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Oh dear, me again!

Discussion in 'Subwoofers' started by AngelEyes, Oct 5, 2005.

  1. AngelEyes

    AngelEyes
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    Hi,

    It has been while since I gave you all a good laugh and I am back for more :)

    Just a recap for those with short memories :)

    SVS PB12 Ultra, hidden away in an alcove.
    Amp sub level +3db, sub gain 11:00
    Connetced via BFD using PEQ to iron out worst of the peaks. Got as far as the first attached gif (alcove.gif)
    All speakers set to small and crossover set to 60hz

    I still felt there was a bit of sound missing and the graph seemed to back that up.

    I just got a new 15m cable from Mark Grant so I could play with different locations. I started with the only real option I have at the moment which is ports about 1 foot from the rear wall (3 feet from the seating position).
    The nearest side wall is about 2m away so it has a lot more breathing room than tucked away in that alcove with about 10cm all round.

    I am still running through the BFD but have set it to bypass mode.

    I decided to run a sweep and the first thing I noticed on the 16hz was a dreadful pneumatic drill/ rapid farting noise. This continues up the next couple of tones to a lesser degree.

    I am guessing it is running too hot so I dropped the amp sub level to -5db and the amp gain back to 8 oclock. I also changed the crossover to 90hz.

    The sub is still belting out so much more noise it is amazing. At least 10db even with everything turned back as above.

    See the sweep on the next attached file (free.gif).

    I am a bit lost now, the farty noise is still there and quite worrying (although to a lesser degree). Any ideas?
     

    Attached Files:

  2. bob1

    bob1
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    Ok i have just about finished laughing from last time :D
    I doesn't get any better does it, the second graph isn't any better and to me the first one with the bfd doesn't look bad at all.What did you mean by some of the sound was missing?
    Have you tried the hands and knees crawl around the room method yet, it does work.
    Are the graphs with the speakers running or just the sub because the graphs drop of where the speakers should have taken over suggesting you haven't the speakers running or the levels are set wrong.
    Have you tried setting the speakers to large yet ,you have nothing to loose by trying it ,i set mine to large sometime ago after trying small settings and different crossovers but i always ended up back at the large setting for the speakers.
     
  3. stevefish69

    stevefish69
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    I'm no expert, but would go back to position no 1 in the alcove. At least you have a fairly flat response there, which actually looks pretty damn good.

    On the second option, you have a major drop out at the lower end of the scale, coupled with a MAJOR peak at 40 Hz.

    Apart from the farting, what does it actually Sound like...............

    I've just grabbed hold of a BFD on the forums, so will soon be joining you in the quest for that perfect response.

    Steve
     
  4. bob1

    bob1
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    Forgot to add, the farting doesn't sound right, the only time i ever got anything like that when i had the dvd connected to the tv via scart and then back to the amp from the tv via rca leads, connecting straight to the amp from the dvd player corrected this.
     
  5. chris

    chris
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    Have you investead in an SPL meter........????( read so many post's i can not remember if you have or not ).

    Also can not remember what front speakers you have......
    Try this......
    Set front speakers to large, if they are floorstanders.....or small if they are book shelf.
    Direct LFE to Sub only.
    Set crossover to 80hz.
    Turn BFD off.....take out completly if need be.
    Put Amp/Reciver setting to 0.0db......Put Sub Volume to 9 o'clock.
    Callibrate Sub for 72db at reference ( what ever that is on your volume control) by adjusting amp/reciver.
    Callibrate speakers for 75db at same volume setting.

    Callibrating the sub to 72db allows for the correction factor of the realistic SPL meter, but it depends what type of test tone's you use.........i would suggest useing the test tones in the Amp/Reciver for now.

    Try a couple of films and see how it works.......
    Then do your test's with the tone disk you have.
    If it's crap then try moving the sub around and test again.
    If no where is any good.......then re-instate the BFD.
    Put the sub where you want it.....poss where it affects the whole room and not just parts and then start adding your filters to get it level.

    Remember to attenuate the peaks and leave the troughs........it might start sounding wierd if you start adding electronics to the troughs and see how you get on then.

    If this dont work, then forget everything you have just read..... :D
     
  6. binbag

    binbag
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    Would it help you to know that I finally managed to connect Room Wizard to my setup today and nailed a flatline response? :clap:

    No? OK I'll go then...
     
  7. kbfern

    kbfern
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    Just sell the sub!!!!!!!!!!! you might make a profit with the current svs situation. :devil:
     
  8. kbfern

    kbfern
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    seriously, this is why cylinders sometimes are better,they can be easier to site (as gonzo will testify)
     
  9. AngelEyes

    AngelEyes
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    hmmm... thanks guys, I think :(

    I have all the speakers running, not just the sub. I used an SPL meter to plot the graphs. The Fronts are Mission 733 floorstanders.

    I'll give them a go set to large.

    Any ideas what is causing the vibrating pneumatic drill, fart noise? It is worrying me, am I damaging my sub? :( :eek: :rolleyes: :confused: :thumbsdow
     
  10. recruit

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    You're 1st graph looks pretty good, and with a little more work could be better.

    Does it make the farting noise in that graph too ? the sub level on the amp seems a little high at +3db u sure it is not clipping ?
     
