Posts Tagged ‘repair’

Audio Cassette Parallel Ingests

Monday, July 27th, 2015

The scale of digitisation jobs we do at Great Bear often varies. We are asked by our customers to reformat single items to large quantities of tape and everything else inbetween.

Reformatting magnetic tape-based media always takes time and care.

Transfers have to be done in real time; if you want a good quality recording there is no way to reformat tape-based media quickly.

Some jobs are so big, however, that you need to find ways of speeding up the process. This is known as a parallel ingest – when you transfer a batch of tapes at the same time.

Realistically, parallel ingest is not possible with all formats.

An obvious issue is machine scarcity. To playback tapes at the same time you need multiple playback machines that are in fairly good condition. This becomes difficult with rarer formats like early digital video tape, such as D1 or D2, where you are extremely lucky if you have two machines working at any given time.

Audio Cassettes

Audio cassette tapes are one of few formats where archival standard parallel ingest is possible if tapes are in good condition and the equipment is working well.

Stack of professional tape machines, including Marantz PMD 502 and Tascam 322

Great Bear Parallel Ingest Stack

We were recently approached by Jim Shields of the Zion, Sovereign Grace Baptists Church in Glasgow to do a large scale transfer of 5000 audio cassettes and over 100 open reels.

Jim explains that these ‘tapes represent the ministry of Pastor Jack Glass, who was the founder of Zion, Sovereign Grace Baptists Church, located at Calder St.Polmadie, Glasgow. The church was founded in 1965. All early recordings are on reel but the audio tapes represent his ministry dating from the beginning of 1977 through to the end of 2003. The Pastor passed away on the 24th Feb 2004 [you can read obituaries here and here]. It is estimated there are in the region of 5,000 ministry tapes varying in length from 60 mins to 120 mins, with many of the sermons being across 2 tapes as the Pastor’s messages tended to be in the region of 90 minutes plus.’

Sermons were recorded using ‘semi domestic to professional cassette decks. From late Sept 1990 a TEAC X-2000 reel recorder was used [to make master copies] on 10 inch reels then transposed onto various length cassettes [when ordered by people]’ chief recordist Mike Hawkins explains.

Although audio cassettes were a common consumer format it is still possible to get high quality digital transfers from them, even when transferred en masse. Recordings of speech, particularly of male voices which have a lower frequency range, are easier to manage.

Hugh Robjohns, writing in 1997 for the audio technology magazine Sound on Sound, explains that lower frequency recordings are mechanically more compatible with the chemical composition of magnetic tape: ‘high-frequency signals tend to be retained by the top surface of the magnetic layer, whilst lower-frequency components tend to be recorded throughout its full depth. This has a bearing on the requirements of the recording heads and the longevity of recordings.'[1]

Preparation

In order to manage a large scale job we had to increase our operational capacity.

We acquired several professional quality cassette machines with auto reverse functions, such as the Marantz PMD 502 and the Tascam 322.

Although these were the high end audio cassette recorders of their time, we found that important components, such as the tape transport which is ‘critical to the performance of the entire tape recorder'[2], were in poor shape across all the models. Pitch and timing errors, or wow (low speed variations) and flutter (high speed variations), were frequently evident during test playbacks.

Because of irregular machine specifications, a lot of time was spent going through all the tape decks ensuring they were working in a standardised manner.

In some cases it was necessary to rebuild the tape transport using spares or even buying a new tape transport. Both of these restoration methods will become increasingly difficult in years to come as parts become more and more scarce.

Assessing the options

There are certainly good reasons to do parallel ingests if you have a large collection of tapes. Nevertheless it is important to go into large scale transfers with your eyes open.

There is no quick fix and there are only so many hours in the working day to do the transfers, even if you do have eight tapes playing back simultaneously.

To assess the viability of a large scale parallel ingest you may want to consider the following issues: condition of tapes, how they were originally recorded and the material stored on them.

