Radial X-Amp Active Re-Amplifier XAMP Recording Re Amp

The Radial X-Amp is an active re-amping device that presents the engineer / producer with a new and innovative creative tool that allows a pre-recorded track from a line level device to drive two guitar amplifiers or effect pedals simultaneously. This opens the door to explore new musical sounds and spur on the creative process.

Following the critically acclaimed Radial JD7 Injector, the X-Amp employs a unique Class-A circuit design that has been optimized for use with guitars. Using the X-Amp is easy: One would, for instance, record a dry track using a high quality direct box, then send this track from the recorder to the X-Amp and then to either guitar amps, effect pedals or combinations thereof.

Recording using the X-Amp has many benefits: Once the basic track has been recorded, replacing or adding tracks can be done well after the session player has gone home. This eliminates tiresome repetition and assures a fresh vibrant performance on the final recording. Furthermore, by driving two amps at the same time, new sounds and textures can be created allowing the engineer – producer to make artistic decisions as the recording progresses.

Features include balanced line level input with LED peak indicator and level control, Class-A circuit topology for optimal reach and frequency response, direct and isolated guitar amplifier outputs, 180º polarity reverse to bring both amps into phase, and dual ground lift options for noise-free operation.

As with all Radial products, the X-Amp is built like a tank to provide years of trouble-free performance. A welded I-beam internal skeleton provides a separate housing for maximum protection against external forces, which may cause stress on the PC board assembly while the outside bookend cover provides a protective zone for the switches, potentiometer and connectors. A full bottom no-slip pad performs double duty by keeping the X-Amp from sliding around when placed on a vibrating amplifier while also providing electrical and mechanical isolation.

X-Amp Development & Evolution

Designed as a creative tool, the Radial X-Amp is an active re-amplifying device that allows prerecorded instrument tracks to be sent through guitar amplifiers and effect devices.

With the X-Amp, you could for instance take a pre-recorded guitar track, and send it through a second distortion pedal and amplifier and then slightly delay the track to add a thick doubling effect. You could also use the X-Amp from a voice track to a distortion pedal to ad some grit to a performance. Another popular use would be to go back and fix a track should an error or glitch somehow appear.

Although the Radial X-amp is new, the process of re-amping tracks has been around for years. Historians credit jazz guitar great Les Paul as the first to employ the concepts of re-amplifying sound in the 1950s as there was no other way to double tracks or create echo effects. In the 1960s, Phil Spector’s work with his famous ‘wall of sound’ employed re-amping techniques. In the 1970s, Roger Nichols built his own ‘re-amper’. Roger used it on all of the Steely Dan records virtually burning out tubes in effort to get the right sound. Only today with the proliferation of affordable high quality multi-track recording has the demand for high-quality recording tools allowed manufacturers to develop devices such the Radial X-amp into commercially viable products.

This is not to say that other re-amping devices have not been available. In 1980, Jensen® Transformers introduced the 1st transformer that could effectuate the process and included an application note on the spec sheet discussing the conversion of balanced to unbalanced guitar signals. The Radial JDI Mk3 in fact employs a newer version of this same transformer and can be easily used as a re-amping device. (See the Radial JDI Owner’s manual for more details).

The forefather to the Radial JD7 Injector (custom built by Radial Chief Engineer Denis Rozon circa 1990) was designed to drive a signal to several guitar amplifiers at once and the introduction of the 1st generation Radial JD7 in 2001 added facilities such as balanced output and input to simplify the re-amping process. The Radial X-Amp is in fact a derivative of the Radial JD7 Injector. It employs the same active balanced input and new Class-A circuit topology as the popular JD7, but in a more affordable and simplified two output configuration.

The Challenges in building a better re-amping device

Up until the X-Amp, pretty much all re-amping devices have been passive, transformer-based. These generally work well but do have limitations: Because the same transformer is used to both convert the balanced line level to an unbalanced signal while changing the impedance, one is required to employ workable compromise to get an acceptable tone. Because varying the output level is required to properly match the amplifier’s input level, a potentiometer is required. Since a potentiometer is in fact a variable resistor, changing the level will introduce a load variation, which will inevitably impact the tone. This is not to say that the tone will be bad, it just means that finding the ‘sweet spot’ may be compromised.

The Radial X-Amp was designed in such a way as to solve these problems. To begin, the X-Amp is active. This means that it is equipped with an external power supply to provide the DC to the circuit. The circuit itself is Class-A meaning that it employs a high performance, audiophile buffering circuit to ensure the cleanest and most natural tone. This design allows us to ad several important features and controls that are not possible with simple passive devices. For instance, we introduced a peak-overload detector that lets you monitor the level coming from the recorder and ensure the signal will not overload the circuit. Because we are active, the X-Amp’s output control can be adjusted at will without affecting the tonal character. Furthermore, by adding a second buffer to the signal, we can introduce a second output that to drive a stereo amp set-up or maybe two completely different amps and effects chains at one time. This opens the doors to significantly greater tonal possibilities!

