Line2Amp RevC DIY Reamp Kit

Brandon Drury —  March 4, 2013 — 9 Comments

For the past few weeks it seems that all Ruprect and I have done here at the studio is conduct reamp experiments for the upcoming Audio Hyperguides > Radical Reampingvideo series. The Line2amp Reamp Kit  from was used a majority of the time.


The DIY Part

Building the Line2amp was a total blast. It’s a very simple device. It’s a transformer, 4 resistors, an inductor, a PCB board, and a few jacks. In short, it’s probably the greatest single way to jump into the DIY world. You feel like you got somewhere. You get a notch on your belt knowing that YOU built something and you did it without too much agony.

In fact, I’d argue there is very, very little agony at all. (The only agony I faced was having the PCB board rotated 180 degrees when I placed the resistors. The incredible amount of time it took to de-solder motivated me to order a de-soldering tool so I don’t have to repeat that mistake.)

Other than my goof ups the build went extremely well. All necessary components are right there and easy to find. All pieces fit perfectly well. I was impressed how well everything came together. I have this magic ability for only 3 out of 4 screws to align on almost everything I do, but everything came together perfectly with the Line2amp.

The instructions are just a hair dispersed, but I have to say that I enjoyed that. Let me explain. First off, there are different versions of the Line2amp. I have the RevC. There are a few instruction sets out there, but it really helps to find the actual RevC page and videos. I generally found that if the text didn’t answer my questions, the video usually did (and vice versa). It does take a combination of the text and video to get the full picture, but when you consume both you should have all the info you need even if you no next to nothing about electronics.

Here’s the video walk thru of building the Line2amp RevC

This image from an earlier version of the Line2amp would have been VERY helpful for me.
soldering jack

Line2amp Assembly Instructions

The Features

For those who care about looks, this thing looks like a WWII shoe polish can….or something. It’s rugged and awesome looking. I like this kind of “lo fi” look. If looks are a pressing issue for you in reamp box you may find what you are looking for here.

The Line2amp RevC is a passive reamper. No battery. No 9V. A transformer is doing all the work. There are a few different options available for the Line2amp RevC. I opted for the the “Passive Pickup Emulator”. This is an additional ¼” output that uses an inductor to knock off a bit of the top end and create a presence peak at about 5k. (Very useful, btw.)

The ground lift has been more handy than I expected.

The Sound

After reamping what seems like a thousand guitar tI have absolutely ZERO reason to keep my Radial X-amp. The Line2Amp sounds 1% different. Both are equally “good” in terms of objective sound quality….if such a thing exists.


Before you buy your Line2amp make sure you have the appropriate connections. My Radial X-amp has an XLR input while my the Line2amp uses TRS. Neither are superior, but this required me to snag one of my XLR male to TRS adapters. No biggie, but I have stuff like that on standby. Not everyone will. Then again, most of you are going to be feeding your reamper with a TRS jack on the back of your audio interface anyway. (It makes you wonder why Radial went the XLR route with the X-amp, actually.)

Should The Laymen Buy It?

It’s always hard for the DIY types to relate to the non-DIY types. My server admin just handed me the keys to the server and said, “Go!”. SLOW DOWN, DUDE!!! I don’t trust myself with any of this server stuff.

I’d imagine this isn’t too much different. I’ve soldered a trillion thingies in my day. However, I have to say that I’m not overly experienced with actually building stuff I use other than cables. It’s my official stance that every guitar dude on the planet who does reamping on a regular basis could buy all the necessary tools to make the Line2Amp reamper and still come out ahead of buying a famous brand reamper.


BTW, I vastly prefer the passive reamper. Getting out the 9V adapter for my active reamper is always just one more step separating me from my guitar fun.


If you are considering a DIY build but are a little intimidated I highly recommend the Line2Amp RevC. You’ll have a blast. Even if you aren’t thrilled about building your own gadget, I’d take a serious look at it. It’s a hell of tool and the price is right.


