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Re-lapping of an analogue head

I have a Fostex B-16 tape machine which I have posted about elsewhere on this website. Produced around 1983 to 1986, it is a 16 track recorder that uses 1/2 inch tape.
I got my machine in the mid-late 90s, it was my first “real” multi-track recorder. It has always been in good condition, worked well and I enjoyed working with it, but it has seen little use from the early 2000s …. until recently.

Fostex B-16 1/2 inch 16 track tape machine. Used for digitisation of old tapes.

In the last few years there has been an increasing amount of work for this machine transferring old 1/2″ 16 track tape to digital for people all around the country. With the increase of use, this 25 year old machine has started to show signs of its age and it has become harder to keep this machine operating within spec – in particular tracks 1 & 16 becoming harder to align properly and keep within the manufacturers specification of +/- 3dB, 40Hz to 18kHz.
My main suspicion was that the head was beginning to show signs of uneven wear.

After some research and ringing around I got some help from Stephen Crane from the 301 Studios engineering dept.
301 have a similar machine (Fostex E-16) that is currently not working but Stephen generously suggested that I take my machine to 301 and substitute parts from their machine to either confirm my suspicions about head wear or otherwise determine the cause of the playback issues.
So, I spent a day at 301 in their engineering, maintenance, repairs room disassembling the 2 machines and testing parts. And … what do you know?? The head from their machine in my machine proved that the 2 outer tracks of my head had worn.

Analogue audio heads for tape machines are essentially not manufactured anymore and haven’t been for many years. 1/4″ stereo heads are still sort-of available on the second hand market. But a 1/2″ 16 track head from a pro-sumer tape machine made in the 80s is virtually impossible to find, and even if one did pop up for sale, the chances of it being in good working order would be vanishingly small.

Stephen told me I had no option but to re-lap the head, that there are a few people in the country who could do the job if I needed but that re-lapping is actually pretty easy and that I should do it myself.
He lent me his Studer re-lapping block, gave me a few instructions and sent me on my way.

Up until this point I had very little knowledge of re-lapping other than it meant grinding the surface of the head with sandpaper.
I’m always keen to give things a go, but the idea of learning how to re-lap a head, and doing my first one all on my own with a head that is irreplaceable scared the pants off me.
So I googled the hell out of it and found a bunch of useful information and tips.

I got all the required materials and equipment together. In particular, I decided to use a larger piece of plate glass as my surface instead of the smaller Studer block so a whole piece of paper could sit flat. And then I waited for a day when I had nothing on and I felt calm, peaceful and had all the patience in the world.

Covid-19 brought that day sooner than I expected.

I disassembled the headblock and examined the head using a (handily cheap) USB microscope. The microscope revealed some damage on the head.

Fostex B-16 half inch 16 track head showing damage before being re-lapped. — Damage on one of the outside tracks before re-lapping

Then the re-lapping began. I was so paranoid about ruining the head that I only did one or 2 passes on the papers before inspecting the head to check progress.
I ended up using 4 grades of paper – 1200 and 2000 wet & dry, and 3 & 1 micron lapping film.

1 Micron lapping film:
The bubbles under paper took a bit to work around

It took me a long time because of my slow and probably over-cautious approach but the results looked amazing.

Fostex B-16 head with damage removed after re-lapping

Fostex B-16 head after re-lapping. Looks like new!

Not only does the head look shiny and new, but once I had re-installed the head and gave it a test run, it appeared to be playing back beautifully.

The following day I put the machine on the Lindos test set, threaded up the test tape and put it through its paces.

The results are far better than I hoped.
All tracks now not only meet the frequency response spec of +/- 3dB, 40Hz-18kHz but they beat it.
All tracks are less than +/- 2dB across the range, and are only +/- 0.5 dB from 100Hz to 10kHz.
Excellent for ~35 year old machine that was designed for consumer / home / project studio use.

I would like to especially thank Stephen Crane for all of his help and for giving me the confidence to undertake this project. It has given my machine a new lease of life and future audio digitisation.

Playback Alignment of a Fostex B-16

Fostex B-16 1/2 inch 16 track tape machine. Used for audio digitization of old tapes.

I have a Fostex B-16. I got it more than 20 years ago, my first multi-track recorder. It’s a 1/2″ 16 track analogue tape recorder and it’s an alright machine. It was made for the pro-sumer market – only 2 heads and ins and outs on RCA plugs. But it runs at 15ips and has Dolby C and if you take care it can make really great recordings.

It hasn’t recorded anything in a long time but I still get requests to digitise tapes.

So, to be sure tapes get the best possible playback, the playback circuit of the B-16 has to be set up / tuned properly. That can only be done with an alignment tape. Here is a video of part of the alignment process.

I’m told people are interested in this sort of thing, so … enjoy.

Yup, 2 minutes of awesome test tone.

