Effects Loops Demystified!

July 16, 2013

Hi everyone, welcome back to the Corner, where we’re nothing short of obsessed with our pedalboards this week. Last week, we took a look at our effect pedals and the order we run them in—today, we’re digging a little deeper and talking about effects loops. Some people swear by them, some people loathe them, and some people don’t know what they are or what they do. We’ll try to answer some common questions about effects loops and make everyone nice and comfortable with Send and Return jacks. Cool? Cool.

So what is an effects loop?  Basically, an effects loop is an input/output that enables a user to insert effects between the preamp/eq section and the power section of an amplifier.  Here’s an example:

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Originally amplifiers were built without an effects loop only allowing effects to be run straight into the front of an amp.  This arrangement is perfect for the guitarist running an overdrive, fuzz, compressor, or booster or for those using the amplifier for clean tones, running all effects into the front.  The problem is when the gain channel of an amplifier is used for an overdrive tone.  In general time-based effects like delay and reverb, and modulation effects, like chorus and phase, tend to sound more natural when applied to the signal after it is overdriven.  As a basic rule of thumb, most guitarists prefer to add modulation to an already overdriven signal.  When the modulation is applied before the overdrive, it can lead to a duller sound or in the case of a delay, the effect could wash out.  If a guitarist is using a pedal to achieve the overdriven tone, then there is no problem running all effects into the front of the amp.  Usually in this setup, the overdrive and gain or level boosting effects will be first in line after the guitar with time-based and modulation effects coming after.  With the introduction of higher gain preamps that produce overdrive, manufacturers started creating effects loops so that modulation and time-based effects could be inserted into the amplifier after the overdrive channel, and before the power amp, thus keeping the overdrive first in line.


Parallel and Series Loops


So now that we have a basic understanding of what an effects loop is and why they exist, let’s look at the two most common types of effects loops.  A series loop means that 100% of the signal is interrupted between the preamp and power amp.  The signal is sent out of the amplifier via the Send jack, run through the effects of choice, and then returned to the amp via the Return jack.  This is the most basic form of effects loop and is perfectly viable for most applications.  Since the entire signal is applied to the effects, a series loop may not be the most transparent way to run your pedals depending on the effects used.  Series loops are also typically designed for line level effects.  In the case of a series loop it’s a good idea to set the effects level controls to minimum and bring it up to match the level of your amplifier with no effects in the loop.  This is called Unity Gain.

Much like a professional mixing console, a parallel effects loop splits the signal with the dry signal both sending through the loop and remaining in the amplifier.  This allows for greater transparency, as the dry signal never leaves the amplifier 100%.  Most parallel loops will have a blend control on them allowing the effected signal from the Return jack to be blended with the dry signal.  This allows greater control over effect depth and gives the user control over how much of the effect is present in the output.  The catch about parallel loops is that they work best with effects that can output 100% wet signal.  Since the dry signal is already present in the amplifier and can be blended via the effects loop, having the dry signal present on the output of the effects themselves can lead to a very faint effected signal.  This is why some processors and digital effects have a “kill-dry” function.  If your effects cannot output 100% wet signal, a parallel effects loop may not be the best choice.



Tube and Solid State Driven Loops


Now let’s discuss how the effects loop is “driven” and what this means.  In order for an effects loop to perform optimally, the signal coming from the Send jack needs to be of similar level to your guitar and low impedance.  When this signal is returned it then needs to be amplified.  There are effects loops that are op-amp driven and tube driven.  The primary difference between is one of headroom and transparency.  The typical op-amp that is used is capable of a lower voltage swing than a tube.  If the output level of the tube preamp is not taken into consideration when designing a solid state driven loop, these op-amps can be driven into a full clip fairly easily.  Keep in mind though that most amplifiers are designed with all these factors in mind and any components in the effects loop, be they solid state or tube, are spec’d out to avoid unnecessary clipping and provide the best possible match for that amplifier.  Many builders prefer solid-state loops to tube driven loops because they produce fewer undesirable artifacts.  Some will say that a tube adds additional “warmth” to the signal but this is subjective.


