nakamichi

Type IV Metal Cassettes and Robert Chenciner’s Daghestan Collection

Type IV Metal Cassettes and Robert Chenciner’s Daghestan Collection

We recently received a fascinating collection of tapes from the archive of Robert Chenciner, an ethnographer with over thirty years experience studying the cultures, human rights and current affairs of Daghestan.

Daghestan is located in the north Caucasus region, its neighbouring countries are Azerbaijan, Chechnya and Georgia, while its eastern border is flanked by the Caspian Sea.

In the early 1980s Robert had unique access to Daghestan and other parts of the Soviet Caucasus in the twilight years of the USSR.

During visits Robert made recordings of Daghestan’s rich culture. This included music, documenting ethnic instruments such as the Chagana, as well as singing and dancing.

Although Robert believes that claims to authenticity must be treated with suspicion, he nonetheless told me that these recordings document the traditional folk culture that was practiced in the villages of Daghestan.

These tapes also document the 31 mutually unintelligible languages spoken in Daghestan such as Avar which is spoken by 900,000 people.

Listen to excerpt of a tape from the collection. The tape had experienced mould growth and had snapped. It therefore needed to be repaired prior to transfer. Robert explains: ‘The recording was made in Untsukul c.March 1990. You can hear Russian being spoken with a heavy accent, some Kumyk and some Avar. It was joking and talk about who was I and where from.’

Type IV metal cassette with shell open. Visible thin layer of dust on the surface.

Type IV Metal Cassettes

When Robert travelled to Daghestan he was keen to get the most professional recordings he could. For this reason he used type VI metal audio cassette tapes, a tape formula that had been introduced in the late 1970s to offer better quality recordings.

By the mid 1980s, the tape tardis explains, these tapes

‘had been adopted by a lot of enthusiasts. They remained too expensive to be bought in bulk by the average consumer, but if you wanted to record something special – and particularly if you produced music yourself – you’d probably be highly attracted by the exceptional recording quality of a good metal cassette.’

The science behind the type IV cassette, according to the Museum of Obsolete Media, was to use ‘pure metal particles instead of metal oxides. This created a hard-wearing tape with superior frequency response and greater dynamic range.’

Since completing the recordings in the mid 1980s, as with so many of the tapes we receive at Great Bear, they have been tucked away in a drawer and out of circulation.

Due to being stored in poor conditions some of the tapes were displaying signs of mould growth.

Another problem some tapes exhibited was the degradation of the foam pressure pad. This had ‘stuck’ onto the tape and stopped it it from playing. In one case the tape had snapped as a result from a previous attempt at playback. Melted foam pressure pad on a type IV metal tape

Fortunately this issue did not effect our ability to do the transfer. We use Nakamichi tape decks to do optimal audio cassette transfers. The transport design within Nakamichi machines doesn’t use the tape pressure pad to play back the tapes. This is because, Wikipedia tells us,

‘Nakamichi found that this pad provided uneven and fairly inaccurate pressure and was therefore inadequate for reliable tape/head contact. Furthermore, Nakamichi found that the pressure pad was a source of audible noise, particularly scrape flutter (the tape bouncing across the head, a result of uneven pressure), and also contributed to premature head wear. Nakamichi’s dual-capstan tape decks provide such accurate and precise tape tension that, unlike other decks, the cassette’s pressure pad is not needed at all.’

Head pad lifter on a Nakamichi tape machine

The insides of a Nakamichi machine that has no need of a pressure pad to play back tapes.

Re-publication plans

Recent interest from musicologist Stefan Williamson-Fa, the driving force behind getting the tapes transferred to digital files with Great Bear, will enable these unique recordings to be heard by new audiences.

These include what Robert believes to be the only recording of an Andi Zikr ritual. Banned by the Tsar and later the Soviets, the Zikr ritual proved to be a resilient part of Daghestan’s Sufi culture. Zikr involves a group rotating in a circle, stamping the ground and grunting in order to create a mystical and ecstatic experience.

Stefan and Robert have plans to make the transferred digital files available online.

Robert reflected that when he was collecting the tapes in the 1980s his imagined audience for the recordings was pretty small. With the possibility of online publication this audience has substantially increased.

Furthermore, through people uploading material to sites such as YouTube the amount of Daghestan’s culture that can be accessed on the internet continues to grow. Robert’s links with the academic community in Daghestan also means the recordings will gain exposure there as well.

It is no doubt that those interested in the cultural history of Daghestan will await the publication of these recordings with much excitement. When the website is available we will of course let you know!

***Many thanks to Robert Chenciner for talking to us about his collection, and to Stefan for putting us in touch***

Posted by debra in Audio Tape, 0 comments

Digitising Audio Tape – Process, Time & Cost

Last week we wrote about the person time involved in transferring magnetic tape to digital files, and we want to tell you more about the processes involved in digitisation work.

While in theory the work of migrating media from one format to another can be simple, even the humble domestic cassette can take a substantial amount of time to transfer effectively.

Doing transfers quickly would potentially keep the costs of our work down, but there are substantial risks involved in mass migrations of tape-based material.

Problems with digital transfers can occur at two points: the quality of the playback machine and the quality of the tape.

First, lets focus on the playback machine.

Each time a cassette is transferred we have to ensure that the cassette deck is calibrated to the technical specification appropriate to that machine. Calibration is a testing procedure where a standard test tape is used to set the levels for tape to be digitised. The calibration process allows us to check tapes are played back at the correct speed and audio levels, that wow and flutter levels are set and the azimuth is aligned.

