music & musings

Twenty Questions you have been dying to ask about Re-amping

Posted on April 5, 2014 Updated on November 6, 2019

The goal of the reamp box is to make the amplifier react in

exactly the same way a live guitar would,

but with a pre-recorded audio source

Q. 1  What is re-amping?

Re-amping is the process whereby the direct signal from a guitar, bass or keyboard is recorded — usually on a separate track alongside the signal captured simultaneously with a microphone from an amp — and later routed to an amp in a studio to be miked up and overdubbed.

Q.2  Why is it used?

This approach allows the choice of amp or amp settings, or mic and mic position, to be changed after the initial recorded performance, but without the compromises and limitations inherent in trying to process an already recorded amp sound. It is a popular and widely used technique, although it is more common in the production of some musical genres than others.

Q.3  Does Re-amping save time?

Re-amping can be both a time saver and a time waster, depending on how and why it is employed! As a way of modifying a guitar part to better suit the track as the mix progresses, it is an invaluable technique, saving the time and effort of having to record a new performance. However, if used to avoid committing to a sound during tracking, it can be an enormous time waster.

Q.4  What does a re-amping box do?

There are various products available with integrated facilities for re-amping, as well as dedicated re-amping units, although the latter approach seems the more popular. There is nothing complicated about a re-amp box, which, in most cases, is essentially a passive DI box used in reverse.

A re-amping box accepts a balanced line‑level signal (nominally +4dBu) and converts it to an unbalanced instrument‑level signal (nominally ‑18dBu), usually via a transformer. A variable level control is often provided to optimize the level fed to the amp, along with a ground‑lift facility to separate the balanced source and unbalanced output grounds, thus avoiding ground‑loop hum problems.

A passive DI box can often be used reasonably well in this role, although it is normally necessary to attenuate the line‑level input significantly, to avoid saturating the transformer and generating an excessive unbalanced output level. Alternatively, the kind of line-level balanced/unbalanced interface intended for connecting domestic equipment to professional systems can be used, and the original ART CleanBox is often recommended in this role. However, for only a slightly greater outlay, a dedicated re-amp box, such as the Radial ProRMP, is rather more convenient to use.  .

Thanks to SOS for the above four answers!

 

Q.5  What musical changes are achieved by re-amping ?

Examples of common re-amping objectives include musically useful amplifier distortion, room tone, compression, EQ/filters, envelopes, resonance, and gating.

Q.6  What is meant by “warming up” dry tracks ?

Re-amping is often used to “warm up” dry tracks, which often means adding complex, musically interesting compression, distortion, filtering, ambience, and other pleasing effects. By playing a dry signal through a studio’s main monitors and then using room mics to capture the ambience, engineers are able to create realistic reverbs and blend the wet signal with the original dry recording to achieve the desired amount of depth.

Q.7  What are some advantages of re-amping ?

Re-amping allows guitarists and other electronic musicians to record their tracks and go home, leaving the engineer and producer to spend more time dialing in “just right” settings and effects on prerecorded tracks. When re-amping electric guitar tracks, the guitarist need not be present for the engineer to experiment long hours with a range of effects, mic positions, speaker cabinets, amplifiers, effects pedals, and overall tonality – continuously replaying the prerecorded tracks while experimenting with new settings and tones. When a desired tone is finally achieved, the guitarist’s dry performance is re-recorded, or “re-amped,” with all added effects.

Q.8  Who were some of the early ‘pioneers’ of re-amping ?

Les Paul and Mary Ford recorded layered vocal harmonies and guitar parts, modifying prior tracks with effects such as ambient reverb while recording the net result together on a new track. Les Paul placed a loudspeaker at one end of a tunnel and a microphone at the other end. The loudspeaker played back previously recorded material – the microphone recorded the resulting altered sound.

Thanks to Wikipedia for answering questions #5 to #9!

Q.9  Why is re-amping so popular?

Re-amping is a technique that gained a lot of popularity in the last 15 years. The technique’s obvious advantages are numerous:

• Direct recording is an ideal way to reserve tonal flexibility for mixing (especially useful in the DIY world);
• Instrument amplifiers and stomp boxes offer virtually limitless opportunities to create the right sound with a not-so-virtual interface;
• It’s fun, which is still allowed.

Sometimes the re-amping goal is simple. An electric guitar can be recorded direct while monitoring a software amp simulator. During mixing the direct guitar track (sans faux amp) will be re-recorded through an actual amp.

