There are complex interactions between tape speed, track width, frequency response, and dynamic range. This article is an attempt to summarize the major influences.
Cross-point screws take two: JIS vs. PoziDriv
I received the following in an email from a person only identified as Ross. I thank him. He sent me the following in reference to this post. concerning Philips and PoziDriv screws as used on Nakamichi Dragons and other Japanese equipment. I, too, have a set of Hozen drivers which I obtained from www.escience.ca
Winding tapes for long-term storage—a quandary
In 2006, I wrote a blog post (here) called “Let Sleeping Tapes Lie: What to do with poorly wound tapes”. For years, tape experts have been suggesting that it is not as good an idea to rewind tapes as was originally thought. This was partially based on the fact that most rewinding in archives was done on the oldest, junkiest machines so as to not wear out the good machines. Unless rewinding is done on high-quality tape transports, it is indeed counter-productive.
We continue to receive poorly wound tapes and are able to play them successfully. So why the quandary now? The reason is that I read portions of another Bharat Bhushan book, Mechanics and Reliability of Flexible Magnetic Media, 2nd Edition, New York, Springer, 2000. Referring to several research papers he makes a compelling case that tapes should be rewound annually if subject to storage environment fluctuations and every 3.5 years if kept in a climate controlled storage area.
StoryCorps experience including equipment discussion
My friend Susan Kitchens and her brother took their parents to the StoryCorps recording session in Los Angeles a few weeks ago. She blogged it here. One of the neat things is that between her article and the discussion she and I had in the comments, we have a good handle on most of the equipment that was used in the trailer. It’s a good selection in my opinion and shows how simply good-quality recording systems can be set up. Further discussions from a StoryCorps representative have shown how clever the setup is.
Hard disk formats for interchange
The question of how to format hard disks (i.e. what file system to use on them) for easy interchange is another FAQ. A recent experience brought home the fact that it is more complex than one might hope. The computer industry is headed towards universal readability, but it is not there yet. The most-able-to-be-read-and-written format appears to be FAT32, although my friend Eric Jacobs makes the point that NTFS is a more robust hard disk file system, and I have to agree.
How to play 4-track 1.875 in/s tapes…
I received a query from a gentleman in Europe about 1.875 in/s 4-track tapes. He was frustrated in finding a good machine for transferring them. Apparently, they have many of these tapes. Here are my suggestions.
Perhaps the easiest answer is to find a Studer-Revox C274 with low speed options. They were made.
Two other options.
Aligning a tape recorder
It seems some people new to tape are confused over how to align a tape recorder. This is the abbreviated version.
If you want to record on a tape recorder (and I do not recommend doing that these days as you’re just generating more tapes that will need to be transferred later) the first thing to do is get the playback correct.
- CLEAN the machine.
Using the proper tools…and don’t try this at home!
I didn’t think I needed to write this post, but it appears that someone purchased a Racal Store 4DS Instrumentation Recorder at least partially because I mentioned it, hoping that it would work as a four-track recorder for creating music.
Magnetic Tape Splicing
I received an email asking me to discuss tape splicing. Most of my work is now repairing old splices so I try and butt them together as best I can in an Edi-Tall block and use the blue Quantegy splicing tape (which will become harder to find with Quantegy exiting the business). I will not be evaluating a replacement for several years as I bought a large supply a few years ago.
RCA “Sound Tape” cartridge and 1/4-track reel introduction dates
David Dintenfass kindly sent me an article from the October 1959 issue of Popular Electronics which says, in part, that RCA plans to have 65 titles in the stores in their new cartridges by Christmas 1959. Other manufacturers were shown to be making compatible players.
Slow speed 4-channel cassette digitization
There has been some discussion recently about the 4-channel cassette recorders that were used for court reporting and other logging- or court-reporter-type applications. It seems that the players only have one output and can select any combination of one or more playback channels into that one output.
This monitoring topology is actually identical to two 1-inch 40-channel reel-to-reel logging machines I have where one can listen to any combination of one through forty tracks on a single output.
TAPE Project Audio Tape Digitisation Workflow
The Training for Audiovisual Preservation in Europe (TAPE) Project has just published an excellent Audio Tape Digitisation Workflow document here. It is authored by Juha Henriksson of the Finnish Jazz & Pop Archive and Nadja Wallaszkovits of Phonogrammarchiv, Austrian Academy of Sciences. It is aimed at the newcomer but still addresses all of the major points without being overwhelming.
