What is re-amping?

Simply defined, re-amping is the sending of a previously recorded signal back into a recorder via playback of the signal through some device that modifies the signal in some way. If we use this definition, J.J. Foor and I were doing this a long time ago here at the studio when we were recording playback tracks with microphones to capture room and speaker sounds of completely arranged tracks for our projects at the time.

The definition of “re-amping” being used now and forever more in the studio is going to be much more specific. For starters, it’s only going to apply to individual guitar tracks. The process is simple – take a completely dry track from a guitar, and once that’s recorded, send it back out through an amplifier or guitar processor. That’s the kind of re-amping we’re doing out here now, and it’s an exciting development.

Why re-amp?

Re-amping is exciting because as more songs are composed and constructed out here, and our backlog begins to fill with songs that have direct takes in them, we can change their guitar sound at any time, for any reason without a guitarist needing to perform the part again. Once a good performance is tracked, that’s it. There’s no need to throw away hours of time playing the same thing all over again because we want to change the sound. This is useful because guitar players here can now record comfortably without a blaring half-stack blowing their faces off, because we can re-amp into it later. If a sound changes halfway through an album, we can re-amp the first songs to match. We no longer have to be married to an initial sound as a project develops. Guitarists can bring their own amps or processors later. We can swap ampheads, ampsims, speaker cabinets, guitar processors – all kinds of devices to build sounds with.

How is re-amping done?

From the guitarist’s point of view, very little will be different. You’ll still be plugged into an amp or an effects processor, and you’re still going to hear its sound so don’t worry about how weird it’s going to feel to play a dry track directly into the recorder. The only difference is going to be that you will notice me plugging you into a direct box before your signal reaches the amp/processor. One signal from the direct box is going to go into the amp/processor, so you can play though it as though nothing’s different, and the other signal will be routed directly into the recorder through a microphone cable. That’s the all-important dry track that may come very much in handy later. Of course, we’re going to be recording the amp/processor you’re using as well, just like always. If you’re paying attention to the monitor, it’ll look like we’re recording one more track than usual. If the sound you have from the amp/processor is great, then well done!  Nothing else needs to happen. If you find that you want a different sound, then the second part of the process will begin.

That begins with us finding the sound you think will be better. Once we have that, all you’ll need to do is sit back and watch me plug a re-amp box into an output from the recorder on one end and into the new or adjusted amp/processor on the other. All I do then is arm a destination track for the new sound, hit record, and all the work is done while we pat ourselves on the back and feel smart.

If we do all of that and find that the original sound was better, just switch back to it if we still have it in the recorder. If we don’t, we can re-amp it. Just don’t lose those dry tracks! We can keep re-amping from the same dry track until the end of time if we need.

Diagrams below show the process in both parts. Keep in mind that the “1/4-inch TS cables” are a more technical nomenclature for what are commonly called “instrument cables.” Much to the same effect,”XLR cables” are commonly known as “mic cables.”  I’ll have more stuff below on the different kinds of cables for anyone interested, but the diagrams below show a re-amping session from an ampsim processor to an actual tube half-stack.

 

Boring technical crap on cables:

This 1/4″ TS cable (commonly known as a 1/4″ instrument cable, less commonly known as a phone connector) is very recognizable to musicians with electrical instruments that use outside amplification. The name comes from the contact points: the tip and the sleeve. It carries an unbalanced signal in both a single hot signal and a ground, with the hot signal (transferred by the tip) being what is translated into sound and the ground (transferred by the sleeve) functioning as the reference, or zero line (do be aware that sound doesn’t travel through the cables, just an electrical signal). Unbalanced signals are prone to noise buildup as they travel the length of the cable, so audio engineers generally like to keep these things shorter than twenty feet, although some will say that they are not comfortable with anything over twelve. This kind of audio cable has been around since the later part of the 1800s, and those who remember operators patching signals through will also be familiar with this kind of cable. Patch bays survive today, but they are used now in recording studios to patch signals instead of phone calls.

