Project Idea: Build a Better Looper

Jeremy and I have been playing with my “new” Akai Headrush E2 looper pedal, which allows you to record an instrument (or whatever) into it; then it plays your mini-recording back for you over and over and over in a loop, and you can play along. You can also overdub, recording more stuff on top of what’s already there and building up a more complex mix in the loop — this is how KT Tunstall does solo performances of “Black Horse and the Cherry Tree”, which are just amazing to watch.

Akai Headrush E2 Delay/Loop controller, cleaned

However, Jeremy and I both have some issues with the feature set and the user interface of the Akai, and we’re thinking about what it would take to build a better looper — or at least, one more suited to our desires.

Feature Wishlist

Here’s what we want:

  • At least 60 seconds of loop time, which would be enough to play 12-bar blues at a fairly slow tempo. The Akai’s 17.8 seconds in low-fi mode is enough for KT to do two measures of rhythm and backing vocals, but not enough to record a full chord sequence.
  • Tap a Record footswitch to begin recording, tap again to end the recording and start looping. It doesn’t absolutely have to be the same switch; but some loopers out there use a potentiometer to set loop duration. We want duration to be determined by the duration of the phrase we played, as it is with the Akai.
  • Independently-addressable tracks or channels. The Akai lets you discard all of your mix except your very first pass and rebuild from there. We want to have (say) eight tracks/channels in the loop mix, each with a footswitch and red/green LED. Tap Record and the next unused channel winks green and records. Tap any channel’s footswitch to put it in (green LED) or out (red LED) of the mix. Not-yet-used channels are dark.
  • Independently rerecordable channels. To rerecord a channel, tap it out of the mix and immediately tap the Rerecord footswitch (which is separate from Record and a little further back or off to the side). That channel winks green and rerecords. Various loopers have varying levels of undo or redub, but none (that I’ve found) let you do this.
  • Ideally have stereo recording so I can loop with the full stereo chorus effect of my analog synths.

There’s room to negotiate on the exact UI, but that should convey the feature set we’re after.

How to Build It?

John suggested using an AudioPint and Pd, and I think I may prototype this with an Arduino to run the control panel and Pd on a laptop to do the audio. But ultimately I’d like to build at least two of these in nice stage-ready stompable enclosures, and I really don’t feel like using a general-purpose OS, for a number of reasons.

It seems to me that this might be a good project for a DSP or an FPGA, but I don’t know enough to make a choice. Any suggestions? (I know I don’t need the full power of a DSP.)

What I’d love to find in one IC would be:

  • Dual 16-bit ADC and DAC capable of 44.1kHz
  • Address and data buses capable of addressing enough external RAM for the audio (say about 1G for stereo * 16 bits * 44100 samples/second * 60 seconds * 8 channels) without my having to worry about DRAM refresh circuitry
  • A processor that I can program for the very simple, core task of summing/averaging samples from the active channels to feed to the DAC
  • ~32 I/O pins to manage the control panel, and/or I2C or SPI to use offboard I/O chips
  • Ideally a USB interface for uploading samples to a computer, but this would be an extremely low priority

Does such a thing exist? Is that necessarily an FPGA? Can I get a development environment for < $500 and a chip for < $30?

Survey of the Marketplace

Here’s my comparison of all the loopers reviewed at Looper’s Delight against my feature wishlist.

Gibson Echoplex

Very darn close, nice recording time, nice controls, even lets you replace part of an existing track. But unfortunately only lets you take things out of the mix via an Undo stack — LIFO.

Boomerang Phrase Sampler

Appears to stack samples and doesn’t have flexible undo/rerecord capability.

T.C. Electronic TC2290

Very pretty rack interface with lots of buttons! 4-second sample time, expandable to 64 (which would be enough if I got one with the expansion already installed; but it was made in 1986 and the expansion RAM is discontinued). Can’t find much other detail on how it works.

Lexicon MPX G2

20 seconds; layers become permanently merged into the sample at the time of recording.


More of a “controllerist” tool with BPM-matching stuff for doing live mixes of prerecorded tunes. Looks kinda interesting, though. Not foot-friendly — definitely a DJ tabletop piece. Oh — and it’s a prototype only that’s not manufactured.

Line6 DL4 Modeling Delay

Apparently no undo feature at all.

Red Sounds C-Loops

Another DJ tool that does tap-tempo for BPM matching; has a maximum of 32-beat sample length.

Eventide Orville

Very, very pretty family of echo/delay/FX machines. 20 seconds of looping.

Boss RC-20XL

16 minutes sampling time!!! But only one layer of undo.

