In late August, we welcomed young hip hop fans aged 16-25 to spend a week in the Central Library sound studio with the Greater Manchester Hip Hop Archive as part of the National Lottery Heritage Fund-supported Piccadilly Radio archive project.
This strand of the project was inspired by Stu Allan’s cult hip hop show Bus Diss which introduced Greater Manchester to the best of the world’s hip hop while supporting local artists. You can listen to over 15 hours of Stu Allan on Central Library’s Sound + Vision pods.
Stu Allan’s Bus Diss intro, 1988 (Ref: 2022/103 CC20040_s1)
The GMHHA includes a dozen or so of off-air recordings of Bus Diss on cassette made at home by fans. This is just as well because no Stu Allan shows survive in the Piccadilly Radio corporate archive. Just goes to show that archiving, like everything else, starts at home with what you have to hand.
The week started with a tour of the building and an introduction to the sound archives. Next I showed the group a massive black crate of tapes. To be honest I’ve been looking at this crate for two years with a looming sense of dread.
Unlike me, the group were totally unfazed and in one morning they had separated out the local, non-commercial and small-release tapes and started to list them. These include American bootlegs, mixtapes and small DIY local labels. These are the priority items – we can safely ignore the shop-bought published music which is not rare or unique.
Prioritisation is important because we don’t need to and can’t digitise everything. Also, we need to be able to justify the energy use in maintaining digital copies in the long term. There are two main questions: is the audio worth it? And, if it is, how urgent is the job based on the format and condition. Cassettes are high-risk because of the obsolescence of the machines needed to play them.
We learned how to inspect the condition of the tapes – looking out for knackered pressure pads, mould or snapped tapes. We learned how to open up cassette shells and splice tape (without swearing too much). We also made a note of anything that had Dolby noise reduction marked on the tape or box – this was a clever compression technique built in to some tape decks used to reduce tape hiss. We didn’t actually run any of the Dolby NR tapes with Dolby applied on the tape decks – we find the results are more consistent using the DDI Codec application afterwards.
Once we had a basic list together (and a box of tapes that seemed to be in decent condition), it was time to prepare for digitisation. We set the gain levels on our eight Tascam 122 tape decks using constant 0dB 1kHz test tones. This involves setting the output volume of each of the decks to deliver the same level in the digital environment (around -20dBFS). This gives us plenty of headroom just in case the home-made tapes are a bit thumpy. It’s generally best to be cautious with gain levels because if anything peaks close to 0dBFS it can cause distortion. Whereas low signals can always be boosted up afterwards.
The next step is to set the decks at a sensible azimuth point to start the day. Azimuth is an anglicised version of the Arabic word ‘al-samt’ which means angle or direction in astronomy. In this context it means the angle of the tape head which reads the left and right channels of the stereo signal relative to the tape as it passes by.
Your brain understands a sound that hits your left ear ever so slightly before your right as coming from your left. If both ears hear the sound at exactly the same time, your brain will place the sound source as directly in front of you. This is the sweet spot. At that point, the sound waves are ‘in phase’ and the channels boost each other. This means that you will hear every bit of the signal. In the same way, any tiny discrepancy in the time the left or right channels hit the play head because of nisalignment will leave the sound waves out of phase, meaning that the channels cancel out certain parts of the frequency spectrum, making the signal muffled.
Most cassette decks have a fairly hidden screw behind the slide-away window with which you can change the angle of the play head. If you only ever played albums you bought from Woolworths then you wouldn’t ever have needed this screw. But if you’re playing home-recorded stuff then it’s well worth investigating. This is because we never really know what decks these tapes were produced on, or how well calibrated they were.
The trick is to turn the screw slightly while the tape is playing until you get the clearest signal. It’s like focusing an analogue camera – and what’s the point of taking a blurry photo? Good tests are applause, cymbals or sibilants in speech. Anything high-frequency that lasts more than a moment can be a good test – are you getting all the high notes? If not, give it a tweak. Counter-intuitively, sometimes it’s worth using tape hiss; the more hiss you can hear when you have it turned up, the better!
We then cleaned our decks using 99% rubbing alcohol on the metal tape heads to clean away any dust or muck. And we inspected the rubber pinch rollers in case they could do with a gentle clean with Platenclene fluid. Before anything gets played, we fast-forwarded and rewound the first eight cassettes to check that they stayed in one piece, and to see what they might leave on the tape heads. Thankfully we didn’t have any nasty surprises. We then tweaked the azimuth screws depending on how each tape sounded.
Finally we were ready to press record on our PCs and play on the cassette decks. We digitise at 96kHz (96,000 samples per second – more than double CD quality) and 24 bit depth (50% more detailed level measurement than CDs gives extra head-room). We can’t really hear the differences between this quality and CD but it means we capture plenty of data in the digital masters to allow audio clean-up afterwards.
After playback finished on all the decks, we stopped the record sessions in Wavelab Pro and then opened up the digital copies. We checked them over for level, glitches, dropouts and audio quality. Then we topped and tailed them – leaving at least a second before the start and after the end of the recording. Finally we saved them using the reference number as the filename, eg. BC0001_s1 for the first side of the first tape from the Big Crate of Doom.
This cassette digitisation zine by Unlocking Our Sound Heritage digitisation manager Siân Williams is a brilliant and concise description of our cassette workflow.
The team got through a whole box of 36 tapes in the week. By the Thursday, they were saying things like, ‘I’ll just put on another lot before lunch’. Letting the machines decide when your breaks are is a dangerous road to go down (trust me) but it does show that they got the digitising bug! Next steps are to add the track lists and any other metadata to the catalogue and make them available at the library.
The learning points for me included:
- How useful it is to have subject specialists doing the prioritisation and cataloguing.
- How tricky it is to talk about phase and analogue and digital levels – I need to get some posters for the sound studio to help!
- How even an old jaded archivist with too many collections can be reminded that real progress can be made in only a week.
- We really need to train up and fund a local hip hop artist from the next generation who can become an archivist and make the most of this amazing collection.
You can find out what the young people thought about all this and listen to some of the material we digitised next week 28 September-3 October on Unity Radio.
Each weekday from 9pm you’ll be able to hear ‘Back From the Source’, a curated mix from the archive plus interviews and teasers in the daytime. And on Saturday 4 October the archive mixes will be played at the Street Heat 4 festival in Salford.
It makes me really happy that these great 1980s and 90s radio shows and mixtapes will be back on Manchester’s airwaves in the 21st century, thanks to the care of a new generation. All thanks to the Greater Manchester Hop Hop Archive, Unity Radio, the National Lottery Heritage Fund and the Manchester Libraries Trust.
