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Mono and stereo cassettes

Filed under: archival practices,cassettes — 2008-05-22 by Richard L. Hess — Last Edit 2012-10-28 by Richard L. Hess

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. (more…)

RCA “Sound Tape” cartridge and 1/4-track reel introduction dates

Filed under: cartridges,history,reels — 2007-11-26 by Richard L. Hess — Last Edit 2012-10-18 by Richard L. Hess

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. (more…)

Source for D5 (Decamethylcyclopentasiloxane)

Filed under: Decamethylcyclopentasiloxane,Tape Aging,tools — 2012-10-09 by Richard L. Hess — Last Edit 2012-10-11 by Richard L. Hess

I have recently been looking to replenish my supply of D5 (Decamethylcyclopentasiloxane) and did not have much luck receiving replies to my email. Others have reported difficulty finding this in quantities smaller than a 55-gallon drum.

I found a promising listing for cyclopentasiloxane and when I queried the supplier, he indicated that the analysis was 97.5% decamethylcyclopentasiloxane and the balance being octomethylcyclopentasiloxane. I suspect that is more than good enough for tape work.


Personal Image Scanning Project

Filed under: project notes,scanning,still images — 2011-11-05 by Richard L. Hess — Last Edit 2012-10-09 by Richard L. Hess

In the 2007-2008 school year, my son Robert asked me why we did not have all our family images in the computer as there were some that he needed for a report. Since this was a project I had desired to undertake for some time (but who has the time), I responded with “I’m very glad you asked, what are you doing for a summer job?”

As of September, 2012, the bulk of the work has been completed and here are the statistics:

scanning stats 2012-09-11


Playing a squealing reel of Sony PR-150 tape using D5 (Decamethylcyclopentasiloxane)

Filed under: archival practices,Decamethylcyclopentasiloxane,project notes,Sony APR-5000,Tape Aging — 2012-10-01 by Richard L. Hess — Last Edit 2012-10-01 by Richard L. Hess

Today I worked on a batch of five Sony PR-150 7-inch reels recorded at 3.75 in/s in one direction, two-track mono. One of the five reels showed marked shedding during fast-wind/rewind (to get the original reel as takeup and to check the tape pack). Four of the five reels played fine. This one squealed horribly. I ran the tape up and back over the dispenser and then fixed it in position for running the tape over it during the playback session. Once again, D5, Decamethylcyclopentasiloxane, CAS Number 541-02-6 comes to the rescue. The lovely thing about D5 is that it evaporates.

APR-5003 with D5 dispenser

Is this better than cold playback? I don’t honestly know. Both work. This is easier if there is no reel machine standing by for cold playback (which there was not today). I keep a Nakamichi MR-1 in the refrigerator so it is ready to go when I need it. The Studer A810 I put in the fridge did not like it. The capstan motor seized up AND the heat output overwhelmed the refrigerator’s capacity to cool. I suspect the APR would also overwhelm the refrigerator’s capacity. Also, it is much easier to lubricate a reel than a cassette.


Speed variation with unmatched reels

Filed under: archival practices,reels — 2012-09-20 by Richard L. Hess — Last Edit 2012-09-20 by Richard L. Hess

I received an interesting question from a European tape user with whom I frequently correspond:

“Is there any speed variation when playing a tape with different hubs on the supply reel and take-up reel?”

And I replied:

You raise an interesting question. The easiest answer to this is simple:
There is a risk of speed variations throughout the reel if the tape tension varies throughout the reel.
followed by the corollary:
This effect is made worse if the condition of the capstan / pinch-roller system is degraded.
Some capstan / pinch-roller / constant-torque systems handle this better than others.


Update (2012-08) Kyread spray-on magnetic viewer fluid

Filed under: magnetic record viewing,magnetic tape developing,tools — 2011-05-30 by Richard L. Hess — Last Edit 2012-08-07 by Richard L. Hess

In several articles on magnetic viewers, we have discussed the spray-on Kyread product.

GOOD NEWS! The company is back! I received a phone call from Ryan Blackwell this afternoon and he pointed me to their new website. The company name is now Kyros Technologies LLC.

