Effects Loop: Series or Parallel?

Pantone 333

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Forgive me for my lack of knowledge with this one. If your amp has an effects loop, how do you know if it's series or parallel?
 

xtian

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Put a 1/4" plug in the FX RETURN, but nothing into the FX SEND (best if the plug is shorted to itself so you don't get hum/buzz). Do you still have guitar sound? Then loop is parallel. If no guitar, then loop is serial.
 
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PushedGlass

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Pedals wired between guitar and amp would be de facto series; not sure what good parallel or even blend in an effects loop would do.
 

rumbletone

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not sure what good parallel or even blend in an effects loop would do.

Te ability to run wet only FX in the loop and without running your dry sound out of the amp, through dozens of feet of cable to front of stage and back, and through unnecessary buffers, level shifter, and/or A-D/D-A stages? Also, the ability to run your dry sound hot enough to drive the PI/output tubes without overloading the wet FX chain (assuming the amp has an FX send level control or one is added at the beginning of the loop).
 

Pantone 333

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I put the 1/4" into SEND and I still get sound. If I put it into RETURN I get no sound. So I guess parallel. But that's strange because from what I've read, parallel usually comes with a MIX dial.
 

Dave M

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Put a 1/4" plug in the FX send, but nothing into the FX return. Do you still have guitar sound? Then loop is parallel. If no guitar, then loop is serial.

Huh? I've seen and played amps with series (ed: and parallel) loops that work just fine with a cable plugged into the Send.
If a cable is plugged into the return, and the loop's level control can regulate the amount of signal heard, then you've likely got a parallel loop.
 
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Dave M

Silver Supporting Member
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I put the 1/4" into SEND and I still get sound. If I put it into RETURN I get no sound. So I guess parallel. But that's strange because from what I've read, parallel usually comes with a MIX dial.

That describes series, not parallel.
 

Jeff Gehring

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A series loop means that all signals must pass through the loop to continue on and be audible. The loop in the VK is just that. It's a simple drop/insert jack pair, wired to normalize if nothing is plugged into the send jack, punched in between the front end (which is a version of a near unity gain stand-alone reverb unit) and the rest of the amp. It allows you to eliminate the reverb unit altogether, if you plug into the 'return' jack instead of the input jacks.
 

JJman

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994
Considering that plugging into a single jack can also switch other things, I don't know if one can universally predict the results of doing so on one end of a loop.

Most newer bass distortion effects now use a "blend" approach which is sonically analogous to a parallel loop. If you have effects that are changing the general tone, and don't have "blend," and you want some blend of the pre-pedal "dry," a parallel approach is what you need.

I have a parallel loop in a homebrew amp because it needs less circuitry.
 

Dave M

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Considering that plugging into a single jack can also switch other things, I don't know if one can universally predict the results of doing so on one end of a loop......

Technically, sure it's possible. But, how common is that? Not very, if at all.
And, the schematic of the amp discussed in this thread shows a basic series loop with a commonly used switched return jack.
 

ShooBooty

"Always be cognizant of the Groove!"
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Put a 1/4" plug in the FX send, but nothing into the FX return. Do you still have guitar sound? Then loop is parallel. If no guitar, then loop is serial.
I'm gonna try not to overstate this but this is the most succinct and therefore the best answer I have gotten to this question in literally years. I just tried it and am pleased to announced that I think you just saved me a grand or two in purchases.

So my next question is: Do most guitarists know this and just take it for granted? Or is the effects loop a sorely misunderstood tool?
 

pdf64

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8,915
Put a 1/4" plug in the FX send, but nothing into the FX return. Do you still have guitar sound? Then loop is parallel. If no guitar, then loop is serial.

Unfortunately, though succinct, generally speaking it’s the wrong way around, doubtless the result of a brain fart.
It should be -
Put a 1/4" plug in the FX return, but nothing into the FX send. Do you still have guitar sound? Then loop is parallel. If no guitar, then loop is serial.

Sorry I missed that 1st time around :oops:
 




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