The critical factors are:

• Azimuth
• Direction
• Polarity

The azimuth of both sides needs to be the same. If the two sides were recorded at different sessions and/or on different machines, then there is no guarantee that azimuth will be the same on both sides. In a large-volume project, this can be addressed by installing two repro heads, one for each direction, and adjusting azimuth separately. This does not work well for stereo tapes with different azimuths because any temporal perturbations in either the recording or reproduce passes will result in severe stereo image shift. If a record head had azimuth scatter between the two channels, it is best to split the difference, if possible without severe high-frequency attenuation.

Obviously, the direction of the playback needs to be reversed in the DAW (Digital Audio Workstation) software, but that happens pretty quickly on a current computer.

Not-so-obviously, the polarity of the signal is also reversed when played backwards. That, too, can be addressed, possibly in the same pass or, worst case, a separate pass in the DAW software.

This is not recommended for any tapes using noise reduction such as Dolby or dbx, nor for the highest quality of music. However, most two-track tapes recorded on both sides are not of this quality.

Related posts

About 2004-2005, I had some full-track 7.5 in/s tapes to transfer that had been badly warped and found that there was enough azimuth wander that the tapes sounded better using one channel of an NAB stereo head. If I used the full track head, while the results were quieter, the azimuth phasing was unacceptable. At that point, I was using a Studer A810 for this type of transfer.

A few years after that, I was asked to recover audio from a 7.5 in/s full-track tape that was part of the Monterrey Jazz Festival. The client was very impressed at my efforts. I was able to use the full-track head, but one of the major differences was that this time it was on a Studer A80RC rather than a Studer A810 and the difference in tape guiding seems to have been the “magic” in that transfer.

The rule is use the most stable transport available and the widest head available to capture as much of the sound as possible without annoying azimuth-wander-based high-frequency combing/phasing effects.

If you use a head narrower than the full-track width, there may be objectionable low-frequency fringing that would need to be compensated.

Related posts

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.

Many analog and digital formats are becoming harder to recover. David Crosthwait at DC Video lists many at-risk video formats that he can transfer. I was contacted today by someone wondering if I knew where to transfer QIC DC-600A data tapes. I said I did, and sent him to Chris Mueller who can transfer many formats including most QIC formats.

The point is, however, I don’t know how much longer all of this equipment will be workable. Ten years is pretty much a certainty. Fifty years is a very long time. Please, search your archives now for obsolete formats that still need to be converted. There are people who can still recover content from a wide variety of formats, but we and our equipment are all aging, as the Library of Congress pointed out. They had to repair the punch card readers before the Kennedy data could be captured. It’s getting more and more common to hear: if you want me to recover that data, first I have to restore the old player.

I have given up maintaining an 8-track cassette playback machine as the call wasn’t there. I sold it to another restorer, so let’s hope he will bring it back to life. Little by little, the less-widely used formats will fade away. My first 7-track 1/2-inch IRIG tape recovery in 2006 came to me after a long search in North America and Europe with no success. At that point, I did not own any real IRIG machines (I now own several). I used a modified audio recorder and a 1/4-inch 4-track instrumentation machine for the FM demodulation. So there are not many people capable of playing IRIG instrumentation tapes. I don’t think there are too many people able to recover 9-track data tapes.

Please, before it’s too late, bring your data into the 21st century. Be prepared to be told at some point in the future “it’s too late–no one can do it”. Another piece of luck was finding some old tape machines in someone’s garage for the recovery of the Lunar Orbiter images. They were almost lost. There are so many formats and all of them require dedicated hardware to recover the data.

This caused me to increase the storage capacity and was actually the impetus for the purchase of the pair of Thecus NAS units in 2008. The storage impacts and other computer-related articles are discussed here.

This article addresses the scanning side of the project.

In reviewing this project, we had a large number of formats (sound familiar?) that needed to be addressed, and it grew beyond the original proportions when we decided to add in the summer of 2011 paper reference files.

