April 28, 2011

Hello folks.  Welcome back to the Corner.  Today we’re going to have a little discussion on effects loops.  Some people love them, some people don’t, and some people don’t know what to do with them.  I’ll try to answer some common questions about effects loops with this article and hopefully by the end of it most of us won’t shiver with fear when we see Send and Return jacks.

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:

Image credit


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


Orange Back Pannel

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 preform 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 opamp driven and tube driven.  The primary difference between is one of headroom and transparency.  The typical opamp 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 opamps 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?


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.

Well there it is.  Effects loops (hopefully) made easy.  As in all things guitar, your own need to either have or not have an effects loop in your next amp will be up to your individual needs and ears.  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.  Thanks for reading folks!  We’ll see you next time, in the Corner.


  1. Rod Homor says:

    Thanks for the interesting article, Andy. Always insightful and helpful.


    posted on April 28, 2011 at 8:46 am
  2. JohnPles says:

    I figured out some of my questions and doubts!
    Great article!


    posted on April 28, 2011 at 9:01 am
  3. Steven Sanborn says:

    Great info.

    posted on April 28, 2011 at 9:16 am
  4. Phil M says:

    If I put the tuner in the effects loop would it still bypass / mute the amp once engaged?

    Do you see any other issues with placing the tuner in the loop, letting the input impedance of the guitar get thru the the pedals at the front of the chain?  I run a Lovepedal Kanji and a Fuzz Factory.  Both sound totally different (and better) when the guitar goes directly to them.  It seems to make the most sense to put the tuner 1st.

    posted on April 28, 2011 at 9:20 am
  5. Alexis says:

    Cool story, bro

    posted on April 28, 2011 at 9:25 am
  6. ken says:

    yeah warmth is right with some amps, less is better. Too much stuff you tone will suffer some and even with the best patch cables. The nova system works really good and wont color your tone.

    posted on April 28, 2011 at 9:35 am
  7. fretto says:

    Always helpful,Thanks Andy

    posted on April 28, 2011 at 9:38 am
  8. Boyd says:

    To Phil M;
    A tuner should still kill the signal of an amp if the effects loop is series, but it won’t if the effects loop is parallel.

    And the impedance that the input of a tuner doesn’t affect the tuner’s ability’s at all as it just measures frequency, and the impedance won’t change the frequency.

    posted on April 28, 2011 at 9:46 am
  9. Sam Freeman says:

    What I don’t understand is, if the goal is to get time-based effects after the gain, then why not put the loop after the power section?  After all, the power tubes can provide a good deal of the distortion that comes from a cranked tube amp.  I know a lot of artists use wet/dry rigs in an effort to achieve this very thing so it’s not just a crazy idea.  Why is it, then, that there isn’t a single amp manufacturer has built this setup into their offerings?  Please enlighten me.  Thanks.

    posted on April 28, 2011 at 9:56 am
  10. Rodrigo says:

    Thank you so much for this information. I wanted to ask, is a buffered/non-buffered loop the same thing as a active/passive loop? I want to get an effects loop installed in my Hot Cat, but was unsure as to which type to get.

    You mentioned running a lot of effects through the loop.. I would be running an eq, volume, delay & reverb pedal (and possibly modulation) through there. Would I want to go with a buffered loop for that?


    posted on April 28, 2011 at 9:57 am
  11. Colton Wedeking says:

    Hello all, I was just wondering how I would run one FX Loop, mono, into two separate amps. It’s probably not hard, I just can’t put my finger on it. If it requires a switching pedal of some sort, could someone point me in the right direction? Thanks!

    posted on April 28, 2011 at 9:59 am
  12. Giddyup Dave says:

    Good stuff.  Know more than I did 15 minutes ago.  Keep it up.

    posted on April 28, 2011 at 11:24 am
  13. Abbacus says:

    Now I get it! Thanks for the info!

    posted on April 28, 2011 at 12:37 pm
  14. Matt says:

    Sam, manufacturers don’t do this because it’s a very involved approach. You’d need a load box that can handle the full output of the amp, a buffer stage for the loop, a return gain stage for the loop and then a separate power amp and output transformer. It’s incredibly impractical to put in one amp head and most amps with effects loops get all of their distortion from the preamp anyways.

    Rodrigo, yes active is the same as buffered and passive is the same as unbuffered.

    posted on April 28, 2011 at 12:57 pm
  15. Sam Freeman says:

    Thanks Matt.

    posted on April 28, 2011 at 3:14 pm
  16. George says:

    Nice article about FX loops and tube amps. So basically if you don’t use effects other than a booster or distortion pedal the FX loop is not necessary. What happens though with a noise suppressor? It know it is better to put after the preamp and in the end of the effects chain so it will have an actual impact in the FX loop. Would it have a better result in a serial or parallel loop?

    posted on April 28, 2011 at 5:01 pm
  17. Tom says:


    Every amp with a speaker jack technically has this function, you could run a line from the speaker jack to the pedal and then out from the pedal to the speaker. Unfortunately this would clip horribly at the volume needed for power tube distortion and would very likely destroy your pedal and amp. It could possibly work at very very low volumes however.

    posted on April 28, 2011 at 6:18 pm
  18. Ollie Woodall says:

    I find it interesting that ‘rule of thumb’ is that Flanger and Phaser go in the FX loop because they are modulation effects. Both effects are predominantly associated with 70’s Rock, whereby the effects were usually in front of the amp (Eddie Van Halen anyone? Lynyrd Skynyrd, Led Zeppelin etc etc). Having heard the horrible metallic swooshing sound that is generated when Phaser and Flanger are in the FX loop (probably ok of course for some styles of music), I beleive most guitarists who want the Flanger or Phaser sound from 70’s records will more commonly want to run these effects in-front.

