I 'm gonna blow up my DIY Sub.

Discussion in 'Home Theater Projects' started by DonHo, Jan 11, 2003.

  1. DonHo

    DonHo Auditioning

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    AGGGGGHHHH!!!

    I am having a little trouble with my 142.5 shiva ebs sub that i just built. I disappointed with the sound especially at lower volumes ~70 dbs. The sound is distorted, buzzy at these levels and seems to improve somewhat at higher levels (still not perfect though). It is especially prevalent with music (I know this not a "musical" sub but I was not expecting it to be this bad).

    The sub is being power by 12 year old 240 watt 2 channel JVC amp(each voice coil be driven by a separate channel).
    I have made sure the wiring is in the correct phase. There is + - on each side of the driver and i wired one channel on one side and the other channel and other side of the driver.

    I originally thought it might be the amp but I got similar results with my HK. The interconnects are good quality and i have tried different pairs.

    I fixed an airleak around the vent port and have resealed virtually everything else. I would assume air leaks would be more apparent at higher volumes correct me if i am wrong.

    Any suggestions would be much appreciated as I am a newb when comes to building these. NOTE - My sub's life depends on you guys, it is begging you to fix it before its owner blows it away.

    Thanks in advance

    Don
     
  2. Tim Morton

    Tim Morton Stunt Coordinator

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    are you sending it the correct signal? Thinking back to my car audio days and using some sweet DVC JlAudio subs....I don't thik i ever sent them a stereo signal...do you have a way to mix the signal into mono? meaning can you bridge that amp? There are many ways to connect a DVC driver...are you sure you are following the instructions exactly?
     
  3. Dan Hine

    Dan Hine Screenwriter

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    Sure Tim...You just use a Y from the Sub out of the main receiver to whatever input on the unit you're using to drive the sub. It is a mono signal being sent, its just being amplified by two amp channels. I think it is typically suggested to NOT send two amp channels to a single VC though.
    Don,
    Is the buzzing sound part of the program material sound being reproduced or more of a cabinet buzzing? Did you follow the Adire plans or did you design the cabinet yourself? If the latter, how did you assemble it and what kind of bracing did you use? Any air leaks around the sub itself? Are you positive its screwed/bolted down good and tight? And have you tried using another sub (did the Shiva replace another one?) to make sure its not a problem with the sub output on your main receiver?
    I've built a few Dayton DVC subs and some using the original SVS drivers. The Shiva should be very similar and should leave nothing but smiles on your face, not doubt. We're all here to help. [​IMG]
     
  4. DonHo

    DonHo Auditioning

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    Thanks for the replies,
    THE SUB WILL LIVE TO SEE ANOTHER DAY!
    Stupid me, I took the brass connectors (connecting the pos and negs) off the dual input cup and forgot all about them. I started reading about parellel wiring and realized what I had done. I put them back on and presto a well behaved sub.
    Thanks again for the feedback, this forum is great
    [​IMG] Don
     
  5. Pete Mazz

    Pete Mazz Supporting Actor

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  6. Geoff L

    Geoff L Screenwriter

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    I am quite sure the amp did not like that much at all and blow a nut. Breaker, fuse, or smoke....

    Good to hear problem solved...
     
  7. Allen Ross

    Allen Ross Supporting Actor

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    aww i wanted pics of that shiva going about 4 inches and then ripping is self out and mameing a bystandard.
    oh well there always another time, glad to hear you fixed your problem now shake the world. [​IMG]
     
  8. Jeremy Stockwell

    Jeremy Stockwell Supporting Actor

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    I agree with Pete. If you're sending one channel of the JVC to each voice coil and you've wired everything correctly inside the enclosure, you shouldn't be using the bridges on the dual input cup.

    I'm using a similar setup with my Tempest being powered by my old Kenwood Pro-Logic receiver. One channel (100W) to each VC and it runs great.

    If you've found a connection that you're happy with, great, but watch out for overheating and/or clipping on your sub amp.

    JKS
     
  9. Jack Gilvey

    Jack Gilvey Producer

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  10. DonHo

    DonHo Auditioning

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    THE SUB'S LIFE IS IN PERIL AGAIN.
    I had thought I had fixed the problem, but I was wrong.:b (Allen R. you still may get your wish)
    A question for Jeremy S (or anyone else with a similiar setup), internally I wired a + & - wire from each cap input to each VC. I did not wire the vc in parellel (ie connect a wire from one + to the other + on the vc and one - to -). Did you add these two wires to connect the pos terminals on vc together (as well as the neg)??
    My bass sounds distorted, kind of like slap a side of big 2-3 foot rubber balloon / ball. It sounds loose, distorted.
    It sounds fine with LOTR effects (ie rumbling) but bad with music both CD and DVD movie soundtracks.
    My setup is a HK 525 with Axiom M3's, vp 100 and qs4's with a good quality y on the sub preout to the JVC 2 channel amp. I followed the shiva ebs plans to the T. I carpenter glued (with clamping) all the joints (butt joints) and bracing. The sub should be air tight, to be sure (after the sub was done) a ran an extra bead of carpenter's glue over all the seams and smoothed it with an expensive smoother (my finger).
    Any help would be appreciated.
    Thanks
    Don
    aka a potential sub murderer
    [​IMG]
     
  11. Hank Frankenberg

    Hank Frankenberg Cinematographer

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    Don't you sing in Hawaii?
     
