something wrong with my 5 yr old KLH sub.some advice needed.

Discussion in 'Archived Threads 2001-2004' started by TonyD, Jan 20, 2003.

  1. TonyD

    TonyD Who do we think I am?
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    ok so i have this sub and it doesn't work and now i'm trying to figure out if it is a sub that is worth getting fixed.

    it's a KLH sw-12. has a freq response of 26-20,000 hz.
    i really don't know what that means so i dont know if it's good or not.

    amp power is 100 watts.
    has auto on.
    phase rev/norm switch.
    low level left/tr switch.
    high level in/outs.

    i suppose much of that is standard on good subs. i just don't know.

    so what happens is that when the sub comes on all i get is a very loud hum or buzzing type sound.
    i opened her up and everthing seems to be connected so i dont know whats wrong.

    could it be the transformer?

    so should i get this sub fixed or get a new one.

    my budget on a new one would be about $500.

    and what new one should i get for that much money?

    thanks for the help.

    edited to corrwect the 100 watts power.

    also the 26-20,000 hz is exactly as it's printed on the back of the sub.
     
  2. John F. Palacio

    John F. Palacio Supporting Actor

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    TonyD.

    Double check your figures:
    26Hz-20,000Hz?????? (these are specs for full range speaker)
    Amp power of ONLY 10 watts?????? (most subs have 100+ watts)

    If you get a loud hum when it comes on, it is not a "transformer" issue. You probably have a bad power supply. Anything from bad rectifiers to open capacitors.

    Now to the meat of things:
    Hard to say what a good tech will charge in your area. I am guessing $75 for an estimate that would be applied to the repairs which could run to $200. Again, hard to say.

    You might want to call around to find a tech that would tackle this sub and see it it would be cost effective to service.

    As far as subs for around $500, there are many: SVS, HSU and Velodyne come to mind. You also have Klipsch, PSB, Paradigm and JBL.

    Of those I would recommend SVS or HSU (IMHO)

    Best regards.

    John
     
  3. Edward J M

    Edward J M Cinematographer

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    I second John's opinion. The amp is probably kaput. Instead throwing good money after bad getting it repaired, I'd just go ahead and buy a new subwoofer plate amp from Parts Express for around $100. It will be a better quality amp than the OEM unit, and you won't have to spend money and time just confirming your KLH amp is shot.

    Also, the FR you listed is wildly optimistic on KLH's part. The 26 Hz is probably the -10 dB point. That sub has an F3 of around 35 Hz.

    If you want to keep the sub, and you are on a tight budget, spring for the new amp.

    If you want to upgrade and put the amp money towards a new sub (recommended IMHO), look at the SVS 25-31 PCi or the HSU VTF-2 (in that order) in your price range.
     
  4. TonyD

    TonyD Who do we think I am?
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    edited to correct the 100 watts power.



    sorry about that goof.

    also the 26-20,000 hz is exactly as it's printed on the back of the sub.

    "I'd just go ahead and buy a new subwoofer plate amp from Parts Express for around $100. It will be a better quality amp than the OEM unit, and you won't have to spend money and time just confirming your KLH amp is shot."
    i guess that would be a good idea but i have no idea what it means. or how i would install it if i got it.

    so it looks like i will end up getting a new sub.


    i have Klipsch so i guess i'll end up getting the matching sub.
    hopefully i'll be able to buy one for $500 or less.

    thanks for the help. anymore ideas would be greatly appreciated.
    ok i just did a qhick check at parts express and now i know what the amp plate is. it appears to be the object with all the parts attached to it on the back of the sub.
    and probably wouldnt be too hard to replace.
     
  5. TonyD

    TonyD Who do we think I am?
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    until i can either get a new amp or sub can i use an old pl reciver to power this sub?

    and if yes how do i hook it up?
     
  6. Jose G

    Jose G Supporting Actor

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  7. TonyD

    TonyD Who do we think I am?
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    thanks jose. i do plan to get an svs. but for now i have to get by.

    so with the old sub i have, there are in/outputs on the back for hooking to my amp.
    more specifically "high level in/outs from amp"

    it appears that i would just hook the outs from my denon3300 right to the ins on the sub then from there to the front speakers.
    is this right and how will this work as a temp until i get a svs?
     
  8. Jose G

    Jose G Supporting Actor

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    Tony,
    Try this site here and go to #5 and especially #6. I think you'll find the answer to what your asking. Good luck and be well.
     
