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  • Reducing (distance from mixing board) hiss

    Hi,

    I have a potential need to feed guitar and/or pianos into a mixing board requiring a line about 40 feet long. Additionally the same distance for one of two small 80 watt range solid state amplifiers being fed from the mixing board. I just tested feeding the guitar in with over 40 feet of guitar chord and it did not seem to add too much hiss. However feeding the amp with 40 feet creates way too much hiss and 20 feet adds a noticeable amount. A simple 6 foot feed into the amp adds no hiss from what I can tell. I believe the lines were not shielded either (they are so old I can't remember for sure). The only things I can think of for reducing hiss are shielded lines and bluetooth. however I don't know of any specific products that can be trusted to be truly better at reasonable prices. I have a need for the same distance for mics but I don't think mike lines will be a problem since they are low impedance. Does anyone have any approach or specific product suggestions for reducing hiss with the (guitars,pianos,amps)?

    Anyway, this is an interesting video regarding a check to make regarding quality 1/4 phono plugs.
    https://www.youtube.com/watch?v=YrorQwwd5IU

    Thanks,
    John
    Last edited by bowesj; 10-19-2016, 06:56 PM.

  • #2
    Look up a book on basic sound systems.

    A 40 foot guitar cord acts like a capacitor and should roll off your highs. I fight to keep any guitar cord under 20 feet. Or use a wireless.

    But ever notice the tiny weak signal from a low impedance microphone can travel up a 20 foot mic cord, down a 100 foot snake, and into a mixer without losing anything or gaining noise? That is because they use balanced lines. A Low-Z mic has three contacts instead of the two in a guitar cord. If you want to send a signal 80 feet into an amp, use balanced lines. You can use XLR connectors like on mics, or you can use 1/4" plugs of the TRS sort ("stereo").

    If you had an unshielded guitar cord, forget the hiss, it would be HUM city. No one makes unshielded mic cords.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Thanks for the balanced line tip Enzo. It has been years since I have read about balanced lines. It is slowly coming back to me. If I understand you correctly it sounds like all I need to do is get the signal into a balanced line A.S.A.P. for all the signals I mentioned (Guitar,Piano,Amps) and out of balanced as late as possible. Wireless is a bit too high cost for me at the moment. I did a google search "guitar chords with balanced lines" and found this link which I will study carefully for now.
      http://thehub.musiciansfriend.com/te...work-with-them

      Thanks again, John

      Comment


      • #4
        Strictly speaking a guitar cord wouldn't be balanced. Guitars are rarely balanced, but you can use a matching transformer. Piano may or may not have a balanced out. Usually there will be a 1/4 jack, but it may be TRS and wired so a TS plug will unbalance it. Many amplifiers with 1/4 input jacks are still balanced with a TRS cable.

        Look up direct boxes. A direct box is an impedance matching transformer in a small box. Usually a 1/4 jack in and an XLR out, the XLR would connect to a snake, or just a long mic cord. We tend to call all balanced cables with XLR connectors "mic cords". They are used when we want to connect the common high impedance unbalanced signals to the balanced low impedance needed for long distance.

        Playing guitar through a mixer usually sucks. The guitar amp is so much a part of the sound. What is usually done is to play through an amp on stage - doesn't have to be very loud - and connect the preamp out to a direct box. Some modern amps have a direct out built in, probably more in the bass guitar segment. They also make special speaker direct boxes that connect to the guitar speaker for a bit more of the amp sound.

        Unless it is ancient, or very basic, your mixer likely already has balanced ins and outs, and power amps usually have balanced inputs as well.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Your jogging old memories Enzo. Use it or lose it as they say. I had three direct boxes like 40 years ago when I had a 4 track teac tape recorder with a tascam board for a little 4 track recording studio. I had a snake too that I wired up myself and I had a special reel on wheels built to hold it for wind/unwind. I sold the direct boxes (wish I didn't do that now). I still have two 40 year old Teac model 2 mixers (no xlr) that I want replace with this Behringer mixer once my musical project idea proves worth continuing Behringer UFX1604 | Sweetwater.com. I just checked the tech specs on it and it has the TRS inputs and both XLR and TRS outputs you speak of. I didn't know what TRS versus TS was so I did the google search and I am am going to read this: Recording Studio Cables: All You Need to Know | Ledger Note My project (Jazz Karaoke using "Band In A Box" for the backing tracks and using restaurant tables rather than a stage since we can't find a place with a stage) is such that I don't think the guitar players will want to bring their guitar amps. The effects on my UFX1604 will have to do. Besides I need complete control of the mix.

          I am checking out the direct boxes. Need to keep the costs down.
          https://www.amazon.com/Recording-Sig...&node=11975581

          I am wondering if there is any way to know if the piano player 's keyboard has a TRS output without their having to go to the user manual? If it has TRS output then I guess I am set with the new mixer having TRS inputs as well.

          You have been really helpful Enzo. I was getting worried about this project realizing I would need to run 40 foot cables. Now I am seeing what I need to do.
          Last edited by bowesj; 10-19-2016, 10:16 PM.

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          • #6
            Find out the make and model of keyboard, you can always look up the user manual. And just look at the legend printed on the keyboard, it might even be written on there. "Bal Out" means TRS.
            Education is what you're left with after you have forgotten what you have learned.

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            • #7
              MCM electronics has DI boxes for under $10 each. I've gotten one from them, decent quality construction. Beats the h3ll out of guitar center brand.
              If it still won't get loud enough, it's probably broken. - Steve Conner
              If the thing works, stop fixing it. - Enzo
              We need more chaos in music, in art... I'm here to make it. - Justin Thomas
              MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

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              • #8
                Okay, thanks guys. Question. Should I be clicking the like link to say thanks rather than post? I have noticed some of the forums are doing this now to save disk space maybe and to gather stats. If yes, all I have to do is remember for the next visit :-)

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