PCM audio on video tape

PCM digital audio recordings on Betamax, VHS or U-matic video tape.
rectangular, dark grey, plastic video cassette

Sony Beta video cassette

introduction to PCM audio on video tape transfer

Developed in the late 1970s, PCM (pulse code modulation) digital audio harnessed the larger bandwidth of video tape technology to record digital audio signals. PCM digital audio was widely used until the introduction of Digital Audio Tape (DAT) in 1987.

At Greatbear, we carefully restore and digitise all variations of PCM audio recorded on Betamax, VHS or U-matic video tape.

We offer a range of delivery formats for our audio transfers. We use the International Association of Sound & Audiovisual Archives Guidelines on the Production and Preservation of Digital Audio Objects, delivering 24-bit/96kHz Broadcast WAV files, together with mp3 audio file or audio CD listening versions. We're happy to create any other digital audio files, according to your needs.

We can provide the appropriately-sized usb media for your files, or use media supplied by you, or deliver your files online. Files delivered on hard drive can be for any operating system MacOS, Windows or GNU/Linux and filesystems (HFS+, NTFS or EXT3).

Due to varying tape durations and extent of physical tape degradation, it’s not always appropriate to create fixed prices for our services. We’ve found that assessing tapes prior to confirming costs a more accurate and fair method.

We offer free assessments please contact us to discuss your project.

machines for PCM audio

Many valuable audio recordings were made on video tape either as a standard video soundtrack in mono or stereo or using the higher quality FM recording system. Having extensive racks of video machines allows us to save these recordings. We use the Sony PCM-701ES for PAL / SECAM recordings and the Nakamichi DMP-100 for NTSC recordings.

 

PCM audio on video tape format variation

 Sony PCM 1600 series recordings supportedSony PCM F1 series recordings supportedAES digital transfer supportedanalogue transfer supportedrecordings on U-matic or VHS tape supportedrecordings on Video8 8mm tape supported
projects recorded with PAL equipment
projects recorded with NTSC equipment

 

close up of cassette shell window and part of label with text: BASF chromdioxid super, Raider (Master)

BASF L500 Beta tape used for audio mastering

3 rack-based machines. Top labelled: Digital Audio + Design, Professional - CTC. Middle: 7 system. Bottom: Betamax with green PAL button lit

Sony PCM-701ES, Sony SL-700ME & Sony SL-T50ME machines

Rectangular, dark grey, plastic video cassette with rulers showing width 15.6cm and height 9.6 cm

Betamax cassette dimensions: 15.6 × 9.6 × 2.5 cm (6​1⁄7 × 3​3⁄4 × 1 inch)

PCM audio on video tape risks & vulnerabilities

Given that PCM audio recordings all use video tape the same issues that can happen to video tape, in particular VHS and umatic also can happen to PCM audio recordings. Often these issues to degradation can be more pronounced as back-coated, high-quality tape was used and these tend to suffer from issues like Sticky Shed Syndrome more often.

  • Given the age of U-matic tape, and its widespread use over the years, it can and does degrade. Certain brands such as Ampex 187 and 197 suffer from binder hydrolysis and need 'baking' before it's safe to replay these.
  • Mould can grow on the unflanged edges of the tape pack and will stick the layers of tape together, needing treatment and manual unwinding, and usually re-shelling.
  • The clear leader at the beginning of each tape can become separated from the rest of the tape as the glue in the splicing tape dries up. The process of unwinding and rewinding tape can cause / exacerbate the problem.
  • Some early Sony brands can degrade in a way where the RF (radio frequency) off tape is very low in level causing severe visual artefacts. Tapes like this often have a distinctive smell of wax crayons

 

 

PCM audio on video tape history

We are now used to living in a born-digital environment, but the transition from analogue to digital technologies did not happen overnight. In the late 1970s, early digital audio recordings were made possible by a hybrid analogue/digital system. It was composed of the humble transport and recording mechanisms of the video tape machine, and a not so humble PCM (pulse code modulation) digital processor. Together they created the first two-channel stereo digital recording system.

Read about the history of its development in our tape blog: Early digital tape recordings on PCM/ U-matic and Betamax video tape