  9. TonyD

    TonyD Who do we think I am?
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    jose thanks again.

    so it appears that from #6 i can set up my old receiver to send lfe to my sub with the blown amp.

    and i can sooner get a svs without an amp built in and power it also with this receiver.

    now i suppose i could power both an svs and the old sub with my old receiver?

    i guess the best thing to do would be to call svs and see what they recommend.
     
  10. Jose G

    Jose G Supporting Actor

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    Just keep in mind what the SVS site said in terms of providing enough power and heat build up on a receiver driving a 4 ohm load to the sub. The SVS appears to be an efficient unit which makes a difference but how efficient your other sub is also something to consider. It looks like you'll be ok powering one sub, but two with one amp I'm not sure about. Yep- contact the SVS people and ask about this last point.
     
  11. Oachalon

    Oachalon Stunt Coordinator

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    The sub plate amp from klh is around $70. I bought one of those amps because it was cheap and made decent power, and i wanted to make a sub cheap.
     
  12. TonyD

    TonyD Who do we think I am?
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    Oachalon also mentioning were or how you got it would be helpful.
     
  13. TonyD

    TonyD Who do we think I am?
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  14. Jose G

    Jose G Supporting Actor

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    Tony
    Did you get this problem fixed? I've been out of town.
    Is your volume on your old amp turned to full up?
    I've never set up a system this way, so I don't know how much I can really help you anyway, but maybe I can trouble shoot with you- even just to spark some new ideas or until someone else chimes in who has done this before. Where do you have your subwoofer level set to? Did you make sure that your amp has enough juice to power the sub? Does it run a 4ohm load? Are you using a 75-ohm A/V cable from the subwoofer out of your receiver to the old amp? Of course, you've set the old receiver to the CD output right? Let me know where your at?
     
  15. TonyD

    TonyD Who do we think I am?
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    yea i have everything set that way so i dont know why it doesnt work.
    i have an old sony dd receiver so its powerful enough.

    i just dont have something hooked up right.

    i first had both fronts going right into the ins on the sub, from the main reciever.
    then out from the sub into the the front speakers.

    i was getting minimal bass that way but not what i should have been.
     
  16. Jose G

    Jose G Supporting Actor

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    I just varified that it should work from an expert sub builder, but he did mention that "...you may have to add some binding posts to the box to get it to work since the internal amp is blown. Also, many subs have some sort of boost built into the amp. So by bypassing the amp, you may not get the same sound. This can be either good or bad depending on how much boost there was..." This FYI is from Brian Bunge of Rutledge Audio Design. I mention him because if this doesn't work out and it comes time to buy a new sub, for your $500 budget- I would contact him to make you something that would blow away anything you could buy in a store for that price.
    Anyway, you said, "i first had both fronts going right into the ins on the sub, from the main reciever..." You mean from the old receiver- the sub amp- right? So you have the LFE sub out from the main receiver going to the old amps cd in and the old amp set to CD and it's main speaker outs going to the subs speaker inputs, right? Yikes! I'm getting a headache. This should work I believe. I'll see what else I can come up with. In the mean time- where's everyone else on this one?
     
  17. TonyD

    TonyD Who do we think I am?
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    no one else cares.[​IMG]



     
  18. Jose G

    Jose G Supporting Actor

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    Tony,
    Post your question on the receivers/seperates/amps forum in terms of how to use your old receiver as an amp in this way- explaining of course what youve done so far. I'm sure one of those amp gurus should be able to help you out there pretty quickly. People care, man! They do! [​IMG]

    I'm thinking your receiver just isn't pushing the needed juice to the old amp even though it's rated high as you say. Or, even more likely, that the amp has that boost level built into it that Brian Bunge mentioned and that's somehow preventing the old receiver from powering up the sub properly. I say this because you are getting some bass- just not the bass that you want. Well, good luck with it and let me know where you go with this project. Take good care, José
     
  19. Andrew Pierce

    Andrew Pierce Stunt Coordinator

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    I think that when using the high level inputs on an active subwoofer, the subwoofer typically just extracts the signal, but still uses its internal amps for power. This would correspond to what you're saying is happening.

    In order to use an external amp you'd need to bypass the blown amp entirely, and run a wire directly from the binding posts (or from a new set up binding posts) to the driver.
     

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