• Reflective material:
  • photographic prints up to 8 x 10 inches, colour and black and white
  • photographic albums containing multiple prints
  • magazine and newspaper articles, standards, other documents up to letter / A4
  • larger-sized newspaper articles
  • engineering drawings up to 11 x 17 inches (ledger)
  • engineering drawings larger than 11 x 17 inches
• Transparent material
  • 110 negatives (colour and black and white)
  • 35 mm negatives (colour and black and white)
  • 35 mm transparencies (including Kodachrome and Agfa Rapid)
  • 127 “Brownie” negatives (colour and black and white)
  • 120 roll film (6 x 6 and 6 x 7 colour transparencies and black and white negatives)
  • 6 x 9 cm (Plaubel? black and white negatives)
  • 616 “postcard” black and white negatives
  • 4 x 5 colour transparencies and black and white negatives
  • 5 x 7 colour transparencies and black and white negatives
  • 5 x 7 black and white glass negatives in tricolour sets
  • 8 x 10 glass negatives in tricolour sets

This collection has come together from many sources. The biggest chunk is mine,  but I have materials from my family, my wife’s family, my stepmother’s family, and my mentor, NYC fashion photographer, Milton F. Gentsch. All of Milton’s prints were donated to the Fashion Institute of Technology, but they did not want the negatives, so I have retained about 3 cu ft of them, including all the tricolour glass negatives.

The bulk of my collection is 35 mm transparencies, and the bulk of the family photos of my immediate family were on 35 mm colour negative.

My son Robert and I scanned in 2008 and my sons Michael and Robert did split-shift scanning in the summer of 2009. Robert did a few family albums in 2010 and did a massive job on paper and slides in 2011.

We started out knowing we’d need a great 35 mm tool, so bought (apparently just in time) a Nikon Super Coolscan ED-5000 with SF-210 slide feeder. We had a Hewlett Packard Scanjet 5590 with duplex sheet feeder. We soon realized we needed a high-end flatbed scanner so, after doing some projects for people, purchased an Epson V700.

Our scanning rules were basically simple:

Quality 35 mm images were scanned to 36 MB files (12 MP, 8 bits/colour) and snapshots were scanned to 18 MB files (6 MP, 8 bits/colour). this was based on many considerations, including the fact that the Nikon D100 images (6 MP) were more than fine for any family images, the Nikon D200 images were really good (10 MP), we were already investing a whole bunch in storage already. We used a light touch of Digital DEE and Digital ICE to improve the non-Kodachrome, non-silver images. We retained all the transparencies in archival hanging slide sheets, and packed the negatives into semi-archival cardboard boxes sorted by year.

A few selected high-quality transparencies were scanned to 144 MB (24 MP, 16 bits/colour). Some of the low-volume high-quality items were scanned at reasonably high resolutions. For example, some 5 x 7 negatives were scanned as 350 MB files (175 MP, 16 bits). Most of the negatives were scanned at 6 MP, but a few were scanned at 12 MP, where I had experimented with higher-quality negative film instead of transparency film.

In 2011, as we started to scan paper documents as well as images, it became clear that the HP needed to be retired, and we replaced it with a Xerox DocuMate 3115 (made by Visioneer) double-sided sheet-fed scanner. The documents were scanned directly to PDF and the original paper copies were recycled after the scans were checked. These were magazine articles and (mostly obsolete) standards that I had saved as general reference. Some of the documents from organizations were returned to that organization (sometime without scanning) to assist in completing their archives. The document scanning was mostly done at 300 dpi, which is about 8.5 MP.

We also found a Brother MFC-J6510DW all-in-one on sale in 2011 and picked that up to handle the 11 x 17 scanning chores. It has a single-sided sheet feed on the scanner, but will print double-sided, but not well at 11 x 17 as it requires a 0.8 inch margin. Otherwise, it is a bargain for large-format scanning, although it still needs to make one splice if you’re scanning a record jacket, but that’s better than three splices, four images!

In all cases, we used the native scanning applications and found them to be adequate.

Other than the document PDFs, we saved all scans as uncompressed TIFF files in folders sorted by year, with month-day-event subfolders. All TIFFs were also converted to JPG images for fast access and ease of use and, due to the Adobe Lightroom requirements, kept in the same folders. We used Advanced Batch Converter to generate the JPGs. The software performed very well with one exception. I have a large number of Nikon D100 NEF images that do not have the corresponding JPG image–all the D200 images are shot with the camera generating both NEF and JPG–and the colour balance of the Advanced Batch Converter conversions from the D100 NEFs was substantially off. I have not looked into the issue due to lack of time.

I love Adobe Lightroom, but have not had enough time to enter every image the way I’d like.