Brandon Drury

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Brandon Drury quit counting at 1,200 recorded songs in his busy home recording studio. He is the creator of and is the author of the Killer Home Recording series.

9 responses to Line2Amp RevC DIY Reamp Kit

  1. This is a cool review, and it has brought up a few thoughts for me…

    First, the cost of some re-amping boxes has always boggled my mind, although most do involve some kind of transformer, and quality transformers are quite expensive and with good reason: they are not trivial to manufacture. However, a re-amping box is basically a DI in reverse, and a DI is, well, pretty basic in terms of parts count and design, so it holds that a re-amping box would be pretty basic, too. I think this DIY kit and its simplicity show you just how simple they are!

    I come from an electrical engineering background, so I have an immediate bias towards a DIY ethic and a scientifically founded skepticism of marketing voodoo. Also, like so many readers of RecordingReview, I don’t have other people’s money to spend on my recording gear! DIY is awesome! Not inferior to manufactured products, not on par with them, but BETTER when done right. You have the freedom to customize things to your exact needs, to buy and use all of the great components that would drive the product cost out of the manufacturer’s target price point, and to tweak and trim them out in ways they can’t afford to spend the time doing. All of this, and you will often save money, depending on the project.

    However, this review inspires me to ask an even deeper question about re-amping boxes, which is: “why do we need them at all?” I could never ask that over at Gear Prostitutes, they’d all shudder and then heckle me. Or maybe they’re just shivering as they stand around naked, all “emperors” in their very, very overpriced “new clothes.” Hopefully here my thoughts will be duly considered. :-)

    To answer my question, we need to consider the interfacing functions the re-amping box is intended to serve. By my estimation, that is the following:

    1. Level matching
    2. Format matching (balanced vs. unbalanced)
    3. Impedance matching

    As far as level matching goes, a line level signal is a little hotter that an instrument level signal, so the raw (“un-amped”) recorded track signal coming from the DAW will generally be a bit too strong for the input of a guitar or bass amplifier. However, this problem is easily solved by simply turning down the output of the DAW! Level matching is not really an issue.

    As far as balanced vs. unbalanced signals go, creating a balanced signal from an unbalanced one takes some doing: you need to derive two signals from just one (and the second needs to be reverse polarity to the original.) However, getting an unbalanced signal from a balanced one (as in the case of re-amping) is easy — you just discard the reverse polarity signal! This is easily accomplished by connecting a standard 1/4″ TS instrument cable between the DAW output and the amplifier input, sending the polarity reversed signal to ground. Achieving an unbalanced feed to the amp is not really an issue.

    Finally, impedance matching: and this is where all of the Ear Shutz disciples would have their knickers in a twist. However, they’d be wrong. Most folks know that because of the relatively high impedance of passive guitar pickups, signal loading takes place at the input of the amplifier that can (and does) alter the frequency response of the signal. The result is a resonant peak in the upper midrange followed by a steep rolloff (12dB/oct,) and the size of the peak is in fact dependent on the length of the cable used to hook the instrument to the amp! Longer cables flatten the resonant peak due to added capacitance, which is why long guitar cables are attributed to a “loss of highs.” This is science, not voodoo, and you can not only hear this effect with various cable lengths, but it can be modeled and shown graphically in SPICE (circuit emulation software.) HOWEVER, there is a misconception that a re-amping box needs to REPLICATE this signal loading, and it is the reason why Brandon’s DIY kit is offered with a “Passive Pickup Emulator.” It’s a cool idea, and probably sonically useful as a creative tool, but the trouble is that the signal loading effect has ALREADY TAKEN PLACE when the output of the guitar hit the input of the DI box (or DAW Hi-Z instrument input) as it was recorded! In fact, if the guitarist was using any pedals upstream of the DI/DAW input, the interaction was actually taking place at the input to the first pedal engaged, and if one or more of the pedals were buffered (not true bypass,) it happened at the input to the first buffered pedal, even if all the pedals were bypassed. The interaction between passive pickups and any high-impedance input stage (whether it belongs to a guitar amplifier, a pedal, a DI box, or an instrument input on a computer recording interface) is the same, and it only happens once — at the first Hi-Z input stage downstream of the pickups. It’s not something created by the guitar amp, or in any way specific to it — the effect occurs because of the pickup design, and will take place irrespective of what the guitar is being plugged into. This effect therefore does not need to be compensated for by a re-amping box. Furthermore, a signal run out from a DAW can easily drive the input to a guitar amplifier with no ADDITIONAL loading effects. Bottom line: impedance matching is not actually an issue.