It may well be that parts of your collection can be reformatted via parallel ingest, but other elements need to be selected for more specialist attention.

As ever we can help with discussing the options so do contact us if you want some specific advice.

Notes

[1] The gendered implications of this statement are briefly worth reflecting on here. Robjohns suggests that voices which command the higher frequencies, i.e., female or feminine voices, are apparently incompatible with the chemical composition of magnetic tape. If higher frequencies are retained by the top layer of magnetic tape only, but do not penetrate its full depth, does this make high frequencies more vulnerable in a preservation context because they never were never substantially captured in the first place? What does this say about how technical conditions, whose design has often been authored by people with low frequency voices (i.e., men), privilege the transmission of particular frequencies over others, at least in terms of ‘depth’?

[2] Hugh Robjohns ‘Analogue Tape Recorders: Exploration’ Sound on Sound, May 1997. Available: http://www.soundonsound.com/sos/1997_articles/may97/analysinganalogue.html.

*** Many thanks to Jim Shields, Martyn Glass and Mike Hawkins for sharing their tape stories***

Digitising Shedding Magnetic Multi-track Tape & the history of John Peel favourites BOB

Wednesday, November 13th, 2013

An important part of digitisation work we do is tape restoration. Often customers send us tape that have been stored in less than ideal conditions that are either too hot, cold or damp, which can lead to degradation.

In the excellent Council on Library and Information Sources’ report on Magnetic Storage and Handling (1995), they set the ideal archival storage conditions for magnetic tape at ‘significantly lower than room ambient (as low as 5 centrigade)’, with no less than 4 degrees variation in temperature at 20% room humidity. They suggest that ‘the conditions are specifically designed to reduce the rate of media deterioration through a lowering of the temperature and humidity content of the media.’

8 Track Headshot 1

Of course most people do not have access to such temperature controlled environments, or are necessarily thinking about the future when they store their tape at home. Sometimes manufacturers recommended to store tape in a ‘cool, dark place’, but often tape is not adorned with any such advice. This leads to us receiving a lot of damaged tape!

As we are keen to emphasise to customers, it is possible to salvage most recordings made on magnetic analogue tape that appear to be seriously damaged, it just requires a lot more time and attention.

For example, we were recently sent a collection of 3” multi-track tapes that had been stored in fairly bad conditions. Nearly all the tapes were degraded and needed to be treated. A significant number of these tapes were AMPEX so were suffering from binder hydrolysis, a.k.a. sticky shed syndrome in the digitisation world. This is a chemical process where binder polymers used in magnetic tape constructions become fragmented because the tape has absorbed water from its immediate environment. When this happens tapes become sticky and sheds when it is played back.

Baking the AMPEX tapes is a temporary treatment for binder hydrolysis, and after baking they need to be migrated to digital format as soon as possible (no more than two weeks is recommended). Baking is by no means a universal treatment for all tapes – sticky shed occurs due to the specific chemicals AMPEX used in their magnetic tape.

Cleaning shedding tape

Other problems occur that require different kinds of treatment. For example, some of the 3” collection weren’t suffering from sticky shed syndrome but were still shedding. We were forewarned by notes on the box:

Shedder

The tapes recorded on TDK were particularly bad, largely because of poor storage conditions. There was so much loose binder on these tapes that they needed cleaning 5 or 6 times before we could get a good playback.

We use an adapted Studer A 80 solely for cleaning purposes. Tape is carefully wound and rewound and interlining curtain fabric is used to clean each section of the tape. The photo below demonstrates the extent of the tape shedding, both by the dirty marks on fabric, and the amount we have used to clean the collection.

Studer A 80

You might think rigorous cleaning risks severely damaging the quality of the tape, but it is surprising how clear all the tapes have sounded on playback. The simple truth is, the only way to deal with dry shedding is to apply such treatment because it simply won’t be able to playback clearly through the machine if it is dirty.