Q.10  What does the work flow look like ?

Other popular uses include adding some grit to a direct bass track, rescuing underwhelming keyboard sounds, or using your favorite stomp boxes as outboard processing. In any case, if the goal of the process is amp-related, you can be sure it is also more or less distortion-related.

Q.11  How do you manage the gain staging of a re-amped signal?

As pictured above, the re-amp process requires us to adapt the balanced, relatively low impedance output from our DAW to the unbalanced, high impedance input of the amp or pedal(s) in question. The biggest factor in managing the gain staging of your re-amping signal chain is your choice of adapter.

The two choices are:

1. A purpose built adapter, like the ones made by the company called Reamp, or Radial Engineering; or
2. A passive direct box (so say some).

The purpose-built re-amping devices (most of which are derivative of John Cuniberti’s early 1990’s design) have the distinct advantage of being designed to operate in the amplitude and impedance ranges typically found in +4dBu pro audio and the instrument amplifier world. The same cannot be said of a typical passive direct box. These are important characteristics of inductive systems.

That’s not to say you can’t get the signal flow happening with a passive DI and an adequate amount of attenuation. However, the passive DI fails to simply supply a properly adapted signal. If your goal is to use the amps and pedals as signal processors, the adapter ought to facilitate that work, not pile on it’s own distortion.

Q.12  How do you address the relative phase of the original & the re-amped signal ?

Relative Phase

In applications where the originally recorded signal and the re-amped signal will be used in the mix together, their relative phase is an important tone-shaping factor.

There are two great options for addressing the relative phase of these two signals (options that put a polarity switch to shame):

1. Speaker to mic distance. For many signals, moving the microphone back and forth along the pick-up axis will reveal a dramatic range of tonal difference. This can be particularly apparent with signals that have complex midrange harmonic content.
2. Phase ‘alignment’ tools, like the IBP from Little Labs. Used as the re-amping adapter or after the mic pre-amplified return, these devices provide sweepable electronic control over relative phase. This allows the mic to stay in the spot you liked the most.

Regardless of your choice of tool, remember that relative phase is a subjective tone control in this setting. Don’t think about what’s right or wrong.

Q.13  What do you do if the two signals do not sound right together ?

Sometimes it can be difficult to decide whether the original signal should be used in combination with the re-amped signal. In these cases there’s usually something unique about each signal, but they may not be working together well.

This conflict can often be resolved by creating more contrast between the original and re-amped signals. On keyboard tracks, for example, I will frequently make significant, crossover-style EQ choices that allow me to more subtly combine the unique elements of each signal type.

Another technique that can be used with remarkable ease is one I dubiously call “Sum and Amp-ness”. I think it kills for gritty bass, particularly with tight, close drums.

1. Use a DI bass right up the middle of your mix. Get it sounding great, and setup a re-amp path;
2. Setup a nicely overdriven bass tone on an amp. Somewhere in signal flow, HPF this path in the 300 – 500Hz neighborhood. I like to do it before the amp;
3. Use the return from the amp just as you would use the ‘side’ component of a mid-side mic array. For maximum sum and difference affect, mic the amp off-axis.

This set-up leaves you with strong, centered low frequency focus, but adds an interesting distorted ‘width’ component. Try it out in mono-tending drum and bass situations.

Finally, don’t be afraid to let the re-amp path hang out in input monitoring while you mix. There’s no real reason to record it until you’re getting close to printing mixes. It’s incredibly easy to make changes as long as it’s all still live.

Thanks to Pro Audio Files for answering questions #9 to #13!

 

 Q.14  How do you load down a guitar ?

THE LOADING ISSUE

To capture a characteristic guitar sound, you need to record the same thing you would hear if the guitar connected directly to an amp. Although many people like the “high-fidelity” sound of a guitar feeding an ultra-high impedance input, others prefer the slight dulling that occurs with a low-impedance load (e.g., around 5-100 kohms) as found with some effects boxes, older solid-state amps, etc. This is especially useful when the guitar precedes distortion, as distorting high frequencies can give a grating, brittle effect that resembles Sponge Bob on helium.

