Tape navigation: Home | Tips & Notes | History | Formats & Resources | Projects | Facility | Site Map | Contact

Magnetic Developers — Seeing the tracks

Filed under: magnetic record viewing,magnetic tape developing,tools — 2006-03-08 by Richard L. Hess — Last Edit 2015-11-29 by Richard L. Hess

This has been updated 2015-07 and now 2005-11. We ordered a new 1022 viewer from Arnold/Flexmag as the 2007 Sigma finally gave up the ghost and the 2011 Sigma that I had as a spare is not as good a performer for this application. As of the end of November, we are still awaiting a response from Sigma. Overall, I am quite pleased how well the “fresh” Arnold unit works and it appears more sensitive than the older 3M unit I had even when it was working well. This is now my top choice. It is not perfect, but fits the budget better and performs much better than the newer Sigma. It is also faster than the Sigma ever was.
Please look here, but there is still good information, below.
Two ways of seeing tracks on a tape are listed here. We’re collecting more in the comments. (more…)

Images of Scotch (3M) tape boxes available

Filed under: history,reels,Tape Aging — 2009-02-04 by Richard L. Hess — Last Edit 2015-02-12 by Richard L. Hess

I was interested in the progression of the Scotch/3M tape boxes over the years, especially after someone contacted me because his father was in the picture on some of the 1960s tape boxes.


A New Year’s view of at-risk audio formats

Filed under: -general,archive operations,audio,project notes — 2015-01-11 by Richard L. Hess — Last Edit 2015-01-11 by Richard L. Hess

There are many factors that affect the ability of people like us to digitize tapes for you, our clients.

One of the most difficult issues to balance is the physical space that different formats take up, the ongoing maintenance of these formats, and, to be brutally honest, their return on investment.

What we discovered is that some of the machines we were archiving for future use would not work when they were brought out of storage. Rubber parts, capacitors, and lubrication are probably the most prevalent causes of failure. We have said to clients more than once (with a wry smile), “Yes we can probably restore your tape, but first we need to restore a machine.”

Manufacturer and maintenance depot support for various formats is waning or fully discontinued. Parts are hard to come by, and good machinists with an interest in doing this are either non-existent or very expensive.


Voltage and power matched audio in 2014

Filed under: audio,audio-video systems design — 2014-04-26 by Richard L. Hess — Last Edit 2014-04-26 by Richard L. Hess

I received an email requesting clarification on my 1980 AES Preprint about the use of voltage audio distribution vs. power matched audio distribution for analog audio signals.

The confusion seemed to be about equipment being rated for driving a 600 ohm load. Yes, most professional audio equipment will drive a 600 ohm load, but might (repeat might) lose a small amount of headroom doing so. The better reason to be able to drive a 600 ohm load is to drive long cables which might create slew-rate limiting if they load the output to the extent that they slow it down. It’s all about current. In fact, merely being able to drive a 600 ohm load may not provide enough current to drive very long cables. (more…)

Dangers of old tape recorders for playback; using the elevator head

Filed under: magnetic tape developing,project notes,Sony APR-5000,storage-care-handling — 2009-09-02 by Richard L. Hess — Last Edit 2013-10-30 by Richard L. Hess

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:



Studer A80 RC modifications for 1/2-inch two track and other modifications

Filed under: project notes,Studer A80 — 2012-01-20 by Richard L. Hess — Last Edit 2013-10-09 by Richard L. Hess

In a discussion on 2012-01-20 in the New Studer list, Todor Dimitrov posted the differences between the record and repro boards between a 1/4-inch and a 1/2-inch two-track A80RC repro cards. Here are the changed components for the 1/2-inch version. There are five different oscillator versions in the manual, including one for 1/2-inch.

RECORD: C34=68pF
REPRO: R1=100K; R21=330

Note that the mechanical modifications between 1/4 and 1/2-inch tape handling may be substantially more complex in terms of tuning the transport. I know of no definitive notes on this subject. [Added 2013-10-09]

CBC A80RC Repro capacitor mod

I had previously posted in the original (and now reconstituted) Studer List on 2008-04-24 that there were other extant and possible modifications. Here is a slightly edited and reformatted version of that post:


Azimuth: Hows and Whys

Filed under: archival practices,education,matching head to tape,recording/mastering — 2006-09-27 by Richard L. Hess — Last Edit 2013-06-27 by Richard L. Hess

There is a recurring question as to what is the best way to set azimuth for playing a tape. Many people assume that using the test-tape alignment is best. Well, that makes another big assumption: The recorder used a proper test tape alignment. While that can be the case, it usually is not. (more…)

DAT’s not good…but I’m back in the business

Filed under: digital,Tape Aging — 2011-10-02 by Richard L. Hess — Last Edit 2013-02-05 by Richard L. Hess

The long-term maintenance of digital formats that I do not get a great call for has become a burden. While I would like to have all formats available for all people, I have such a backlog of analog, that I will not be accepting digital-only projects in many formats that I used to.

