Record Store Day is usually 'the one day each year when over 200 independent record shops all across the UK come together to celebrate their unique culture. Special vinyl releases are made exclusively for the day, in what’s become one of the biggest annual events on the music calendar.' This year, due to COVID-19, Record Store Day is being split across 3 dates: 29th August, 26th September and 24th October.
This Record Store Day, Saturday 29th August 2020, is particularly exciting for Greatbear as it sees the release on Vinyl Revival, Manchester of The High - Martin Hannett Sessions, a restoration and digitisation project we worked on earlier this year.
One of the Martin Hannett session DAT tapes digitised at Greatbear
Martin Hannett - Manchester music producer, known for his era-defining creative work with Buzzcocks, Joy Division, New Order, John Cooper Clarke, The Stone Roses, Happy Mondays and many others - died aged 42 in April 1991.
The tapes we received were DAT (Digital Audio Tape) masters, produced by Hannett at recording sessions with The High in 1989 (at Strawberry Studios) and 1991 (at Great Linford Manor), and included Hannett's last production work before his untimely death.
The High - Martin Hannett session at Strawberry Studios 1989: producer Martin Hannett / Hannett inspecting DAT manual. Stills from footage by Nigel Couzens.
The High - Martin Hannett session at Strawberry Studios 1989: mixing desk / Andy Couzens. Stills from footage by Nigel Couzens.
The High were formed in 1989 by former Turning Blue singer John Matthews and former Buzzcocks F.O.C. members Andy Couzens (guitar, also formerly of The Stone Roses and pre-Roses bands The Patrol and Waterfront), Simon Davies (bass), and drummer Chris Goodwin (also formerly of the Waterfront as well as the Inspiral Carpets). They were signed by London Records and had three UK Singles Chart hits in 1990 before breaking into the top 30 in 1991 with a revamped version of their debut single, the Martin Hannett-produced "Box Set Go".
The High DAT cassette insert card tracks 1-4
The High DAT cassette insert card tracks 5-9
analogue to digital
From the Nigel Couzens footage (see video clip below), it looks like the Strawberry Studios sessions were recorded to 2 inch analogue tape, on a 24 track Studer A80. This was quite an old machine at that time as there would have been the A800 and possibly the A820 available too - but maybe they just loved the sound on the A80.
DAT, introduced by Sony in 1987, became popular in the audio and recording industry for mastering during the 1990s. The initial recordings would be made to 2" (or other width) analogue tape, but the mixed and produced final versions would be recorded to DAT - allowing the benefits of lossless encoding and avoiding the addition of further analogue tape hiss at the mastering stage. This process could be seen as a stepping stone towards an emerging all-digital production chain, and the development of hard disk recording.
fragile tape
At 3.81mm wide and 0.013mm thick, DAT is more fragile than other cassette-based digital tape formats such as DTRS/DA-88, ADAT and PCM digital audio, or any of the reel-to-reel formats (analogue or digital).
This makes it vulnerable to ripping. The High - Martin Hannett Sessions DAT masters arrived at Greatbear with visible signs of mould growth along the edges of the tape. (See the fuzzy white threads along the surface of the tape pack in the pictures above and below.) When this happens, the mould sticks the layers of the tape together - particularly along the edges - which inevitably leads to the tape ripping under the high tension of playback.
A ripped tape is especially problematic because DAT uses a helical scan recording system, based on a miniature video transport, and so cannot be spliced for clean edits. (Splices also risk irreparable damage to heads on the drum of the playback machine.) A ripped DAT tape - the helically-imprinted signal being bisected - results in irreversible signal loss.
Red arrow showing point where a speck of mould caused this DAT to rip. (Not one of The High - Martin Hannett tapes, but one previously brought to Greatbear in this state!)
Disassembly: unscrewing The High DAT cassette shell to access tape inside
restoration
We've found the safest way to restore mould-stricken DAT cassettes to a playable state and avoid ripping is to:
Acclimatise the tape to the controlled temperature and humidity of the Greatbear studio, driving the mould spores to dormancy
Disassemble the cassette shell
Very slowly and carefully unwind and rewind the tape by hand, dislodging the 'sticky' mould
Re-house the spools in a new, clean shell
Digitise via multiple passes, cleaning the DAT machine between plays. For these tapes we used our Sony PCM 7040
Sony ceased production of new DAT machines in 2005, and working, professional machines are becoming rare. We spend a considerable (and usually enjoyable) amount of time and resources keeping our machines in good condition. The Sony PCM 7040 is one of the better DAT machines in terms of the robustness of the tape transport and machine parts availability, as the same transport system was used in many Sony DDS DAT drives used in computer backup.
