wookie
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    These speakers must use a series crossover!
    But if it were a posibility, isn't the cable from (speakers A only) electrically the same as the shorting links anyway??

    This is Mad :eek: Boinkin Mad :eek:
     
  15. dj001k4727

    dj001k4727
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    Hello just finshed bearing my back side. Try carefully checking each run of cable for any splits or cuts in case you have a break in one of runs which may run to one of the bass sides of your speakers resulting in only one channel of bass operating. Another way of doing this is ,,,,,,, have it set up the way i described earlier and play a track fairly loud. Then place a finger very gently on each of your bass drivers and see if they are respoding to the lo bass freqencies....ie pumping in and out ,if not there may be a break in one of your cables......Dont worry ill stay with you on this one because i want to get to the bottom of this one .......see you tomorrow.
     
  16. spk

    spk
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    checked the cable and it all looks ok. check and rechecked polarity.

    just ran auto setup with 1 speaker on normal wire to chan A and the other on biwire also to chan A. the results are, front left - large, front right - small, x-over 160hz. change right speaker to to normal wire also. reran setup, both appear as large and x-over is 60hz :suicide: .

    before switching the right speaker to normal wire i ran a test tone from 20 to 20k and sat close to the speakers. you can feel/ hear, vibration/ responce in the left (normal) at around 60hz, nothing from right (biwire) till late 160+hz :suicide: .

    also auto setup always sets my center (905c) to small. I cant see how a speaker rated 60-22k hz can be small :confused: . center is normal wired which doesn;t help to clear any confusion !. i truely darent run a test tone on the center as the last thing i could cope with now is more confusion.

    as i'm new to this i haven't a clue if it's normal for auto setup to set the center to small. but one thing for sure, the £100 ht in a box is starting to look real attractive ......

    as always thanks for the continued input :thumbsup:

    spk
     
  17. spk

    spk
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    oh yeah...

    when i ran the test tone with one speaker on normal wire and the other on biwire. the bottom cone in the biwired speaker never showed any sign of reaction. but just to add to the confusion, it does when on normal wire :suicide: .

    spk
     
  18. belgrade

    belgrade
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    Spk,

    This is really beating the cr@p out of everyone. :D
    I think Tons of Fun must be on holiday, otherwise he would have definately replied to this.
    See if you can catch him, but dont beat yourself up over the problem. Biwiring isnt the be all and end all of front speaker difference. I'm sure there is not much difference between single wiring and bi-wiring, so you are not missing out on anything fantastic if you decide to go back to single wiring.
    I only have my fronts biwired because I had a lot of spare cable, - does it sound better? Aint got a clue :D

    Time to sit back and enjoy mate, rather than worry
     
  19. Andy_t

    Andy_t
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    Have you got a subwoofer? If not then check that the receiver is set to Sub - none. It could be sending frequencies below 160hz to a non-existent subwoofer. Also check that the bass output is set to Both and not just Sub.

    IMHO it's gonna be a setting on the receiver rather than a problem with the speakers. If your receiver is like mine when a speaker is set to small it will send any frequency under the specified crossover to the Sub, which would explain why you aren't getting any bass under 160hz.

    If you know anyone with a stereo amp (or have one yourself) then i would definitely check them with that.
     
  20. dj001k4727

    dj001k4727
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    Think andy t may have your answer there ,if not you said earlier about your bass driver reacton, if only one of the left or right is reacting in this way swap over the cables and see if it happens in the other speaker if it does then there is a break in the cable you may not be able to see ,,, if both are reactin in this way then it will be andy t`s sollution....remember in a home cinema you will be in minimum 5.1 mode,the five being 2 fronts, 2 rear, 1 front and the point 1 is your sub your amp is supplying the lowest end of the bass freqency to your sub and treble, midrangeand upper bass range to your fronts thats why you cant hear the lowest of the bass because its going to a sub that aint there ....as andy t said switch your sub off at the amp....hats off to andy t!!!!!!!!
     
  21. Andy_t

    Andy_t
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    Having read the entire thread again and also looking at the manual on the Yamaha website I'm convinced it's just auto setup that's not doing its job properly.

    This would be my course of action:

    1) Do auto-setup with the speakers bi-wired.
    2) Go into the sound menu and make sure your front speakers are set to large (I'd also set the centre to large as well).
    3) Go into the Bass Out bit of the menu and select BOTH rather than SWFR or FRNT.
    4) Go into the cross over bit of the sound menu and select 60Hz. The manual states "All frequencies below the selected frequency will be sent to the subwoofer" which would explain why your front speakers weren't getting anything below 160Hz when the crossover was set to that.