This is an XLR cable which is also likely recognizable to many musicians. The X stands for the Cannon X Series, which was a line of cables with connectors similar to the one pictured that were developed and marketed in the early to mid 1900s. The L stands for the locking mechanism on the cables and the ports that receive them.  The R stands for the synthetic rubber insulation used in these cables. Commonly called a mic cable, these carry a balanced audio signal with the same hot (transferred by pin 2) and ground signal (pin 1), but with the addition of a “cold” signal (pin 3) to offset – or balance – the hot. The cold signal is an inverse (not reverse) of the hot, with it’s wave function troughing out where the hot signal peaks and peaking out when the hot signal troughs (the terse explanation is that the signals are out of phase by 180 degrees to each other).

The signal source – like a microphone – splits the original non-ground signal into two, the hot and cold, before it travels the cable and inverts the cold signal.

Noise will build on both the hot and cold signals as shown above, just like it will on the lone hot signal of an unbalanced cable, but it will build up on both signals in phase. Thus when the cold signal is inverted back into phase with the hot and added to the hot signal by the signals’ destination (a P.A. system or a recorder), the noise buildup is now out of phase and cancels, leaving a clean, noiseless audio signal.

Because the two signals are merged they add and wind up being stronger. Thus, XLR cables can be run for hundreds of feet without noise being any kind of trouble.

This is a 1/4″ TRS cable. Although it looks like a TS cable, it carries a balanced signal like the XLR cable,  which are received from a source and imparted to destination by its three contact points: the tip (hot), ring (cold, absent from the TS cable), and sleeve (ground) instead of the three separate pins the XLR uses. While it is much less common than both the XLR and TS cables, it’s certainly not unheard of to even find these in use for audio somewhere. As a fun fact, WHW Studio uses these to connect our audio interface to the PA System and the studio monitors, as those are all balanced 1/4″ inputs and outputs (at least with the studio monitors – the specs for the PA head are quite confusing).

There are a couple things of note that should be known about balanced cables, especially the TRS cable above. First is that they can also be used to carry stereo audio signals as well as balanced audio, but not at the same time. This means that when you are carrying stereo audio through a balanced cable, you’ll be carrying two unbalanced (hot) signals with no cold to balance either one and cancel any noise accruement at the signal’s destination. Second is that if either your source of audio and/or its destination are not built to handle a balanced signal, your signal will be unbalanced, even though you are carrying the signal through a balanced cable. This means that you cannot balance a signal from an electric guitar simply by plugging a TRS cable into it. If your guitar is wired to send a balanced signal – something I’ve personally never seen though some Gibsons in the 1970s apparently were built to do this, and God knows what you could talk an independent luthier into doing – through a TRS signal and its destination is a TS jack that nearly all amps and 1/4 inputs that receive guitar signal are designed to be, you’ll still have an unbalanced signal. The same is true in the inverse – if your source and destination are wired for TRS cables and you connect them with a TS cable, the signal will be unbalanced. The good news, is you’ll unlikely damage audio equipment by using TS cables with TRS jacks or TRS cables with TS jacks unless the folks who designed said equipment were real jackasses.

In order to simplify the previous paragraph of information, I can reduce all of that info to the following simple math formulae:

Balanced source + balanced cable + balanced receiver = balanced signal chain (this is the only formula that gives a balanced signal chain; all other combinations yield an unbalanced final signal).

By the way, your 1/8″ headphone wires and jacks are TRS, but everything above with the TRS 1/4″applies to them as well. Most 1/8″ jacks are used to carry stereo audio, and therefore are acting as unbalanced cables.

Also, other unbalanced cables include co-axial cables (TV), and RCA cables. Even the bundles of two of three RCA connectors carry one hot signal each, with no cold balance.

Why isn’t everything just sent as balanced signals?  Why all these differing cables?

I have no clear answer. Part of the reason is the unbalanced TS cables were a late 1800s invention, and were widely in use to carry audio signals when the electric guitar was invented and established. Cannon’s XLR balanced audio cables became common in the 1950s. Also, all of the infrastructure with guitars includes destination sources like amps, pedals and effects processors that have TS jacks, so a balanced output jack would be useless with most gear. I don’t know when TRS cables were invented, or even why they were, as they can carry two audio signals that are only balanced if the source sends balanced signals and the destination converts them. Seeing as how there are TRRS and TRRRS cables that keep adding contact rings, I suspect that these cables were meant as a way to carry more than one hot signal at once.

 

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