The High - Martin Hannett Sessions DAT master shell open with white mould visible on surface of tape pack
DAT during manual unwinding, showing mould-induced tendency for tape to stick to itself
The problem of mould growth on DATs is not unique to these precious Hannett / The High recordings.
Most DATs are now between 20 - 30 years old, and it only takes one period of storage at high temperature and/or relative humidity (RH) for mould to set in. To avoid damage, magnetic tape must be stored consistently at levels of 18 - 21 °C, and at 45 - 50% RH - something which no garage, attic or back room can guarantee...
We regularly receive mouldy DATs at the Greatbear studio. So much important material was mastered to DAT in the 1990s, and its vulnerabilities make it a priority for digitisation.
Support your local independent record shop on Record Store Day and every day!
The effects of mould growth on both the integrity of the tape and the recorded sound or image can be significant.
Mould growth often sticks the tape layers in a tightly packed reel together often at one edge. If an affected tape is wound or played this can rip the tape.
DAT audio cassette shell opened to reveal visible mould on edge of tape pack
DVCPRO video cassette lid lifted to show tape split longitudinally
If the mould has damaged the record side of the tape then the magnetic tracks are usually damaged and signal loss will result. This will create audible and visual artefacts that cannot be resolved.
Mould develops on tapes that have been stored in less-than-optimum conditions. Institutional collections can exhibit mould growth if they have not have been stored in a suitable, temperature controlled environment. For magnetic tape collections this is recommended at 15 +/- 3° C and 40% maximum relative humidity, although the British Library's Preservation Advisory Centre suggest 'the necessary conditions for [mould] germination are generally: temperatures of 10-35ºC with optima of 20ºC and above [and] relative humidities greater than 70%.'
For domestic and personal collections the mouldy tapes we receive are often the ones that have been stored in the shed, loft or basement, so be sure to check the condition of anything you think may be at risk.
We do come across cases where mould is not easily visble to the naked eye without dismantling a cassette shell - so unless you can be sure your tape has been kept in optimum storage conditions for its entire 'life', it's better to err on the side of caution. Playing a mould-affected tape in a domestic machine can very easily damage the tape.
It is important to remember that a mouldy tape is a hazard not just for the individual tape. If not handled carefully it can potentially spread to other parts of your collection, so must be treated immediately.
filaments of mould on Hi8 video tape edge
Hi8 tape showing longitudinal tear caused by sticking
There are several stages to our treatment of your mouldy tape.
Firstly, if the mould is still active it has to be driven into dormancy. You will be able to tell if there is active mould on your tape because it will be moist, smudging slightly if it is touched. If the tape is in this condition there is a high risk it will infect other parts of your collection. We strongly advise you to quarantine the tape (and of course wash your hands because active mould is nasty stuff).
When we receive mouldy tape we place it in a sealed bag filled with desiccating silica gel. The silica gel helps to absorb the tape's moisture and de-fertilises the mould's 'living environment'.
When the mould becomes dormant it will appear white and dusty, and is relatively easy to treat at this stage. We use brushes, vacuums with HEPA filters and cleaning solutions such as hydrogen peroxide to clean the tape.
Treatment should be conducted in a controlled environment using the appropriate health protections such as masks and gloves because mould can be very damaging for health.
All machines used to playback mouldy tape are cleaned thoroughly after use - even tapes with dormant mould still carry the risk of infection.
Most tapes-infested with mould are treatable and can be effectively played back following the appropriate treatment procedures. Occasionally mould growth is so extensive however that it damages the binder irreparably. Mould can also exacerbate other problems associated with impaired tape, such as binder hydrolysis.
gently dislodging mould from U-matic video tape
Edge and upper-surface mould causing U-matic video tape to stick
When it comes to tape mould the message is simple: it is a serious problem which poses a significant risk to the integrity of your collection.