To Buffer Or Not to Buffer?


We’ll keep this one simple.  Most modern amps come with a buffered effects loop to help compensate for the lower level output of most stompboxes.  In a non-buffered effects loop this lower output can cause a somewhat anemic tone.  A buffered effects loop makes up for this signal mismatch and cures the problem.  If you’re suffering from the woes of a non-buffered effects loop, there are products that are designed to help such as the Ceriatone Klein-Ulator.  Most mainstream amplifiers will have a buffered effects loop while boutique amplifier builders may only offer this as an additional option.



Do I Need an Effects Loop?


If you have to ask yourself this question, then you probably don’t need one.  As we discussed earlier, the order of effects relative to the source of overdrive can play an important role in getting the perfect tone.  If you are running an amp clean or just breaking up, then you probably don’t need an effects loop.  If you’re only using a compressor and a boost pedal, you don’t need a loop.  If you have 4 chorus pedals, 3 delays, a reverb, 7 phasers, and 3 flangers (hey, it could happen) AND you are getting your overdrive tone from the Lead channel of your amplifier, you would probably benefit from a loop.  If you are using the above but getting your overdrive tone from 4 different pedals instead of the amp, you can avoid needing a loop by putting these pedals first in your chain.  No matter how many effects you run, if you have a setup similar to the one mentioned (a LOT of effects) you might find that a nicely buffered effects loop can reduce noise and provide a very pristine path for your modulation and delays.  Most of the talk about effects order relative to the source of overdrive is a starting point.  It certainly won’t hurt anything to run delay and reverb into a fully overdriven amplifier input.  While the tones created may not be for everyone, they may be for you so as usual, trust your ears over any articles or opinions.

Now there are pedal-based units out there that provide an effects loop on your pedalboard.  These are not the same thing but they do provide some great functionality such as true-bypass for those vintage tone suckers or a blend control such as the Xotic X-Blender.  This allows you to mellow out those over the top effects or use a kill-dry function with it to create your own unique blend.

So there it is: effects loops made easy (hopefully).  As in all things guitar, whether or not an effects loop is “for you” depends on your ears and no one else’s.  I personally like to keep things simple but when cranking the JTM-45, I sometimes wish I had an effects loop for the Echoplex.  That being said, I still love the warmth when plugged directly into that sucker so I don’t feel the need to add a loop or get an amp with a loop.  As always, we love to hear what you guys are doing with your rigs—if you’ve got any tips or tricks with FX loops, be sure to share them in the comments below!


  1. Charles says:

    I’ve tried a number of different types of loops in a number of different types of amps. I’ve never found a single one that didn’t effect my tone in unacceptably negative ways. Fortunately, I only use verb and delay (no drives) as pedals. So these go in between the guitar and the amp. Not perfect, but better than using a loop IME. The above applies to pedals mostly. Rack effects that want line level to be happy… this is another story. And yet still there was a priced to be paid in using the loop. Things went backwards some.

    posted on July 16, 2013 at 4:54 am
  2. Tom says:

    Great Article. Thank you.

    posted on July 16, 2013 at 4:58 am
  3. gypsy says:

    just was wondering if you could do a piece on modeling amps. i have a peavey vypyre. thanks

    posted on July 16, 2013 at 4:58 am
  4. chris osborne says:

    i struggled with this for years until a became familiar with switching systems. now it’s a breeze especailly with some of the higher end systems that allow you to not only switch multiple effects on and off with a single tap of the toe but also change amp channels simultaneously. the best system i have seen (and i am ordering one) is the gigrig G2. it has 15 loops, 2 banks of 15 presets, 4 function switches (changing amp channels, reverb, etc), MIDI capability, pregain for each loop, post gain for each loop, and an amp 1 & amp 2 output!! it costs about 1100 bucks here in the USA but in my opinion its well worth it!! Eventide, Strymon, Line 6, and all the rest - no problem for this guy and i can use one amp dry NOFX and another amp with all my favorite pedals - tap dance is over not to mention that i am not using FX loops at all!! whether your pedals are true bypass or not the switching system is so no tone loss or signal strength loss - long live the switching system!!!

