Amps Effect Loop Problem

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by sinlimo, Feb 13, 2008.


  1. sinlimo

    sinlimo Member

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    I have a Yamaha solid state DG130H head running into a 2x12 Avatar cab. (effin amazing amp btw!)

    However, I'm having a problem with the effects loop, especially with non-stomp box f/x.

    When a Yamaha DG Stomp multi-effects unit (used only for phaser, Flanger, etc) is used in the effects loop, it sucks a part of my overall sound, NO MATTER if the particular effect on the Stomp is on or off. Hard to explain, I know, but the overall tone, just with the stomp plugged in, is a bit more "hollow", as if some faint phaser effect was on and stuck on some frequency... or it kind of sounds like a faint wah pedal left in one position, somewhere near the middle of it's range.

    When I turn off the power to the DG stomp, the amp's normal sound returns and I'm good to go (sans effects).

    I duplicated the setup using a Digitech Rp5 (oldie but goodie), again, just for the effects, and got the same results. As before, the "sound sucking" was apparent no matter if I had the effects unit bypassed or the actual effect turned off. As long as the effect unit had power, the sound was adversely affected.

    I've tried adjusting the "MIX" knob on the back, and it didn't help improve the sound issue. Of course, turning the knob all the way to "dry" did get rid of the problem, but again, no effects.

    When I ran a single flanger stomp box, the tone did not appear to suffer.


    Any suggestions?
     
  2. Yek

    Yek Member

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    Most probably you're a victim to the dreaded "parallel fx loop meets dry sound" issue.

    If you're using a parallel fx loop, you must disable all dry sound coming from the fx device! That's why devices like G-Major have a "DRY KILL" feature nowadays. Max the output level on your fx devcie and use the MIX knob on your amp to mix the desired level of your effects.

    If you don't disable the dry sound in your fx device, the dry sound from your amp that doesn't go through the parallel loop will meet and get mixed with the dry sound coming from your fx device in the parallel loop, but there always be a slight difference in timing. This causes a slight phasing and the loss of certain frequencies, in other words: crap sound. So you must configure the Stomp to only output 100% "wet" signal.

    Alternatively, you can set the loop to 100% wet. If it's well designed you'll then have turned your parallel loop into a series one, and you don't have to "dry kill".
     
  3. sinlimo

    sinlimo Member

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    Wow! Thanks much Yek! Finally, a place to start.

    I honestly don't know too much about effects loops so don't know if mine is a series or parallel loop. I'm guessing since it has a "Mix" knob it's parallel?

    My multi-effects unit has an overall volume knob, as well as a knob to adjust the mix of the effect within the patch.

    To make sure I understand you correctly, should I turn the effect mix (within the patch) to 100%?

    That's my initial thought as I'm thinking turning the unit's overall volume to maximum might send some distorted signal through the effects chain... ??

    Davey Rockets

     
  4. sinlimo

    sinlimo Member

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    well, I spoke with Yamaha tech support about this effects loop issue. The good news is Yamaha has really good tech support, especially for an amp that hasn't been made in quite a few years. The bad news, I'm not sure I understood what the solution is.

    Tech support sd (per the schematic), the DG130H has a Series effect loop, not parallel. He said the effects loop signal level and impedance was designed for stomp boxes, not multi-effects units. Apparently, something with the hot signal hitting the input of the multi-effects unit is responsible for some phasing that occurs...???? Huh?

    He suggested I run from the "line out" on the amp, not the effects SEND to the effects unit input, and then back into the effects return on the amp.

    He also said having another gain device (like an overdrive stomp with the gain set to off or low)) in the chain could possibly flip the phase and bring things back to normal.


    Anybody else ever have this problem? I'll have the weekend to try all the suggested fixes, but is there something else I can try?
     
  5. Dexter.Sinister

    Dexter.Sinister Minister of EffedUpness, approximate ately Gold Supporting Member

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    I know this an old thread, but I am having my own issues with series loop, creating parallel mix with effects and blending with amp.

    IMO, the Yamaha tech support gave bad advice. The line out is probably tapped at the output of the amp. If you send this to effects and then fold it back into signal path at the effects return (UPSTREAM OF THE LINE OUT), you would create a positive feedback loop with reiterated effects processing of output signal. Also, since the line level is hotter than the instrument level effects loop, you would need, at elast, to pad it down a lot because the signal would be too hot for that part of the amp.

    Probably old news for OP, but for archives maybe this needed clarification.

    Thank you, DS
     
  6. VicLesnaik

    VicLesnaik Member

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    Hi,

    I have this thing happening when I use the effects loop on my 84 Fender Concert II. The volume wavers and seems to dissappear (but in horror, I hit standby!!).

    Any ideas as to what the problem could be?
     
  7. erwin.zeez

    erwin.zeez Member

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    i find different type of post,actually i was surfing net and came here. find this post different one!Well someone who dont know about it may get interesting type of information from this postÂ…good sharing of ideas
     
  8. seena

    seena Member

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    Effects units are electronic devices that affect the sound of an electric or electronic instrument or other audio source. Effects can be used in "real time", during a live performance (typically used with an electric guitar, electronic keyboard, or electric bass), or in post-production, with recorded vocals and instruments. To use an effect in a live performance, the effect is plugged in to the electrical signal path of the instrument. In a post-production setting, the source'sauxiliary output is patched into the effect. Effects can also be used on other instruments or sound sources, like the Rhodes electric piano, acoustic instruments, or drums. While some effect units "color" the sound in a subtle way, others transform the sound in a dramatic fashion.An effects unit consists of analog or digital circuitry which processes audio signals. In some cases, effects processing circuitry is similar to that found in music synthesizers, as it may include active and passive filters, envelope followers or envelope modifiers, wave-shaping circuits, voltage-controlled oscillators, or digital delays.Effects units come in several formats, the most common of which are the stomp-box and the rack-mount unit. A "stomp box" (or "pedal") is a small metal or plastic box containing the circuitry which is placed on the floor in front of the musician and connected in line with the patch cord connected to the instrument. The box is typically controlled by one or more foot-pedal on-off switches and it typically contains only one or two effects.





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    Last edited: Apr 1, 2011
  9. cap47

    cap47 Member

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    Could just need a cleaning of the EFX loop jacks. Spray some contact cleaner into the jacks and work a plug in and out. Do this several times.
     
  10. jcarry

    jcarry New Member

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    hi i am jcarry i want to share some information with you.
    Does your amp lack effects like reverb (or any sort of echo), chorus, flanger, tremolo, or any of those effects that effect the volume of things? Well, it probably does. But here's the deal, if you buy pedals of these effects then put them before the amp in your effects chain, and you try to do distortion (on the amp), it sounds terrible and your echoes don't fall off, volume boost pedals don't do anything, you get the idea. So how do you get around that? Effects loop. It goes in between the pre amp and power amp stages in your guitar amplifier and when you patch in effects there, they work great.
     

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