tape

azimuth adjustment when you transfer and convert cassettes to cd

Cassette tapes run at a very slow speed of 178 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 drift, get knocked out or manually ‘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 not 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 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, audio technology, machines, equipment, 1 comment

repair of snapped DAT

D120 broken DAT tape

We often get sent Digital Audio Tapes or DATs 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 its 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 irreparable 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.

 

 

 

Posted by greatbear in audio tape, 6 comments

Replace pinch roller on Sonifex NAB Cartridge machine

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.

Sonifex NAB cart pinch rollers

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.

Sonifex NAB cart machine microhs transport removed

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.

Sonifex microHS new pinch roller

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.

Sonifex NAB cart machine capstan flywheel

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.

NAB cartridge pinch pressure adjustment

That’s it, time to play carts again.

Posted by greatbear in audio tape, audio technology, machines, equipment, 8 comments

Replace Tascam BR 20 Capstan Belt

We have two of these excellent machines in addition to our Sony APR 5003s and Studer A80s. 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.

Tascam / Teac BR 20 rear panel removed

  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.Tascam BR 20 capstan motor board with cables removed
  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.
    Tascam BR 20 capstan motor board unclipped from assembly
  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!
    New Teac capstan belt for Tascam BR20 reel to reel tape machine
Posted by greatbear in audio tape, audio technology, machines, equipment, 2 comments

Tascam BR 20 reel to reel new in box (not for sale)

Tascam Br 20 reel to reel tape machine box

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 its 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..

Tascam BR 20 reel to reel tape recorder

Posted by greatbear in audio tape, audio technology, machines, equipment, 12 comments

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 brought 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, 8 comments

U-matic transfer to DVD, Uncompressed Quicktime and Digi Beta

sony_bvu_950p_umatic

We’ve been honored recently to have won a large contract to help in the digital migration of an extensive educational video archive by the transfer from U-matic archive copies to uncompressed video files.

While the archive had been stored in an suitable environment and rarely if at all played, they had not survived well. The Sony branded tapes from the 1970s and 1980s all exhibited binder hydrolysis or sticky shed syndrome. We were still able to get good transfers though using our range of U-matic machines, particularly the Sony BVU-950P and For-A Time Base Corrector.

Posted by greatbear in video tape, 10 comments

Microcassette Transfer to CD helps Crown Court case

www,mowbraywoodwards.co.uk

We’ve recently been happy to be involved, with Mobray Woodwards Solicitors,  in the audio transfer of important evidence in a  local Crown Court case.

Even given the poor quality or the recordings, made on the slowest tape speed of 1.2 cm/s we were able to make transfers to CD which were clear and understandable with CD track markings for easy access to specific sections of the audio.

Microcassettes, until recently, were used regularly for voice recording in small, portable dictaphone type of machines. Their fidelity is not high but when used for voice it is usually acceptable.

Greatbear are able to transfer all formats and speed of microcassette in addition to 1/2 speed standard cassettes that were common for voice recording of interviews and meetings in the police service, inquests, etc.

For more information on high quality audio tape transfer and restoration please visit our transfer pages.

Posted by greatbear in audio tape, 0 comments

how not to pack a reel to reel machine

I use eBay alot. I have to, nobody makes new tape machines anymore and about two or three years ago it took over from the local freeads papers as a way to sell things you didn’t want.

I recently bought an old Teac X7 4 track 1/4″ reel to reel. Seemed like a good deal and I took a chance. With large heavy items I always ask politely if they can ensure it’s packed with lots of bubble wrap in preferably two boxes. I even offer to send the packaging myself if they haven’t budgeted for that or can’t be bothered to wrap that well!

This is what I received after a few days of waiting. The seller seemed excited, saying he’d specially bought a box that cost over £10…

reel_to_reel_packaging_bottom

Reel to Reel packaging bottom

The whole of the bottom of the box had cracked and fallen away. If it hadn’t of been for the nice Parcelforce people who lined it with a bit of cardboard I wouldn’t have got anything.

There was a Teac X7 in it but it didn’t look pretty and is a perfect example of how heavy items can destroy themselves and the packaging if not packed correctly.

reel_to_reel_packing_side

Reel to Reel packaging destroyed

Posted by greatbear in audio tape, 0 comments

reel to reel transfer

studer_nab_reel_spinning

Studer A80 RC reel spinning

Over the last few years we’ve gradually built up our equipment inventory so we can now offer a wide range of audio and video transfers.

We’re very happy to offer all track formats and speeds of 1/4 inch reel to reel tape transfer, from mono / stereo tapes or multitrack recordings.

15 inches per second (ips) and 7.5 ips speeds are normally transferred on, our pride and joy, one of two Studer A80s. We also have a Tascam BR20 and several Revox A77s for backup. The slower speeds and 4 track mono stereo formats are catered for by Teac and Sony machines.

30 ips, 15, 7.5 and 3.75 can also be transferred on our Sony APR 5003.

We take pride in making sure these machines are calibrated and cleaned before each transfer.

Quite often we receive tape in poor condition, frequently a result of splicing tape ‘drying out’ as it’s a bit like sellotape and the splices breaking as the tape is played.

We are able to clean, resplice and repair tape before transfer.

Prices are competitive but not published here as we’ve found each job is different and needs certain attentions that need to be quoted for on an individual basis. We are happy though to offer an assess / listen service, as many customers don’t know what’s on their tapes and either don’t have a machine or their old machine is broken.

Recent work has included many valuable family history 5 inch reels. Remember tape is fragile, very susceptible to magnetic fields and doesn’t last forever. It’s worth transferring it or getting it transferred now to keep your memories safe.

You can see a more comprehensive list of all our audio equipment in our studio here:

http://thegreatbear.net/audio-tape-transfer/studio-equipment-audio/

Posted by greatbear in audio tape, 1 comment