I finally figured out how to power the Sennheiser MKH-104, 404, and 804 from 48 V phantom power (P48) which is very common on professional and many prosumer mixers and recorders. The MKH-X04 series requires -8V for operation. Please note that some portable recorders do not generate P48 even on their XLR connectors. This will not work with P12 or P24 inputs. It works like a charm on P48 inputs (at least from Mackie, Yamaha, and Sound Devices). Thanks to everyone for their input and assistance.
Year: 2009
Images of Scotch (3M) tape boxes available
| I was interested in the progression of the Scotch/3M tape boxes over the years, especially after Carmine Lauri contacted me because his father was in the picture of a chamber orchestra on the 1960s Scotch tape boxes. Click on each image to see a larger one. Any moire pattern you may see is the screening of the printing on the box beating with the pixel/dot pattern of your monitor. |
 
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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.
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.
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.
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.
40th Anniversary of Apollo 11 Moonwalk and the loss of data
There has been much discussion over the last few years about finding and saving original tapes of the Apollo 11 Moonwalk videos downlinked from the moon. There is also an exciting project going on to restore and digitize the Lunar Orbiter tapes from more than 40 years ago.
The Lunar Orbiter tape digitization folks have just posted a commentary that bears reading by all archivists who are holding tapes. You may link to it here. The main site is www.moonviews.com
NASA, in their press conference yesterday held at The Newseum, admitted that the original 14-track 1-inch instrumentation (IRIG) tapes that contained the slow-scan video direct from the moon were most likely recycled and reused for later missions. Apparently, over 350,000 reels of instrumentation tape were recycled by NASA over time. No one apparently thought to preserve the 45-odd reels of the original moon walk.
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.
Rechargeable battery solutions 9V, AA, AAA
Battery technology continues to improve. In 2007, I bought some Sony fast-charge nickel-metal-hydride (NiMH) AA cells and charger. They have worked well for digital cameras, electronic flashes, and a portable audio recorder. NiMH cells are available in major stores and some offer long-shelf-life-per-charge and come pre-charged.
Recently, I did a thorough search for 9 V rechargeable batteries for wireless microphones at church. I was pleased to discover that iPowerUS (they have a Toronto office) was able to provide lithium polymer 9 V batteries that far outperformed the available NiMH offerings. We bought one DC9V charger and eight DC9V-520mAh batteries for alternate use in four wireless transmitters that we use regularly. We expect this system to pay off in a year or less.
I also bought their GC-60 tester/charger for my NiMH AA and AAA cells which, so far, looks excellent. Both chargers come with a “wall wart” and a car cord.
Zoom H2 line input
The Zoom H2 HandyCorder is perhaps the lowest-cost digital recorder on the market that provides reasonable and useful results. While I have a Sound Devices 722 for my more serious work, I bought the Zoom to test it out to see if it could be part of a simple tape digitization system for archives on a budget who wish to do the work themselves. It does this reasonably well.
As with much equipment–and especially with lower-cost equipment–the performance specifications and the actual operational data is not published. There are reports of the H2 clipping on the line inputs in some of the reviews and it appears that a lack of understanding how the inputs were configured exacerbated that situation.
There is nothing wrong with the line inputs on the H2. BUT there are some caveats:
Kodak Durol triacetate tape with bad vinegar syndrome
I recently received two 7-inch reels of Kodak Type 31A Triacetate tape (1250 feet, Durol Base) that smelled of vinegar even before I got the envelope open.
These tapes were badly warped due, most likely, to the vinegar-syndrome induced differential shrinkage. Other factors may have been poor winding during long-term storage (I had received them after several attempts to play them on another machine).
An unorthodox dual-WAN approach
Since moving to Aurora in the fall of 2004, and going into audio tape restoration full-time, I have struggled with the correct mix of connectivity. My rather unique needs require that I have upload speeds as fast as reasonably possible.
Microphone Powering Schema
In addition to my business of transferring tapes, I also record a few community groups for fun. Someone recently gave me an older Sennheiser MKH-804 interference tube (“shotgun”) microphone. Finding information on how to connect it proved more difficult than expected.
In the 1960s, transistorized microphones from AKG, Neumann, Schoeps, and Sennheiser became available. There are several niches of early microphone powering that continued on for many years. Perhaps the easiest way to look at it is backwards.
Dangers of old tape recorders for playback; using the elevator head
We are currently working on some un-published tapes for a major Canadian folk artist. We have a 7.5 in/s 2-track stereo recording that was one of (if not the) first studio recording of this artist from circa 1972.
At some point, this tape was played on a 1/4-track machine that injected hum onto the left channel. Here’s what the magnetic viewer showed:
Rechargeable battery solutions: AA and AAA
I wrote about rechargeable batteries back in April 2009 and while I have expanded the installation of the iPowerUS 9V batteries to three chargers and twelve batteries at the church and one charger and four batteries in my facility, I have adopted a different approach to AA and AAA cells from that outlined previously.
Long-term stability of different batches of Ampex 456 – a guest article by Gary Galo
Here’s some info that might be useful concerning which batches of Ampex 456 are good and which have sticky shed problems.
I recently unearthed 26 brand new 10 1/2-inch reels of 456 from 8 different batches. I checked one reel from each batch by playing them back and forth at 15ips (I only played the bad reels in one direction – that was enough!). The following batches were bad: