Please help: Rivera, Soldano out of phase?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Ariel Pozzo, Jul 12, 2005.

  1. Ariel Pozzo

    Ariel Pozzo Member

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    I'm having lots of trouble trying to make my Radial Headbone to work with my amps, a Rivera Knucklehead 100 and a Soldano HR100+.
    Whenever I connect all this stuff together, using the correct cables, the correct connections, and all (I'm absolutely sure I'm hooking things up the right way) I get an annoying feedback howling out of the Rivera (that i never get when playing the amp by itself). This feedback goes away when i turn the gain down on the amp, but I can hear the tone sounding like there's something weird with the phase...it really sounds like there are two out of phase signals going.
    I emailed Radial but they never responded.
    So...one last pry for help before I throw the Headbone in the trash: Could it be that my Soldano and Rivera amps are out of phase with each other, thus causing all this mess??? If so, how can I fix that?
    Many thanks! :)
     
  2. John Phillips

    John Phillips Member

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    Ariel, are you still running the two amps into the same cab? I remember you having a ground loop issue caused by the metal jacks and plate on the cab.

    Even if you did cure that - does the problem persist if the amps are run into two separate cabs? If not, it's probably being caused by some sort of inductive coupling via the cab cabling (even if the ground loop as such has been removed).

    It's certainly possible that the amps are out of phase, but that by itself won't cause feedback unless there is some sort of unintended linkage - although it will cause odd tone.

    Are you running the two amps physically very close together as well? (eg one on top of the other.) That could also cause inductive coupling via the magnetic fields of the transformers.
     
  3. TheAmpNerd

    TheAmpNerd Member

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    Hey John,

    If the transformers are coupled...then either physical separation

    or

    perhaps (if stacked) turning one amp 90 degrees or 180 degrees should help or at least let him know that is was
    the problem.


    Next question

    Would placing one amp in a Faraday cage help?
    or
    Is that only with EMP (Electro Magnetic Pulse).
     
  4. Priestunes

    Priestunes Member

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    Doesn't sound like a phase issue to me. You can check by reversing the + and - to the speaker(s) in one of your amps (or the speaker cord if you can open the jack and switch them, or use a cord already wired like that). If after switching there's a noticable loss of bass, then your amps weren't out of phase. But who knows! Maybe you're on to something peculiar about the Tonebone into two amps. One thing, though. Peter over at Radial Engineering is a really great guy. He's a bit swamped, like most, but he is usually very responsive, even if it takes a week. Please don't take this the wrong way because I'm not making any claims: I've noticed that with these fellas who are SWAMPED by the tsunami sized flood of emails that they receive every day, if you're concise, polite, patient, (and patiently persistent if required) you've just made a friend. They really appreciate a "thank you for your time," or a "I know you must be busy, but..."
    :)
     
  5. Priestunes

    Priestunes Member

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    Headbone... right! That's what I meant.
    :jo
     
  6. Randy

    Randy Member

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    Could it be a borderline microphonic preamp tube in V1 of the Rivera that is being driven over the edge by a buffer in the Headbone? That would be my guess.

    Even if your 2 amps are out of phase with each other (as in they have a different number of gain stages) each should sound normal when played by itself.
     
  7. Ariel Pozzo

    Ariel Pozzo Member

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    Thanks for all the replies! :)
    There's no speaker cab issue, since the Headbone switches amp inputs and outputs, thus sending only one amp at a time to the speaker.
    The tubes in the Rivera are definitely NOT microphonic.
    I think the most probable cause is transformer coupling as some of you suggested...I'm running the amps one on top of the other. I'll try placing one amp somewhere else and see what happens.
    Many thanks guys, you really helped me!!! :):)
     
  8. Ariel Pozzo

    Ariel Pozzo Member

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    Well, just back from my tech's.
    We have found the Headbone itself is defective, we tried it with several other amps and it does the same high pitched sqealing when turning the gain up.
    We even tried it with only one amp hooked up on AMP 1 and it's exactly the same thing...my Rivera is OK, it was not the amp itself.
    We found out it's some kind of feedback inside the Headbone, when turning the Presence knob on the amp, the squealing changes pitch. On a JCM800 2210 head we tested, it produced not a high pitched squealing but a lower octave harmonic, much like an octave effect...weird.
    So...I'm here with a $250 doorstop. Shipping it back and forth to the factory is amost the cost of a new one from where I live.
    Mark my words: This is the LAST time I buy something without trying it first.


    :mad: :mad: :mad:
     
  9. Ariel Pozzo

    Ariel Pozzo Member

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    SOLVED!!!!!!!!!!!!!!!!!!!

    I thank Paul Blake of Radial for the quick answer...but I just found the solution...read on!!!!

    Paul
    Thanks for the quick reply
    We've just found the problem...and you might want to hear about it...
    We found there was a solder joint touching the back cover...more precisely, one of the solder joints on the Speaker Out jack was too high, and it was located right below one of the metal screws holding the back cover on, so it was making contact to ground thus causing this annoying feedback, I just clipped it so it won't touch the screw again, assembled it back and VOILA!!!!!!!!!! No noise and it's working wonderfully.
    I hope this info may help you guys in the future.
    Thanks
    Ariel Pozzo


    On 7/13/05, Paul Blake <paulblake@cabletek.ca> wrote:
    > Hi Ariel, I will look into this problem. For the time being what kind of
    > speaker cable are you using.
    > It should be at least 12guage and as short a length as possible. Please
    > get back to me on this.
    >
    > Regards
    >
    > Paul Blake
    > Service Technician
     

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