Once a common sight in Radio stations around the world, the NAB Cartridge machine or Fidelipac was used for short jingles and announcements, sometimes even for longer recordings. Using a similar sized cartridge to a domestic 8 track machine the NAB cartridge was different in that the pinch roller was not in the cartridge but would hinge up in the player and hold the tape against the capstan. Running at 7.5 inches per second (ips) compared to 3.75 ips in domestic cart machines the recording and reproduction quality good be very good but it was the ease of use and cueing ability offered by these machines that made them so useful in broadcasting.

We have Sonifex cart machines that while very well built do have rubber parts that will degrade over time and reduce the transport performance. Luckily we have some of the last remaining stock of new pinch rollers, motors and capstan drive belts.

The pinch roller in one of our machines had become quite hard and the rubber shiney over time. A pinch roller in this state may not hold the tape as securely and could also have flat spots both leading to increased wow and flutter and poor tape handling. These pinch rollers also have high quality cartridge bearings pressed into their shell. Over time these loose their lubrication, wear, become rough feeling and will also add to poor tape handling.

Older, fragile and valuable tape must be handled and used carefully. A ‘chewed’ tape caused by a poorly maintained tape transport in any tape machine, audio or video is a disaster and hard to recover from perfectly.

Both halves of the cart machine case need to be removed to easily change the pinch roller. While the access is good and the machine, in this case a Sonifex microHS, had been designed for easy servicing the pinch roller is still a little fiddly to get to so I removed the transport from the main chassis.

To remove the pinch roller a small slightly hidden C clip must be removed you can see in the image above the slot machined into the roller shaft where it sits and holds the roller. This is hard to remove as the plastic bush on top of the roller stops you getting a small screwdriver in. I managed to remove the C clip with some fine circlip pliers. Be careful not to loose the clip if you don’t have spares, they fly away very easily!

Now the new roller can be placed on the shaft. It’s a good idea once all the transport is out to give everything a good clean with IPA.

On this machine, the castan drive belt was quite slack so a new one was fitted, which is easy now the transport is removed. First though the capstan flywheel and motor pulley were cleaned of all the old rubber belt residue that tends to accumulate over time.

The last thing to do is check the pinch roller pressure. This is important to as to high or too low will increase wow and flutter, increase wear to the bearings and capstan surface and give poor tape handling. Due to the design of these NAB cart machines, the pinch pressure needs to be checked with a special cartridge. The pinch pressure is then adjusted from a screw pot on the top PCB seen outlined below in green.

That’s it, time to play carts again.

The capstan drive tape recorder is (or was) very common and was used in a huge range of cassette tape audio, video and open reel machines from cheap domestic to very expensive broadcast tape machines.

Occasionally we receive quarter inch tapes, always be on small 3 inch spools, that reproduce on our capstan drive machines with terrible speed variation. They start off very fast then gradually slow down over the duration of the recording to around normal speed.

These reels must have been recorded on rim drive machines. These type of open reel tape recorders didn’t use a capstan and pinch roller to save space and more often cost. As there is no capstan, as the supply reel gets smaller the tape recording speed increases. When replayed on a rim drive machine the speed, while not likely to be ‘Studer stable’ will be pretty stable and the recording sound OK.

It’s not feasible or desirable for us to own unlimited machines of all types due to the time to service and repair them, find parts and storage space therefore we use a small range of carefully picked high quality tape machines that with care can replay most tapes, speeds and track formats. This is the problem with rim drive recordings and an analogue or digital solution must be found.

The tapes we received were 15 reels of family recordings from the Welsh Valleys. Others apparently had tried to transfer these tapes but gave up finding no material. This was easily solved as the tapes were wound the opposite way to normal so the oxide was facing out not in. This is the same as in audio cassettes. The original tape machine must have had it’s heads in a similar position to a cassette machine.

We’re very happy to be working with Mike Wright and the Archive for Mathematical Sciences and Philosophy on a large scale and ongoing transfer, restoration and online management programme.

akloster tape 2a Download whole video to your computer

We often receive enquiries about audio and video tape that is not in the best condition having been stored in humid conditions, suffering from binder hydrolysis (sticky shed) or not wound on it’s reel well but we were surprised when we received this tape recently.

It literally is a bag of tape! It is a cassette tape that had at some point become unspooled, probably when the cassette shell was opened for a repair. We can and did restore the tape by respooling and reshelling before playing on one of our Nakamichi dual capstan cassette decks.

This is a time consuming job though as thin tape twists, turns and crinkles up very easily needing careful tension, customised winding systems and protection from contaminants such as dust, grease, etc that could cause more damage to an already compromised recording.

High resolution audio and video digital tape conversions can use large amounts of computer storage. 8 bit uncompressed Standard Definition (SD) PAL video runs at 70 GB per hour and 24 bit 96 kHz audio files at 2 GB per hour.

As a result of this many of our analogue to digital tape transfers require the use of external storage, usually USB 2.0 portable hard drives, to supply the copied digital transfers back to the customer. Some drives supplied by customers have not been of great quality and not designed to be sent about in the post. One such drive we had recently, a Sony Vaio branded 2.5″ USB drive wouldn’t copy certain directories of important files with the Mac OS Finder or the Windows Explorer. While most of the drive copied this certain folder always resulted in a crashed computer!