Loss of lubricant

Another problem we have dealt with has been the loss of lubricant in the tape binder. Tape binder is made up of a number of chemicals that include lubricant reservoirs, polymers and magnetic particles.

Dirty Cloth

Lubricants are normally added to the binder to reduce the friction of the magnetic topcoat layer of the tape. Over time, the level of the lubricant decreases because it is worn down every time the tape is played, potentially leading to tape seizures in the transport device due to high friction.

In such circumstances it is necessary to carefully re-lubricate the tape to ensure that it can run smoothly past the tape heads and play back. Lubrication must be done sparingly because the tape needs to be moist enough to function effectively, but not too wet so it exacerbates clogging in the tape head mechanism.

Restoration work can be very time consuming. Even though each 3″ tape plays for around 20 minutes, the preparation of tapes can take a lot longer.

Another thing to consider is these are multi-track recordings: eight tracks are being squeezed onto a 1/4″ tape. This means that it only takes  a small amount of debris to come off, block the tape heads, dull the high frequencies and ultimately compromise the transfer quality.

It is important, therefore, to ensure tapes are baked, lubricated or cleaned, and heads are clear on the playback mechanism so the clarity of the recording can realised in the transfer process.

Now we’ve explored the technical life of the tape in detail, what about the content? If you are a regular visitor to this blog you will know we get a lot of really interesting tape to transfer that often has a great story behind it. We contacted Richard Blackborow, who sent the tapes, to tell us more. We were taken back to the world of late 80s indie-pop, John Peel Sessions, do it yourself record labels and a loving relationship with an 8 track recorder.

A Short History of BOB by Richard Blackborow

Richard adjusts the levels on the 8 track mixer in the Banwell Studio. He is smoking a cigarette and wearing ripped jeansBack in 1983 I was a 17 year old aspiring drummer, still at school in North London and in an amateur band. Happily for me, at that time, my eldest brother, also a keen musician, bought a small cottage in a village called Banwell, which is 20 or so miles outside of Bristol, near Weston Super Mare. He moved there to be near his work. The cottage had a big attic room and he installed a modest 8-track studio into it so that he could record his own music during his spare time. The studio was based around a new Fostex A8 reel-to-reel machine and the little mixing desk that came with it.

The equipment fascinated me and I was a regular visitor to his place to learn how to use it and to start recording my own music when he wasn’t using it.

Skip forward a couple of years and I am now 19, out of school, deferring my place at university and in a new band with an old friend, Simon Armstrong. My brother’s work now takes him increasingly abroad, so the studio is just sitting there doing nothing. Simon and I begin to write songs with the express intention of going to Banwell every time we had a decent number of tunes to record. Over the next ten years it becomes part of the routine of our lives! We formed a band called BOB in 1986, and although we still lived in London, we spent a lot of time in that small studio in Banwell – writing, recording demos, having wild parties! By this time my brother had moved to the US, leaving me with open access to his little studio.

The band BOB had modest success. John Peel was a keen fan and a great supporter, we toured loads around the UK and Europe and made lots of singles and an album or two, as well as recording 5 BBC sessions.

To cut a long story short, we loved that little studio and wrote and recorded some 300 songs over the ensuing 10 years…the studio gear finally dying in about 1995. Most recordings were for/by BOB, but I also recorded bands called The Siddeleys and Reserve (amongst others).

The tapes we recorded have been lying around for years, waiting to be saved!

Four men (BOB) stand outside the cottage in Banwell

Recent interest in BOB has resulted in plans to release two double CDs. The first contains a re-issued album, all the BBC sessions and a few rarities. The second CD, planned for next year, will contain all of the BOB singles, plus a whole CD of the best of those demos we recorded. It was for this reason that all of those old tapes were sent to Adrian to be transferred to digital. I now have a studio near my home in West Cornwall, close to Land’s End, where I will be mixing all the material that Great Bear have been working on. The demos map our progression from pretty rubbish schoolboy aspirants to reasonably accomplished songwriters. Some of the material is just embarrassing, but a good chunk is work I am still proud of. We were very prolific and the sheer number of reels that Adrian has transferred is testament to that. There is enough material there for a number of CDs, and only time will tell how much is finally released.