Azimuth refers to the angle between the tape head(s) and tape. Differences in Azimuth alignment arise from the azimuth of the original recording. You cannot know this information from just looking at a tape and you will get a sub-optimal transfer unless you adjust your machine’s azimuth to match the original recording.

sony-apr-5003-headblock-azimuth

Regularly checking the Wow and Flutter on the tape machine is also very important for doing quality transfers. Wow and flutter refer to fluctuations in speed on the playback mechanism, flutter being a higher rate version of wow. If you have listened to a tape you will probably be familiar with the sound of warped and woozy tape – this is the presence of wow. All tape machines have wow and flutter, but as components in the mechanisms stretch there is the potential for wow and flutter to increase. It is therefore essential to know what level the wow and flutter are set on your tape deck –less than 0.08% Weighted Peak on our Nakamichi 680 machines – to ensure optimal transfer quality.

Not all cassette machines were made equal either, and the quality of playback is absolutely dependent on the type of machine you have. There is a massive difference between the cheap domestic cassette machines made by Amstrad, to the cassette decks we use at Great Bear. Nakamichi machines were designed to squeeze the most out of the cassette, and their performance is way above the standard ‘two head’ cheap domestic machines.

Even with a Nakamichi deck, however, they have to be regularly checked because they are fragile electromagnetic machines that will drift out of specification over time. When machines drift they slip out of alignment, therefore effecting their operating capacity. This can occur through subtle knocks, everyday wear and tear and general ageing of mechanical and electrical components. For example, with extended use the grease in the components dries up and goes hard, and therefore affects the movement of the mechanisms.

Wow-and-flutter-monitor

Problems can also arise with the tapes themselves.

Most issues arise from tapes not being played back in well calibrated machines.

With audio cassettes the potential for azimuth error is increased because the speed the tape moves pasts the head is very slow. The tape therefore needs to be assessed to see if it is in a playable condition. It is played back in mono because it is easier to hear if there are problems with the azimuth, and then the azimuth is manually adjusted on the machine.

Migrating tape is unquestionably a ‘real time’ process. You need to listen and monitor what’s on the tape and the digitised version to ensure that problems with the transfer are detected as it is happening. It is a very hands on activity, that cannot be done without time, care and attention.

Posted by debra in Audio Tape, tape machines, 2 comments

azimuth adjustment when you transfer and convert cassettes to cd

Cassette tapes run at a very slow speed of 1 7/8’s inches per second (ips) with a very small track width of 1.59mm

Cassette decks when they left the factory or a service centre should have been aligned to a standard reference for the position of the record and play heads. Unfortunately they often weren’t all the same and over time the alignment can get drift, get knocked out or manual ‘fiddled with’ by an owner.

What this means is that unless you’re playing back your tape on the machine it was originally recorded on you may be getting the maximum quality as the angle of the head to the recording or azimuth will not be optimal.

Without calibration tones recorded at the start of the tape which is very unlikely on most domestic cassette tape recordings you must set the playback azimuth manually. A few high end tape decks, namely those made by Nakamichi, either had a easily accessed Azimuth adjust or could even automatically adjust this throughout the tape. The Nakamichi Dragon was one such tape deck and could be the best, if working well, for high quality playback.

If you want to transfer or convert a cassette to CD and adjust the azimuth yourself this is the an easy way to do it:

  1. Look at the tape path (everything the tape will move across) and if it looks brown and dirty get some isopropyl alcohol and give it a good clean with a cotton bud.
  2. If you haven’t demagnetised your deck for a while now would be a good time to do it..
  3. Power up your cassette deck, which hopefully works correctly and doesn’t have too much speed instability!
  4. Pop your tape in the cassette well and start to play.
  5. Turn your amplifier’s volume up and if you can put it in Mono.
  6. Now, look under the tape machine’s playback or combined record and playback heads you should see a small screw or nut possibly with anti tamper paint on it.
  7. Using an appropriate tool, turn this nut or screw a little left or right while listening to the audio.
  8. You should hear the recording, especially if it has a lot of high frequency content such as cymbals etc get bright and dull sounding or more technically get more in or out of phase.
  9. Your aim is to get the most in phase or bright sounding playback.
  10. Sounds better now?? Great, start to record using you favourite computer audio software. We like SoX for the control but there’s a huge range out there.

 

Posted by greatbear in Audio Tape, 1 comment

Information Terminals M-300, cassette tape transport alignment gauge

The regular service of analogue machines which will involve the mechanical alignment then electrical alignment / calibration is really important if you’re attempting to get optimum transfers and reduce any risk of damaging the potentially fragile tape.

While some of our machines are serviced by others we like to regularly check them and have gradually bought our regular servicing in house. Of course this needs specialised tools, test tapes and gauges, often totally unavailable new now.

On a lucky eBay day I happened to win one of these beauties, an Information Terminals M-300 gauge. This enables you to accurately set the tape guide height and also the head stroke. It is a universal gauge and can be used across many decks.

information_terminals_m300-boxed copy

Nakamichi tape deck owners have had a hard time doing this part of their servicing as the original Nakamichi gauges are very very rare now as is this.

A member of the naktalk mailing list though recently borrowed our gauge and has had it measured and will soon have a small batch CNC machined and made available. These remanufactured gauges will have a few small modifications to improve the design.

Thanks to Willy at www.willyhermansnervices.com many more tape deck transports will be able to be aligned correctly.

Posted by greatbear in Audio Tape, 3 comments