Digital storage file systems and topologies
Once again, an interesting post on Jill Hurst-Wahl’s Digitization 101 Blog. She started by discussing tape backup issues. In the comments, I discussed my solution of using multiple spinning disks. Another commenter, Ike, provided an extensive review of file system options and his opinions on what works (and doesn’t) for long-term storage. Ike’s comment is fascinating and has lots of food for thought. Here is the post.
Who invented the electret? And some microphone basics…
My friend Susan Kitchens blogged about the history of the electret as in electret condenser microphone. It’s an interesting piece of history. I added a little primer to the post on microphone basic types. Look here.
Headworn microphones and other means of recording voice
For the last several years, I have been involved with sound reinforcement and recording at my church. I have upgraded the PA system and we’re in the midst of final editing/mastering for an upcoming Christmas CD.
In the process of doing this work, I have learned a few things which might be of assistance. This is the first post in the blog in the live sound and recording category. Many of the posts relating to microphones will also be tagged in the oral history category.
Studer A807 digital noise improvement
I received an email from Andrew Pearson of the British Library providing some hints in reducing noise during playback on the Studer A807 tape machine. He would be interested in hearing from people who had other ideas and people who had either successes or failures attempting his techniques.
New Degrading Tapes page
We have pulled the list of degrading analog audio tapes out of the blog postings (which age) and put this information into the Formats hierarchy under Analog Audio Tapes, click here. Please note that we have fudged the hierarchy by starting the title with a hyphen, so it sorts to the top of the Analog Audio Tape grouping, above 0.15″ cassettes.
We hope to update this as we come across more types. January 2009 was, sadly, fruitful in finding at least some batch(es) of two tapes from 1990 (Agfa PEM 526) and 2003 (Emtec SM911) are degrading. The Emtec SM911 was thought to be more-or-less immune from this disease. As of this writing, it has been confirmed that batch number B0134007 was involved.
Back-coat turning to powder
We have just seen a modification on the Sticky Shed Syndrome (SSS) failure mode. This is a case where the back-coat of the tape is turning to powder. The oxide was brown but yet it left a black, non-sticky accumulation of powder on the reproduce head. This accumulation would drastically reduce the high frequency response of the system due to spacing loss. We did bake the tape and we’re not sure that helped significantly, although it did not appear to make the problem worse. We would NOT recommend baking these tapes in the future. Ultimately, Pellon wiping of the mag coat during transfer after several pre-wipes for the length of the tape solved this.
Agfa PEM-526 exhibited this odd behaviour. The tape was recorded in 1990.
There is also a discussion about PEM-469 showing similar behaviour here.
For a current list of degrading analog tapes, click here.
ARSC Journal Tape Degradation article available online
My paper on “Tape Degradation Factors and Challenges in Predicting Tape Life” that was published in the Fall 2008 issue of the ARSC Journal is now available online. Click here.
Microphone (XLR) connector history
Ray A. Rayburn has just updated his page on the XLR microphone connector and its antecedents. Very interesting. While not a major issue in tape recorders, it is in studio practice and for microphone collectors.
A solution to reduce spoking in old acetate tapes
It appears that many old acetate tapes when played on high-quality audio recorders will suffer spoking when left in a play wind condition. I have discussed this problem here. Since posting that, I have taken one of my Racal Store 4DS recorders and removed the heads to save them from wear and now use that to re-spool any tape that shows spoking when played on a Studer A80, Sony APR-5000, or Studer A810.
Packing equipment for shipment
It has become obvious to me that there are good ways and bad ways to pack equipment for shipping.
There are some basic goals that one needs to achieve in the packing.
- Protect the equipment from excessive shock and vibration
- Keep the equipment solidly centred within the outer box(es)
- Keep the equipment safe from small object impacts
- Prepare it to be dropped
CD-DVD printing revisited
For many years, I had been in favour of the Primera Z1 small optical disc printer. When Primera discontinued this several years ago, I was not pleased and purchased two as spares, hoping at least the ribbons would continue.
It appears that I am not alone in thinking this is a good product as it has resurfaced as the U-Print CDP78, now in black, and available from many online distributors. The cartridges appear to be interchangeable with the Primera. I can now suggest that this is a good alternative for safe, long-lasting, and reasonably attractive text labeling of CDs and DVDs. It appears that the Teac P11 is also similar. The last time I checked, the Casio required manual rotation of the disk, rather than the Primera’s automatic rotation.