We used two older XP computers for this task. Both were Pentium 4 computers with 3.0 GB of RAM. One was 3.0 GHz and the other 3.2 GHz. The Brother, Xerox, HP, and Nikon have all been connected (at one time or the other) to our newer Windows 7 64 bit machines. I haven’t tried the Epson, because that sits nicely with the 3.2 GHz XP machine as a photo workstation.  The Xerox now sits in the studio to quickly handle all document needs, and the Brother connects over the network, though we often use a USB key when we scan on it. The Nikon created a challenge for 64 bit Windows, but we fortunately found this link. Nikon’s response is here and I did purchase Vuescan prior to finding the fix link. I went back to Nikon Scan as while Vuescan is competent, I thought Nikon Scan looked better. I did try Silverfast which came with my Epson V700 and preferred the native Epson scanner software. I know Silverfast is well respected, but I did not want to spend the money when I was happy with the Nikon scanning software.

We currently have about 1 TB of images. We have two redundant Thecus N5200 PRO NAS units, each with five 1 TB drives, for a total capacity of about 4 TB per unit. These two units are located in different buildings and the remote one is a mirror of the local one. We also have a set of large-capacity (mixed 500 and 1000 GB) portable USB hard drives that hold a third copy of the images and other portions of our NAS units. These are in a rugged steel case, located about 3 km away. This set was added following the devastating tornado that hit Goderich.

Total scans:

Year   35 mm negs   35 mm transparencies    other       document pages
----------------------------------------------------------------------
2008      2,500            10,500
2009      5,500             2,050            775
2010                                         300               200
2011                       11,650                           11,200
----------------------------------------------------------------------
Total     8,000            24,200          1,075            11,400
Total scanned 44,675    digital images 17,299 NEF + 1000s of JPGs
      over 62,000 images total

Going back to the initial list, as of 2011, the following are complete:

• Reflective material:
  • photographic prints up to 8 x 10 inches, colour and black and white
  • magazine and newspaper articles, standards, other documents up to letter / A4
  • larger-sized newspaper articles
  • engineering drawings up to 11 x 17 inches (ledger)
  • engineering drawings larger than 11 x 17 inches
• Transparent material
  • 110 negatives (colour and black and white)
  • 35 mm negatives (colour and black and white)
  • 127 “Brownie” negatives (colour and black and white)
  • 120 roll film (6 x 6 and 6 x 7 colour transparencies and black and white negatives) (my collection)
  • 616 “postcard” black and white negatives
  • 4 x 5 colour transparencies and black and white negatives (my collection)
  • 5 x 7 colour transparencies and black and white negatives (my collection)

And the following remain to be completed. The key thing here is that all of the personal/immediate family items except the 35 mm transparencies are complete.

• Reflective material:
  • I do not want to say this is 100% complete as there is always something that comes up to scan, but, overall, all the back archives have been scanned.
• Transparent material (my collection)
  • 35 mm transparencies (including Kodachrome–perhaps 15,000 images, although some pre-selection process may occur)
• Transparent material (my father’s and stepmother’s collections)
  • 35 mm transparencies (including Kodachrome, Agfa Rapid, and possibly some silver-based images–perhaps 5,000 images, although these may be scanned selectively)
• Transparent material (Milton F. Gentsch collection–perhaps 2,000 images, although only several hundred may be scanned)
  • 120 roll film (6 x 6 and 6 x 7 colour transparencies and black and white negatives)
  • 6 x 9 cm (Plaubel? black and white negatives)
  • 4 x 5 colour transparencies and black and white negatives
  • 5 x 7 colour transparencies and black and white negatives
  • 5 x 7 black and white glass negatives in tricolour sets (also contact prints exist)
  • 8 x 10 glass negatives in tricolour sets (also contact prints exist)

This has been great fun, and I enjoy having access to these images. I find I use some of them more.

My great joy will be to be able to publish online my series of images of the Cathedrals and Abbeys of England and recreate the personal slide show in a modern format. That won’t go online as the music is copyrighted.