Note their jump into the 21st century with a real website and great domain name: — they even have a shopping cart for online ordering. This is apparently the same product I’ve been using for the last eight years.

DTRS (DA-88) Transfers now available through TASCAM

Filed under: digital,outsourcing — 2012-07-20 by Richard L. Hess — Last Edit 2012-07-20 by Richard L. Hess

TASCAM has set up a very reasonably priced transfer service for multiple-cassette projects recorded in the DTRS format (DA88, etc.).

For more information, click here.

I cannot warrant this service, but what could be better than having it attached to the service facility. I have listed other resources on my format page.


File backup strategy and utilities

Filed under: data storage,infrastructure,tools — 2008-07-25 by Richard L. Hess — Last Edit 2012-05-19 by Richard L. Hess

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).


Phantom powering of early proprietary- and T-powered Sennheiser mics

Filed under: history,live sound and recording — 2009-03-07 by Richard L. Hess — Last Edit 2012-05-09 by Richard L. Hess

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.  (more…)

Tape recorder bias frequencies

Filed under: cassettes,recording/mastering,reels — 2008-02-02 by Richard L. Hess — Last Edit 2012-03-25 by Richard L. Hess

The discussion of what bias frequencies were used over time keeps recurring. Special thanks to Jay McKnight of Magnetic Reference Lab, Tom Fine, and Brian Roth  for input to this list. I posted this to the ARSC list, but wanted to include it here as well. This knowlege is useful for those who wish to archive the bias along with the audio for future application of time-base-error correction tools such as the Plangent Processes.

Bias frequences started low, apparently with 60 kHz for early consumer recorders, but Ampex started with 100 kHz. Other later machines used different bias and erase frequencies. We can see with a few exceptions, the top bias frequencies were commonly limited to 250 kHz for audio, with the Sony APR series and the Ampex ATR series in the 400 kHz region. For cassettes, a practical maximum appears to be about 150 kHz. Much higher frequencies (up to at least 8 MHz) were used in instrumentation recorders. An enumeration of several machines follows. (more…)

Gap Length

Filed under: magnetic tape developing — 2012-03-06 by Richard L. Hess — Last Edit 2012-03-06 by Richard L. Hess

This page provides a table of signal wavelengths for different speeds and frequencies. It is sometimes useful in understanding bandwidth limitations at the high end for a particular head. The first null occurs when the wavelength of the signal is about 112% of the optically measured length of the gap. A common place to set the gap length is for a 4 dB loss at the highest frequency of interest. This corresponds to the half wavelength indicated in the table below. See Mallinson, John C., The Foundations of Magnetic Recording, Academic Press, San Diego, 1993. pp 95–96. (more…)

Agfa PEM-469 success

Filed under: project notes,storage-care-handling,Tape Aging — 2012-02-26 by Richard L. Hess — Last Edit 2012-02-26 by Richard L. Hess

We had success transferring two reels of one-inch Agfa PEM-469 tape that was shedding and leaving a waxy clear-to-yellow exudate on everything. We were happy to get through these and recover the content. This is discussed in more detail towards the bottom of our Degrading Tapes page—hopefully the most up-to-date resource on the Web about problem tapes. Please let me know if you would like to help me add anything to the page. It is there for everyone struggling with old degrading tapes. If you haven’t looked already, please look at my paper on the subject.

Capturing both directions of a half-track mono tape

Filed under: archival practices,matching head to tape,recording/mastering — 2012-01-06 by Richard L. Hess — Last Edit 2012-01-06 by Richard L. Hess

It is possible to capture both directions of a two-sided half-track mono tape in one pass.