Looper Construction Kit for Kyma

Looks like OS X software, so I’d need to come up with hardware to drive it, and that doesn’t suit my embedded notions.

TC Electronics D-Two

10 seconds.

Maneco Filter Eko, Nanolooper, ManecoLooper Elite, ManecoLooper, MicroLooper

Look like homebrew jobs that I couldn’t buy. 32 seconds, 16 seconds, 64 seconds, 32 seconds. Feature set is hard to tell but they definitely don’t have enough buttons to do the cut in / cut out that I want in realtime.

Akai Headrush E2

Described above, but I’ll reiterate for thoroughness: 18 seconds loop time, can only erase everything except first take.

Electro-Harmonix 16 Second Delay Reissue

Only three footswitches (and not included); loop duration is set with slide pots instead of tap to start recording, tap to stop.

Boss DD-20 Giga Delay

23 seconds, doesn’t have enough footswitches to cut tracks in and out.

Digitech JamMan

Only two footswitches.

Boss RC-50 Loop Station

Looks hot! But only has overdub (add to what’s already laid down), replace (replace EVERYTHING that’s laid down), and one layer of undo/redo.

There are a very few other products mentioned without reviews posted
yet, so I’m not being completely exhaustive.

At John’s suggestion, I’ve also submitted a query to Sweetwater asking whether they know of anything that does what we want.

21 Responses to “Project Idea: Build a Better Looper”

  1. J. Peterson says:

    A single FPGA that could do your entire project is probably over the $30 mark in small quantities. If you have a capable microcontroller running the show, a smaller, less expensive FPGA or CPLD could probably be used to manage the real-time audio capture and storage.

    There are some very nice, inexpensive, FPGA dev kits available from and (among many others).

    Fortunately, the development tools for most FPGA’s are available for free (usually as a loss-leader to sell chips). The free Xilinx “WebPack” tools available for download have more than enough to get you started. You can also find a lot of resources at (e.g., if you want to include a CPU directly in your FPGA).

    I was able to learn everything I needed for a basic project (see ) entirely by surfing the web. Don’t bother spending $100 for a textbook on the subject. is a good place to start.

  2. Keith Neufeld says:

    JP, beautiful blinkenlights restoration on the PDP console! I’m honored to have you drop by!

    When you say “a capable microcontroller running the show / a [. . .] FPGA [. . .] to manage the real-time audio capture and storage,” can you tell me more about the division of duties you have in mind? I have no experience with FPGAs (just like I had no experience with microcontrollers until three years ago), so I don’t know what to expect. Will an FPGA be programmable to do ADC and DAC? What would the role of the microcontroller be in that context?

    I’ll read up on fpga4fun, and if you don’t mind, I may have more questions later.

  3. Philip Tinney says:

    I think a single Spartan 3 or 3E could handle the job. Here is a link to a logic analyzer project using an XC3S200-4 dev board, that I think shows it would be capable

    A quick search on Digikey lists 3E chips starting at roughly $11. A comparable Dev board is under $150.

    I think an interesting design would be to implement the audio capture directly to one or two SD cards.

    Not really sure if it is feasible since I really haven’t started playing with FPGAs yet.

  4. J. Peterson says:

    There’s two ways to use an FPGA in a design like the one you’ve discussed. The first is to use a traditional microcontroller, and use the FPGA to extend the I/O speed, pin count, etc. That’s essentially what I did in the PDP-11 design.

    The other way to go is to use a “soft core” and actually include the CPU as part of the FPGA logic. The logic description for an FPGA is typically programmed in a language like VHDL or Verilog. A basic CPU (say, like an eight bit PIC) described in one of these languages is remarkably compact, around 5-10 pages of code.

    Several of the dev kits I linked to above have A/D & D/A converters either on board or as plugin options you could use for reference designs. For audio rate processing, you should be able to have the logic on the FPGA (I haven’t tried this myself though).

    The FPGA is just one way to go. With a fast enough CPU (say, PIC32,
    ARM, Luminary, etc.) you could probably just do everything in software. The PDP-11 design could have been implemented less expensively by using shift registers for I/O, but I found it fascinating to design my own special purpose chip for the task.

  5. Benjamin says:

    First let me say that am a regular.
    I have been reading your blog for over a year and i have been enjoying everything you have done.

    Often you do what i just think about.

    Now to the point:
    Please take a look on how to REALLY use a looper here:

    Main page for Reyn Ouwehand

    If you are into Commodore SID music then he is the ‘lets do it with real instruments’ guy.