I cannot talk a lot about this project, as I have other work to do, but one of the major influences on some of the decisions I’ve made has been the writings of Tim Vitale. His papers provided great insight into what scanning resolution was necessary. I highly recommend these three papers:

• Brief History of Imaging Technology
• Film Grain, Resolution and Fundamental Film Particles
• Estimating the Resolution of Historic Film Images: Using the Resolving Power Equation (RPE) and Estimates of Lens Quality

I would like to thank Sue Bigelow of the Vancouver City Archives for introducing me to Vitale’s work. Sue is a great resource in this area and has a published paper. That link points to a copy of the paper at Wilhelm Imaging Research, which is a fascinating site for this type of work.

Here are links to the scanners mentioned:

• Nikon Super Coolscan 5000ED (going for crazy prices on eBay)
• Epson Perfection V700 Photo
• Xerox DocuMate 3115
• Brother MFC-J6510DW
• HP Scanjet 5590 (currently in retirement)

As an alternate perspective to what I did with the availability of inexpensive labour which needed some work to occupy their summers, you might want to consider Larry Bolch’s approach. It has merit if you are scanning for access. I believe I’m scanning for preservation, so I think what I did was correct for my needs and available resources, but Larry’s points should be read and understood prior to making any decision.

The formats that I am still accepting are:
—Digital Files on CD, DVD, hard drive, USB drives, etc.
—CD
—MiniDisc (normal stereo, not porta-studio multitrack)
—PCM-F1 on VHS or Betamax
—Sony DASH (3202 or 3402) 2-channel reel

I will, however, attempt to play digital tapes in other formats that I used to accept as stand-alone projects if there are one or two in a larger collection that I am digitizing and the machine still works. These formats include:
—DAT
—Digital Compact Cassette (DCC)
—20-bit ADAT (8 track)
—DA-38/DA-88 DTRS tapes (8 track)

DATs have become especially problematic of late, and I have decided not to risk my remaining machines attempting to play them. I recently discovered, when attempting to play a client DAT, that two of my four machines, which I had considered backups, were non-functional after having been in storage for about a half-dozen years without use. I also have a personal collection of DATs that I need to transfer.

One thing that appears to be happening is that DAT tape may be in need of baking. I have had success with one tape, but more research needs to be done.

As with all formats, my ability to transfer them is limited by available working machines. While I did not make a big announcement about dropping 8-track analog cassettes, it was uneconomical to maintain the machine for that format as well, and I sold it.

I have listed other resources that might be of assistance on this link for dedicated digital audio formats and this link for digital audio formats that used an adapter with a VCR.

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.

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!

An example is here.

Last October, when my friend Christopher Campbell visited to exchange knowledge** with me, he brought along a Quasar Sensor Loupe from VisibleDust. I had to have one. It is designed for showing dust on digital SLR camera imaging sensors, but its built-in lighting and 7X magnification make it perfect for looking at the magnetic viewer. This link appears to be a new and improved version. They also make a smaller version (called the Mini) which I have never tried, but you can look at it here. It is a little bit less expensive as well as being smaller.

Details about this system can be found here.

When I am not using the VisibleDust viewer, I use my older Surefire L4 LED flashlight for illumination of the viewer, although any good LED flashlight, such as those from 4Sevens and Fenix, would work. I still think the Zebralight in the full-flood mode is the ultimate headlamp for hands-free working—there is no hotspot.

Finally, a note about the viewer images. The majority were made with a Nikon D100 digital SLR camera (6 MP, APS-sized sensor) and a Nikon 60 mm f/2.8 autofocus Micro (macro outside of Nikon-speak) lens. Although the reticle of the B&L magnifier is shown in some of the images, the lens of the magnifier was removed and only the Micro-Nikkor lens was in the image-forming path.

**Christopher is an artist, photographer, large-format image printer, and is involved in tape restoration. I helped him with tape recorder and electronics skills and he helped me with colour profiling, Lightroom and Photoshop tricks and techniques, and camera image sensor cleaning. It was a good time, I think we both learned a lot from each other. Funny thing about knowledge…when it’s shared both parties win!

I provided some information for the listing of tape equalizations, and I find the compiled table (here) most useful.

Thanks to Kevin Bradley and the IASA team for their work in making this available. If you want a PDF copy, join IASA and it’s available.

As I stated here in 2006, there is a 4 dB ambiguity at 16 kHz.

Many things conspire to make this 4 dB ambiguity essentially meaningless in a generally low-fi medium. The only reason I’m mentioning this now is that I’ve been bombarded with email from more than one participant in this discussion and apparently there may be some editorial judgment attached to what is posted.