    With the preceding analysis in mind, if Brandon uses the Passive Pickup Emulator output on his re-amping box, he will effectively be doubling this presence peak effect, because it will already have taken place once as the guitar was recorded, and then be replicated by the re-amping box. It may result in something that sounds good, but the additional presence boost will be a coloration, not a compensation — creative, not corrective. However, if the guitarist used a very long cable (>20′) to feed the DI as the guitar was recorded, the inductor in Brandon’s box could be a good way to put back some of the presence that the long cable took away. However, the same thing could be accomplished with plug-in EQ in the DAW before the signal is sent out to be re-amped.

    As far as I can see, a re-amping box is unnecessary. It’s easy to think that it would be, though, considering the necessary functions of a good DI in terms of leveling, balancing and impedance matching a signal. However, the signal conditioning that’s needed to go from instrument level to line level doesn’t quite apply the same way in reverse, as I hope I have shown. Of course, it’s quite possible I’ve overlooked a valid concern, and if I have I hope someone will bring my attention to it! I hope that perhaps Brandon will run some experiments both with and without his re-amping box and let us know what his results are.

    There is ONE exception to my conclusion, and that would be if the output of the DAW was a long physical distance from the amplifier it was feeding. A balanced, line level signal is much more resistant to induced noise than an unbalanced instrument level signal (that’s why balanced signals are used.) If the signal coming out of the DAW was going to be traveling a long distance in an electrically noisy environment, it might be wise to use a re-amping box so that the signal could be lowered and un-balanced closer to the amplifier, protecting it from induced noise along the cable run.

  2. Agreed. I’ve been using a Line2Amp for over a year, and I used to use an X-Amp before it. Things go SO MUCH smoother with the Line2Amp – It’s much less noisy and doesn’t require me to manually change output settings on my interface everytime I want to reamp (because the X-Amp operates at a much lower signal).

    Took me about 15 minutes to build and I couldn’t be happier for for the $40 I spent on mine!

  3. First off, I am Peterson, the guy who sells the LINE2AMP. Many thanks to Brandon for the kind review.

    Sam, it was a pleasure to read your post because very rarely to I get to geek out this deeply about reamping boxes! Now please allow me to point out why you are wrong ;)

    You wrote:
    “…getting an unbalanced signal from a balanced one (as in the case of re-amping) is easy — you just discard the reverse polarity signal! This is easily accomplished by connecting a standard 1/4″ TS instrument cable between the DAW output and the amplifier input, sending the polarity reversed signal to ground. Achieving an unbalanced feed to the amp is not really an issue.”

    If only it were that easy! When you “convert” balanced to unbalanced in this way, you are connecting the chassis return path of the balanced system to the signal ground of the unbalanced system. This gives noise currents from the balanced system a path to flow into the audio path of your unbalanced system. Using a transformer allows bal/unbal systems to interface without coupling their grounds. See the excellent Rane note 110 for a better explanation of this:

    Regarding your point about output impedance and loading, you make a good point that whatever loading effects we are trying to emulate with a reamping box also happen at the time the DI’ed guitar is being tracked. However, your typical DI is not a very “interesting” load; that is, they have sufficiently high input Z and low capacitance that the output impedance of the guitar pickup is practically irrelevant. When reamping, however, we’re typically playing with more “fun” loads and we want their loading characteristics to be part of the sound, so we want our output to have a guitarish output impedance. If you have a fuzz face pedal at home, you can experience this yourself by sending it a signal directly from your DAW and another through a reamping box. The signal from your DAW will probably be brighter, as it has no problem driving the fuzz face’s load and thus bypasses the filter effect that is part of its sound.