The Fatty Cramps DA-88 Tapes

3 DA-88 tapes for The Fatty Cramps live at The Espy. Digitally transferred (digitized) by Infidel Studios

I have just spent several worthwhile hours wrestling with these 22 year old DA-88 tapes. The Fatty Cramps, live at the Espy, St Kilda, 1996.
Early digital formats are now very fragile, if they play at all. These ME formulation tapes were right on the edge of playable and took quite a few of my best tricks before they were willing to give up their secrets. All on hard drive and a usb stick now – saved.

And yes, The Fatty Cramps were a real band. They are in this superb snapshot of the Melbourne music scene in the late 90s – at approx 2:10.

Enjoy.

Construction of New Rooms

The Foley arm of the studio has been getting more & more busy recently and when the space below the studio became available I decided that the universe was telling me to take our Foley work to the next level.

Up until now we have been recording Foley in the music studio space that was built in ’99. This space has always been great for music and while this has worked well for Foley too, there are some limitations with using this space that we have had to work around. The only real way to fix these issues is to build new, purpose built rooms.

So, I got the keys in April and came up with a simple design that would get the 2 biggest rooms in the space and leave room for storage, a machine rack and room to grow (a little).

I engaged the very capable Joel Cabban to help / build / stop me from injuring myself / do all the heavy work (note: Joel is a musician himself. It is important to have people who are sympathetic to sound and acoustics on board)

And we got to work.

The results not only look fantastic but both rooms sound amazing. Joel and I managed to get the internal dimensions of both rooms to within 5mm of my initial specifications. Internal dimensions are crucial in small to medium sized rooms. Rooms modes have a massive impact on the bass response of a room, if you get the dimensions wrong and you will have endless problems with low frequency resonances and nulls.

The air-conditioning is silent, not quiet, but actually silent, and you can scream in an air con vent in one room and hear nothing in the other room. The acoustic isolation of these rooms is amazing, they are essentially boxes sitting on rubber and pin-board and clad in 10mm thick rockwool – as decoupled from the building as we could possibly make them. Only the very loudest external noises get in and only the very low frequencies at that – easy enough to filter out if it happens. The noise floor in these rooms is un-nervingly low and does take a bit of getting used to.

Near the end of the construction process I bought a chair shoe from my local school fete and put it in these rooms. The rooms soon became known as “The Shoebox” … perfect.

I have to say a big thank you to Joel Cabban, who was very patient with me and my fastidiousness/obsession about some of the design aspects. Thank you to Adrian Stopford, who helped out for several days with the gyprock, Joel’s plasterer mate (whose name escapes me) who did all the sealing of the gyprock, and Mint Air conditioning for being helpful and flexible.
Thank you also to everyone else who helped in some way or just gave encouragement along the way. You are all fantastic.

Update: The Shoebox quickly proved very useful not only for Foley (we have recorded eyes opening believe it or not!), but also group loop recording, voice overs, vocalists, acoustic instruments, sound effects and other sound design. There is lots more I want to try out in there. I really want to put a drum kit in there but just haven’t had the opportunity yet.

Have you ever recorded at Infidel Studios?

Did you record at Infidel Studios or with either Duncan or Paco anytime before 2005?

Have you ever wondered “How come I lost all my copies of that CD we made??” or wondered “Gee, I wonder if I could get my old tracks and have a go at mixing them?”.

Well, now is the time to do something about it.

Tascam DA-88, Tascam DA-38 & Tascam DA-30 mkII. All these machines are now used for digital transfer of old tapes

All Infidel Studios recordings made from when Paco began, around 1996, through until about 2004 – 2005, were multi-tracked to DA-88 & DA-38 machines and mixed down to DAT tape. Although archiving and storage of old recording projects has never been formally offered by the studio, we have tried to keep one copy of every project we have worked on over the years in one format or another. Old projects that were recorded to these tape based digital formats have been stored only on the tapes and there is no second copy. And as anyone who works in IT will tell you, data that is in only one place doesn’t exist!

The big issue now is that any recordings on these early digital format tapes will soon be almost impossible to retrieve. Machines to play them back have not been manufactured for many years and the ones that are left are breaking down. Many parts for them are hard to come by or simply made of unobtanium. The tapes themselves are a whole lot less robust than first thought.

Now is the time to get them transferred before they become unplayable and lost forever.

Currently we have one DA-38 machine that is running well and a DA-88 that, although it is too unreliable for audio playback, is very useful for synchronisation. We also have one working DAT machine. This year I have successfully transferred a good number of DA-8 and DAT tapes, covering 3 different recording projects, without any losses.

Over recent months I have done a stocktake of all the DA-8 and DAT tapes we hold. We have about 350 DA-8 tapes and 180 DAT tapes that span over about 130 separate recording projects. So there is a very good chance we hold yours. Associated paperwork ranges from “none at all” though to comprehensive sessions notes. At the very least, I can link nearly every tape to a band or artist name.

If you do want your old projects or want more information, please get in touch.

For more information about our audio digitisation services click here