  12. Geoff L

    Geoff L Screenwriter

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    Don

    Do you have the SUB AMP (JVC) hooked up as Dan mentioned?

    Y-adaptor from HT Receivers sub out to the JVC's RCA R & L input? This is a mono signal.

    Terminal cup on sub woofer cabinet, no bars connected!

    Then inside, positive on one coil to one set of teminal cup posts, then the other negative to the negtive on the same side of thet driver to the negative on the same side of the cup you just hooked the positive up. The same for the other coil to the other set of connections on the terminal cup.
    + to + and - to -

    The power wires from JVC's R & L hooked to the terminal cup on the outside. R channel from JVC hooks to one set (dose not matter which) of the Positive and Negative on the terminal cup. Then use the L power wires from the JVC to the other set of terminals on the cup. Keep the R on one set of posts and the L on the other.
    Make sure all connection are correct + to + and - to -!!! Every thing is now wired in phase.

    **NO STRAPS** on the terminal cup!

    Hopefully this makes sence. If you mix up any of the + or - it will screw everything up.

    If you want to reverse phase, just change the + to - and - to + (backwards) for BOTH where the receiver is hooking to the terminal cup. You have to do both not just one. + to - and - to + on both R & L at the cup on the outside of the sub where the JVC wires are connecting.

    Leave the driver coils inside to the cup wired the same.

    Hope this makes sence.

    Edit: Make sure the Balance control is centered on the JVC...
     
  13. DonHo

    DonHo Auditioning

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    Geoff,
    Thanks for your response.
    If I understand you correctly, your saying the correct wiring is simply wiring one of the cup pair (+ and -) to one VC and the other cup pair to the other vc. You would wire each of them pos (cup) to pos (vc) and neg (cup) to neg (vc). Also don't install the bridge between the cup's two inputs. Finally there is no independent connection between the two VC's (ie pos vc to pos vc, neg vc to neg vc).
    If this is the proper wiring, I have tried it and the problem still is there. I would then assume my wiring is correct and something else is causing the problem.
    Going back to what Dan H ask "Is the buzzing sound part of the program material sound being reproduced or more of a cabinet buzzing?"
    The buzzing / looseness seams to be part of the program material and not the cabinet buzzing. The driver when you touch it feels buzzy or resonating. The bass notes are not a single punch but seem to resonate.
    The room size is ~12' by 16'8" if this matters.
    Any further input/ideas would be appreciated.
    Thanks
    Don
    ps
    Hank F - If you heard me trying to sing karoake like Don Ho, (or anyone else for that matter) I think the sound system would be permantly damaged.[​IMG]
     
  14. Dan Hine

    Dan Hine Screenwriter

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  15. DonHo

    DonHo Auditioning

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    Thanks Dan for replying,

    The receiver is connected by two channels, one channel to each terminal on the cup, + to + and - to -. The sub -receiver (sub amp) is connected throught its cd inputs to the main receiver sub preout via y adaptor rca cords.

    I am sure everything is connected properly, i set the main receiver HK 525 sub +/- level to 0 and use the JVC to control the level of the sub output. Is this right or should it be reversed??

    What noises or sound characteristics does air leaks cause, maybe there is still an air leak?

    Could the driver be faulty??

    Or is the source material, (everything from DVD's, Cd's to television) vary alot in the quality of the lower frequencies.

    Any input would be appreciated.

    Thanks
    Don
     
  16. Allen Ross

    Allen Ross Supporting Actor

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    blow it up common you know you want to see it, think of how cool you'd be, capture it with a DV camcorder and post it on the web, hell i will give you free space, and you will be the talk of the town.
     
  17. Dave Poehlman

    Dave Poehlman Producer

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  18. Geoff L

    Geoff L Screenwriter

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    Have you tried wiring just one channel of the receiver to each coil to rule out a bad coil or a bad power channel in the receiver???

    If not try that and do both channels one at a time to rule out bad driver coil or a bad power channel in the receiver.

    Also as Dan pointed out try using a different input on the back of the receiver. Aux, tape, CD, inputs etc, anything except Phono!

    Also check the y-adaptor & cable if using one to see if that might be bad.

    A process of elimination. As Dan made mention, there is a bad driver ever once in a great while. It's rare but dose happen! Just make sure you check everything twice to rule that out.

    Geoff
     
  19. Ryan Schnacke

    Ryan Schnacke Supporting Actor

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    If, at some point, you had the wiring such that the JVC's outputs were shorted together then you may have blown one of the output devices in the JVC amp.

    For instance, if you had both the right and left channel outputs from the receiver connected to the terminal cup's dual inputs and you had the shorting bars in place then that's bad. You were driving one output into the other and they don't like that. At least you were playing the same signal through both channels but still there is potential for damage.

    Try connecting the JVC to some full range speakers and playing some music. Push the balance all the way to the right and then all the way to the left to test each channel individually.
     
  20. Geoff L

    Geoff L Screenwriter

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    As Ryan pointed out excellent idea.

    If you did blow an output stage, pull the cover and check for fuses on the inside of the JVC receiver/Amp.

    Allot of their models were fuse loaded inside. Be sure to unplug it first if you need to go inside!!!
     

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