Was there always a function called audio mastering? With special boxes and super speakers, engineers hunched over a myriad of dials and knobs, in strange rooms with peculiar wall and ceiling coverings, magically making the music sound amazing? The short answer is no: It’s a history of time and tricks — and ultimately hands-on experience combined with cultivated expertise — that led to audio mastering. And through that evolution, quality equipment has become paramount for mastering engineers to deliver their #1 goal: make the music sound its best everywhere.

Going back to the very first recording sessions, live players gathered in a room and performed a piece of music while the ‘recording engineer’ made sure a mechanical lathe cut ‘grooves’ into a wax or soft metal cylinder (circa1880-1910), and eventually a lacquer disc (circa1910-1950). Imagine a small jazz band and a singer in the 1920’s huddled around one or more large ‘horns’ that transferred the sound energy from the band to the cylinder or disc (these horns were like the old “Gramophone speaker” on a record-player — remember there were no microphones yet!). Once everyone got it right —the players and the engineer — then recording was done. One take. No editing. No ‘mastering’ involved. The recorded medium was used to create consumer versions in a mechanical copying process.

In the 1940’s recording technology took a giant leap and reel-to-reel tape recording took over in the music studio.  While the delivery medium was still a ‘record disc’ on vinyl, the consumer disc was not only a different format as what was being recorded onto, but was the result of a multi-stage process:  The mixed tapes needed to be cut onto a laquer disc for each side (A, B, etc) using a record-cutting lathe, then shipped to a metal plating facility where plates for each recorded side of music are created, with the final consumer record disc being “pressed” from these metal plates onto vinyl discs which were then distributed to consumers.

All of this required special expertise passed down from one engineer to another directly with hands-on experience. Careful listening, set-up and literally watching and adjusting the record lathe at work cutting away the lacquer grooves are an extremely critical processes; Almost a lost art, but fortunately not quite.

Every medium has their limitations, and it was the limitations of the vinyl medium that created an opportunity to birth the mastering industry.  For vinyl, the fidelity of the music recorded needed to be ‘tamed’ to fit and playback correctly on the lacquer disc master. Loud dynamics needed to be compressed and the spectrum of tones equalized so the grooves were not too large.  Why?  While larger grooves allow more bass and louder sounds, they can easily cause skips and other playback problems. Processing like EQ and compression were already in use through radio broadcast for many years, so audio mastering engineers embraced these tools and techniques to improve their own results. So it was in the late 1960’s that Lee Hulko at Sterling Sound helped pioneer the idea that “Mastering could be an industry unto itself.” As we saw previously, recording studios would purchase a Neumann, Skully or Presto disc cutting system that included a tape machine, a little console, EQ and compression and had a ‘studio assistant’ prepare the discs for duplication — but it wasn’t a formalized process like mastering has become today. Hulko innovated the idea that after the recording session, he could play the tapes in a special room and work with EQ and compression rather than just having the tape transferred to disc so the record wouldn’t skip. Thus Mastering became a separate step in the recording process altogether. What began as an assistant transferring tapes to disc became a separate industry of dedicated professionals with tools, techniques, and studios unique to their role in the recording process.


The equipment that mastering engineers started to require, describe, and request created a new level of quality and sonic capability, and this rarefied air that mastering engineers breathe in their studios continues today. The creation of this new mastering equipment niche created the highest sonic goalpost ever: “Mastering Quality”.  Although the term is degraded all-too-frequently in marketing literature today — it does still have a meaning to mastering engineers and it is the basis of Dangerous Music equipment.

By the time we reached the 80’s we saw a growing audio mastering industry, and with more experience under their belts, mastering engineers began to demand more from their equipment.  Along with increased demand for audio mastering, digital recording first appeared in the 80’s, and it was during this time that Dangerous Music co-founder and equipment designer Chris Muth was commissioned by mastering engineer Jack Skinner of The Hit Factory (and formerly Sterling Sound) to build a custom mastering suite to Skinner’s specifications, thus began Muth’s mastering equipment saga.
In 1990 Muth went to work at Sterling Sound for chief technician Brad Johnson as the CD format began really selling as a consumer medium. Working with famed Sterling mastering engineers Ted Jensen, George Marino and Greg Calbi, Muth modified existing mastering gear, which led to designing custom gear for the studio that met the new sonic challenges of dynamic range and reproduction on consumer playback devices by allowing the engineers more refined control over monitoring, routing, level handling, and other innovative ideas never seen in mastering equipment before such as M/S (or Mid/Side) processing. (Click here to read a full description of Mid/Side). With the ears and experience of the Sterling engineers, Muth was able to collaborate to create gear that “sounded really fantastic,” as Muth states today.  After also working at MasterDisc studios, in 1995 Muth began making mastering equipment under his own company name that grew out of all the custom and modified gear he had made for these studios.  Eventually Muth returned to Sterling to create 6 all-new mastering suites, 14 rooms in total, using his Muth designed gear integrated with each engineers’ other equipment; A project that took several years to complete.  Today, the Dangerous Music line of equipment springs from this sonic innovation during this time period, and fulfills the promise of revealing and preserving the highest audio quality.


When a mastering engineer can truly hear what a recording contains – and today that means mostly what the ‘stereo mix’ of the music tracks is — they can make decisions to use their specialized equipment to bring out the best that exists in the mix and balance it so that any playback device (home hi-fi, car, iPod, etc) will offer a fair expression of the music.

In typical audio mastering studios today, a digital mix is played by computer, through a digital-to-analog converter, then to a transfer console which has switches to insert various gear, (EQ, compressors, etc.) into the signal path for mastering treatment. Next the audio goes to the monitor control for listening, and finally the signal is sent to a capture platform (another computer, vinyl lathe, etc) for prep & delivery on the target medium being mastered for.  The mastering engineer must analyze the source signal via his/her ears and other measurement tools at the studio and decide what processing/treatment is required to bring the track to its full potential. That being said, it is imperative to monitor this signal in clinical way, free of any sonic imprint or “color” the gear may impart onto the signal (tubes, etc) before processing.  Obviously ‘color’ can be added at-will with compressors, equalizers and such when inserted into the processing signal path, but key components like the transfer console, DAC, analog summing and monitor control must be transparent to serve the mastering process rather than challenge the engineer with unwanted changes to the source signal that must be mentally compensated for.

Dangerous Music equipment provides this truth in listening. Check out the product pages for a deeper understanding of these products which were designed by mastering engineers, built by hand with top-of-the-line components, and with stepped controls throughout for simple recall and repeatability.