    Keep up posting!


  6. Keith Neufeld says:

    Benjamin — thanks for the links! I’m enjoying them and want to give them a fuller listen later.

    The first looping I ever heard was Paul Dresher Ensemble’s “Sleeping with the Light On” back in about 1989 or so . . . but KT Tunstall is more familiar to most people, :-) and I do think she does a pretty impressive job of looping live.

  7. Benjamin says:

    Thank you very much for sharing.

    I will listen to it right now while reading in the ATmega 168 specification about the analog comparator.

  8. tumnao says:


    Hum, yes, building a FPGA or uC based looper would be a nice project (and I would like to have the skill and the time), but I think that the looper that you need is the Electrix Repeater :

    Sadly it was discontinued, but I found one on ebay for a friend, and he is reeeally happy…

    And while I am here, thanks for taking the time to blogging all your projects :-)

  9. Drew Franklin says:

    I am a little late to the discussion, so hopefully Benjamin is still listening so I can say great find with Reyn Ouwehand. Also Dosh is a great one to look into. He has solo albums and and plays with Andrew Bird in which they do two man looping together, absolutely brilliant stuff.

    As to your looping pedal Questions. I think the Echoplex is the way to go if you are looking for a non-computer based solution.

    I feel like the “Independently-addressable tracks or channels” goes against the grain of natural flowing loops. To me the benefit and fun part of looping is the constant overdub in which what you just played comes zooming at you instantaneously. In the solution you describe I feel like you would play a loop, wait set up the next channel and then wait again, and so forth. And still you would be limited to 8 overdubs.

    How I use the echoplex is that there are 4 loop buckets. I group similar loops into those buckets and mute and play them as needed. So I can bring in a chunk of loops during a chorus or something and then take them off during the verse. I mainly use undo only if I horribly screw something up.

    I think there is a way to do randomly accessible loops, but I think it is with a touch interface like the iPhone.

    I have a project idea where the overdubs are recorded individually and they are displayed on the iphone like a Protools timeline interface. You can then grab a loop and either toss it off the screen to delete it, or move it arround it 4 channels using the four corners of the device to represent the four speakers spatially. I was thinking could be done using OSC from the computer to the iPhone.

    Also another cool part that you might like about this Keith, is that the echoplex and my dream software looper would be controlled (at least the loop commands) by a arduino based MIDI controller that I am using one of your articles to help me build. (Which I have a question about but I will ask in that article’s comments).

    Okay I think I have said way too much. End of rant.

  10. Keith Neufeld says:

    Drew, thanks for all the thoughtful remarks!

    Jeremy and I had a long conversation this weekend about overdubs and undos. What we’re coming up with sounds very much like what you’re describing doing with the Echoplex — and maybe I misunderstood its “bucket” functionality. Do I now understand correctly that all of the buckets are the same length and you’re just taking them in and out of the mix (muting them) on demand?

    I don’t like its user interface at all — I’m sure you get used to it, but I think it’d be a lot more clear having a button for each “bucket” with a red/green LED right next to it to indicate whether it was in the mix or muted. Maybe I need to pick one up on eBay and try it out. Oh, ha ha, I see someone thinks they can get $700 for one. :-)

    Regarding how a performance would work out using the mechanism I propose, I need to add one thing I hadn’t thought of and refine another.

    First, with the Akai Headrush, if you’re overdubbing and you keep playing, it just keeps wrapping around and overdubbing cyclically. I think I would suggest that with this proposed looper, if you keep playing, it automatically cycles to the next unused channel and starts recording that. If you tap out after a recording but don’t perfectly sync with the timing of the end of the loop (if you overrun by a second or less), it should be smart enough to discard the overrun.

    Second, when I watch Jeremy use the Headrush, he’ll play an overdub, then tap out and sit back to think of what he wants to do next. But he wouldn’t have to — he could tap out and keep on playing something that’s not getting recorded (because not everything has to go into the loop). So in live use of this proposed pedal, I don’t think you’d have to record, wait, record, wait. You could record, spill over and record into the next channel, spill over and record into the next channel; or you could record, tap out and keep on playing along, tap in and record, tap out and play along, etc.

    Does that make sense? Would you still not use it that way?

    For what it’s worth, Jeremy thinks he’d really like to be able to overdub existing tracks. I’m trying to wrap my head around whether eight “takes” really wouldn’t be enough, or whether it’s a matter of the right interface and feel to the unit. These may be questions that can only be solved by prototyping — and I have something in mind for that. :-)

  11. Drew Franklin says:

    Hi Keith,
    I really like talking about this stuff, so I thank you for having this awesome blog to make my remarks.