Listen to the recently transferred Convenience demo

This is a bit of a rarity! It’s the demo (recorded on the little 8-track machine in Banwell) for a BOB single that came out in 1989. It’s called Convenience and I wrote and sang it. This early version is on one of the tapes that Adrian has transferred, so, like many of the rest of the songs, it will be re-mixed this winter for digital formats and released next year.

This is a link to the video we made for the song back in 1989 in a freezing warehouse in Hull! It appeared on Kats Karavan – The History of John Peel on the Radio compilation that was released in 2009.

***

If you want the latest news from BOB you can follow them on twitter. You can also pre-order the expanded edition of their 1991 album Leave the Straight Life Behind from Rough Trade. It will be available from the end of January 2014. A big thank you to Richard for sending us the photos, his writing and letting us include the recording too!

Bristol Archive Records – ¼ inch studio master tapes, ½ inch 8 track multi-track tapes, audio cassettes, DAT recordings and Betamax digital audio recordings

Monday, October 7th, 2013

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.

REVELATION-ROCKERS-ARC242V-Cover

Great Bear 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 Great Bear Studio.

BLACK-ROOTS-Antholgy-cover

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 mold, 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”.’

electric_guitars-cover

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.

Repairing obsolete media – remembering how to fix things

Monday, June 17th, 2013

A recent news report on the BBC website about recycling and repairing ‘old’ technology resonates strongly with the work of Great Bear.

The story focused on the work of Restart Project, a charity organisation who are encouraging positive behavioural change by empowering people to use their electronics for longer. Their website states,

the time has come to move beyond the culture of incessant electronics upgrades and defeatism in the face of technical problems. We are preparing the ground for a future economy of maintenance and repair by reskilling, supporting repair entrepreneurs, and helping people of all walks of life to be more resilient.

We are all familiar with the pressure to adopt new technologies and throw away the old, but what are the consequences of living in such a disposable culture? The BBC report describes how ‘in developed nations people have lost the will to fix broken gadgets. A combination of convenience and cultural pressure leads people to buy new rather than repair.’

These tendencies have been theorised by French philosopher of technology Bernard Stiegler as the loss of knowledge of how to live (savoir-vivre). Here people lose not only basic skills (such as how to repair a broken electronic device), but are also increasingly reliant on the market apparatus to provide for them (for example, the latest new product when the ‘old’ one no longer works).

A lot of the work of Great Bear revolves around repairing consumer electronics from bygone eras. Our desks are awash with soldering irons, hot air rework stations, circuit boards, capacitors, automatic wire strippers and a whole host of other tools.

OLYMPUS DIGITAL CAMERA

We have bookshelves full of operating manuals. These can help us navigate the machinery in the absence of a skilled engineer who has been trained how to fix a MII, U-Matic or D3 tape machine.

As providers of a digitisation service we know that maintaining obsolete machines appropriate to the transfer is the only way we can access tape-based media. But the knowledge and skills of how to do so are rapidly disappearing – unless of course they are actively remembered through practice.

The Restart Project offers a community-orientated counterpoint to the erosion of skills and knowledge tacitly promoted by the current consumer culture. Promoting values of maintenance and repair opens up the possibility for sustainable, rather than throwaway, uses of technology.

Even if the Restart Project doesn’t catch on as widely as it deserves to, Great Bear will continue to collect, maintain and repair old equipment until the very last tape head on earth is worn down.

repair of snapped DAT

Wednesday, October 19th, 2011

D120 broken DAT tape

We often get sent Digital Audio Tapes or DAT’s 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 it’s 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.

snapped dat tape

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 unrepairable 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:

disassembling dat shell

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.

 

 

 


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