DC-5 FX loop mod

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Fxrs, Jan 7, 2006.


  1. Fxrs

    Fxrs Member

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    Hi, can anyone guide me thru modding my loop to series? DC-5 combo, saw a thread @ HC about the F-50 loop, not sure if mine is the same. I'd really like to be able to use a delay pedal, don't have the cake for a rack unit, which seems to be the way Mesa is leaning with their loops. Thanks, Paul.
     
  2. John Phillips

    John Phillips Member

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    If you want to use a normal delay pedal where the dry signal remains analog (eg Boss DD-3) you don't have to mod the loop at all. The loop level is fine for pedals.

    I did find that a Line6 DL-4 caused trouble though - this one digitizes the dry signal and even though the Mesa loop goes to about 90% (not the 100% that is marked), the remaining 10% dry is enough to cause trouble.

    If you do need to convert it to series, all you need to do is disconnect the wire that goes from the send socket to the CCW end of the Mix pot - from memory it's the orange wire, but it might be red - not the one that goes to the middle tag of the Mix pot. Just unhook it at one end and tape it up. Leave the mix set to maximum and you're done.

    (IMO Mesa should fit a switch on their amps, since all-digital pedals are becoming much more common. I did think about fitting a pull pot to mine, but in the end I ditched the DL-4 and just put the loop back to parallel.)
     
  3. princeton

    princeton Member

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    I have a DC-5 myself and there is a pot that goes from series to parallel near the in / out from the loop, at the back of the amp.
     
  4. John Phillips

    John Phillips Member

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    Actually it remains parallel at all times and goes from about 10% wet/90% dry to about 90% wet/10% dry depending on the output impedance of the effects unit (it's incorrectly marked 0% to 100%). You can't get it to series without modding the amp.
     
  5. Fxrs

    Fxrs Member

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    You think so? I hate the sound of delay pedals thru my loop. If I do this, will it improve the tone? I've tried lots of pedals, floorboards (GT-8,GT-6,RP-100,RP-50,etc.) my loop doesn't play nice with any of them. What would you recommend? Right now my delay is an old Boss DD/sampler. HELP!:NUTS
     
  6. John Phillips

    John Phillips Member

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    I would take a bet that all those floorboards digitize the entire signal (certainly the Boss ones do). The problem with this - apart from inherently bad tone IMO - is that it causes latency on the signal, which means that there is a very short delay, typically a few milliseconds, as the signal passes through the digital processing. When you add that slightly delayed signal to a dry, undelayed signal - which you do unless the loop is series or a parallel that can go truly to 100% wet - you get a sort of fixed flanging effect called a comb filter, which sounds slightly out of phase, thin and harsh.

    So you cannot use any effect which digitizes the entire signal path in the loop of most Mesa amps, because they all have this same (slightly crude) parallel mix.

    Some effects, even though the effect is digital, leave the dry part analog even when the effect is on. The Boss DD-3 and DD-5 do this, but I'm not sure about the DD-6 or any of the pitch shifters, samplers or other digital pedals... I'm guessing that if yours sounds really bad it will be one of those that does digitize the whole lot.

    I run a digital delay - actually a Boss DE-200 rack unit (which keeps the dry part analog) now, but before that a DD-5 - in the loop of my DC-5, with the stock parallel mixing, and it sounds fine. The DL-4 did not.

    The other alternative (without modding the amp) if it's just the delay you use in your loop, is to set the pedal to 100% effect, then use the mix knob on the amp to control the effect level. That way it doesn't matter if the dry signal in the pedal is analog or digital, but the disadvantage is that you can't control the mix from the pedal, if you need to. This should in theory sound the best too, since the dry signal hasn't even gone outside the amp.
     

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