There are several ways to load down your guitar:

•  Find a box that loads down your guitar by the desired amount, then split the guitar to both the box and the mixer or audio interface’s “guitar” input.
• If your recorder, mixer, or sound card has a guitar input, try using one of the regular line level inputs instead.
• Use a box with variable input impedance (e.g., the “drag control” on Radial products)
• Create a special patch cord with the desired amount of loading by soldering a resistor between the hot and ground of either one of the plugs. A typical value would be 10 kohms.
• If you’re going through host software with plug-ins, insert an EQ and roll off the desired amount of highs before feeding whatever produces distortion (e.g., an outboard amp that feeds back into the host, or an amp simulator plug-in). However, this doesn’t sound quite as authentic as actually loading down the pickup, which creates more complex tonal changes.

 Note that you need to add this load while recording, as it’s the interaction between the pickup’s inductance and load that produces the desired effect. Once the dry track is recorded, the pickup is out of the picture.

But just because we have a signal doesn’t mean we can go home and collect our royalties, because this signal now goes through a signal path that may include pedals and other devices. As guitarists are very sensitive to the tone of their rigs, even the slightest variation from what’s expected may be a problem. For example, the transformers in some direct boxes or preamps color the sound slightly, so the guitarist might want to send the signal through the transformer, even though transformer isolation is usually not necessary with a signal coming from a recorder.

 Q.15  What are some plug-ins and interfaces available ?

Traditional re-amping is replaced by virtual re-amping using guitar-amp plug‑ins, many of which offer remarkably good quality and enormous versatility. The process is exactly the same, but without having to physically route the signal out of the DAW and into a real amp in a real studio, miked up with real mics.

Plug-ins and low-latency audio interfaces have opened up “virtual re-amping” options. Guitar-oriented plug-ins include IK Multimedia AmpliTube, Native Instruments Guitar Rig, Line 6 POD Farm, Scuffham Amps, Waves G|T|R|, iZotope Trash, Peavey ReValver, Overloud TH2, McDSP Chrome Tone, and others.

The concept is similar to hardware-based re-amping: Record the direct signal to a track, and monitor through an amp. The key to “virtual re-amping” is that the host records a straight (dry) guitar signal to the track. So, any processing that occurs depends entirely on the plug-in(s) you’ve selected; you can process the guitar as desired while mixing, including changing “virtual amps.” When mixing, you can use different plug-ins for different amp sounds, and/or do traditional hardware re-amping by sending the recorded track through an output, then into a mic’ed hardware amp.

Q.16  What are the limitations when using a plug-in ?

Using plug-ins has limitations. If feedback is part of your sound, there’s no easy way to create a feedback loop with a direct-recorded track. This is one reason for monitoring through a real amp, as any effect the amp has on your strings will be recorded in the direct track. Still, this isn’t as interactive as feeding back with the amp that creates your final sound. And plug-ins themselves have limitations; although digital technology does a remarkable job of modeling amp sounds, picky purists may pout that some subtleties that don’t translate well.

Furthermore, monitoring through a host program demands low-latency drivers (e.g., Steinberg ASIO, Apple Core Audio, or Microsoft’s low-latency drivers like WDM/KS). Otherwise, you’ll hear a delay as you play. Although there will always be some delay due to the A/D and D/A conversion process, with modern systems total latency can often be under 10ms. For some perspective, 3 ms of latency is about the same delay that would occur if you moved your head 1 meter (3 feet) further from a speaker—not really enough to affect the “feel” of your playing.

If latency is an issue, there are other ways to monitor, like ASIO Direct Monitoring. Input signal monitoring (often called zero-latency monitoring) is essentially instantaneous; the signal appearing at the audio interface input is simply directed to the audio interface out, without passing through any plug-ins. With this method you can also feed the output to a guitar amp for monitoring, while recording the straight signal on tape.

In any event, regardless of whether you use hardware re-amping, virtual re-amping, or a combination, the fact that the process lets you go back and change a track’s fundamental sound without having to re-record it is significant. If you haven’t tried re-amping yet, give it a shot—it will add a useful new tool to your bag of tricks.

Q.17  When did the term “re-amping” come into use ?

Background: A History of Re-Amping

by Peter Janis, Radial Engineering

As with so many aspects of audio, it’s hard to pin down exactly when a technique was first used, and that goes for re-amping. While Reamp made the first commercial box designed expressly for this purpose, engineers had already been creating re-amping setups for years.  Recording historian Doug Mitchell, Associate Professor at Middle Tennessee State University, comments that “The process of ‘re-amping’ has actually been utilized since the early days of recording in a variety of methods. However, the actual process may not have been referred to as re-amping until perhaps the late ’60s or ’70s. From the early possibilities of recording sound, various composers and experimenters utilized what might be termed ‘re-amping’ to take advantage of the recording process and to expand upon its possibilities.

