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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…)


Protecting the container: Heritage Building Fire Safety

Filed under: archival practices,history,infrastructure — 2014-04-14 by Richard L. Hess — Last Edit 2014-04-14 by Richard L. Hess

While this post does not specifically pertain to audio tape restoration, it does pertain to keeping originals and copies safe, especially in heritage buildings.

This article is prompted by a devastating fire in Aurora, Ontario, Canada, where I have lived for the last 10 years and also from 1981-1983. On Friday, April 11th, there was some roofing work being done on the 135-year-old Aurora United Church. Roofers were using hot tar and allegedly some sort of open flame. Humidity is not high in the winter and we had a cold one. The church roof structure (and much of the ceiling structure of the nave) was wood. Hot tar, flame, low humidity, wind, and very dry old wood do not mix well, and the results, sadly, were predictable. The church is now a ruin. The fire department spent 4-5 hours with up to maybe 7-8 master streams running into the attic and other parts of the structure.

2014-04-12_19.01.24

(more…)


Mouse alternative … the graphics tablet

Filed under: computer/data,tools — 2013-10-30 by Richard L. Hess — Last Edit 2013-10-30 by Richard L. Hess

When I made a 30th anniversary photo book to give my wife, I nearly killed my mouse hand working in Lightroom. Also, a mouse is a difficult way to do fine adjustments of the cursor. (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:

hum_overwrite_dsc_0571

(more…)


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:

(more…)


Thoughts about 8-track cartridges…

Filed under: archival practices,project notes,Tape Aging — 2013-10-01 by Richard L. Hess — Last Edit 2013-10-01 by Richard L. Hess

I have just transferred three 8-track cartridges and I thought I’d share my thoughts about these transfers and what are realistic expectations for these cartridges. (more…)


A summer of archiving…

Filed under: archival practices,project notes,still images — 2013-08-13 by Richard L. Hess — Last Edit 2013-08-31 by Richard L. Hess

This summer, we have completed the project we described at the end of last summer. We began the summer of 2008, with Robert working every summer to some degree since. Michael split the work with Robert in 2009. More commentary below the graphic (UPDATED 2013-08-31) and the break.

2013-08-31_snapshot

(more…)


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…)


US Music Media Statistics

Filed under: history — 2013-04-10 by Richard L. Hess — Last Edit 2013-04-11 by Richard L. Hess

Pete Hammar and Tom Fine came across a great site detailing 40 years of music statistics in a series of pie charts for each year. I thought it might be interesting to show this as a graph:

Formats_1973-2012

(Click image for full-sized view)

(more…)


Power options for field recording

Filed under: live sound and recording,tools — 2013-03-03 by Richard L. Hess — Last Edit 2013-03-28 by Richard L. Hess

I had the first failure to capture an entire concert in my recording career. I had become complacent and considering that I had new (April 2012) Li-ion batteries for my Sound Devices 722 recorder, did not think twice about recording a concert on the approximately 50 Wh 6-cell packs. Well, one failed, and did so spectacularly without a warning. I did not notice the in-process warnings, because I do not wear my headphones during the whole concert. I try and take in the concert so that I can then see what’s missing in the studio. Here is what the after-the-fact results showed:

batts4a (more…)


Open Source software…and other tools

Filed under: education,software,tools — 2011-01-01 by Richard L. Hess — Last Edit 2013-02-15 by Richard L. Hess

I have been having a lot of fun recently looking for specific software tools that avoid having to purchase multiple licenses of the high-priced programs. Here are a list of my picks of free and low-cost software tools. I am sticking with Samplitude Professional for audio and Adobe Photoshop and Adobe Photoshop Lightroom for photo-graphics. The other alternatives, however, are wide open. (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.
—CD
(more…)


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…)


The Digital Cliff and HDMI

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

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. There were issues with the application of a TRS phone plug (another story).

The church had a PC and two 60-inch diagonal video monitors plus a smaller monitor for the choir. There appeared to be a powered splitter/amplifier at the balcony console to split the HDMI to the two big monitors, with one cable running down each side of the church. I believe there must have been a second two-way splitter (hopefully another powered splitter/amplifier) to tap off the feed from the right main monitor for the choir monitor.

When I arrived, the PC was set up for 1024 x 768 display with the HDMI output mirroring the laptop built-in display. The laptop built-in display was capable of 1366 x 768. The slide show was a 16:9 WMV file. I tried expanding the display to the widescreen resolution and it was fine on the PC, but the monitors would not sync.

(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…)


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.

(more…)


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

(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.
and
Some capstan / pinch-roller / constant-torque systems handle this better than others.

(more…)


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: magneticdeveloper.com — they even have a shopping cart for online ordering. This is apparently the same product I’ve been using for the last eight years.


Magnetic Developers — Seeing the tracks

Filed under: magnetic record viewing,magnetic tape developing,tools — 2006-03-08 by Richard L. Hess — Last Edit 2012-08-07 by Richard L. Hess

This has been updated 2007-06. 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…)


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).

(more…)


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.


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