Reamping rests on a simple idea. Instead of freezing an amp’s sound at tracking, you first record the raw instrument signal, then play it back later into a real amplifier to capture it on a microphone. The performance is set once, but the tone, the amp, the settings and the mic position stay open until mixdown. It is a safety net as much as a playground.
Capture a clean signal first
It all starts with a dry take. You plug the guitar or bass into a DI box with a thru output, which lets you record the dry track in parallel with, if you like, a live amp take played at the same time. The dry track carries no processing: no amp, no EQ, no effect. That bare signal, high in level and high in impedance like a guitar pickup delivers, is what you keep to reamp later.
Two approaches coexist. Either you record the dry take alone and push the whole tone decision to the mix, or you capture a mic’d amp and the DI together, to keep a reference and reinforce or replace it later. The second method avoids ending up at the mix with a dry track and no tonal reference at all.
Why an interface output will not do
The temptation is to plug an interface output straight into the amp input. Levels and impedances stand in the way. An interface output works at line level, balanced and low impedance, while a guitar amp input expects an instrument signal, unbalanced and very high impedance, on the order of a megohm. Feeding line level to an amp overloads its input stage immediately and skews its frequency response, because that stage is not loaded the way it expects.
A reamp box does exactly the opposite of a DI box. Where the DI lowers impedance and balances the line to send an instrument into a mic input, the reamp box drops the level and raises the impedance to present the amp with a believable instrument signal. Most carry a transformer, a level control and a ground-lift switch to kill the hum caused by ground loops between the interface and the amp.
The path, step by step
At the mix, you route the dry track to a physical interface output. That output feeds the reamp box, whose output drives the amp input. The amp is mic’d as for a normal take, the mic goes into a preamp, and the whole thing returns to a new track. You can then try ten amps and twenty settings without ever asking the guitarist to play again.
- Mind the send level: start low, raise it until you recover the attack of real playing without clipping the amp input.
- Compensate for round-trip latency. The reamped track returns offset by the conversion time and the analogue path, so line it up with the original DI.
- Lift the ground at the box if hum appears, and check the mic placement in front of the speaker as you would when positioning a microphone on any source.
One precaution and a few creative uses
Watch out for phantom power: a passive reamp box does not want it, and a guitar amp input wants it even less. Make sure +48V is off on that channel before you patch. Beyond that, nothing ties you to guitar. A vocal, a drum machine, a synth pad or a drum loop sent through an amp, a cabinet or a pedal chain comes back with a colour and a grit no plugin reproduces. Reamping then becomes a sound-design tool in its own right.
The technique was developed in the early 1990s by engineer John Cuniberti, who wanted to rework guitar takes after the fact. The name stuck, the boxes spread through Radial and a few others, and the habit of recording a DI alongside the amp became standard in most studios.
My take
Reamping is one of the few studio moves that cost almost nothing and transform the comfort of a session. Recording a DI alongside the amp buys you a way out when the tone chosen in the moment no longer holds at the mix. The dedicated box is not a gimmick: without it, impedance and level betray the amp and the result sounds wrong. And once the habit sticks on guitar, you soon extend it to anything that gains from a real speaker.