    Also, remember that reamping is not limited to pre-recorded guitars! When reamping non-guitar signals, most people want and expect the signal to behave similar to a guitar–the output impedance (especially one with an inductive characteristic like the PPE mod) is a big part of this behavior.

    Thanks for a well thought out post, Sam, I look forward to hearing your thoughts on my response.

  4. Alright! Thanks for that clarification, Peterson!


  5. Sascha Franck March 6, 2013 at 4:39 am

    First off: Thanks to Sam and Peterson for their thoughtful replies.

    FWIW, I have been thinking quite a lot just like Sam *and* I have as well been doing quite some reamping experiments without using any dedicated reamping device.

    I once came up with a setup that looked like this:
    Guitar > passive switchable Loop thingie (from Lehle, but that really shouldn’t matter much, also).
    Path A (without the loop) went straight into the amp(s).
    Path B went into the Hi-Z input of an RME Fireface UC then out of the unit through one of the (balanced) outs, the output leveling was done through its Totalmix software.

    Now, with that setup, both paths were pretty much different.
    Path A was just a passive guitar running straight into an amp (I think I used like 2 3m cables).
    Path B contained a Hi-Z input (and we all hopefully know how much these can vary in quality, fortunately RMEs Hi-Z ins are doing very well), AD and DA conversion with a balanced signal at line level (at least per default) coming out – and I only used a standard instrument cable to run it into the return of the loop switcher.

    FWIW, I used either a Fender Twin or a Boogie MKIV amp for these tests, both of which are very wellknown for their “acccurate” amplification.

    So, what was the difference between the two paths like?
    After some careful leveling of the RMEs output, I did manage to get pretty much similar results out of either signal path.
    One noticeable difference was a sort of somewhat “brighter” signal when using path B. Pretty much what you’d expect when you feed an amp with a buffered, low impedance signal. But well, those differences could almost be “fixed” by simply using the amp EQs (which are not exactly made for “analytical” purposes).
    The more noticeable difference however was a change in terms of dynamics. Especially when using single coils, some of you folks might have experienced that sort of a difference when comparing the sound of a straight passive high impedance signal to a buffered low impedance one (even when using the most neutral buffering). And well, I don’t think you can exactly change that behaviour with a reamping box because the signal coming out of your DAW has already been treated as running your guitar into a buffer (including impedance conversion), so the possible changes in dynamic reaction and what not have already been there while recording.

    After that first testrun I added a Boss GT-10 before the loop switcher. I was just using it as a looper (so I could tweak either signal chain while a guitar loop was playing), everything else was bypassed. But obviously you can’t bypass the buffer of the GT-10.
    With that setup the differences are a LOT smaller (both frequency and dynamic wise). Now, the GT-10 might not offer the best buffer amp ever (even if it does quite well IMHO) and of course the ADDA conversion might add (or substract…) quite something else due to the GT being a relatively cheap unit. To find out about possible differences added by what might be a cheap device I replaced the GT with a high quality buffer (unfortunately I don’t remember what exactly it was, some guitar electronic dude built it for a friend which I borrowed it from).
    The result was a slightly (but subjectively) “better” sound, but as with the GT-10 that was true for either signal path. I really couldn’t hear much differences at all anymore.

