ATR Magnetics announces Spring Calibration and Alignment Seminars.
Topics cover: theory of magnetic recording, mechanical and electronic calibration of machines (tape operating level, speed, azimuth, zenith, head wrap, bias and equalization adjustments), choosing tape formulations, media care and storage and trouble-shooting and maintenance issues.
Planned dates for 2013 seminars are:
Friday, March 22nd,2013,
9:30 – 5:00
Friday, April 26th,2013,
9:30 – 5:00
Friday, May 3rd, 2013,
9:30 – 5:00
Cost per day is $250, with discounts available for ATR customers. See details at http://www.atrtape.com/ and http://www.atrservice.com
A couple of interesting papers about analog audio recordings preservation by digitization:
- Capturing Analog Sound for Digital Preservation: Report of a Roundtable Discussion of Best Practices for Transferring Analog Discs and Tapes (click here to download the pdf hosted by The Council on Library and Information Resources)
- Sound Directions: Best Practices for Audio Preservation (click here to download the pdf hosted by the Indiana University)
Shelves of vinyl records (Photo credit: NFSA Australia)
Superior sonic quality of tape and ease of editing of (digital audio on) DAWs make a nice pair. A rather common strategy is to take advantage of both media during music production: record on tape and transfer later to DAW of editing and/or edit on DAW and later mixdown to tape.
A more flexible solution consists in inserting a tape machine in the signal path by recording on tape and immediately playing the signal back to the DAW, in realtime. The tape deck may be fed by live inputs or send/returns on the DAW/mixer.
A major problem of this procedure is that the output from the tape machine is delayed (see part4 about tape delays) due to the distance between the rec head and the playback head.
The following video in two parts (by Brad McGowan and Ken Mahru of Little Red Wagon Studios) shows how to time-align the delayed signal by using a latency delay plugin and DAW’s latency compensation.
Tape loops as featured in part 2 and part 3 involve a “record once – playback forever” process, for use as rhythm generators or polyphonic instruments. Those would be signal sources.
What about using tape as part of a signal processor instead, by feeding a live signal to the tape loop while it’s playing?
Placing a recording head and one (or more) playback head displaced along the tape path implies a delay due to tape travelling from one head to the other. The delay duration changes when changing tape speed.
That’s how a tape echo device works, here is an example showing a Roland RE-201.
The tape echo effect isn’t limited to dedicated devices. It can be obtained on most reel to reel decks too (depending on the head pack). While tape echo devices always use loops, a reel to reel can be used as a delay by loading a loop or a normal tape reel (it makes no difference). Here is a demonstration of usage of a deck as an effect.
We are apparently still off-track regarding the original post topic (audio editing) however we’re here for a good reason: head displacement, while being an advantage for the purpose of obtaining delay effects, is a problem when coupling a tape deck with DAW for advanced multitrack editing. In this case the delay is called latency, and is undesired.
Next post will address this problem and solutions.
What I like most when journeying for fun is to temporarily abandon the main route to explore something that catches my attention along the track. While tape audio editing is the main topic of this multi-part post, there’s something I’d like to discuss for a moment.
We talked about stutter-editing (in part 1) and looping (in part 2), two techniques that remind the use of digital samplers. Now the question is: is there any point of contact between such different technologies as analog tape machines and digital samplers?
The answer is, yes, analog samplers. Here is a video about a drum machine based on tape loops. The device is monophonic, having a single magnetic head that the operator can manually move from one loop to another.
A more advanced device, used in albums by Beatles and Pink Floyd, is the Mellotron. This is a polyphonic device, having a magnetic head for each individual tape loop. Here is a vintage demo video presenting the Mellotron.
This video captures a maintenance procedure allowing to see the internal tape pack. Tapes are visible side by side, mounted on a frame. Each individual tape corresponds to a key on the keyboard, and to its dedicated magnetic head.
As seen in part 1 (posted here), inertia inherent to mechanical parts of a tape machine prevents seamless playback of audio fragments scattered along the tape. A solution to this problem involves physically cutting tape and joining splices to create a new sequence as required.
A similar problem, and solution, occur when trying to seamlessly repeat an audio segment multiple times, a technique called “playing a loop”. Usually a loop requires accurate alignment of its boundaries, in order to create a correct rhythmic pattern or anyway a continuous texture.
With a reel-to-reel machine, this is again a matter of razor blades and sticky tape.
Here is how to make a tape loop with analog tape, recreating in this tutorial the intro of the song “Money” from the album “The Dark Side of the Moon” (Pink Floyd, 1973).
Now back to the Sixties. Here lovely Delia Derbyshire, at the BBC Radiophonic Workshop, shows how to layer multiple loops by tapping transport buttons on the beat. Amazing.
A brief journey in audio editing history, from razor blades to DAW integration, in multiple parts. Instead of typing long boring text, I decided to compile a selection of video material available courtesy of YouTube.
Let’s start from a fact..
Tape being a linear medium is unable to seamless playback parts of a recording in random order due to inertia of mechanical components in the playback device.
Overcoming this problem involves cutting tape in segments, rearranging their order as intended, then attaching the parts together. Here is a video demonstrating this classic technique.
The degree of accuracy made possible by hand-cutting is impressive, compared to alternatives such as using an extra deck, set in record mode, to copy splices sequences using punch in/out.
Here is a terrific example from the 80’s. At the time, stu-stu-stuttering effects were becoming common in some commercial music genres , also due to the introduction of early digital samplers (Paul Hardcastle’s hit “19” comes to mind).
Checkout the amazing synchronization starting around 2.55 in this video.
A strongly recommended technical reading, the book Manual of Analogue Restoration Techniques by Peter Copeland is provided by the British Library as a freely downloadable resource.
Recorders at the British Library
Peter Copeland, after a career at the BBC as a sound engineer since 1961, worked as Conservation Manager at the British Library Sound Archive from 1986 until his retirement in 2002. Peter died in 2006 after a lifetime dedicated to understanding the history and complexity of analogue audio technology.
The British Library makes the book available as a downloadable pdf on their site on this page.
Direct download, at British Library site, here.