    So you are assuming correctly that you can set up the echoplex in a way in which all the buckets are the same length and you can assign a midi note to each Loop and turn them on and off with a midi note message.

    But let me back track a little because I tend to speak in hyperbole when I get excited, and not choose my words carefully :)

    I agree completely that the user interface is pretty pathetic so take that as very much a down side when I say that there are all these functions, and to change them you have to deal with that.

    So I checked the manual for these Loops functions and there are tons of settings (dealing with the interface again). So one setting is LoopCopy=(Off or Loop or Timing) which when set going to the NextLoop copies either the Loop or the Timing. I believe the default is Off in which when you go to the NextLoop you start from scratch recording the loop.

    There is also a AutoNextLoop= in when you hit NextLoop it acts as hitting next loop and the record button for to start and all you have to press it record again to end. LoopCopy overrides this setting so you can only have one or the other.

    I also checked an you can have up to 16 Loops but now I remember setting it at 4 because it seemed like a good balance of max loop time and number of loops. But now that I think about it I don’t even remember how much memory I have. Also the number of loops is set in a preference (a pain) which can’t be changed mid loop.

    Finally if you do decide to get one, I would check if it has the LoopIV software. Maybe it just my geekery in liking the upgrade, but if I remember correctly the one benefit is that you can assign midi notes to any setting and change it through midi instead of the faceplate. I have never used this feature though so don’t quote me on that.

    As to your looper having an overdub being an auto copy of a new channel makes a lot of sense.
    I think the sentiment we are both getting at, is how much granularity is needed to access these overdubs verses channels (or Loops in my case), and the interface to access them. I am more for the side of a little less granularity for the sake of a cleaner interface, but I think it depends how much dancing you want to do if you are using a foot controller :) Thats exciting that you have a prototype in the works to get these questions ironed out.

  12. benjamin says:

    Drew Franklin, I am still here :-)
    I am listening to Dosh – “Capture The Flag” Live At Home right now.
    Not bad, really not bad.

    Thanks for pointing me to him.

  13. niclas says:

    Hi guys, I read this blog and find it very interesting. Thanks for sharing all this with the world!

    Now, I have a question and I hope maybe someone here can help me out with it (due to extensive experience with looping pedals ;) ). I’ll describe it all below and let me just add to that I’m not technical at all…

    Here we go!

    I would like be able to loop both my vocals and (acoustic) guitar, without stealing away the options of mixing the individual channels afterwards.

    Hmz, might sound a little vague, so let me try to explain myself.

    I play
    - guitar: Martin D1 (with active Fishman Matrix II element)
    - mic: Sennheiser E865 Sting Signature
    - loop-pedal: AKAI HEADRUSH E2

    My AKAI Headrush E2
    main pro’s
    - easy to use
    - nice sound
    - all in one (easy to carry, since I’m a singersongwriter performing solo a lot of the time, I cannot carry too much stuff with me)

    main cons
    - only 1 input
    - only 1 output

    Problem: when I let my vocals & guitar go into the Headrush input through the output of a tiny mixer (which receives outputs from both guitar & mic), it all comes out as 1 mix, stealing away the opportunity of mixing the sound of all individual channels for the room. (so the sound guy can’t help me out if the mix is no good)

    Now I was thinking, maybe the best option is to:
    - send the mic to one channel of the (big) mixer
    - send the guitar to another
    - send the output of both to my Headrush
    - send the output of my headrush to a third channel

    which leaves the sound engineer with:
    - 3 channels (mic, guitar, headrush output) to mix


    tried it yesterday, but didn’t work out and had to do 2 songs without the loop pedal. kind of stank… so hopefully someone can help me out here

    what’s most important to me is
    - i can’t carry a shitload of stuff around (so racks and stuff are no option)
    - i really like the easy handling of the Headrush and right now I’m thinking the greatest option would be if someone could rebuild it (to have 2 inputs & outputs)

    That’s my main question.

    Another question is: what gear did KT Tunstall use for Black Horse In A Cherry Tree? Might help me out as well…

    Hope to be hearing from you guys!

  14. Drew Franklin says:

    Hi niclas,
    That is a good question, and at least from my research (it has been awhile since I have really looked around) it has not been solved well yet.
    One option as you have mentioned is to have a splitter on your mic and guitar and run three outputs to the mixer. The problem I had with that is if the guitar or mic output was not balanced well with the loop output you would get a drop off or increase in volume after you recored the loop.