    Bottomline so far:
    If you are used to the sound of a passive guitar signal running straight into a quality amp, reamping in the first place might not be what you are looking for at all, because, all devices you may use after the DAW output aside, you will record a buffered sound, brought to low impedance and up to line level by your interface. And this is what the guitar will “feel” like while recording. It could be that a proper reamping box might sort of “mimic” a passive signal path behaviour, but it will never be exactly the same.
    If you are however used to a buffer in your signal chain (and most people using pedals are just that – either because one of the pedals is buffering anyway or because you might’ve added a dedicated buffer to avoid long cable run signal losses), then reamping should be no big deal regardless of whether you use a dedicated reamping device or not.

    Personally, after reading this review, in spite of all the things I just wrote, I am quite interested in getting me such a box (is there an easy way to get hold of one in germany?).
    Why? Well, the main reason being, that leveling the line signal down to instrument level, while initially looking like a rather trivial thing, is defenitely not as easy at it seems. I always found very small changes to my DAW output level to make up for quite a noticeable change in the amp sound. If you compare that to, say, adjusting an OD pedals output level, it’s a way more sensible thing. At least that’s what I always felt it to be like.
    In addition, while I don’t believe that *any* reamping scenario could ever bring you back the “true” sound of a purely passive signal path, I could imagine that the Line2Amp thingy might at least get you a little closer. Personally, I usually don’t need really “pure” signal paths, but well, it’s always nice to have some options. And at the price of the thing, you probably can’t go wrong, even if you just end up using it to have less trouble getting your amp input level right.


  6. Peterson –

    Thanks for the clarification! I had neglected the ground isolation that the transformer provides (which was pretty short-sighted of me!) I would imagine for short cable runs and depending on your studio setup, you might still be ok without it from a noise standpoint, but you are right, that really is the proper way to unbalance the signal. Also, I wasn’t thinking about driving pedals off the re-amper, but the point you make about load interactions with pedals like a Fuzz Face, etc., is valid. I myself am a bass player much more than a guitarist, and although I am definitely into guitar tone, etc., I tend to overlook those nuances sometimes! However, the guitarist in my band has opened my eyes to some of the more esoteric qualities of really “playing” a pedal, and load interactions are certainly one of them. I don’t think he would’ve overlooked that the way I did! Truthfully, though, I was just simply not thinking of driving pedals with the re-amper, only thinking of driving amps. Thanks for expanding my creative thought!

    In any case, that output with the inductor provides some cool possibilities, and it seems like a useful gadget at a great price, and a fun project that’s easy to build. Thanks for setting me straight, and thanks for providing these cool DIY kits. I should mention that I have been to your website before, and I think it’s SUPER COOL. Exactly the ethic I am into, and it’s awesome to have so much information in one place and so many links to cool projects. Thank you!

    Also — Sascha — thanks for providing your experimental findings! They were interesting to read.


  7. Looking deeper into the very cool Rane App Note that Peterson sent (, building cable #11 would give you the interconnection you need between DAW and amp while maintaining a reasonable grounding scheme. This would be vastly better than simply using a standard TS instrument cable like I described in my initial post (that method would create a ground loop.) It provides a viable alternative to transformer isolation as long as the cable run isn’t too long.

  8. Peterson Goodwyn March 6, 2013 at 9:31 am

    Sam, you’re absolutely right–a properly wired cable may solve the bal/unbal connection problem in many cases. A reamp box is one of those devices we use in the studio that in many cases aren’t strictly necessary, but we use them because they remove some variables for what can go wrong. For example, you could plug many a condenser mic on a loud source right into your converters with no adverse effect, but a mic preamp guarantees you against those effects.

    Thanks for your response, I’m glad you found something worthwhile in mine.

  9. Radial also has a $100 passive reamping box, so Brandon is comparing different things here.
    $50 sounds about right for the parts with maybe a little profit but pretty reasonable. I talked to an electrical engineer and he designed a passive reamp circuit for me, which would’ve cost around $30 without the box for just the parts so sounds like you’re getting a good deal here.

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