If you do find mould on your tapes all is not lost. With careful, specialised treatment the material can be recovered. Action does need to be taken promptly however in order to salvage the tape and prevent the spread of further infection.
Feel free to contact us if you want to talk about your audio or video tapes that may need treatment or assessment.
Established in 2013 and based at the University of Kent’s Special Collections, the BSUCA aims ‘to celebrate, preserve, and provide access to the archives and records of British stand-up comedy and stand-up comedians.’
In 2014 the BSUCA became one of the University of Kent’s 50th anniversary ‘Beacon Projects‘.
Beacon Project funding will support work to ‘catalogue, preserve, digitise, and make accessible the existing collections, and identify new relevant collections.’
We are honoured that project archivist Elspeth Millar took time out of her busy archiving schedule to tell us a bit more about the BSUCA.
She told us:
‘I’m really enjoying the variety of material that I get to work on, including printed material (posters, flyers, letters, notebooks), audio-visual material on a range of formats (audio cassettes, VHS, DAT, MiniDisc, U-matic), and also born-digital records held on obsolete formats (such as 3.5” floppy disks).
In addition the content of the material is, of course, really interesting, and I feel that I am learning a lot from our collections, including about the history of stand-up comedy (from the alternative cabaret movement, to alternative comedy, to the comedy ‘industry’ today) but also political and social topics (for example Mark Thomas’ collection includes a lot of material on the arms trade and large corporations). We are also holding events with some fantastic comedians (Richard Herring, Stewart Lee, Mark Thomas, and at the Edinburgh Festival Fringe, Jo Brand, Alexei Sayle, Susan Calman) so it is wonderful to hear comedians themselves reflecting on their work and on material that they have deposited with the archive.’
You can keep up to date with the latest news from the BSUCA archive on twitter and view images from their collections on flickr.
Read on for more from Elspeth. Her answers cover issues such as selection and appraisal decisions, metadata and dissemination plans for the BSUCA.
They also provide useful insight into the digital preservation tools BSUCA use to manage their digitised and born-digital assets.
Once again, massive thanks to her for responding to our questions and best of luck to BSUCA in the future.
BSCUA Responses to Greatbear Questions
1. What motivated you to get the tapes you sent to us re-formatted now? i.e., what kinds of selection and appraisal processes were behind the decision?
The British Stand-Up Comedy Archive has AV material on a number of audio and moving image formats, magnetic and optical, including audio compact cassettes, MiniDiscs, DATs (Digital Audio Tapes), VHS, DVCams, Audio CD and U-matic tapes. None of these formats are suitable for archival storage and all material will need to be digitised or transferred from their original carrier to digital files. We can carry out the digitisation (or digital transfer) of some audio in-house and we have started our project by transferring material originally captured or stored on MiniDiscs, Audio CDs, and audio compact cassettes1. After assessing all the formats we currently have it was decided to outsource the digitisation of DATs and U-matic tapes. Both of these are priority formats for transfer from a preservation perspective2 and after some research I learnt that DATs can be problematic to transfer due to ‘DAT compatibility’ and dropout problems3. In addition, we have neither a DAT machine or U-matic machine already within Special Collections or within the University, and with the number of recordings on these formats currently limited, it was felt that it would not make sense to purchase already obsolete equipment, which would then need to be professionally maintained.
The other important reason for transferring the tapes of course was for accessibility, so that we can make the recordings accessible to researchers. In addition, our funding is currently only for one year4, so it is vital to ensure that audio-visual material on obsolete formats are transferred during this first phase of the project.
2. Can you tell us how metadata helps you to describe, preserve and aid discovery of the Stand Up Comedy archive.
Providing information about our audiovisual items (and resulting digital items) is incredibly important from both an access and preservation perspective. Metadata about analogue items (and subsequent digital files) and born-digital files will be included in the cataloguing collections management system used by the British Stand-Up Comedy Archive (which is part of the University of Kent’s Special Collections & Archives). The catalogue records will include descriptive metadata and administrative metadata. Metadata which comes under the ‘descriptive metadata’ heading describes the item/file and includes a summary of the contents of the recording, all of which helps to make recordings discoverable for researchers. This metadata is also vital from a preservation perspective as it allows archivists to retrieve and identify files. Metadata which comes under the ‘administrative metadata’ heading provides information to help manage the file(s)/recordings, and includes information related to Intellectual Property Rights (including copyright) and preservation information such as the file format and the digitisation/digital transfer. Researchers will be interested in some of these issues (e.g. copyright, as this determines how archived recordings can be used) but from a digital preservation perspective this metadata is extremely important as it records information about the format of the digital file, information about the original carrier, as well as fixity information, to measure whether the file has changed over time.