The formats that I am currently committed to transferring are:

—DATs with two options:
         -straight transfer where we listen for glitches and look at the waveform for glitches (four Tascam DA-20 MKII)
         -error-logged transfer where the machine logs all of the errors it has concealed (Sony PCM 7030)
—PCM-F1 on VHS or Betamax (multiple machines and multiple ES-601 and PCM-F1 decoders)
—Sony DASH (3202 or 3402) 2-channel reel (two each Sony PCM-3202 and PCM-3402)
—MiniDisc (normal stereo in regular and HI-MD, but not porta-studio multitrack; multiple )
          (Sony MZ-RH1 Hi-MD Minidisc recorder with USB download; Sony MDS JE-530 and two other MD players)
—Digital Files on CD, DVD, hard drive, USB drives, etc.

The Phone Plug—Uses and Misuses

Filed under: audio,audio-video systems design,video — 2012-12-12 by Richard L. Hess — Last Edit 2012-12-12 by Richard L. Hess

The ubiquitous phone plug, especially in the 1/4 inch (6.3 mm) size, is extremely confusing to the uninitiated. I was at a church today where I struggled to get a video to play properly in advance of an event in a few days.

The church had a PC and two 60-inch diagonal video monitors (another story). The audio was fed to the good-quality 16-input mixer (Allen and Heath, I think) from the PC’s headphone output.

In the video, there are two places where there is speech and the music is faded into the background. When played in the church, the voice disappeared! This created some angst coupled with erroneous assumptions. I hope this post will perhaps help solve this problem for others. (more…)

Cassette Equalization: The 4 dB ambiguity at 16 kHz

Filed under: cassettes,Tape Aging — 2006-05-17 by Richard L. Hess — Last Edit 2012-12-03 by Richard L. Hess

There have been rumours that Nakamichi used a different cassette standard than the other manufacturers. This is not really the case. Everyone thought they were using the same 3180/120 or 3180/70 microsecond equalization as specified in IEC Pub 60094-1, 1981. There is further discussion from 2010 here.

As I understand the history, both Nakamichi and STL in the late 1970s discovered that when they made calibration tapes based on the published time constants in the standards, their response showed that the then-common BASF alignment tapes were approximately 4 dB high (hot) at 16 kHz.

It is assumed that BASF, who made the calibration test tapes made an error in calibrating their reproduce heads’ response in one of two areas: (more…)

VCR Tracking and Cleaning—A guest article by Jim Wheeler

Filed under: archive operations,digital,video — 2006-03-17 by Jim Wheeler — Last Edit 2012-11-04 by Richard L. Hess

There was an off-line discussion about VHS-Hi-Fi tracking and breakup in Hi-Fi playback and how to correct it. I brought Jim Wheeler into it, and he agreed to write this article. —Richard

I invented the automatic tracking system in 1976 but it is pricey. If you want to pay about $2,000 for a pro-VHS machine, you can get true auto-tracking. Manual tracking works for most tapes. If not, there was a problem with the recording VCR. Alcohol is not good for cleaning heads and tape guides. I always use Xylene and you can buy Xylene at hardware and paint stores. Do not use Xylene on a pinch roller! Have your window open when you use it. I sniffed Xylene for over 30 years and am still okay–okay–okay….I recommend using Xylene for cleaning all components in the tape path except the pinch roller. I recommend Isopropyl alcohol for cleaning pinch rollers. [Some of us are using Formula 409 on pinch rollers—it depends on the pinch roller and its application—Richard] (more…)

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…)

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.


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…)

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.

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…)

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).

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.

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…)

Update to magnetic viewer accessories

Filed under: magnetic record viewing,magnetic tape developing,tools — 2011-04-14 by Richard L. Hess — Last Edit 2011-05-30 by Richard L. Hess

I remain a fan of the Sigma MV-95 magnetic viewer despite its slowness at times. I discussed it at length here in June of 2007. It has helped analyze many problematic tapes and has helped me understand the issues enough to apply the correct solution to transfer damaged tapes.

An example is here. (more…)

Next Page »

Tape navigation: Home | Tips & Notes | History | Formats & Resources | Projects | Facility | Site Map | Contact

©2006–2007 Richard L. Hess — Aurora, Ontario, Canada      Contact Richard