    I'd be tempted to sack off auto-setup completely once you get familiar with the setup process.

    Let us know how you get on and don't even dare thinking about getting an all in one system! ;)
     
  22. bob1

    bob1
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    After reading this thread its making my head hurt, why don't you just replace metal strip on the speakers with speaker cable, that’s what people with any sense do.
     
  23. dj001k4727

    dj001k4727
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    Because audiophiles dont do that BOBBY BOY. This is how hi fi and all other consumer electronics are continually improved......By not being truely happy with the sound there is always room for improvement....Thats why you now have relitivley cheap hi fi products that dont cost the earth but sound fantastic. Hi fi anoracks like me want the last drop of performance out of there kit......Sorry to do your head in Robert but thats just me OUR KID!!!!!! This is what the forum is for......
     
  24. Andy_t

    Andy_t
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    Oh dear! :eek:
     
  25. bob1

    bob1
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    The ones with any sense do, do a search on the subject,a lot of people have the strange notion that the bass goes down one cable and trebble down another.All your doing when bi-wiring is making the link longer,think about that.
    An "audiophile" would bi-amp anyway.

    Thats how they constantley make money out of us.
     
  26. spk

    spk
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    took a very quick look at the setting auto setup was doing, late last night and replaced them with the suggested ones. things sounded great. once i get the wife/ son off to work/ school i'll look more closely and get a tape measure etc, out to check over all of auto setups settings. will also give me the chance to run some decent test material :D .

    even if this isn't the 'cure all' it has totaly helped to ease my mind and clear the anxiety/ confusion. was getting myself in a 'pickle' over what test tone was saying and not plain 'listening'.

    will report back later, thanks again for the various imput :thumbsup:

    spk
     
  27. Andy_t

    Andy_t
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    Thinking about it, you'll probably want to experiment with the Bass out setting to BOTH or SWFR and see what sounds best. With it set to BOTH you're probably getting a bit of overlap in the frequencies from 60hz (or whatever the amp crossover is set to) down to where your speakers cut off. All down to personal preference probably.
     
  28. spk

    spk
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    yes noticed that, which was a little problematic. i'm trying a workaround atm where i've clipped the sub via it's own setting lower than the x-over.

    while set to both i still get the benifit from the x-over sending to fronts with the sub cutting in for real low things. or is that wrong ?.

    seeming i thought this path for myself things are pretty good and have almost seemless transer without much overlap or directional distraction. just a matter of playing around some to fine tune it, then checking it with some heavy lfe dvd's. but a test tone on full system is pretty smooth from full system to, surround + fronts to, fronts and then to sub. in fact it so smooth i shocked myself.

    there is a small problem that the lower bass from my fronts is quieter but i think this is down to it only been fired from 2 chans. i may end up trying a small over lap to strengthen it. but will need to wait for the spl i just ordered to arrive to see.

    btw auto setup was way off, all my speaker distances where out by a mile. but cant check the levels till said spl arrives.

    so atm i have things setup up like this.

    center - small (to use it's 60hz as cross-over cut off)
    surrounds - large (as they rated a little lower and that little extra seems to help with sacd/dvd-a, also helps to spread the directional higher freq bass), correct me if that sizing is fundamentaly wrong.
    fronts - large (to take advantage of their 45hz rating)
    sub - set at roughly 45
    lfe - set to both
    cross over - set at 60hz

    that about right ?.

    in conclusion, i feel rather embarassed that i totaly over looked the cross over point made by Andy_t. being very new to all this before i started i read as much as possible to learn all i could, most from these boards. but when i hit this problem i couldn't work out why adding the extra wire resulted is such a drastic differance in auto setup. in truth i still cant but, thanks to all your support and views, i soon came to the understanding that it wasn't a problem. it was just something that happened and not something i'd broken :rolleyes: .

    so huge thanks to all for showing me the light and helping to solve this. i know i still have much more to learn but your help as seen my knoweldge and confidence grow :thumbsup:

    spk
     
  29. Andy_t

    Andy_t
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    Sounds like you've got your set up spot on. I think you're right to use the sub's crossover and have the amp set to both - should be better for music that way providing there's no drop in bass volume at the frequency where the speaker crosses to the sub.

    I think the moral of the story is not to trust auto-setup!!
     

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