This metadata will be recorded in our catalogue and will be searchable via the University of Kent’s website and in the future some archive aggregators. However, we are also experimenting with different processes and tools for embedding metadata in files, and researching different metadata standards for this. The benefits of embedding some metadata within the file include the removal of the risk of losing the link between the metadata and the digital file that it is describing. In addition, metadata embedded in born-digital master and digitised master files can also be transferred to ‘access’ copies (generated at a lower specification/resolution) which will also assist in user accessibility. Embedded metadata has its limitations and it is not that flexible, which is why we are using a dual approach of embedding some metadata, but also keeping this information externally in our catalogue.
3. How do you manage, and plan to manage digital audio and audio visual materials in the Stand Up Archive? What digital preservation tools do you use?
The first process in managing digital AV materials in the BSUCA is to think about the file formats that we will use for long-term preservation and access. For audio material we are digitising as LPCM (Linear Pulse Code Modulation) in a Wave format (.wav) wrapper. The addition of embedding metadata into these wave files extends the file to become BWF .wav files, the standard recommended by the International Association of Audiovisual Archives (IASA).5
Deciding upon a file format for digitising moving image has been trickier, as the Greatbear team have already written about on this blog; we hope to get underway with digitisation of VHS in September and we are looking at using the FFv1 codec (an open-source lossless compressed codec) wrapped as either AVI or Matroska (MKV).
We are also experimenting with a number of digital preservation tools; one directory that has proved great for discovering such tools is the COPTR wiki (Community Owned digital Preservation Tool Registry), a really useful collated list of various digital preservation tools . One aspect of our digital preservation planning is the creation of checksums as early in the lifecycle of the digital file as possible. We are using a tool called Blackbush, which is a checksum tool6 which generates MD5 hash files which was developed for the British Library’s Sound Archive. To embed metadata into .wav files we are using the BWF MetaEdit tool, a free open-source tool developed by AV Preserve and the Federal Agencies Digitization Guidelines Initiative. When our archival master is a compressed format (such as an mp3 on a data or audio CD which has been deposited), we are using tools such as Adobe Bridge to embed metadata in the ID3 format (or Adobe Audition’s metadata tools as we transfer audio). The advantage of BWF MetaEdit for wav files is that it is a free open-source tool, which also has other functions such as batch editing (we can edit multiple wav files at once) and batch import and export functions, which will be useful for when we catalogue this material to item level.
Other tools that we have found useful include DROID (Digital Record Object Identification), developed by The National Archives, and, for other digital material we are using forensic imaging tools such as FTK Imager and ImDisk to mount virtual images of disk images.
4. How do you think the material will be used by future researchers? As a Stand Up Archive I imagine you get a lot of requests for material from broadcasters. How do you manage requests and expectations from different user communities?
The British Stand-Up Comedy Archive is still in its infancy; although we have had material since 2013, it has only been since the beginning of this year that we have been funded to digitise and preserve the material already deposited, start to catalogue it, make it accessible, and publicise what we have and what we are aiming to do.
But two of our core purposes are to ensure access (that these archives are universally discoverable and accessible), and to ensure that the archives are used, and used in a variety of ways (popular culture, academic research, teaching, journalism, general enjoyment). Our main user group at the moment is actually students studying stand-up and popular performance at the University of Kent (at BA and MA level) who have used AV material as part of their course, and we also have a number volunteering with the project, doing summaries of recorded interviews and stand-up performances.
Notes
[1] We have purchased an audio cassette deck (Denon DN-790R) and are using a MiniDisc deck on loan from colleagues within the University, and have also purchased an external audio capture card/A-D converter.