The critical factors are:

  • Azimuth
  • Direction
  • Polarity


Playing full-track mono tapes

Filed under: archival practices,matching head to tape — Richard L. Hess — Last Edit 2012-01-06 by Richard L. Hess

About ten years ago, when I transferred the oldest tapes in the United States as part of the Mullin-Palmer collection, my good friend Don Ososke pressured me to use a full-track head for the project. I had started transferring these full-track tapes with a Woelke NAB stereo (two 80 mil (2 mm) tracks) head and recording both channels. When I obtained a Nortronics full-track head, the difference was night-and-day. The full-track reproduction sounded fuller, smoother, and quieter. There were no tracking problems to speak of that would cause azimuth wander large enough to create a “flanging” or “phasing” effect of in-and-out high-frequency loss. (more…)

Playback of NAB 2-track tapes on a DIN Stereo (Butterfly) head

Filed under: archival practices,matching head to tape,reels — 2007-09-12 by Richard L. Hess — Last Edit 2012-01-06 by Richard L. Hess

I received a query from Sweden today asking

I have a Studer machine with butterfly heads with which I’d like to reproduce
tapes recorded with normal two track heads. Theoretically, how much more noise,
in dB, would I get from playing the “empty” part of the tape?

Let’s look at the assumptions.


Tape speed, track width, frequency response, and dynamic range

Filed under: matching head to tape,recording/mastering — 2007-08-26 by Richard L. Hess — Last Edit 2012-01-06 by Richard L. Hess

There are complex interactions between tape speed, track width, frequency response, and dynamic range. This article is an attempt to summarize the major influences. (more…)

Track Configuration page updated

Filed under: reels — 2011-02-04 by Richard L. Hess — Last Edit 2012-01-06 by Richard L. Hess

I added a Track Configuration page to the resources hierarchy in the sidebar at the right. This points to other resources on the web to provide further insight into the various analog audio track configurations. There is also a brief note there about the variation in the two-track, half-inch format. These differences are minor, but they could be a source of some problems under some extraordinary circumstances.

This page was updated 2012-01-05 to provide track widths on higher-density audio multi-track formats.

A link to the Studer track dimensions page was added 2012-01-06.

Data storage options — small scale

Filed under: computer/data — 2006-03-07 by Richard L. Hess — Last Edit 2012-01-05 by Richard L. Hess

Large-scale, enterprise-class storage is using combinations of both disc and tape. LTO tape appears to be growing more than any other format.

What is described in this article is obsolete in a large part. Please see the Data Storage category for current thinking.

For those of us who are working at a much smaller scale, I have provided references on what I do for fairly robust storage on a budget. Please see these two attachments: description and map. It shows a unified (I hope) approach useful to small archives and businesses. (more…)

What those little ©, ?, and ® symbols mean…

Filed under: -general — 2011-12-21 by Richard L. Hess — Last Edit 2011-12-21 by Richard L. Hess

There are several symbols that are widely used to denote that intellectual property is protected.

Circle with a C in it © Wikipedia

Circle with a P in it ? Wikipedia (more…)

Obsolete data formats

Filed under: archive operations,audio,computer/data,history,video — 2011-11-22 by Richard L. Hess — Last Edit 2011-11-23 by Richard L. Hess

This is a reminder that data formats come and go just like audio and video formats. On this, the 48th anniversary of the JFK assassination, this article was posted at the Library of Congress website. It talks about first locating and then converting research data held on IBM 80-column punch cards. I remember working with those my first summer job back in 1967! I guess I have a penchant for obsolete formats, as I learned a good deal about IBM’s unit record equipment, including the amazing 407 (introduced in 1949). That certainly was not as useful as knowing about analog tape now.

The punch cards were found and converted. This is a much happier fate than that suffered by the original IRIG 14-track 1-inch tapes of the Apollo Moon Walk from 1969! I am currently digitizing 14-track 1-inch seismic tapes surrounding the Mount St. Helens eruption in 1980. (more…)

Slow speed 4-channel cassette digitization

Filed under: loggers,loggers — 2008-02-23 by Richard L. Hess — Last Edit 2011-11-12 by Richard L. Hess

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. (more…)

Slide Storage Warning – Airequipt 2 x 2 Slide File

Filed under: archival practices,photography — 2011-08-22 by Richard L. Hess — Last Edit 2011-08-22 by Richard L. Hess

Over the years, I’ve used various methods of storing 35 mm colour transparencies. Until 1992, I used mostly metal slide boxes, but I do have about five Airequipt 2 x 2 Slide Files which are a hard plastic. One of them was sitting on a painted steel shelf and I found some oozing degradation components that were oily/greasy and rust where the paint on the shelf was scratched (probably prior to the box being placed on it).

