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External hardware as insert

Discussion in 'Recording' started by andymasiero, Jul 15, 2012.

  1. andymasiero

    andymasiero Active Member

    Hello,

    This is my first post on ANY studio/recording forums.

    I have a Digi 003 Factory and a Boss GT-8 guitar effects processor.
    I'm trying to use the GT-8 as an insert with the analog inputs.
    It took me a while to figure out how to get ANY sound at all and now I do and its too much. I get constant level.
    (to clarify) This wasn't a problem before when I just plugged my guitar in and used it as a normal input.

    Analog out #5 of 003 factory is connected to input on the GT-8.
    Stereo outs of GT-8 are connected to analog inputs 5-6 on the 003 factory. I've also tried hooking it up in mono and I have same problem.
     
  2. Boswell

    Boswell Moderator Distinguished Member

    Hi, and welcome to the forums!

    I think your problem is that the output from your 003 is at too high a signal level for the GT-8 to handle. There is a secondary difficulty that the 003 outputs are balanced and a guitar input is inherently unbalanced, so it has to be connected up carefully.

    The signal level problem is best tackled by using an attenuator, which you could make from a couple of resistors if you are handy with a soldering iron, or else you could buy a suitable one. The sort of attenuation you would be looking for is around 20dB plus the 6dB you get from unbalancing. You could approximate this by using a 4K7 resistor in series with the +ve output (tip) from the 003 TRS jack plug together with a 470 Ohm resistor from input to ground (sleeve) on the GT-8 TS jack plug. Leave the -ve (ring) on the TRS plug unconnected, as connecting it up this way gets round the balanced/unbalanced problem as well.
     
  3. andymasiero

    andymasiero Active Member

    Thanks for the response Boswell. I very much appreciate it.
    I've been looking into what you said and it's been a good learning experience for me. Yep, I have all TS cables connecting everything, so that's one thing I'll need to fix.

    I don't want to spend the time to make the parts if I can get them at decent prices. I'm working 60 hours a week and have 2 toddlers terrorizing my house.

    I'm not sure what to buy though.Seem as though attenuators come in 20dB and 30dB. Which should I get? Should I run a balance or unbalanced cable from the attenuator to the input on the GT-8? Will I need an adapter for that to get the best sound?
     
  4. Boswell

    Boswell Moderator Distinguished Member

    If you can get an 20dB attenuator that has TS jack sockets for input and output, the easiest thing then is also to get a TS jack cable (to run from the attenuator output to the GT-8 input) plus an insert lead for connecting the balanced 003 output to the unbalanced attenuator input. You would connect the insert lead's TRS plug into the 003 line output and use the "send" TS plug to connect to the attenuator input. It would be wise to tape up the unused "return" TS plug on the insert lead to avoid it short circuiting on things like guitar strings, metal cabinets and toddlers.
     
  5. andymasiero

    andymasiero Active Member

    Well, I've done some shopping at sweetwater. The inline attenuators I could find are all XLR. All of the components I need, including 2 balanced cable to go back out of the GT-8 into the 003 would cost about $110. If I bought all male balanced cables and used adapters to get through the XLR pad it's actually $20 cheaper ($91 total now).

    So, I decided to go the DIY route you explained earlier. I got very confused when shopping for resistors at Radioshack. It's a little advanced for me at this point.

    What I've ended up with in my shopping cart (not purchased yet) is bulk cable, an attenuator, and all the connectors I need for $61.76.

    This last question (hopefully?) concerns the cable going from the attenuator to the GT-8. My plan is to connect the XLR on one end and a 1/4" TS on the other end to connect that attenuator to the input of the GT-8. Can I just tape off the ring wire on the TS end and leave it that way? Essentially the same thing at taping off the return for an insert lead, correct?
     
  6. Boswell

    Boswell Moderator Distinguished Member

    I had a quick look at the Sweetwater site, and, indeed, in the sub-$50 range they seem only to have XLR in-line balanced attenuators. Unlike taking an unbalanced output directly from a balanced output of a piece of equipment, you could run into some problems taking an unbalanced output from a balanced attenuator. So for the feed from your 003 line output to the input of the GT-8, I think the lowest-cost thing to try is wiring up the cable yourself.

    You will need to buy: a 1/4" TRS plug, a 1/4" TS plug, a 4K7 (4700 Ohm) and a 470 Ohm resistor (both 1/8W) and a length of single-conductor coax cable. Thread the two plug covers on to the cable in the appropriate orientation and then carefully strip the cable outer back about 1" from each end to reveal the inner conductor insulation. Pigtail the outer screen at each end of the cable and wire to the sleeve of the two plugs. Cut away about 1/4" of the insulation on the inner conductors and twist the inner conductor ends lightly together. On the TRS plug, solder one end of the 4K7 resistor to the tip contact and the other end to the cable inner conductor. Sleeve this joint lightly with tape to avoid shorts and screw the cover on. At the other end, wire the cable inner conductor to the tip connection but also to one end of the 470 Ohm resistor. Wire the other end of the resistor to the sleeve and screen connection. Check that there are no shorts when the resistor is pushed down sufficiently for you to slide the cover on. That's your input cable done.

    You can do the output (GT-8 to 003) in two ways. One way is to use a pair of TS jack leads (not balanced TRS) from the L and R GT-8 outputs to a pair of line inputs on the 003. The other way is to use a single 75 Ohm RCA coax cable from the S/PDIF output of the GT-8 into the coax S/PDIF input of the 003. This second route is digital and avoids the double conversion (D-A-D) inherent in using the analog path.

    Good luck with this and let us know how it works out!
     
  7. andymasiero

    andymasiero Active Member

    Boswell,

    I got my cable wired up and everything set up and it sounds perfect. Pure silence when I stop playback and great effects processing when I want it.

    You're awesome, Boswell! Thank you so much for all the help!
     
  8. Boswell

    Boswell Moderator Distinguished Member

    That's good. Did you use the S/PDIF output of the GT-8 into the 003 or did you stick with the analog connections?
     
  9. andymasiero

    andymasiero Active Member

    I forgot about that. I'll have to do that, I'm noticing a bit of delay, so that ought to cut that down.
     
  10. Boswell

    Boswell Moderator Distinguished Member

    I doubt that you would notice any difference in any delay when going in digitally via S/PDIF from the GT-8 to the 003 rather than in through the analog ports. What it should do is improve the noise and digitization accuracy of the effect returns. My guess is that if you are hearing a delay it's due to other latencies in the loop.
     

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