The first commercially available box for re-amping has been tweaked and revised over the years.

“In 1913 Italian Futurist Luigi Russolo proposed something he termed the ‘Art of Noises.’ Recordings of any sound (anything was legitimate) were made on Berliner discs and played back via ‘noise machines’ in live scenarios and re-recorded on ‘master’ disc cutters. This concept was furthered by Pierre Schaeffer and his ‘Musique Concrète’ electronic music concept in the ’30s and ’40s. Schaeffer would utilize sounds such as trains in highly manipulated processes to compose new music ideas. These processes often involved the replaying and acoustic re-recording of material in a manipulated fashion. Other experimenters in this area included Karlheinz Stockhausen and Edgard Varèse.

“With the possibilities presented by magnetic recording, the process of what might be termed re-amping was utilized in other ‘pop’ music areas. Perhaps the first person to take advantage of this was Les Paul. His recordings with Mary Ford often utilized multiple harmonies all performed by Mary. Initially these harmonies were performed via the re-amping process. Later, Les convinced Ampex to make the first 8-track recorder so that he might utilize track comping to perform a similar function. Les is also credited with the utilization of the re-amping process for the creation of reverberant soundfields, by placing a loudspeaker at one end of a long tunnel area under his home and a microphone at the other end. Reverberation time could be altered with the placement of the microphone with respect to the loudspeaker playing back previously recorded material.

“Wall of sound pioneer Phil Spector is perhaps the most widely accredited for the use of the re-amping process, and because of his association with the Beatles, is potentially regarded today as the developer of the process. However, Phil was actually refining a process and exploring its possibility for use in rock music.

Thanks to Harmony Central  for answering questions #14 to #17!

Q.18  Can you build your own re-amping box ?

Yes!  How to Build a DIY Reamping Box

Q.19  What does guitar re-amping sound like?

In a nutshell, it sounds real. Follow this link for examples from Pure Mix Advanced Audio.  Thanks to Ben Lindell for this awesome tutorial

Quite a difference right? I love how the reamped track is crunchy but with some life to it. So what was my signal path? This track started with my Telecaster running into the Demeter Tube DI box connected to a DBX 386 pre and into my Digidesign 192. Then for reamping the signal traveled out of a Digidesign 192 into the Little Labs Redeye then into a Mesa Boogie Nomad 55 on the clean channel with the ‘Pushed’ switch flipped. I recorded it with a Beyerdynamic M 201 TG about a foot away going through one of my custom germanium preamps and combined that with a Neumann U87 in omni a bit further away running though an API 3124 preamp and into an 1176 to maximize the room tone.

 

Q.20  What are some of the applications promoted by “REAMP” ?

courtesy of http://www.danalexanderaudio.com/reamp.html :

1. Change amplifier make, tone settings, and effects at any time after original performance. A flat direct safety track is recommended but not always necessary for the best results. Preserve the inspired first-takes, always knowing you can REAMP later if you are unhappy with the amplified sound.

2. Engineers and producers can experiment with mic placement and room ambiance without asking the musician to keep playing over and over. Record a scratch direct signal on tape/disk and feed it to the musician’s amp via the REAMP and experiment.

3. Insert instrument effects at any time during production. REAMP from tape/disk to any stomp box (such as a wah-wah, or overdrive), then take the effects output and return it to the console via a direct box.

4. Live recordings direct from the instrument’s output to tape/disk can later be REAMP’ed in the studio. This solves many problems related to remote recording. You can match the sound for a punch in by using the original instrument and direct box, thereby making only small repairs. After the repairs are done, REAMP to any amplifier instead of re-recording the entire performance. The REAMP is the cheapest insurance policy going!

5. Insert studio pre-amps, equalizers, signal processors, and dynamics control before reaching the instrument amplifier.

6. Synthesized guitar and bass tracks can sound more live-like by RE-AMPing into an instrument amplifier and using mics. Send drum tracks to various instrument amps and mic the room for ambiance.

7. No need to record instrument amps during a tracking session if space or leakage is a problem; perfect for late night home recording. The next day plug in your amp, turn it up and REAMP the previous night’s performance. Record the bass direct and REAMP later to tape/disk or during the mix.

8. REAMP the same performance with different amps and stack the sounds for various textures and panning. You can use the REAMP to overdrive the front end of a guitar amp for intense distortion by turning up the REAMP’s trim control to eleven!!