jm4looper300x200Have I mentioned lately that I love the Line 6 JM4 Looper?

I’ve been a musician for years, and I mainly play acoustic shows. You know, singer-songwriter kind of stuff. While a bare-bones guitar/vocal performance can be quite entertaining, the recording engineer in me wants to add more to it.

Enter the JM4.

I’ve always been absolutely fascinated with looper pedals. Any time an artist uses one in a performance, I’m spellbound.

As soon as you introduce a looper pedal into your setup, suddenly all the rules change.

You’re no longer a solo performer, you’re an entire ensemble. It’s like you brought a recording studio right on stage with you, and now you’re doing an overdub session for all of us to see.


Needless to say, I’ve wanted a looper pedal for years. Thanks to the good folks at Line 6, now I have one!*

What I love about the JM4 is that it’s not JUST a looper. It’s an entire guitar workstation. It has both amp modeling and three different selectable effects.

Amp Modeling

The folks over at Line 6 are probably best known for their amp modeling technology. If you’ve ever used a Pod or any of their amps (Spider, Flextone, Vetta, etc.), then you’ve experienced the Line 6 modeling technology.

There’s a lot of debate as to whether the digital amp modeling sounds as good as a “real” amp, but I’m not getting into that today. What I can tell you is that there are a LOT of guitarists in the world who swear by Line 6.

The amp models on the JM4 cover a wide range of amps. You can choose from Clean, Twang, Blues, Crunch, Metal, and Insane.

In addition to amp models, you have knobs for Drive, Bass, Mid, Treble, and Channel Volume.

While there are a handful of good clean tones in the JM4, Line 6 tends to cater towards the heavier, over-driven tones.

The presets alone on the JM4 will keep you entertained for hours. The presets are categorized by time period, artist, genre…you name it. And, of course, you can create your own presets as well.


When I play out with my electric guitar, my entire rig consists of a pedalboard with a Boss tuner, a Tech 21 SansAmp Character Series Blonde pedal, and the JM4. I prefer the tone I get from the Tech21, so I use the JM4 as an effects unit. It’s GREAT for this.

With three selectable effects, you can dial in all sorts of tones. The first knob allows you to choose from Chorus/Flange, Phaser, and Tremolo. The second knob is for time-based effects: Delay, Tape Echo, and Sweep Echo. And the third knob is dedicated to Reverb.

The way I set up my JM4 is in “Guitar Preset Mode,” with three or four presets – one for just reverb, one for tremolo, one for delay, and one dry. All I have to do is step on the “next” footswitch and cycle between them.

There’s also an “Amp/FX Mode,” where you can manually dial in the effects and then toggle them on and off by pressing the corresponding footswitch.


And now on to the main event, the looping feature of the JM4. The very first thing that caught my eye with the JM4 was the fact that it loops not only guitar, but also vocals! Not only that, it has a standard XLR mic input. Other looper pedals in this price range give you a 1/4″ mic input. (Who uses 1/4″ mic inputs anyway?)

In addition to allowing you to loop both your vocal and your guitar, the JM4 also allows you to output the guitar and vocal signal separately. This is GREAT for your sound guy, because he can still have full, separate control of the guitar and vocal levels.

The rest is pretty straight forward. Here’s how it works:

  1. Select your input source (whatever input you want to loop first). You can choose from the mic or guitar inputs, and even a stereo aux input (for using an mp3 player or something similar).
  2. Press the “Record” footswitch.
  3. Play/sing the part, then press the Record footswitch again to begin looping. The JM4 will loop what you just played/sang. Now, simply press the Record button to “overdub” as many parts as you want. You can switch between sources on the fly, using the footswitch.
  4. Press the “Play” footswitch to stop/start playback.

If you make a mistake, simply press the “Undo” footswitch. Once your song is finished, you can save it to an SD card, or simply delete it and move on to the next song.

Just like with any instrument, it takes a while to learn how to use the JM4 well, but once you master it, it can add so much to your next show. I played my first show with the JM4 a few weeks ago. I was nervous coming into it, since I hadn’t used the looper live before. I’m glad I used it, though. The crowd really seemed to enjoy it. Heck, I know I love to listen to somebody play with a looper!

Since no review is complete without a list of pros and cons…


  • Price – As of today, the JM4 sells for $329.99. It’s a great value for everything you get with it.
  • Amp Modeling
  • 3 Selectable Effects
  • Easy-to-use Looping Feature – Other loopers I’ve tried have left me very frustrated. The JM4 is straight-forward.


