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Thread: buzzing from hrdx?

  1. #1
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    buzzing from hrdx?

    got a usa hrdx and Im getting a good amount of hum coming out, amp sounds normal but the the humming is annoying, bought it used so , I tried a new one and didnt make noise , any ideas? also my extension speaker jack inst working, only the internal jack, could this be the problem?

  2. #2
    Forum Member NTBluesGuitar's Avatar
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    Re: buzzing from hrdx?

    Always start with the tubes. Swap them around or swap them with known good ones and see if the problem persists.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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    Re: buzzing from hrdx?

    yeah all tubes brand new , its weird how the internal speaker jack works but not the external seeing as the signal runs through the external then the internal??

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    Forum Member FrankJohnson's Avatar
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    Re: buzzing from hrdx?

    Is your first speaker plugged in? (the internal speaker) I can't remember, but I think you can plug in the external WITH the internal, or use an external instead of the internal, but I think (I could be wrong and don't have time to check right now) that you need that first connection made.

    Also - what ohm load is the external cab?

    Could it be your ext. cable?

    if in doubt - look up the manual and read to be sure......
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    Kenny Belmont
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    Forum Member NTBluesGuitar's Avatar
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    Re: buzzing from hrdx?

    You HAVE to have something plugged into BOTH the internal speaker jack and the ext. speaker jack for it to work. They both have to have 8ohm loads on them, too.

    The only way to use the 4ohm tap in the ext. speaker jack is to have an open plug in the internal speaker jack.

    Anything else is not healthy for the amp.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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    Forum Member FrankJohnson's Avatar
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    Re: buzzing from hrdx?

    I thought I recalled something like that.....
    Kenny Belmont
    >:^{I)>

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    Re: buzzing from hrdx?

    I need both plugged in to work?? why if they are both 8 ohm they are wired parallel no?

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    Re: buzzing from hrdx?

    if I plug in both I get nothing out of either thats whats puzzling the extension cab work when plugged into internal jack though

  9. #9
    Forum Member NTBluesGuitar's Avatar
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    Re: buzzing from hrdx?

    Quote Originally Posted by 155 View Post
    if I plug in both I get nothing out of either that's whats puzzling the extension cab work when plugged into internal jack though
    So, does the internal speaker work in the internal jack? If not, and the ext. cab DOES work in that jack, I suspect your problem lies in your internal speaker. Check the spade connectors and wires on the internal speaker and check for continuity from the speaker plug to the spade connectors.

    Quote Originally Posted by 155 View Post
    I need both plugged in to work?? why if they are both 8 ohm they are wired parallel no?
    Take a look at the schematics. The speaker jack connectors for the plug tips are wired in common. With nothing in the ext. jack, that common connection is on the 8ohm tap.

    However, by plugging into the ext. jack you are putting the 4ohm tap on the speaker jack tip connectors, but, more importantly, by NOT connecting something in the main speaker jack along with it, those commonly-connected tips on the 4ohm tap are shorted to ground at the same time.

    Because the jacks are in common, and when both are plugged in they're looking for a 4ohm load, you need to have the two 8ohm speakers, in parallel, to achieve that load.

    So, nothing in main jack with something in the ext. jack = 4ohm tap of OT and speaker shorted to ground.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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    Re: buzzing from hrdx?

    yes the internal speaker works with the internal jack also external cab works with internal jack, so must be a bad external jack but ites just weird that the internal works and it wired off the external that doesnt work

  11. #11
    Forum Member NTBluesGuitar's Avatar
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    Re: buzzing from hrdx?

    That is strange.

    However, in looking at the jack wiring, there are a lot more wires on the ext. jack compared with the internal jack. They could be having problems. Give those a look, too.
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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    Re: buzzing from hrdx?

    thanks for the help ntblues ill keep you posted!

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    Forum Member FrankJohnson's Avatar
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    Re: buzzing from hrdx?

    NTBLUES is Wise................

    And that is all I have to say about that.
    Kenny Belmont
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    Re: buzzing from hrdx?

    I traced it to a wire going to the external jack it was barely connected and looked fine until I removed the jack and resoldered it. Buzzzing gone! thanks all , jacks both working too

  15. #15
    Forum Member NTBluesGuitar's Avatar
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    Re: buzzing from hrdx?

    AWESOME!!!

    Glad you got it nailed down!
    "...pray do not imagine that those who make the noise are the only inhabitants of the field;
    that, of course, they are many in number; or that, after all, they are other than the little,
    shriveled, meagre, hopping, though loud and troublesome, insects of the hour."

    -Edmund Burke

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