[2] https://psap.library.illinois.edu/format-id-guide/audiotape#dat and https://psap.library.illinois.edu/format-id-guide/videotape#umatic.
[3] https://siarchives.si.edu/sites/default/files/pdfs/digitalAudioTapesPreservation2010_0.pdf (page 5-8) and http://thegreatbear.co.uk/audio-tape/transferring-dats-to-digital-files/.
[4] The British Stand-Up Comedy Archive is part of the University of Kent’s Special Collections and Archives, but it currently has specific funding for one year (as a Beacon Project) to digitise and make accessible its current holdings; more about the Beacon projects can be found at http://www.kent.ac.uk/beacon/about.html.
[5] Guidelines on the Production and Preservation of Digital Audio Objects, IASA-TC 04, 2.8.2
[6] A checksum is ‘an algorithmically-computed numeric value for a file or a set of files used to validate the state and content of the file for the purpose of detecting accidental errors that may have been introduced during its transmission or storage. The integrity of the data can be checked at any later time by recomputing the checksum and comparing it with the stored one. If the checksums match, the data was almost certainly not altered’. National Digital Stewardship Alliance Glossary, http://www.digitalpreservation.gov/ndsa/ndsa-glossary.html.
While this is by no means a final figure (and does not include the holdings of record companies and DATheads), it does suggest there is a significant amount of audio recorded on this obsolete format which, under certain conditions, is subject to catastrophic signal loss.
The conditions we are referring to is that old foe of magnetic tape: mould.
In contrast with existing research about threats to DAT, which emphasise how the format is threatened by ‘known playback problems that are typically related to mechanical alignment’, the biggest challenges we consistently face with DATs is connected to mould.
It is certainly acknowledged that ‘environmental conditions, especially heat, dust, and humidity, may also affect cassettes.’
Nevertheless, the specific ways mould growth compromise the very possibility of successfully playing back a DAT tape have not yet been fully explored. This in turn shapes the kinds of preservation advice offered about the format.
What follows is an attempt to outline the problem of mould growth on DATs which, even in minimal form, can pretty much guarantee the loss of several seconds of recording.
Tape width issues
The first problem with DATs is that they are 4mm wide, and very thin in comparison to other forms of magnetic tape.
The size of the tape is compounded by the helical method used in the format, which records the signal as a diagonal stripe across the tape. Because tracks are written onto the tape at an angle, if the tape splits it is not a neat split that can be easily spliced together.
The only way to deal with splits is to wind the tape back on to the tape transport or use leader tape to stick the tape back together at the breaking point.
Either way, you are guaranteed to lose a section of the tape because the helical scan has imprinted the recorded signal at a sharp, diagonal angle. If a DAT tape splits, in other words, it cuts through the diagonal signal, and because it is digital rather than analogue audio, this results in irreversible signal loss.
And why does the tape split? Because of the mould!
If you play back a DAT displaying signs of dormant mould-growth it is pretty much guaranteed to split in a horrible way. The tape therefore needs to be disassembled and wound by hand. This means you can spend a lot of time restoring DATs to a playable condition.
Rewinding by hand is however not 100% fool-proof, and this really highlights the challenges of working with mouldy DAT tape.
Often mould on DATs is visible on the edge of the tape pack because the tape has been so tightly wound it doesn’t spread to the full tape surface.
In most cases with magnetic tape, mould on the edge is good news because it means it has not spread and infected the whole of the tape. Not so with DAT.
Even with tiny bits of mould on the edge of the tape there is enough to stick it to the next bit of tape as it is rewound.
When greater tension is applied in an attempt to release the mould, due to stickiness, the tape rips.
A possible and plausible explanation for DAT tape ripping is that due to the width and thinness of the tape the mould is structurally stronger than the tape itself, making it easier for the mould growth to stick together.
When tape is thicker, for example with a 1/4 ” open reel tape, it is easier to brush off the dormant mould which is why we don’t see the ripping problem with all kinds of tape.
Our experience confirms that brushing off dormant mould is not always possible with DATs which, despite best efforts, can literally peel apart because of sticky mould.
What, then, is to be done to ensure that the 3353 (and counting) DAT tapes in existence remain in a playable condition?
One tangible form of action is to check that your DATs are stored at the appropriate temperature (40–54°F [4.5–12°C]) so that no mould growth develops on the tape pack.