Jay McKnight has graciously permitted my posting of his comments to me:

The problem, I think, is that people now-a-days are used to measuring digital equipment with digital measuring equipment, and think that precision measurements are always possible. As you well know, THIS JUST AIN’T SO WITH AN ANALOG MAGNETIC TAPE RECORDER! We try hard, and often come close, but there are just a lot of complicating factors, and most engineers are not aware of them.

For instance, there has NEVER been a measurement standard for tape flux vs frequency (“frequency response”) in ANY format. I have published on it (link here), but when we approached the IEC committee way back when, they said “we don’t write measurement standards like that”, which I think really meant “don’t confuse me with facts, my mind is already made up”.

There is also a problem revealed in the excessive spacing loss document, here . We suspect that this is the cause of the discrepancy in the wavelength-response  of the Philips cassette calibration tapes, but they would never admit that. Note that the German Open Reel calibration tapes even at the higher speeds 15 in/s (380 mm/s) also show this problem.

Note also that the AES Standard for measuring the medium-wavelength fluxivity ( AES Standard AES7-2000 (r2005): AES standard for the preservation and restoration of audio recording — Method of measuring recorded fluxivity of magnetic sound records at medium wavelengths (Revision of AES7-1982)) does not exist as an IEC standard, and we think that the amplitude of the medium-wavelength fluxivity on the German Open Reel calibration tapes at the higher speeds are about 10 % in error (link here).

When we approached BASF with these problems on their Calibration Tapes circa 1978, they said something to the effect “Your measurements are probably right, but we’ve been doing it this way for years, and we’re not going to change it now.”

So between the technical problems and the political problems with the IEC Committee (which, to a great extent WAS Philips and BASF), plus the fact that this is OBSOLETE technology, I think that trying to solve the problem with a 4 dB error at a 3 um wavelength on a cassette tape is futile. Take it for what it is. If it sounds bad, fix it as best you can.

To this, I might add that a colleague (and former member of the Ampex Standard Tape Lab) who would prefer not to be mentioned by name (and I can understand why after this week’s barrage of emails) has noted in at least some high-end cassettes back in the 1980s and 1990s that, if put away in storage for a year, they would lose substantial amounts of high-end. Some might have lost close to 10 dB at 10 kHz.

This high-frequency loss due to aging has never been studied, but it is one potential explanation for the very poor Dolby tracking with older tapes.

The same colleague also noted that in his measurement of cassette calibration tapes all of them were hot at the high end. The ones prior to the Prague Compromise were hotter than the ones after, but all were hotter than what the standard states.

A hot calibration tape will cause the repro EQ to be turned down. Adjusting record EQ to match playback EQ will mean that the tapes recorded on a machine calibrated with a hot calibration tape will be hot. Tapes recorded on machines that meet the standard will play back sounding dull on machines calibrated with the hot calibration tapes.

Please note, according to  IASA TC04 IEC Type I tape reached its final equalization curve in 1974, and that was 3180/120 µs, and the change was in the low end from 1590 to 3180 µs. IEC Type II and IV tape reached their final equalization in 1970, and that was 3180/70 µs.

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.

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.

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:

90297, 91049, 91055, 91079 and 91149

The following were fine:

94132, 94133, 94298 and 96190

The reels that were bad did not squeal during playback, but left debris on the heads and guides that was just barely sticky, so these are obviously in the beginning stages of deterioration.

All of these were Ampex (pre-Quantegy) tapes purchased in the early 1990s. Batch 96190 have lighter grey boxes as opposed to the textured, darker grey background found on the earlier batches, and the reel labels appear to be silk screened, rather than having sticker labels. None of these reels have the old rainbow-style logo.

I would guess that the good batches will probably remain OK – they’ve had a good 17 years to go bad and would probably have done so by now if there was a problem.

For whatever it’s worth…

Gary Galo
Audio Engineer
SUNY Potsdam
…speaking for himself

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:

At the very top we can see a remnant of the left channel material, then the 120-Hz bars (62.5 mil spacing), then the remainder of the left channel material. In the middle is the guard band and at the bottom, the right channel.

Using a specially manufactured (by JRF Magnetics) assembly that contains a 4-channel 8-track head with a continuously variable height adjustment, we were able to lower the track one head to the middle of the good portion of the left channel. With that height positioning, track five’s head was well into the right channel, so we got a good transfer without the hum.

