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Since the arrival of MIDI, keyboardists could avoid thinking too much about the final sound of recorded tracks as it could have been changed in post production.

The trick was to record a MIDI track together with the audio ones. The MIDI track was to be used in post production to pilot expanders or software instruments to get the right sound different from the tracked one.

Also guitarists and bassists can use a similar technique called Reamp. Let’s see in this post how and when it becomes useful.

A little background

We learned, in a post published a few weeks ago, that the amount of signal delivered over a load by a signal generator depends on the impedances of the two.

That was the case of synthesizers but the principles apply also to stringed instruments that use magnetic pickups. Well, the principles apply to all the generator-load connections…

The condition to be verified is that the load impedance connected to the guitar (or bass) has to be a lot greater than the instrument’s output impedance.

The magnetic pickups are realized (let’s keep it simple) with a thin metal wire wrapped around a magnetic core.

The pickups are connected to the Tone and Volume controls and, via the cable, to the input of the amplifier (or effects).

Without getting too technical and simply reasoning about the circuit architecture we can say that:

  • The wrapped wire (the coil) implies an inductive component
  • The space between the wires in the coil yields a capacitive (parasitic) component
  • The material that makes the wire (copper) implies an electrical resistance

The resulting circuit has a frequency dependent behavior as well as an impedance value that also depends on the frequency. The result is also influenced by the Tone/Volume circuits and by the quality and the length of the used cable.

So, finally, the input impedance of the instrument’s amplifier must be very high to properly load the guitar/bass and keep all the nuances of the performance..

We typically find 1MOhm (one million of Ohms) which is a lot more than what we find in the Line inputs where we have 10KOhm (ten thousand Ohms).

Let’s keep this in mind and let’s go back to our problems (how to modify the guitar or bass sound in post production).

The Reamp technique

The Reamp works in two phases: track and mix.

During the tracking phase the Engineer has to record the miced tracks plus a clean one.

For the last part he/she needs a Direct Inject box (often known as DI box). This device gets the signal from the instrument and makes to things:

  • Level adjust (from Instrument to Mic or Line) to make the signal compatible with the audio interface input’s
  • Impedance matching and signal balancing to keep the whole harmonic content of the sound and avoit capturing noises along the path

A DI box sample is the RND RNDI that you can find in our store.

DI box RNDI by RND
DI box RNDI by RND

The DI box must have a Thru output to be able to send the signal to the amplifier.

In this way a clean and reliable signal can be recorded together with the tracks coming from the microphones around the speakers.

At the mix phase it is obviously possible to use the recorded tracks but, if required, the clean signal can be used to feed a new set of amplifiers to get a sound that can even be very far from the original one.

With this procedure the clean track works for the guitar/bass just like the MIDI one does for the keyboards.

Unfortunately the signal available at the Line output of the interface it is not suitable to feed the amplifiers. It needs to be processed to go from Line level and impedance (+4 dBu, 10 KOhm) to values compatible with the instrument inputs available on the amplifiers or the pedal effects (-10 dBm, 1MOhm).

The Reamp box come handy for this task. They can even be integrated into the audio interfaces. Let’s see some examples.

The Radial devices

Since ever Radial comes to help us with several tools very useful for the studio life. For Reamp we have the JCR and the X-Amp (with the latter being available for both System 500 standard as well as a separate unit).

Radial JCR is a passive unit. It utilizes the original Reamp circuit designed by recording industry legend John Cuniberti, providing exceptional audio quality that preserves every detail of the original recording while optimizing it to feed amplifiers and effects pedals.

Radial JCR front panel

Radial X-Amp has the same features as the JCR but is provided with an active circuit designed by Radial engineers. It can operate with two outputs at the same time.

Radial X-Amp 500
Radial X-Amp 500

The Antelope Audio interfaces

Among the several positive features provided by the Antelope Audio interfaces there is also (for selected models) the full support to the Reamp technique both in tracking as well as in mixing phases.

Antelope Orion Studio Synergy Core gives us the possibility to track with up to twelve inputs at Instruments level. Virtual amps are available among the effects to have a suitable guitar/bass sound without using any amp.

While mixing it is possible to reamp without using external devices thanks to the availability of two specific Reamp outputs.

With the Antelope Audio Discrete 8 Pro Synergy Core we have the two frontal inputs that can be configured as Instruments.

Also in this case to Reamp outputs are available in the back panel as shown in the following picture:

Reamp output in Discrete 8
Reamp output in Discrete 8

Let’s close this section with a video tutorial provided by Antelope Audio showing hot to configure the interfaces to have Reamp realized.

How to reamp with Antelope Audio

Unusual applications

As always happens with audio, these techniques and tools can be used in different scenarios.

Have you ever tried to amplify your vocal tracks with a Marshall stack? Results are weird for sure but they can be interesting in several situations. The same can be done with synth tracks that can be processed by guitar or bass amplifiers or with full guitar effects chains without losing anything of the original quality.

The limit, as usual, is the fantasy of the producer or the engineer. Try by yourself and have fun!

Sono un ingegnere elettronico con la passione per la musica ed il suono. Mi sono avvicinato alla musica da autodidatta (salvo una breve parentesi alla University of the Blues di Dallas) e ho suonato nei peggiori locali italiani (con casuali puntate all'estero).
Ho costruito la mia prima radio FM appena finita la terza media. Ho continuato con amplificatori a valvole e transistor fino ad arrivare alla produzione di circuiti integrati.
Collaboro da anni con varie riviste (cartacee e web) di musica nelle quali mi occupo di recensioni di strumenti musicali e sistemi per l'elaborazione del suono. Trovate le mie pubblicazioni su Accordo (accordo.it), la rivista Chitarre (dal 2010 al 2015) e su Audio Central Magazine (audiocentralmagazine.com).
Produco musica da un po' nello NTFC Studio che serve sostanzialmente per le produzioni di NTFC Band.