The other thing to do is simple: get your DAT recordings reformatted as soon as possible.
While we want to highlight the often overlooked issue of mould growth on DATs, the problems with machine obsolescence, a lack of tape head hours and mechanical alignment problems remain very real threats to successful transfer of this format.
Our aim at the Greatbear is to continue our research in the area of DAT mould growth and publish it as we learn more.
As ever, we’d love to hear about your experiences of transferring mouldy DATs, so please leave a comment below if you have a story to share.
At Greatbear, we carefully restore and transfer to digital file all types of content recorded to Digital Audio Tape (DAT), and can support all sample rate and bit depth variations.
This post focuses on some of the problems that can arise with the transfer of DATs.
Indeed, at a meeting of audio archivists held in 1995, there was a consensus even then that DAT was not, and would never be, a reliable archival medium. One participant stated: ‘we have tapes from 1949 that sound wonderful,’ and ‘we have tapes from 1989 that are shot to hell.’ And that was nearly twenty years ago! What chances do the tapes have now?
A little DAT history
Before we explore that, let’s have a little DAT history.
SONY introduced Digital Audio Tapes (DATs) in 1987. At roughly half the size of an analogue cassette tape, DAT has the ability to record at higher, equal or lower sampling rates than a CD (48, 44.1 or 32 kHz sampling rate respectively) at 16 bit quantization.
Although popular in Japan, DATs were never widely adopted by the majority of consumer market because they were more expensive than their analogue counterparts. They were however embraced in professional recording contexts, and in particular for recording live sound.
It was recording industry paranoia, particularly in the US, that really sealed the fate of the format. With its threatening promise of perfect replication, DAT tapes were subject to an unsuccessful lobbying campaign by the Recording Industry Association of America (RIAA). RIAA saw DATs as the ultimate attack on copyright law and pressed to introduce the Digital Audio Recorder Copycode Act of 1987.
This law recommended that each DAT machine had a ‘copycode’ chip installed that could detect whether prerecorded copyrighted music was being replicated. The method employed a notch filter that would subtly distort the quality of the copied recording, thus sabotaging acts of piracy tacitly enabled by the DAT medium. The law was however not passed, and compromises were made, although the US Audio Home Recording Act of 1992 imposed taxes on DAT machines and blank media.
How did they do ‘dat?
Like video tape recorders, DAT tapes use a rotating head and helical scan method to record data. The helical scan can, however, pose real problems for the preservation transfers of DAT tapes because it makes it difficult to splice the tape together if it becomes sticky and snaps during the tape wind. With analogue audiotape, which records information longitudinally, it is far more possible to splice the tape together and continue the transfer without risking irrevocable information loss.
Another problem posed by the helical scan method is that such tapes are more vulnerable to tape pack and backing deformation, as the CLIR guide explain:
‘Tracks are recorded diagonally on a helical scan tape at small scan angles. When the dimensions of the backing change disproportionately, the track angle will change for a helical scan recording. The scan angle for the record/playback head is fixed. If the angle that the recorded tracks make to the edge of the tape do not correspond with the scan angle of the head, mistracking and information loss can occur.’
When error correction can’t correct anymore
Most people will be familiar with the sound of digital audio dropouts even if they don’t know the science behind them. You will know them most probably as those horrible clicking noises produced when the error correction technology on CDs stops working. The clicks indicate that the ‘threshold of intelligibility’ for digital data has been breached and, as theorist Jonathan Sterne reminds us, ‘once their decay becomes palpable, the file is rendered entirely unreadable.’
Our SONY PCM 7030 professional DAT machine, pictured opposite, has a ‘playback condition’ light that flashes if an error is present. On sections of the tape where quality is really bad the ‘mute’ light can flash to indicate that the error correction technology can’t fix the problem. In such cases drop outs are very audible. Most DAT machines did not have such a facility however, and you only knew there was a problem when you heard the glitchy-clickety-crackle during playback when, of course, it was too late do anything about it.
