Question:
The difference is... ?
Answer:
On an amp or in regards to pedals?
I don't know that I've ever heard of an amp with parallel effects loops. If you're referring to pedals...
Series: Imagine you have three loops. They are all layed out in succession. The effects in the first loop impact the second, which then impacts the third. Imagine you have distortion in the first, flange in the second and delay in the third. Turn on the second loop and you effectively apply flange to a distorted signal. Turn on the third and you delay the flanged distorted signal.
Parallel: Same three loops. Each acting independent of each other and not impacting any of the other loops at all. You have distortion in the first and turn on the second loop (flange). You're "flanging" the dry signal, while the distortion in the first loop is effecting the dry signal also - but neither the first or the second loop are impacting each other at all - they're completely independent. Same for the third loop.
The only useful application that I see for parallel loops (that I'd ever use it for) would be if I'm running two delays. If you're running two delays in loops that are in series, the delay in the second loop is functioning off of the already delayed signal in the first loop. If you want a slap-back echo and a digital delay at the same time, but want both independent of each other, put them in parallel loops and you can use each effects as if it were the only one on your board, but both are being used at the same time (again though, independently of each other). Neither delay "hears" the other.
Answer:
I'm talking about amps. Apparently a lot of amps have parallel effects loops.
Answer:
I am somewhat curious about this too, if someone could enlighten us...
Answer:
Ryan gave a great description. With an Amp it's about the same thing. With a series loop, the whole signal passes out into your effects and back. With a parallel loop, the signal is split, sending one line to your effects and keeping another dry. These two are then blended back together.
The Parallel loop is great for keeping your natural amp sound untouched. You're not running your whole preamp through a bunch of outboard stuff. A possible disadvantage would be the need to run your effects at 100% wet to avoid phasing issues.
Answer:
Thanks for the help LWatford.
Answer:
Thanks.