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).

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.

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.

For AAs and AAAs, I have selected the Maha Powerex Imedion cells which retain a charge for an extended period of time (spec’d at 15% loss per year). I have invested in two of the MH-C9000 Wizard One chargers for my office and two MH-C401FS Mini chargers, one for my bedroom and one for the church sound booth. These are both available alone and in kits with cells from Paul’s Finest where he is selling the international version with a multi-voltage “wall wart” for a reasonably good price with great service.

While the MH-C401FS charges batteries individually, and does a good job of it, the MH-C9000 Wizard One is amazing. It will determine the remaining capacity and will even test and condition cells to the IEC standard. For example, I was having a problem with some cordless phones that used 3-cell NiMH battery packs. I took the pack apart and put the three cells in the MH-C9000 and it told me that they had a capacity of about 70, 40, and 40 mAh for each of the three cells. I immediately replaced these three cells with three new Imedion AAA cells that have about 800 mAh capacity each.

I have been using the Maha cells and chargers since April and am very pleased.

A special-purpose option in this are the 3.7 V 14500 lithium polymer AA-sized cells. These will obviously damage many devices that could physically accept them, but for the latest breed of LED flashlight, such as the 4Sevens Quark AA lights (USA site),  these provide superior peak output at the highest setting with the understanding that you can also use standard NiMH cells in an extended emergency with the loss of some peak output.

I have been using the AW-139 dual-cell fast charger also since April with great success. These will charge the 14500 cells mentioned above as well as 17670 cells which are the size of two 123 cells and work well in some LED lights that use two disposable 123 cells. I have been using the Pila version of these cells for about five years in my SureFire L4 LED light and have now bought four more cells for other flashlights. These are available from 4Sevens (USA) as well as other places such as www.dealextreme.com. Make sure you get the protected cells.

Note: This information has been incorporated into this page which contains a more in-depth discussion.

I received an urgent phone call yesterday from a man who had digitized several reels of 2″ 24-track analog recordings that he wished to re-mix.

The tapes were originally recorded in about 1978-1979 and he said that he needed them to have Dolby C noise-reduction processing applied to the files.

I did a bit of research, as that did not sound correct from an historic point of view.

Here is an approximate chronology of the major noise-reduction systems and their dates of introduction:

DOLBY
A – 1967 (pro)
B – 1971 (consumer)
C – 1983 (consumer/prosumer)
SR-1986 (pro)
S – 1990 (consumer/prosumer)

dbx
I (pro) & II (consumer) – 1971

Telefunken (later ANT)
C4 – 1977

He later wrote me back saying the engineer was pretty sure it was Dolby A.

When I applied Dolby A, Dolby B, Dolby C, dbx I, and Telcom C4, only the dbx I sounded close to correct.

Fortunately, dbx I is less critical than the Dolby noise reduction systems for accurate level setting, since there are no test tones digitized along with the audio.

This work requires playing the digital files out through the D-A converter and then re-recording them via the A-D converter.

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.