The bad news for people with large, yet to be migrated DAT archives is that the format is ‘particularly susceptible to dropout. Digital audio dropout is caused by a non-uniform magnetic surface, or a malfunctioning tape deck. However, because the magnetically recorded information is in binary code, it results in a momentary loss of data and can produce a loud transient click or worse, muted audio, if the error correction scheme in the playback equipment cannot correct the error,’ the wonderfully informative A/V Artifact Atlas explains.
Given the high density nature of digital recordings on narrow magnetic tape, even the smallest speck of dust can cause digital audio dropouts. Such errors can be very difficult to eliminate. Cleaning playback heads and re-transferring is an option, but if the dropout was recorded at the source or the surface of tape is damaged, then the only way to treat irregularities is through applying audio restoration technologies, which may present a problem if you are concerned with maintaining the authenticity of the original recording.
Listen to this example of what a faulty DAT sounds like
Play back problems and mouldy DATs
Mould growth on the surface of DAT tape
A big problem with DAT transfers is actually being able to play back the tapes, or what is known in the business as ‘DAT compatibility.’ In an ideal world, to get the most perfect transfer you would play back a tape on the same machine that it was originally recorded on. The chances of doing this are of course pretty slim. While you can play your average audio cassette tape on pretty much any tape machine, the same cannot be said for DAT tapes. Often recordings were made on misaligned machines. The only solution for playback is, Richard Hess suggests, to mis-adjust a working machine to match the alignment of the recording on the tape.
As with any archival collection, if it is not stored in appropriate conditions then mould growth can develop. As mentioned above, DAT tapes are roughly half the size of the common audiocassette and the tape is thin and narrow. This makes them difficult to clean because they are mechanically fragile. Adapting a machine specifically for the purposes of cleaning, as we have done with our Studer machine, would be the most ideal solution. There is, however, not a massive amount of research and information about restoring mouldy DATs available online even though we are seeing more and more DAT tapes exhibiting this problem.
As with much of the work we do, the recommendation is to migrate your collections to digital files as soon as possible. But often it is a matter of priorities and budgets. From a technical point of view, DATs are a particularly vulnerable format. Machine obsolescence means that compared to their analogue counterparts, professional DAT machines will be increasingly hard to service in the long term. As detailed above, glitchy dropouts are almost inevitable given the sensitivity and all or nothing quality of digital data recorded on magnetic tape.
It seems fair to say that despite being meant to supersede analogue formats, DATs are far more likely to drop out of recorded sound history in a clinical and abrupt manner.
They therefore should be a high priority when decisions are made about which formats in your collection should be migrated to digital files immediately, over and above those that can wait just a little bit longer.
Bristol Archive Records is more than a record label. It releases music, books and through its website, documents the history of Bristol’s punk and reggae scenes from 1977 onwards. You can get lost for hours trawling through the scans of rare zines and photographs, profiles of record labels, bands, discographies and gig lists. Its a huge amount of work that keeps on expanding as more tapes are found, lurking in basements or at that unforeseen place at the back of the wardrobe.
Greatbear has the privilege of being the go-to digitisation service for Bristol Archive Records, and many of the albums that grace the record store shelves of Bristol and beyond found their second digital life in the Greatbear Studio.
The tapes that Mike Darby has given us to digitise include ¼ inch studio master tapes, ½ inch 8 track multi-track tapes, audio cassettes, DAT recordings and Betamax digital audio recordings. The recordings were mostly made at home or in small commercial studios, often they were not stored in the best conditions. Some are demos, or other material which has never been released before. Many were recorded on Ampex tape, and therefore needed to be baked before they were played back, and we also had to deal with other physical problems with the tape, such as mould, but they have all, thankfully, been fixable.
After transfers we supply high quality WAV files as individual tracks or ‘stems’ to label manager Mike Darby, which are then re-mastered before they are released on CD, vinyl or downloads.
Bristol Archive Records have done an amazing job ensuring the cultural history of Bristol’s music scenes are not forgotten. As Mike explains in an interview on Stamp the Wax:
‘I’m trying to give a bit of respect to any individual that played in any band that we can find any music from. However famous or successful they were is irrelevant. For me it’s about acknowledging their existence. It’s not saying they were brilliant, some of it was not very good at all, but it’s about them having their two seconds of “I was in that scene”.’