    posted on April 28, 2011 at 8:12 pm
  19. Joshua says:

    Andy, your corner rocks. Thanks for all the great info.

    posted on April 28, 2011 at 10:52 pm
  20. CAstolfo says:

    Another great article.. they cant be paying you enough over there :)


    posted on April 28, 2011 at 11:03 pm
  21. Jon Harley says:

    Hi Andy,
    Thank you for a very informative article.  I run a Mesa Boogie LoneStar Special, and also do not bother with the effects loop.  I run a lot of pedals, but all controlled through a GigRig Pro-14 which allows a huge number of options, but takes any or all out of the chain at the click of a single button (including putting some thro efx loop if one wishes).  Check it out - brilliant product which you might want to sell thro your shop.

    posted on April 29, 2011 at 1:34 am
  22. Neal Purvis says:

    Hello Andy,

    thanks for the article…..a question if I may….if the output/volume of the pedal in the effects loop is higher/crank will it push the power amp section overdriving it?  even in a buffered effects-loop?

    thanks again for the articles!


    posted on April 29, 2011 at 1:54 am
  23. Jeff Sopha says:

    Sadly, I go back and forth - I’ll re-cable the rig with the FX loop for a while then change my mind and front-end it for a while. Then I get to thinking I’m wasting all tha great Mesa overdrive and I’ll quit using dirt pedals and go back to an FX loop so I cna use the Amp OD. ...I guess it gives me somethign to do on Sundays…

    Anyhow - my only real issue with using FX loops is all the extra cabling to get everything from my pedal board to the amp back to the board where I can control it. Maybe someday I can afford a Bradshaw…

    But it does get me to thinking…how much impedence am I adding with all those cables? One has to think - 15’ to 20’ cables to and fro has to impart some affect on the tone, yes?

    posted on April 29, 2011 at 3:26 am
  24. Paul says:

    BTW: Andy, I have been enjoying the TC Electronic tone print patches you created for the new TC pedal series. Great pedals by the way, campers! The price is ridiculously low for TC quality. Andy did a great EP3 mimic for the delay pedal and a nice chorus mix on the chorus unit.

    As to loops, I am old school, a long in the tooth player, and over the years I have tried all sorts of pedal hook ups. I always end up going back to using my loop. Just sounds better, fuller, modulators more sweep and depth headroom. I run a BBE, TC DDL, TC CHorus, T-Rex Viper, EH Small Stone in my loop, and often a Lovepedal Pickle Vibe which changes from end of chain to the loop pending my mood. I have never liked the popular deal of trying to run a phaser or vibe before gains or ODs, just does not sound as good, sort of ruins the overall sweep and pulse of the unit. It is not like EVHs Phase 90 into a cranked Marshall. Try it and see. Those arguing Vibe first have to listen to old Trower and new Trower and allowing for the better component tech of pedals and amps does the new really sound better? Not really and that was before loops, modulators after gains or ODs sounds better and in the loop gets around the dist and freq notching of the front end preamp. Some like a vibe before but having tried it over and over, rip goes the velcro and back to the loop.

    The loop rules. Anyone running a DDL into amp in, even a chorus or a phaser is missing out on a much better tone. The new TC chorus into the DDL through the loop is a beautiful tone.

    posted on April 29, 2011 at 8:03 am
  25. Andrew says:

    @ Tom, What you describe is possibly one of the quickest ways to destroy all of your equipment.  Never run FX on a speaker output under any circumstances.  It’s not difficult to make a line out off of any amp with minimal components that won’t destroy your equipment.  You would need to run the line out to either another power amp or direct to your mixing console/PA.  The thing is that you lose the tone of the speaker when you do this, micing the cab and adding the delay on the mic’d signal is optimal, although not practical in a live situation.

    posted on April 29, 2011 at 8:43 am
  26. GIBBIE777 says:

    Thanks Andy!

    posted on April 30, 2011 at 12:40 am
  27. Alex says:

    I asked myself so many times why so many GREAT manufacturers (Dr.Z, Divided by 13, Tone King for example) dont use FX loops on theirs amps… Maybe you Andy can answer this intriguing question? Thanks!

    posted on April 30, 2011 at 1:49 am
  28. Brett Gallagher says:

    One additional pointer - If you place delay pedals in the effects loop, be sure to set your loop blend control to fully wet. My sound with a Line 6 Delay Modeler was very out of phase and bad until I set the blend to 100% wet on my Marshall JVM head.

    posted on April 30, 2011 at 11:36 am
  29. Keith says:

    With most of the greatest ‘guitar’ albums ever recorded having been done at a time when amps didn’t even offer FX loops, I struggle to understand why people think their tone could somehow be improved over those classic high-water marks (Hendrix, Clapton, Page, Townsend, etc, etc).  Would have been interesting to know when exactly the first major amp maker started offering an FX loop in their design… anybody?  I have about 8 pedals on my board but the key to great tone in my opinion is that (with the exception of a little wah) I never have more than 2 pedals on at any given time…. and if I’m getting my OD from a pedal, I don’t use the drive channel on my amp.  Keep it simple and let the fingers bring the tone.

    Oh, and to Tom and Sam, agreed with Andrew’s comments.. don’t take a speaker output (typically 20 watts or more) and run it into anything other than a power soak or a speaker.. not unless you want your pedal to get as hot as your speakers.  (Can you say magic smoke?)  Speaker impedances are typically 4-8 ohms while FX in/out’s are high impedance… this sounds like a really really bad idea.

    posted on May 13, 2011 at 6:27 am
  30. Jay says:

    Can I run a guitar through the effect loop as my main ?
    With a effect unit?

    posted on June 4, 2011 at 4:42 am
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