These boxes have bubbled to the top of the priority list. The interior and slides seem to be fine…for now, and the other boxes are showing little or none of the symptoms of the one (which is probably not the oldest). The slides in this box date from 1983, but the box is almost certainly older. The Logan and Brumberger steel files are, as expected, holding up well, but I am migrating the images to hanging slide sheets from Transparent Office Products. I suspect that I’ll end up with about 2,500 sheets with probably 16 slides/sheet on average…and that will fit in seven file cabinet drawers (2′ deep). These sheets were originally sold by Franklin Distributors until Transparent took them over about half a decade ago. I bought my first sheets from them in 1991 or 1992 and they are still doing fine. Some other alleged to be archival sheets from the same time did not do as well.

We are scanning all of the images as we move them using a Nikon Coolscan 5000ED with SF-210 slide feeder.

Peter Copeland Audio Restoration Handbook now available

Filed under: archival practices,audio,education — 2008-09-14 by Richard L. Hess — Last Edit 2011-08-20 by Richard L. Hess

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).

CD-DVD printing revisited

Filed under: archive operations,tools — 2008-05-22 by Richard L. Hess — Last Edit 2011-06-30 by Richard L. Hess

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.

End of the 3.5″ floppy disk

Filed under: archive operations — 2010-04-27 by Richard L. Hess — Last Edit 2011-06-30 by Richard L. Hess

CNET reported yesterday that Sony will be stopping sales of its 3.5-inch floppy disk media in March 2011 in Japan. Apple stopped supplying these as standard equipment in 1998 and Dell ceased that practice in 2003.

While this medium is not widely used for audio or video, there is, I suspect, still a large amount of ancillary data kept in this format. I will look through my collection and see if there is anything else I need to capture to my servers before my drives die.  I would not entrust anything important to this format.

We stopped using these about three or four years ago, with the last holdout being school work brought home. Now, even that is done on USB keys.

Open Source software…and other tools II

Filed under: education,software,tools — 2011-03-01 by Richard L. Hess — Last Edit 2011-06-30 by Richard L. Hess

This is the second installment of my open-ended quest for great software. The previous (and inaugural) article is here.

The excitement is that the current version of LibreOffice has removed a good deal of the startup sluggishness. While still not as fast as MS Office 2003, remember with LibreOffice, you are starting the whole suite essentially. There is an option to load it at startup, which I do not use. (more…)

StoryCorps experience including equipment discussion

Filed under: archive operations,digital,live sound and recording,oral history,recording/mastering — 2008-02-03 by Richard L. Hess — Last Edit 2011-06-30 by Richard L. Hess

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.

Watch those insects!

Filed under: -general,archival practices — 2011-05-31 by Richard L. Hess — Last Edit 2011-05-31 by Richard L. Hess

OK, this is not directly related to audio, but three audio people I know have been bitten by insects this spring and have suffered greatly for it. One was bitten by a spider in California, one almost died from a flea bite in Texas, and another received a suspected spider bite in Pennsylvania…so be careful…you never know where nasty insects might be hiding…maybe even under a tape box!

If you are worried about what to do, a friend, though a staunch vegan, squashes spiders. Of course, certain spiders are good and eat other insects, so this is just another one of those tough decisions in life.

And then there is mold. A good friend’s life was cut short by interaction with mold, though he was a smoker much of his life, so I’m certain that contributed to it.

As my Dad used to say, “you don’t get out of this life alive”, but he made a good run for it, living until age 93!

Seeing the tracks II — An improved magnetic viewing system

Filed under: magnetic record viewing,magnetic tape developing,tools — 2007-06-20 by Richard L. Hess — Last Edit 2011-05-30 by Richard L. Hess

I first wrote about seeing the tracks here in March of 2006. While these solutions work, the Plastiform viewer needs to be kept in a humidor and the Kyread spray is a bit of mess to use and the results are variable. One result of the Kyread treatment can be seen here (please wait for the pictures to load, it’s a big page).

Here is what appears to be a vastly improved solution:

Closeup of the viewer (more…)

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