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Hum in Guitar Amp/ DI question

Discussion in 'Guitars' started by jg49, Aug 5, 2009.

  1. jg49

    jg49 Well-Known Member

    Before I purchased the Minimee tube amp I would frequently record a guitar amped (solidstate) and direct by employing a Roland A/B/Y switch routed as follows Guitar to Roland switch A to amp B direct to one of my Presonus FP instrument channels. This never gave me any problems. When I tried this same routing with the tube amp I encountered an unacceptable level of hum in the amp. I assumed it was ground loop and sent the B cable to an ART8 Isolating transformer 1/4" input
    http://www.artproaudio.com/products.asp?type=88&cat=11&id=108 and took the 1/4" output to the Presonus. This reduced the amount of hum but it is hardly quiet.
    So I guess my question is can I send the guitar direct into the isolating transformer 1/4" input and take the xlr input (in order to stay on the same side of the transformer) with the correct cable and go into the input of the amp or will this alter the impedance in a way that will affect tone or amp response? I would then send the output side to the Presonus. If I send the output side to the recording will the resulting recording allow me to reamp later? Which is the purpose of this to begin with.
    Or is the simplest solution to purchase a DI box that has a thru-put and send the xlr to the Presonus? If so any recommendations for a multipurpose DI, I already own a Radial Reamp box so I don't need necessarily a passive DI to use in reverse.
    Basically I would rather work something out with ART or some other cabling set up if I can but if not spend some $.
     
  2. Davedog

    Davedog Distinguished Member

    When I try to use an A/B/Y switch with any of my amps and guitars I encounter the same problems. I have Morleys. I have tried isolating each output with a transformer and wasnt ever successful. Although there was a reduction of hum it wasnt ever enough for me. The DI approach will get you that split signal between a direct guitar input and the mic'd amp without the hum.

    Why the A/B/Y boxes do this is beyond my comprehension.
     
  3. jg49

    jg49 Well-Known Member

    Ok. Here are a few I am looking at. Correct me if I am wrong but I probably don't need an active box because all my cable runs are less than 25'. But I have been told that they have more headroom and the Countryman was a friends recommendation
    http://countryman.com/store/product.asp?id=52&catid=3
    I have read here about Jensen equipped boxes
    Melodyne this one is passive
    and the active J48 which seems to have a bunch of other features, pad, high pass, merge, etc.
    http://www.radialeng.com/pdfs/smartsheet-j48.pdf

    Just looking for some input. Other uses bass DI recording, my Taylor direct to PA, and the above posted situation. They are all in the same price range.
     
  4. Davedog

    Davedog Distinguished Member

    You cannot go wrong with any of those. Countryman and Radial are heads above any off the shelf crap you can buy at gitarmart.
     
  5. rockstardave

    rockstardave Active Member

    actually you can buy radial and countryman at guitarmart
     
  6. Guitarfreak

    Guitarfreak Well-Known Member

    Yeah but you know that they would try and steer you away from those and into a Behringer model or something like that. I am so tired of hearing 'you don't need that' or 'that's not what you want' whenever I walk into that place. I never understood why people didn't like Guitar Center until I joined this site and started learning the facts.
     
  7. Sundhy

    Sundhy Active Member

    There are some A/B/Y switchers that have ground lift switches for each output that are claimed to solve the hum problem. Haven't tried them so can't say for sure.

    Conrad
     

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