The history of re-amping

We recently looked into the history of re-amping and were amazed at the response we received by asking around. These are brief historical accounts and letters we received. Many thanks to Frank Wells at Pro Sound News and Mitch Galagher at EQ magazine for helping us track down these folks.

When we asked recording historian Doug Mitchell (*1), Associate Professor at Middle Tennessee State University the question: 'Who invented re-amping'. Doug gave us this reply:

"The process now called 'reamping' has actually been utilized since the very first days of recording, though it may not have been referred to as such until perhaps the late 1960's or 1970's. From the early days of sound recording, composers and experimenters have used techniques that include what we now call 'reamping' to take advantage of the recording process and expand upon its possibilities. 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 recollected on 'master' disc cutters. This concept was furthered by Pierre Schaeffer and his 'Musique Concrete' electronic music concept in the 1930s and 1940s. 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 Karlheinze Stockhausen and Edgard Varese."

"With the possibilities presented by magnetic recording the process of what might be termed reamping was utilized in other 'pop' music areas. Perhaps the first person to take advantage of the process was Les Paul. His recordings with Mary Ford often utilized multiple harmonies all performed by Mary. Initially these harmonies were performed with the reamping 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 reamping 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 reamping 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, which had been utilized for decades, and exploring its possibility for use in rock music."

"The process of reamping is often used in film sound design as well. In order for sounds recorded in a post production environment to match the scene, it is common for them to be re-recorded utilizing a reamping procedure. In film sound this process is also termed 'worldizing'."

"The history of first use of the term 'reamping' is vague. It may have come into the recordist's vocabulary as early as the late 1960's, but I am not sure when the term was first utilized."

We then posed the same question to Bob Ohlsson (*2) of Motown fame, (Stevie Wonder, Marvin Gaye, Kinks, Animals, Donovan, Herman's Hermits). Bob kindly answered:

"I began doing it in 1968 shortly after we got the sixteen-track machines because for the first time we could separately record direct guitars, clavinets and e.pianos. I had never heard of it being done and am pretty sure I was the first to try it at Motown but I can't imagine lots of others weren't doing the same thing. It seemed like a very obvious thing to do in a world where electric instruments were taken direct primarily to cut down on bleed rather than for tonal quality."

We then contacted Roger Nichols (*3) (Steely Dan, Crosby Stills and Nash, John Denver, Roy Orbison, Zappa) and when posed the question: "Roger, I know you have been re-amping for a while, when did you start using this process?"

"That would be 1972 when I built the re-amper we used on the first, and almost every Steely Dan album after that. We used it to play direct guitar tracks back through an amp. We were going through a lot of amps. The speakers would get tired or the tubes would melt or something during a night of guitar overdubs."

"We would go through one amp to make sure we got the sound we wanted, and then when the right guitar and settings were locked in, we recorded the direct signal and let the amp rest. After the part was completed, we ran the signal back through the guitar amp and it only had to last long enough to print the results to tape. I still have the box around here somewhere."

Interestingly, when Jensen® introduced the JT-DBE audio transformer in 1980, the application notes on this unit contain a complete paragraph discussing using it to convert low impedance balanced lines to guitar levels. This same application is mentioned in the Radial JDI direct box owner's manual and referred to as 'using the JDI backwards'. In the 1980's, the Whirlwind company also produced a device that could accommodate low-to-hi conversion using a transformer.

In 1994, Reamp® commercialized the process by producing a box that incorporated a transformer and a volume control. This allowed the user to adjust the volume at the amplifier instead of at the mix position. In 1996, the 1st generation Radial™ JDI was introduced.

The 1st generation Radial JD7 Injector was released in 2001 with a balanced output and input to allow re-amping and subsequent re-distribution of signals to many amplifiers. In 2003, Radial will be introducing the Radial X-Amp which is an active device that allows a pre-recorded balanced signal to drive two amplifiers at the same time.

* References

(1) Doug Mitchell, Associate Professor MTSU Department of Recording Industry http://www.mtsu.edu/~dsmitche

(2) Bob Olhsson Audio Mastery Recording, Project Design and Consulting Box 90412, Nashville TN 37209

(3) Roger Nichols Mastering 11461 SW 93 St. Miami, FL 33176 http://www.rogernichols.com

X-Amp Features & Specifications 

The Radial X-Amp is a creative tool designed to advance recording and open the door to new sounds and processes. Although highly complex on the inside, the Radial X-Amp is easy to use on the outside. It is loaded with features and jam-packed with discreet components to make re-amping simple and sound great!