Please provide me with any feedback pro or con—preferably as comments to this post.
Mono and stereo cassettes
The format page for 0.15 inch wide tape has a drawing (click for large version) that clearly shows that mono cassettes have one wide track and stereo cassettes split this track in half and add a small guard band. Most mono cassette recorders follow this format. It turns out that the mono Marantz PMD201 uses a two-channel head and records dual mono. Most other mono recorders seem to follow the standard.
While this is a theoretical problem, few if any good mono recorders are available for reproducing these tapes anyway, so most of us in the domain transfer field use good quality stereo machines for all cassette transfer work.
UPDATE 2012: While it is often possible to sum the channels if the Dragon finds proper azimuth, on many low-quality tapes this proper azimuth is not achieved. Now that azimuth correction (at least the time delay portion) is available for a reasonable price in iZotope RX2 Advanced, I have found that after correcting for time delay between channels that I can now sum both (if they are worthy of it) and reduce the noise prior to applying the noise reduction plug-in.
Comments in this blog…
I apologize, but I have been receiving 2000 spam comments a week recently and it fills up my inbox and the users have to be deleted. They’re not going to get their comments posted, but I’m tried of this. If you wish to leave a comment on this blog, please email it to me and I will post it in the article. Sorry. I am moving all the excellent comments into the articles and that should be done shortly.
File backup strategy and utilities
My storage systems have grown to keep up with storage needs. I am currently running two NAS units in RAID-5:
Unit #1 for client audio projects is a Netgear ReadyNAS NV+ with four 1500 GB drives, providing about 4.3 TiB of storage.
Unit #2 for personal projects and general data is a Thecus N5200 Pro with five 1000 GB drives, providing about 3.6 TiB of storage.
These two units are then duplicated off-site and connected by a fibre optic link (currently running at 100 Mb/s while the rest of the network is running at 1000 Mb/s).
Five historic standards now linked from the history page
About two years ago, I asked the EBU to make available a copy of their historic document, Review of existing systems for the synchronisation between film cameras and audio tape-recorders and they complied, making it available on their website.
I asked the National Association of Broadcasters about their Cartridge, Cassette, and Reel tape standards as well as their Disc standard and they gave me permission to post these standards at my website.
These five standards plus some other articles of historic interest are available here in the history portion of this website. I hope that you find these of use in unraveling some of the challenges that old media present.
Another way to identify a tape with Sticky Shed Syndrome (SSS)
For a current list of degrading analog tapes, click here.
Teaching people how to identify tapes that are suffering from sticky shed syndrome is often difficult.
I would like to propose that a careful inspection of how the tape comes off the pack may be a good way. Please provide comments as to how it’s working for you.
The tape should come off the tape pack at a precise tangent to the tape. If the tape starts to adhere and not pull off straight, that is a sure sign that the tape needs baking.
Of course, don’t bake acetate tapes even if they show this indicator, but on the last batch of questionable SSS tapes, I’ve been looking at this and it’s a fair indicator, and it seems to show at the outer edge of the pack.
More than one “test” or “factor” is needed to be sure, but this one is looking good.
Another almost sure sign of SSS is brown oxide and black back-coat.
Peter Copeland Audio Restoration Handbook now available
I consider myself fortunate to have been one of many recipients of Peter Copeland’s generous assistance while working with some challenging tapes. I was saddened by his too-early passing in 2006.
The British Libary has now published his Handbook (click here).
Sony APR-5000 head assembly problem
I was having slightly intermittent connections on one head assembly on a Sony APR-5000 and was concerned as to the cause because the 78-pin head connectors are essentially unobtanium and a headache to change.
As I installed and de-installed the head, I got to thinking that the connector might not be positioned correctly (i.e. perhaps the wrong hardware had somehow found its way into the connector mounting system.
When I measured the bottom (oriented as if the head were mounted in the machine) face of the connector mounting flange referenced to the bottom of the mounting posts (using a straight-edge across two of them), I discovered that, indeed, this connector was recessed about 25 mils (0.025″) further into the head assembly than several other ones. Adding a 25-mil thick washer should solve the problem.
This is posted in case you’re scratching your head with a similar problem. This is something I wouldn’t have immediately thought of. I don’t know if this was caused by aftermarket work or if it perhaps represents a manufacturing error.