    Another option like Howie Day is to use two looper one for each mic and guitar but then you get into timing issues with trying to keep the two synced which is hard.

    I remember the line6 DD4 having two inputs and outputs. I also remember trying to use that and it not working, but I can’t remember why. (can’t check since switched to the echoplex) so maybe look into that. I also haven’t looked at any software solutions, but I feel like it would be easy to create that feature in software.

    What I do for now is bite the bullet and have one output and control volume myself. Maybe this could be part of the Better Looper? I would definitely use it.

  15. Keith Neufeld says:

    Niclas, here’s KT in the studio demonstrating that for live performances, she uses the Headrush exactly the same way you are.

    She even rerecords the backing vocals because they weren’t loud enough the first time.

  16. niclas says:

    Hey Keith, thanks for your reply.

    I watched the video (nice performance :) I got the info on her equipment, but apparently she has the same (thing that I see as a) problem: she separates input of the Headrush by putting a mixer in front of it (between guitar&mic and Headrush).

    My problem though is, that – since the Headrush has only 1 input and 1 output + 1 volume button – I lose the ability to adjust the volumes of guitar/vocals afterwards.

    So when I perform in a certain room/hall, the sound guy can’t help me out when I lose either guitar or vocals in the mix. He can just turn everything as a whole up or down.

    Shitty shitty… Help!? :)

  17. Keith Neufeld says:

    Niclas: Yup. :-)

    Partly KT works around it by only playing or only singing when she’s overdubbing the loop, and then she’ll sit out a couple of bars to sample it and make sure it’s at a good level before going on.

    This is a little bit crazy, but it might be worth trying in the practice studio. What if you send voice, guitar, and Headrush to your sound guy, and have him mix live voice and guitar onto a submaster that he sends back to the Headrush input?

    Then he can control the mix going into the loop; and even if it’s not the perfect balance for the PA, at least he’ll be able to get a good mix on what you’re laying down.

  18. niclas says:

    Thanks Keith, exactly my idea. Shouldn’t be a problem for the sound guy, right? Thing is that at the first gig I wanted to try it out, the guy wasn’t able to fix it. Guess that was just him, coz I can’t see why it shouldn’t work…

    I’ll be trying out some more in the practice studio and will keep you posted :)

    Thanks all!

    (other suggestions are still welcome of course)

  19. Brad says:

    Hi, Keith-
    I came across this page while researching the AKAI Headrush. I absolutely love the pedal, as it seems to be the best sounding and most simplistic, live-operating looper available. Sure, there are other options, but none fit the bill quite like he Headrush.

    In my experience with loopers, I have owned several. I’ve owned two Headrush E2 pedals, the LIne 6 DL-4, the Line 6 M-13 and a few others (BOSS, etc). I keep coming back to the Headrush, however. But, just as you discussed in your entry, there is SO much room for improvement.

    So… to my question: Did you ever come up with a solid build idea? Is it even possible to create a looper this sophisticated? After investing as much as I have into various loopers, I would be willing to pay an almost unheard of amount of money for a pedal that functions as the one you discussed building.

    At any rate- I love this topic. The idea that no large company has taken it upon themself to build such a pedal encourages me to believe that it’s either impossible at this time or that it would cost to much to build and then sell to the mass-market to make profit. But… as a musician who pays thousands on my hobby, I’d be willing to pay just about anything to have the sort of LIVE capabilities one would have with such a “smart” pedal.

    Anyway, thanks a ton! Keep up the creative thought! I love it!

  20. Keith Neufeld says:

    Brad, wow, I hardly know where to start!

    It’s nice to hear that of what’s available today you have such a preference for the Headrush — it means I made a lucky choice in starting with one, and I’m making a good choice in using it as a mental foundation for what I wish a looper could do.

    No, I haven’t build up a looper yet; however, I have no doubt it’s possible to make. I think it’ll be more difficult to come to an agreement how the user interface should work than to build the device itself, :-) and your experience with many different loopers could be very valuable here if you were interested in participating.

    To build the “real” thing, I’d like to use some specialized hardware. To build a prototype, I have an interfacing idea that would require using a computer with guitar-level audio I/O, or build some level-translating hardware, and then do the looping in software on the PC using an audio development environment called Pd. If you think you could get guitar-level sound in and out of your computer (laptop?), I’d be game to put together a board of stomp switches and LEDs and work something up for you to play with — although probably not in September.

  21. Brad says:

    Absolutely- I love the idea. I record on a Mac using an Apogee Duet, so I should be good with the I/O audio levels. Just email me with any details!

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