  • Squeaky buttons – The footswitch buttons tend to let out a metal-on-metal squeak if you don’t press them down just right. I’m sure a little lubricant would fix that, but it can be annoying when that squeak gets picked up by the microphone while recording a loop!
  • Occasional Gritty Recording – I tend to go overboard with my loops sometimes. Occasionally, if I add a lot of passes, the sound quality will begin to get “gritty.” It hasn’t done this at a show. It mainly happens when I’m goofing around doing 20 passes of some silly part.
  • No tap tempo in Amp/FX mode – This is the main reason I don’t use Amp/FX mode for my electric rig. It allows you to turn on and off the delay using a footswitch, but to tap in the tempo you have to reach down and press a button with your hands. In Guitar Amp Preset Mode, one of the footswitches becomes your tap tempo button. This is nice, but it means you have to go in and set up presets for whatever effects you want.
  • No input select footswitch when looping – This is along the same lines as the previous con. When in loop mode, you have to kneel down and press a button to change input sources (from guitar to microphone, for example). The only way around this is to cycle through to a different mode that allows you to change the input with a footswitch, and then cycle back to the looping mode. The other mode is mainly for recording, not looping, so I’m not even sure why it’s there.


All in all, I really like the JM4. If you’re in the market for a looper pedal, I highly recommend it. And now, I leave you with a video of the JM4 in action:

*[Disclaimer – Line 6 did give me the JM4 to review. However, the views expressed in this article are my own. Had I not liked the JM4, I would have sent it back and refused to review it.]

  • Scott Lance

    Can I adjust the effects to my own liking?? The chorus flange option is kind of shitty in my opinion. I like a more true chorus effect and over the past 5 or 6 years eve has this thing I can’t figure out how to just use the chorus. HELP ME PLEASE. I’ve started to think about selling it do to frustration on this issue alone.

    • Sorry man. I haven’t owned this thing in like 5 years. I’d say just find a chorus pedal you like and add it to your rig.

  • EmilyRandall12

    Nice work Joe! I haven’t tried the JM4 yet but personally, I chose the Boss RC-3 when
    I was in the market for a looper but I’ve also used my friend’s Ditto looper and it’s AWESOME at what it does. My looper has drastically improved my skills – I highly recommend them to everyone that asks.

    What I did was I scoured Amazon’s best seller list and really weighed the features as well as the pros and cons before plunking my cash down and deciding for myself:

    Whether it’s the Ditto, Boss, or DigiTech…they’re all solid loopers it’s all about what you need and what you do with them. Cheers!

  • Andy

    Hey man, thanks for the review! Just one question – is there a limit to the time (except the overall time of course) of an individual loop??

    • Sorry…I don’t know. Sold it a couple years ago. 🙂

  • Charlie Glasgow

    The JM4 is a great wood shedding tool, but I use mine mainly for acoustic shows quite often. I’ve learned to tap the Aux/Vocal/Line button with my toe to switch it and that works fine. I run a Takamine into the guitar input and in record mode it bypasses the amps and tone levels for the most part. I had players in the audience last night who play Taylors and they loved the sound of my Tak, so no signal loss or degradation. I play in drum parts off the body of the guitar and add in other guitar parts, solos or harmonica. My only problem is that after several years of squeaky buttons, the “UNDO” button gave out last night. I’m taking it in for servicing and just picked up a MINT condition spare JM4 off of Ebay! I’ve even used this unit with a trio and played an extra part, but the drummer had issues with following a loop. Most studio players can follow the JM4 easily. My other complaint was I am on my third AC unit as they keep wearing out on the thin cable. I now wrap heavy tape around the thin AC line to prevent wear and tear, but they still go out when you run this several shows per week. The amp sounds are heavy transistor sounding crap and not anything you’ll use if you’re used to running good tube amps. The effects are quite good by on their own! I’ve never used the SD cards, but intend on trying one out soon. Anybody who uses one of these for a living should consider a backup! It really is built tough and blows the other loopers on the market away. If somebody were to steal it, I’d knock em’ over the head with it and plug it back it in for the next show. 

  • I am selling mine. I bought it and never use it, in great shape. $200 plus shipping.

  • Michael

    Can you comment if the device compensates for slight timing issues when tapping out at the end of a loop? I think the term is ‘quantizing’ .. I had a digitech jamman and wanted something better… thanks for your review… Great song performance too..

    • It just took practice to know when to click the end of the loop. Wasn’t too hard.

  • Rich O

    Nice review..
    Can you use this to load backing tracks for acoustic gigs?
    Have you tried an acoustic guitar and have you noticed any sound degradation?

    Song you did was really cool…sweet

    Rich O

  • william wilson

    Hello Joe…

    What are your thoughts on using the JM4 for doing live acoustic/vocal performance? If you think the fidelity is there then it could be my one stop solution.

    • That’s EXACTLY what I would recommend it for.