    posted on July 16, 2013 at 5:23 am
  5. Stan Fortier says:

    I find the effects loops on my Fender amps to be extremely well designed and although I play primarily clean I always run the modulation effects through the loop.  In fact I run two amps in stereo, splitting the signal right out of the pedal board, utilizing both loops in both amps for pristine clarity and tone.  When I step on the dirt it’s all good.  I love loops. All my modulation pedals play very well in the loop.

    posted on July 16, 2013 at 5:59 am
  6. Ethan says:

    I use a Hot Rod Deluxe clean as a pedal platform and get all my sounds from my pedals. I have 2 overdrives, 1 delay, a POG, a tremolo. Should i look in to using an effects loop?

    posted on July 16, 2013 at 6:08 am
  7. Abbacus says:

    Well said, sirs! That’s as plain, and to the point, as I’ve ever heard it in this golden age of gear!

    posted on July 16, 2013 at 6:25 am
  8. Pete V says:

      The best amp I have EVER used that was the “friendliest” with tons of pedals…..meaning had the best working effects loop hands-down was the EVH 5150 III 100watt amp head.
      Absolutely NO tone/volume loss even with amp distortion pretty cranked!!!  I wonder what type of effects system they use because in my opinion, is the best! 
      I wish I knew because I would put a loop like that in at least two other amps I have here!

    .....ANYONE know what type of loop the EVH 5150 III 100watt amp head uses???

    posted on July 16, 2013 at 6:47 am
  9. JOE MEIERS says:

    I have no volume control when I run the effects loop of my Ampeg Reverberocket. Am I doing something wrong?

    posted on July 16, 2013 at 7:16 am
  10. Dave says:

    One thing folks might want to note: using an effect loop requires two additional lengths of cable which have to run all the way from the amp to the looped effects your board and back (send & return).  Not a huge deal, but it will likely make an impact on your setup time (and budget).

    posted on July 16, 2013 at 7:29 am
  11. Ken says:

    Thanks for another great article. I own a number of pedals as well as a Vox Tonelab Le. I’ve been running all the pedals ahead of the amp but now I’m going to try them the way you suggested. I’ve Ben running the Tonelab into the effects in of my amps second channel. It has its own tone stack and preamp so I’ve been bypassing the one in the amp. Any thoughts?

    Also, how about an article on Master Volume VS Attenuater? I’ve been using an Attenuater because I think using the Master Volume doesn’t allow the output tubes to break up. If I’m using a pedal for distortion does it matter?

    posted on July 16, 2013 at 10:33 am
  12. DrDan says:

    The best effects loop I’ve ever heard is in my old(er) Fender Prosonic. No tone suck! In fact, it seems to add to the richness of the amp. I also recently started using a Boggie mini-rec, and again, a great effects loop with no tone suck. And as PeteV says about the 5150 III, I’ve heard nothing but great things about the effects loop. What do they all have in common? Tube buffered effects loop…. hmmmm…

    As a side note, I had a Rivera Fandango for several years, and I hated the effects loop! Very harsh sounding and nearly impossible to dial in, since I had to balance the both the output of the loop and the input, and there was no reference to use to find unity gain! Very tiresome to figure out.

    posted on July 16, 2013 at 12:05 pm
  13. Ben says:

    Really loving the articles! Well written and easy to understand, thank you guys!

    Not sure if anyone else would benefit from this but I’d really appreciate an article about tone/signal loss when using lots of pedals, what type of pedals can suck your tone (I’ve read germanium fuzzes need to be placed first in a chain but not completely sure why) and how buffers work and when they should be used.


    posted on July 16, 2013 at 7:57 pm
  14. John S says:

    The most transparent loop ive ever/never heard is the Zero-Loss FX Loop from metro amp. Totally transparent!!!  Its a series loop.

    posted on July 16, 2013 at 8:47 pm
  15. Rob says:

    Great article on a topic that will be relevant to most electric guitarists at some point in their musical journeys .  I run all modulation pedals (phaser, delay, chorus, trem) in the amps effects loop.  I run my dirt pedals in a separate loop through a Boss noise gate pedal after my tuner & compressor and before a boost pedal for completely noise free operation through a Peavey Classic 30 tube amp.  This (for me) is the holy grail of noise free tone options (so far)!  Keep the great articles coming.  They are all worthy of a read!

    posted on July 16, 2013 at 11:04 pm
  16. imreoir giotar says:

    I enjoyed reading this and many of your other articles. Nice explanations and or drawings for the most part. Having been away from guitars for some time (from about 1985 to 2009) until recently, I missed out on many technological advances in the interim—before (from about 1973 to 1985), well, hell I just hooked up my guitar and or pedals into my amp. But today I discovered things are quite a bit different what with youtube and guitar websites. I check out other guitar rigs online and have to say that some guitarists do just as you have outlined. But others like Viv Campbell with Def Lep and Billy Gibbons, well their respective live show guitar rigs are a sight to behold what with power conditioners, rack effects, midi controllers, and stereo sound, I’m just floored. But I bet even when Viv and Billy drop in and play at some local blues jam at the local tavern they probably just plug in to the house band amp and whatever pedals are there and they still sound awesome.

    posted on July 16, 2013 at 11:53 pm
  17. MagnusW says:

      A notch higher for the solos -
    I spent a long time searching for a neutral “boost” pedal, that wouldn’t add distortion or cut any frequencies. A great solution turned out to be a very cheap Behringer Preamp Booster in the effects loop.
    Thanx for all great articles PGS.

    posted on July 17, 2013 at 1:22 am
  18. Rob says:

    I’ve used 2 boost pedals recently that would both suit you very well.  The EP booster from Xotic pedals and the Keeley Katana.  I like the Keeley better but both are GREAT boost pedals!

    posted on July 17, 2013 at 2:34 am
  19. kenny says: this is why the volume seemed to drop when I put a stomp box in the loop on my old marshall head ..??

    posted on July 17, 2013 at 3:13 am
  20. Mike says:

    41 years, many changes…very little use for most tone-in-a-box stuff. An occasional hint of this or that. When you hear me playing…it’s always me…good, bad or indifferent! My sincere regrets if you can’t place me in any of those boxes…lol. No, I don’t know and I don’t care. But keep up the good work…there’s always something to learn!


    posted on July 17, 2013 at 3:38 am
  21. mark says:

    nice one magnusw, i use the behringer pb100 the same way. great article.

    posted on July 18, 2013 at 11:20 pm
  22. bob says:

    I built my own JTM - 45 head amp kit from mojotone with the added darlington array 80 volt transitor buffer.  It’s a serial loop add-on to an other-wise all tube el-34 amp.  This works well. All the distortion and overdrives go in front like they say.  With a dunlop distortion three I get crushing tone and sustain on channel two.  I need some new pedals to take advantage of the effects loop. I’d like a tremelo I could change speeds with a expression pedal…love PG videos and lessons

    posted on July 19, 2013 at 2:55 am
  23. mark says:

    bob, buy a middle of the road multi effects unit with a expression pedal. it will always have tremelo you can control speed and depth with the expression pedal.

    posted on July 20, 2013 at 11:17 am
  24. Jeff says:

    Thank you Andy. This is helpful. I have a Bogner XTC that I can run in either series or parallel, and that helps me understand the difference. I tried the parallel with just the regular setting on the pedals (i.e., not set to 100% wet but set like I normally set them), and it sounded very odd. Now I know why. Thank you.

    posted on July 22, 2013 at 5:36 am
  25. Alf Persson says:

    I use my rack effect TC-Electronic G-major 2 in an serial effects loop. That kind of high quality rack effects has a perfectly transparent signal chain, so they don’t benefit from using parallell effects loops.

    posted on July 23, 2013 at 6:45 am
  26. Lenn says:

    Hey Andy,

    Nice article, as always! Could you do a piece on Stomp compressors and how they integrate into the loops or the front end with the other effects? I’m a guitarist 47 years and still how to use these little buggers properly escapes me.

    posted on July 23, 2013 at 3:48 pm
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  28. Frederic Pinsonnault says:

    You forgot to put envelope filters between the Wah and the Compressors

    posted on August 4, 2013 at 10:07 pm
  29. matthew conte says:

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    posted on August 6, 2013 at 6:44 am
  30. Jaime N says:

    Got a question that might be very important for many folks out there: is it dangerous to use the loop to raise your sound level? For instance, if I use a clean boost over an already mid-boosted (eq also in the fx loop), could it damage my amp? Is it a problem to have a highly mismatched level between the fx send and fx return? Thanks in advance!

    posted on May 10, 2014 at 1:02 pm
  31. agustin says:

    thats a nice setup but i don’t see the volume pedal where i should put it before way pedal or after or between distortion pedals and amp?

    posted on July 19, 2014 at 1:54 am
  32. Dean says:

    I use the TC Electronic G-Major in my effects loop for some slapback delay. It works great because the effect it present after the gain stage.

    posted on March 6, 2015 at 5:22 am
  33. Darryl Foley says:

    Hi i have a Mesa MK 3 simu class and want to split the effects send into 3 channels ,line 1 with long delay into volume pedal ,line 2 chorus into volume pedal , line 3 dry then summed into a reverb pedal then into the return is this possable without having large volume discrepancies when using varing combinations of the 3 lines ? Do i need buffers and if so where ?

    posted on April 24, 2015 at 4:01 pm
  34. Paul says:

    The Effects Loop is one of those topics one find finds a cast array of comments and notions, often contradictory, and sometimes really wrong. Watch out for the “wise” advise that tells you “there are no rules”. There are, and being ignorant of them does not make them invalid. If ears were all that was needed in proper sound engineering we would have no measurement tools to “see” the signal beyond human ear capability or definition. See: pink noising a studio or room, eq adust.
    Simple rules regarding the amp loop:
    ome el cheapo effects will not handle the headroom and fidelity of the loop which is carrying the preamp’s signal and gain structure to the power amp section, so you have to understand a pedal in the loop is carrying the core tone right into the power amp. The signal impedance and proper handling capacity is the ball game.

    Most modern delays and reverbs are designed to work in the amp loop and they simply sound better no matter what you advise someone the sonic range and clarity of that issue is measurable as well as hearable. Contrary to popular notions of ear technicians using at best vastly variant and capable measuring quantification (aka “ears”). Modulation sounds very good in a quality loop even chorus which can exceedingly beautiful and moving, a phaser also. The difference is if you want to dirty up the phasing quality. Running into dirt pedals reduces the sweep bandwidth and muddles the effect, making it perhaps more “organic” which may be what you want or are after. Exceptions I find in my own pedal knowledge is that where you place a pedal can be the pedal itself, some sound better and a very few have a versatility to move around and sound good everywhere. We used to run delay or echo in front of amps like the echo plex not for how the delays sounded which was really crappy, but what the preamp in the unit did to the front end. With the age or marvelous quality pedals we have overdrives, distortions, and boosts no one ever dreamed would exist because we have no idea of the how and why of such circuits. So being able to optimize the sound is a huge advancement in pedal sonics.
    If you experience noise problems or lack of tone structure then you have to consider first the possible quality of the amp loop itself. what is the impedance range, is the level adjustable or set line or instru level, is it buffered? When you split pedals front and loop you also have the possibility of ground loop hum and hiss which can be impedance mismatch or need of a good buffer. May be as well the pedal you are trying to put in the loop cannot handle it. I was delight to see on the recommends here putting phaser in the loop. If the pedal can handle it truly is a marvelous tone// Your pedal might sound better to you up front. A Vibe to me always sounds better into overdrive and amp in, while a chorus with most dirt sounds terrible into dirt. Now a Phaser into gain is the core of the EVH tone, but we do all not want to sound like Ed all the time. I try to find more musically useful ranges of tones I can get through my pedals so the amp loop gets a lot of use from me. You should hear this new custom shop Phase 99 in my stereo rack preamp effects loop a separate phase 90 in each channel something you haven’t heard and is pretty versatile in options.

    posted on February 8, 2016 at 8:05 pm

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