Thanks to GNU/Linux we have a bit more power and information at our disposal about hard drives and IDE or USB interfaces. It’s always best practice to copy as much information from the drive or mirror it before attempting any other types of data recovery or file system repair. Using the standard dd

One of our recent and ongoing jobs is a very large, over 2000, NAB 10.5 inch reel to reel archive of quarter inch professional tape recordings.

To fit into the budget but maintain quality we needed to find a way to streamline our workflow in converting the high resolution 24 bit 96 Khz master .wav  files to CD quality (16 bit / 44 Khz) and MP3 (320 kbps) audio files.

Typically this would be done manually with 2 track audio software such as Audacity, Peak Audio Tools, Wavelab, etc with a Graphic User Interface (GUI). For such a large amount of individual files this is time consuming, expensive and unnecessary. While many audio editors have batch processing tools, Amadeus Pro being one of our favourites, they are still not as flexible as combining command line tools with a Bash script.

SoX is a powerful command line audio tool that can be used to edit, convert, process, record and play a wide range of digital audio files. It also has a very high quality resampling algorithm which we are using here.

Once the tape reels have been digitised they are split into individual .wav files which are then renamed with artist and track details using a php script that accesses a .csv file. These 24/96 resolution files are then converted to lower, CD resolution using SoX and to 320 kb/s MP3′s using LAME. The script also uses sed, the stream editor, to add the text _16_44.wav or _mp3.mp3 to the filename for ease of identification. The script finds all files with the suffix _24_96.wav in all the subdirectories of it’s working directory and processes these.

At the moment this script is running under Mac OS X 10.5.8 using the MacPorts project but will, in time, be moved to one of our Apple G4 servers running the PowerPC version of Debian GNU/Linux 5.05 ‘Lenny’.

We have two of these excellent machines in addition to our Sony APR 5003 and Studer A80′s. The Tascam BR-20 was Tascam’s last and top of the range 1/4 inch reel to reel tape machine and available in two track stereo and stereo with centre timecode option.

The capstan drive in the BR20 is belt driven by a wide belt. Both belts in our machines looked OK but we’ve replaced all roller bearings, belts and pinch rollers in both of our machines anyway as a matter of course. These parts are still available from Teac UK via Acoustic Services on 01-844-347600.

Below is a simple explanation of how to change the capstan belt.

1. Unplug machine from mains power and move to a strong stable base.
2. Remove cross head screws from the rear panel and lift plate off. Depending on the type of plug in your country you may not be able to remove it completely.
3. You’ll now be able to see the capstan motor and it’s control board attached to it.
4. Remove the 4 cross head screws and gently lift the analogue audio output board away from the machine as in the picture above.
5. We now need to remove the whole capstan motor assembly with the control board still attached. Remove the 4 cross head screws right at the front of the assembly, NOT the six nearest to you when looking at this image. 
6. Carefully unclip the 4 cable connectors from the motor control board. The other connector cannot be removed from the board and must be removed where it connects to the other board.
7. The whole assembly can now be lifted out from the machine. Be careful to not snag any cables and remember to unclip the black cable ties.
8. You’ll now be able to unclip the control board from the assembly by carefully compressing the black clips with some needle nose pliers.
   
9. Now remove the six cross head screws holding the capstan motor assembly together. This is the only way to remove and refit the capstan belt. There’s not enough room to do it any other way!
10. Now you can remove the old belt and capstan shaft. It’s a good idea to clean the capstan with IPA where the old belt has run and reapply a little grease to the bearing end of the capstan.
11. Fit your new belt and reassembly is the reverse of dissasembly! Be careful though to not drop the screws into regions you can’t get them out of – luckily there aren’t that many on this machine but a long magnetic screwdriver is very useful.. just don’t get it anywhere near the headblock and heads!
    

This is something you don’t see everyday! An almost unused and boxed 1/4″ 2 track reel to reel tape machine, a Tascam BR20 one of their highest quality machines sometimes installed with a Timecode head for broadcast and editing applications.

This machine somehow turned up at an IT Recycling centre in Essex but is now in much safer hands transferring tapes, in particular a very large archive of library music on 10.5″ NAB reels owned by Mood Media Ltd.

As you can see this machine is in it’s original box, with packaging and first look at the heads show almost no head wear but some nasty oxide that took a while to clean off.

This machine needed little work to bring it back to spec, a new capstan belt, pinch roller, tape tension and speed setting and a full calibration.
The capstan belt change is the subject of another blog post here..

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.

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.

not far though – just upstairs to a much roomier space with better natural light.

Anyone who’s visited will know how much equipment we have and this move has meant quite alot of downtime as we’re taking the opportunity to re-rack, redesign and re-wire. Anyone with existing orders will have these processed as soon as possible but please bear with us for the next week or so….

Our revised address is:

greatbear analogue and digital media
Unit 26
The Coach House
2 Upper York Street
Bristol, BS2 8QN

0117 985 0500

To contact us by email, please use our contact form here…