      • william wilson

        Could you give me some suggestions re settings you have dialed in for the acoustic. I have read several disgruntled reviews online re how using the “guitar” input degrades the acoustic signal significantly despite people’s best efforts.

        I suspect you may be ever so slightly more adept at eking out good tone than some others.

        • Sorry, William, I really don’t have any suggestions. I just plug it in and play.

          • william wilson

            Good to know. I will give it a whirl.

  • Grant Viscus

    watching this guy convinced me to go Ableton Live:


  • wow, that's great!

  • Ken

    Did you try the drum patterns for a song?

    • I’ve not messed around with the drum patterns much, but they’re great for practicing!

  • Hey Joe, I’ve always been a fan of Line 6. This sounds like a pretty killer piece of gear to have in your arsenal. There will definitely be a time to come for me to obtain one of these. Very convenient, very strait forward.

    Thanks for the review bro!

  • I had this for a few weeks and ended up trading up for the Line 6 M13. The way you engage loop record on it is similar to the DL-4 (no double tapping) and is more intuitive to me. It has no amp models but the FX are stunning.

  • David

    Nice review Joe!

    Like so many other items, this is on my “must buy eventually” list. A good friend of mine has a Boss looper pedal and we’ve had way too much fun layering guitar, vocals, and even drums (played through the mic) into a ridiculous mush of audio. Love the potential these pedals bring to the table.

  • Dun

    Hey Joe very good review, great harmonies…
    I use the Line 6 Pod XT Live to record guitars in the studio and also rocks!
    One question: How would you connect this gear to pro tools?
    I don`t know if I have to use a DI box, or use the line inputs or the mic inputs. In the XT manual says that it has a “studio” mode but I don’t know what is diferent in this mode…
    If you can help me It would be great, thank you, and sorry for my english… I’m from Spain….

    • I imagine you should just connect it to your line inputs on your interface.

  • Joe, really great review, and yes definitely +5 on the organic loop & vocal arrangement. Great take on a great song.
    Being the newb non-gigging musician that I am, I just kind of looked at loopers as a guitar practice tool. I never fully comprehended what a looper can bring to a live performance. Wow. Saw a coffee shop performer using a looper, but only now do I realize it. Heh. I thought it was a pre-canned multitrack or something. Had no idea I was witnessing something so cool. /facepalm

    Is looping the guitar vs mic inputs just a matter of switching the input it will loop on, or can it just loop either one?

    • Yep, that button on the top left has “GUITAR” on top and “MIC/AUX” on the bottom. You just toggle between which signal is feeding the looper. There’s a mode where you can toggle this with one of the footswitches as well.

      • Thanks again. I may just snag this in the New Year (there goes my household’s “no gear for a year” idea for now, lol). Besides looping, the “band in a box” features seem like a nice jam-a-long practice tool as well.

  • Hey Joe,

    Great review. I make my living as a “loop artist” up here in KC. I love the technology and I’ve wanted to check out this unit for a while now, so I’m glad I got to see your video.

    I love the sound of Line 6 products, I did have problems with my DL4 breaking down, I went through about 3 of them before I switched permanently to a boss gigadelay.

    I use the Boss RC-50 for my shows, but after watching this I’m thinking I might add one of these fellas and sync it with the RC-50 via midi, more loopable tracks=more gooder.

    Thanks for the review, and great job on the song. Here’s a video of a song that I did at a college show last fall.

    Merry Christmas!

    • Awesome video, Ryan. Very cool. Your setup blows my mind. Merry Christmas!

      • Thx Joe! Have a good one.

    • That is an awesome video. With these loopers you guys can be one-man-bands without carrying that hefty Bass Drum on your backs, lol.
      This is amazingly cool stuff, thanks for sharing!

      • Thanks Julian. I always get a kick out of trying to explain what I do when people ask me. I like to refer them to Dick Van Dyke in Mary Poppins. Cheers.

  • Wayne

    Great harmonies at the end, they wouldn’t have been great if I sang them. Very kewl to I hope Santa brings me one I’m sure I could put it to use. Have a great holiday and looking forward to our next lesson.

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  • Great review Joe! Love the crazy harmonies at the end 🙂 Btw, does it have a true bypass?

    • Hmm…I don’t believe it does. I have a “Bypass” preset programmed, so I can bypass all amp modeling and effects, but I’m pretty sure it’s still going through an A/D and D/A.

      • Mark

        What is you bypass program? I would like to run this looper with my pod HD 300 but I just want the looper and no effects. I like the JM4 for its other features for practice and jamming but for live performances, I found it too cumbersome to change presets and get to the looper. A lot of psts I’ve read say it’s possible but they don explain how.

  • Nate West

    Well Joe, you made me a fan! Nice arrangement yo ;o)