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Question for B7K users.

Discussion in 'Effects [BG]' started by Spencer!, Nov 17, 2013.

  1. Spencer!

    Spencer! Supporting Member

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    Stompbox designer/builder for 3Leaf Audio & Darkglass Electronics
    I've got a question for anyone who uses a USA-made B7K....have you ever been in a situation where lifting the ground (button not pushed in) on the balanced output helped?

    I ask because I have a theory that lifting the ground never helps. I've never personally run into a situation where I had to lift it.


    (this question doesn't apply to the Finnish B7K as that used a different grounding scheme)
  2. Veldar

    Veldar

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    No idea man, I just leave mine on, sorry I couldn't help.
  3. StingrayDerek

    StingrayDerek Supporting Member

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    I've kept mine in since day one so I can't really help. But I'll try it lifted next band practice!
  4. franksgbass

    franksgbass Supporting Member

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    Yes. I sure did. I played a show at a local venue that has pretty good sound. During sound check I heard an annoying hum from my rig. I thought it was the Orange Terror I was using. Because I was using the B7K as a DI I figured I'd check the connection and I noticed the ground lift button. Pushed it and the hum was totally gone. That was actually the only time I ever used a ground lift. But it made a huge difference in that particular situation.
  5. Adamixoye

    Adamixoye A PT Pro is cool for worship, right? Supporting Member

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    This is only for using the DI?
  6. franksgbass

    franksgbass Supporting Member

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    Yeah. You wouldn't need the ground lift without the DI
  7. Spencer!

    Spencer! Supporting Member

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    Was the button pushed in or out when the hum went away?
  8. franksgbass

    franksgbass Supporting Member

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    It was a few months ago. I would just be guessing. All I remember is being stoked that I finally used a ground lift button. Sorry I couldn't be more helpful.
  9. zwkoch

    zwkoch You can't do that on bass enthusiast Gold Supporting Member

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    I have used the DI on the B7K for a few months. In our church, I have had to use the ground lift on passive DI boxes and my Verellen MS Pre to eliminate hum from my signal. A few weeks after switching to the B7K as my primary DI, I noticed a hum from my channel (I normally do not have a hum from the B7K DI). I released the ground lift switch (button out) and the hum went away. Later, I went and looked at our sound board (I also run sound) and noticed that the phantom power was toggled on for my channel. This is not normal or necessary. Once phantom power was off, I pressed the ground lift toggle back in on the B7K, and the hum was no longer there. This is my only experience with the B7K ground toggle.
  10. Spencer!

    Spencer! Supporting Member

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    Stompbox designer/builder for 3Leaf Audio & Darkglass Electronics
    I would expect the hum to go away if you went from lifted to grounded, but not the other way around.
  11. jumblemind

    jumblemind I also answer to Bryan Supporting Member

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    Yeah, I always assumed that ground lift was tied to phantom power. I use the ground lift switch on my M80 DI to accept phantom power from the board to power the pedal.
  12. Trombassix

    Trombassix

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    Why not research why manufacturers decided to add the option to lift the ground? Those with the incentive to avoid adding to a circuit are doing so because...?

    I used to live in an old house. It was cheap to rent but the ancient electrics brought a world of noise into my audio path. Some of it could be gotten rid of by using transformers to decouple from ground or by lifting the ground, but the RF was so bad that the only real solution was to filter the supply with a Furman Power conditioner or a UPS that bypassed direct connection and you receive through a battery.

    I think the key to deciding if a ground lift is unnecessary is to understand the different forms of noise and hum that spoil a good, pure bass sound.

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