  11. Andywilliams

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    Yep in my room the pc- ultra sounds much better than i could get the pb12-ultra-2 to sound but was due to my room me thinks .Kinza who had my pb-ultra has no such problems in his room and is a very happy man.
    I know you dont want to hear it but you may have been better off with a tube.Is there anybody near you who owns a svs tube that could bring it round to yours just to see what that performs like.
     
  12. niceguy235uk

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    Should have bought a closed box sub.

    Sounds like the ports to me.
     
  13. AngelEyes

    AngelEyes
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    Ok, this is the point where I die of embarrassment...

    I detected a little tiny light on the amp I hadn't notice before, on closer inspection it appears some little roving hands have been at play... 'Bass Boost' anyone? :oops: :rotfl: :rotfl:

    Well I haven't had a chance to run another test but my guess is that has been causing the sub to make those horrid noises.

    On the plus side I have now truly had the SVS trouser flapping experience :)
     
  14. Gary_W

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    It's not always roving hands.

    My DVD player (an aging Toshiba SD220) seems to turn dynamic range control on all by itself. I never ever do it, and no-one else would even know how. But it does it. My SVS sounded less than impressive earlier and sure enough the cursed thing had turned it on again....

    Perhaps it knows that I'd like to replace it?

    Hope you've fixed it now. If not, take the engineering aproach and only change 1 thing at a time. If it still makes noises that would embarress the vicar then swap the cable back to the old one and see if it still does it.

    Gary
     
  15. chris

    chris
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    Is it a very low freq farting noise........???

    If it is then it is prob something in your room shaking/rattleing.....

    I get this, and have done with every sub i've owned........still have not found it.....maybe it's the sette's shaking or the A/V rack's rattleing, but it only happens once the tones get down to the 30-20hz region.
    Unless you can see the cone on the SVS reaching it's limit and shaking vigouriosly, then you will have to live with it, untill you can see what it is that is shaking.

    Maybe it's the windows.....or the foundations..... :eek:
     
  16. Mr Incredible

    Mr Incredible
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  17. Smurfin

    Smurfin
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    Angeleyes, if you get any more problems and want a second opinion then just give me a shout, I'm in Cambridge alot (there all this weekend) and only live down the road so it would be no hassle popping round one evening.

    Cheers
    Matt
     
  18. AngelEyes

    AngelEyes
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    It's definately coming from the sub, the ports in particular and there is a tornado eminating from there.

    I haven't had chance to try is out since I disciovered bass boost was on but I'm hoping that was the problem.
     
  19. AngelEyes

    AngelEyes
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    Hi Matt,

    That is a very kind offer. If I come unstuck today / tomorrow I may well take you up on it :)

    Adam
     
  20. Smurfin

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    No worries:) Sunday afternoon would probably be best for me if you did need any help.
     
  21. Ian J

    Ian J
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    It is probably worth taking Matt up on his offer whether you need help or not as he has heard enough subs to be able to tell you how far off optimum you are with your sub and/or room
     
  22. AngelEyes

    AngelEyes
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    Yes, it would be nice to have a bit of input from someone (unlike me) who knows what he is doing :)

    BTW I have managed to make a massive improvement to the performance curve by moving the sub to the right of the front left speaker. It scores -10 on the WAF scale but she will put up with it for now (I shall screw it to the floor :devil: ).

    The response curve is a tad bumpy but probably less so that my original attempt (in the alcove) with the BFD, so I am confident I can get an almost flat curve :)

    The whole thing is running a little cool at the moment so I still need to play with it and set the levels with the other speakers but it already sounds cleaner with a smoother transition across the frequencies.

    The only down side is having to move my fronts even wider apart which means the front steering is exagerated a bit.

    I guess there is no substitution for an ideal position!
     
  23. Mr Incredible

    Mr Incredible
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    Put the sub next to your amp, then I can buy that 15m Mark Grant cable off you. :devil:

    On a serious note though, don't forget to take readings for Mains + Sub and then compare the curves for different phases. You may get a nice suprise. :)
     
  24. AngelEyes

    AngelEyes
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    Absolutely, I had a lot of difference thrown up with different phase settings in my original position.

    This is about the 4th reply to one of my posts where someone suggests an action that involves me either selling my Sub cheap or the cables! You lot are mercenary B*stards! :rolleyes:
     
  25. Smurfin

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    Ian's too kind, me knowing what I'm doing is open to debate :D I'll turn up, tell you your SVS is crap and offer to buy it off you for a fiver ;) (but only if you throw in the Mark Grant cable :D )
     
  26. Mr Incredible

    Mr Incredible
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    Out of interest (coz I've gone through my first ever sub set up), do you use the BFD to flatten the sub's FR response on its own, or do you BFD the sub to flatten the sub + mains FR response? Using the Room EQ Wizard software I was able to overlay a number of FR's and manually play with the Sub FR to get a flat overall response curve. The final result was very good (IMO) but the sub's FR on its own is no way near "flat" when adjusted with the mains in mind.

    Good luck!!
     
  27. AngelEyes

    AngelEyes
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    I am trying to get a flat response with everything running together, as you say the mains can affect the higher end of the range so it seems pointless without everything running.

    What I will do if the BFD PEQ adjustmnents don't flatten the higher frequencies... I don't know? :confused:

    I think my next AMP will have an auto room configuration doobry :D , I hear Yamaha are pretty good?
     

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