We believe this hum was written by the record head due to a malfunction in the recorder rather than an intentional erasure. If there had been an erasure, more of the left channel would have been erased and there would be a guard band between hum bars and the left channel audio as almost all erase heads were wider than the audio heads.

This type of damage is all too common using old consumer tape machines for playing tapes. I had an old junker machine in the 1960s that did this once to a tape. Unfortunately, it was also a quarter-track recording, so it was gone.

The magnetic record is fragile.

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.

The loss of the original IRIG tapes of the moonwalk is truly sad because this data could be re-converted to standard television formats using far superior methods than were available in 1969. There may be 2-inch helical Ampex VR-660 video tapes still extant of the slow-scan data,  but those have not surfaced. It appears that all surviving copies of the moonwalk videos are ones that had gone through optical standards converters. An optical standards converter is one that has a monitor displaying the image in real time in the transmitted standard and a television camera taking a picture of that monitor using the desired standard. Even the Australian Broadcasting Corp. tapes would have gone through this type of device, although they would be in PAL rather than the U.S.’s NTSC versions.

Lowry Digital is doing a great job of restoring what they have, but the Polaroid screen shot that survives of the slow-scan monitor is alluring of what could have been preserved. More information is available on the Parkes website and from NASA.

Vigilant migration of data as new storage techniques become available is the only way to assure long-term preservation. Even if the IRIG tapes are found, we are almost at the point where the tapes would be un-decipherable. I think one of my machines could play them (I say think as I’ve never tested it to full 500 kHz bandwidth), but I don’t have the specialized video decoder. NASA apparently preserved some equipment should the tapes ever show up.

This also raises another spectre. We MUST be selective as to what we keep in our archives because if we keep everything we won’t be able to afford it–or find it. This is one of the key jobs that archivists do. However, blindly following retention practices, as was done by NASA for the IRIG Apollo 11 tapes, needs to be tempered by historians as well. Certain small subsets of data (moonwalk slow scan video) are much more important than others (astronauts’ blood pressure and other biometrics throughout the entire flight).

All organizations who keep archives need to address this. In a generation (or less) if we save everything, it will become an overwhelming burden and the high points will be lost if they are not properly indexed.

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:

1. DO NOT use the input level control on the line inputs to go below 100 or the preamps will clip before the signal reaches 0 dBFS.
   ALTERNATE WORDING (thanks Greg H.):
   Set Zoom H2 RECORD LEVEL to 100 or greater to avoid clipping at the Line In preamp stage.
2. Use an external attenuator with the gain set at 100 to avoid overdriving the line inputs.
3. The noise floor is not spectacular, but is not too bad. With the inputs terminated in 150 ohms, the peak noise was -70 dBFS, but that improved to about -85 dBFS or better, measuring it as an A-weighted rms figure, which is how most noise is measured. While this certainly isn’t what one would expect out of the Sound Devices, it is far better than the 50-60 dB(A) that one can achieve with an analog cassette tape without Dolby.
4. The maximum input level to the line input should be no more than -5 dBV or -3 dBu.
5. Try to avoid clipping as there appears to be a delayed recovery in some instances.

With this information, you can optimize a pad between the source and the H2 line input so that the recorder is never overloaded. Try to keep the levels as high as practical as there is a relatively limited dynamic range. On the other hand, I have found that the recorder noise is not objectionable even when I’ve boosted the levels 20 dB for a quiet choir piece from our church. The room ambience totally swamps the recorder noise–at least as far as I hear.

The H2′s internal mics are reasonably good for many purposes. While I still prefer the SD722 for many things, I think the H2 is one of the better oral history conversation capturing devices I’ve seen. It uses SDHC cards which may require a new card reader. Don’t use the built-in USB connection unless you’re recording MP3 files as you’ll be there all day. The internal card-reader mode is limited by the USB 1.1 interconnection. This interconnection is adequate, however, for using the H2 as a 16-bit live audio interface/microphone connected to your computer (at either 44.1 or 48 ks/s). The unit will record up to 96,000 samples per second, 24 bits,   but many of those bits will be noise.

Please let me know if this has helped or if you have any questions or comments.This work was done with version 1.50 of the H2 firmware.