While Darby admits in the interview that Bristol Archive Records is not exactly a money spinner, the cultural value of these recordings are immeasurable. We are delighted to be part of the wider project and hope that these rare tapes continue to be found so that contemporary audiences can enjoy the musical legacies of Bristol.
Early tape based digital formats such as DAT, Tascam DTRS and ADAT, etc are often problematic now, partly with tape issues and also reliability and spares availability. In 20 or even 10 years time these machines will be much less serviceable than the analogue tape machines of the previous generation and as a result more obsolete and a higher priority to migrate to a file based digital format.
We’ve also started to see a particularly nasty problem with some, and usually the 120 minute length, DATs. The first symptoms are a broken DAT tape usually on wind. The tape pack seems to become slightly sticky, with intermittent tension between the layers of tape and with the thinner tape in 120 lengths this can sometimes break the tape on wind.
You can see in the above image how the tape sticks slightly to the pack and then releases when hand wound. With the greater tension of a machine wind and the tape also wound around the head drum this becomes risky.
With large transfer jobs checking each DAT by disassembly is a mammoth task, but the permanent damage and / or part loss of a section of audio caused by a break is not feasible either!
We often get sent Digital Audio Tapes or DATs for transfer to .WAV computer files. As these recordings are already digital or ‘born digital’ the process should be straightforward. Our audio interface cards accept the SPDIF or AES digital audio stream from the DAT machine and record this as a WAV or BWAV file. This file can then be burnt as a CD or delivered digitally on a hard drive or removable media.
The big problems though come with the tape that these digital recordings are made on. The tape is only 3.81 mm wide and moves at a very slow 8.15 mm/sec. The tape is also very thin at 13 microns. The recording system and transport used is helical scan just like in video recording but with the very slow tape speed and small tape dimensions any defects or problems with the tape can result in many errors which may not be correctable by the error-correcting system of the DAT machine.
One problem we’re starting to see more and more are tapes that snap. The tape pictured above was a D120 which was never recommended by the DAT machine manufacturers but was still often used for its extended recording time. This tape snapped without warning a quarter of the way through the recording. There were no outward signs or potential problems just a sudden clean break on a diagonal.
To recover this tape it could have been spliced with splicing tape of the correct width like in analogue recording but there is a high risk if not done perfectly of irreparable damage to heads on the drum. Even with this type of repair some of the material would have been lost. A safer solution is to rehouse each spool in another shell. This lets you recover as much as possible from the tape, without the risk of head damage.
Whichever solution you decide, the DAT shell must be disassembled. A small crosshead screwdriver needs to be used to remove all the case screws. There are two hidden ones, accessed by sliding part of the cassette shell down:
You can now carefully lift both halves of the DAT shell apart, making a note of the tape path inside the shell. Be careful not to touch the tape with your bare skin as fingermarks and grease can cause head to tape contact problems and audio errors and dropouts.
We have several of these large, wonderful machines. It’s not often we need or want to get involved in DAT machine repair as generally they are not easy to service machines and many key transport parts are becoming unavailable. The Sony 7030 DAT though has been designed with easy servicing in mind. There’s alot of room in these things and each section is clearly marked and separated into distinct boards much like Sony Broadcast video machines.
These are timecode DAT machines and were once common in video post production houses and the more well funded recording studios. The problem with some of this well built kit though is exactly that it works too well and gets left on for long periods through it’s life and this can take a toll on certain components, especially electrolytic capacitors. Heat builds up in electronic circuits, especially in switch mode power supplies that larger broadcast items often use. Capacitors have a rated life at 85°C or 105°C at several thousand hours. With hotter environments, substandard parts and long operating hours these capacitors can soon outlive their original design life.
Our 7030 DAT had started behaving oddly and at first the display would flash on and off after a short while powered on. Another machine would power up for 30 secs then just die. Before delving into the enormous service volumes it’s always worth replacing the Switch Mode Power Supplies (SMPS). These like many broadcast machines use supplies that are sometimes generic made by other companies and which can be bought at Farnell or RS. We did it the harder way and desoldered all the old capacitors in the power supply and replaced these with high quality low ESR Panasonic ones which should give us another 6000 hours of running time. So far this machine has worked perfectly although you do need good soldering and desoldering technique on these boards. A powered air desoldering station is a good idea, much, much better than a hand solder pump.
