please explain amps effects loop

[docmh]

Can someone explain an amps effects loop to me as I've never used them before. I've always run pedals through the front end of the amp. I have an amp with a passive effects loop. Can I run regular pedals through it? I've read that you should run distortion pedals in the front end and delay and reverbs in the FX loop. I heard that some rack type effects need an active FX loop. What's the difference? If I run a reverb pedal through the passive FX loop could there be a volume drop in the amps volume?
Thanks

[guitarslinger21]

I'm being general, and just talking about a series loop.

Effects send = the preamp's line level output.

Effects Return = the power amp's line level input.


Of course, there are variations on this with parallel configurations, and other such options.

I prefer a straight, series, line level loop.

[Ronsonic]

An FX loop simply interrupts the signal going from the preamp before it gets to the power amp allowing you to insert effects into the signal path. Yes, you can run regular pedals through most FX loops. There is hardly any standard, many recent amps are starting to evolve loops that are switchable from guitar to line level others operate at some intermediate level.

As for the question of whether your pedal will work with your amp's loop, please just go ahead and try it. None of us are psychic and we cannot know the answer to this other than the generic "probably,it is an effect loop and your pedal is an effect." You will probably have to adjust some knobs for best results. I'm reasonably confident in assuring you that nothing will blow up.

[jerrydyer]

keep the volume low though or you will mess up a good pedal.

[mbratch]

There are lots of different facets to this question. A lot of good inputs so far.


As was stated, the FX loop generally runs at line level. Some pedals can handle this and some can't. An experiment is likely necessary to tell. If the pedal can't handle the line level, you'll get unwanted distortion in the signal.



The notion of putting time-based effects in the loop, and distortion/other effects in front of the pre-amp has to do, at least in part, with sound. Time-based effects like delay and reverb are supposed to provide an "ambiance" to the sound and arguably make more sense after your pre-amp, especially if you've got high gain or distortion going on. That way, for example, you are echoing the distortion, not distorting the echo. If you put a delay in front of a gainy pre-amp, then the gain may make the fainter echos of the delay sound louder and continue longer than desired.



If you run a pedal in an effects loop and you have no way to control level at the effect or the amp, you may experience a difference in volume when the effect is engaged versus not engaged. Depends upon the pedal and the amp.

Ultimately, it still leads back to exprimenting to get the sound you desire out of your pedals.

[Unadan]

keep the volume low though or you will mess up a good pedal.

How can this mess up the pedal?

[franchelB]

There are lots of different facets to this question. A lot of good inputs so far.


As was stated, the FX loop generally runs at line level. Some pedals can handle this and some can't. An experiment is likely necessary to tell. If the pedal can't handle the line level, you'll get unwanted distortion in the signal.


The notion of putting time-based effects in the loop, and distortion/other effects in front of the pre-amp has to do, at least in part, with sound. Time-based effects like delay and reverb are supposed to provide an "ambiance" to the sound and arguably make more sense after your pre-amp, especially if you've got high gain or distortion going on. That way, for example, you are echoing the distortion, not distorting the echo. If you put a delay in front of a gainy pre-amp, then the gain may make the fainter echos of the delay sound louder and continue longer than desired.


If you run a pedal in an effects loop and you have no way to control level at the effect or the amp, you may experience a difference in volume when the effect is engaged versus not engaged. Depends upon the pedal and the amp.
Ultimately, it still leads back to exprimenting to get the sound you desire out of your pedals.

I agree. And personally, I've tried running my "boosters" in line (between guitar and amp) and my "modulators" in the effects loop in gigging situations. I realize that I was using more cables and spending more time to get set-up...it was just a headache. I suppose it woudn't be so bad for studio use, but live wise, I wouldn't use the effects loop.

[Keyser Soze]

How can this mess up the pedal?

If the voltage of the line out, or that same signal amplified within the pedal, exceeds the ratings of the pedal's components, then you could fry some of those components.

But generally, if it is a modern pedal running off of 9v volts, the chances of doing any damage are minimal. Most of those pedals will have parts rated at anywhere from 12-16 volts or greater, and even if you drive the signal all the way to the power rails (9v) you are still safe.

18 volt pedals, or multi effects units might be another story...

[medblues]

Can you plug in any line level signal (from a line out, for instance of a Micro Cube) into the effect return without plugging anything into effect send ? I am afraid to try and see lest I damage my amps...

[Keyser Soze]

Yes, you can feed a line level signal into a typical effects return, so long as you are not attempting to use the pre-amp section of the amp at the same time. Typically the return jack is wired so that when a plug is present it disconnects itself from the pre-amp section (otherwise the un-effected signal would continue to run in parallel to the effects loop.)

It is generally a bad idea to run a speaker out into a line level return.