Often a tape comes in for restoration that has been poorly wound or poorly stored. Here is an example:

One of the interesting things about this particular tape was it had been recently wound on a constant-tension professional machine prior to shipping to me.

We think that the entire tape had not been re-wound, allowing the higher tension wind to compress the inner core slightly, causing this cinching. After transferring the tape (which didn’t show much ill effect for its cinching), we still found it difficult to get the tape to wind smoothly on the reel.

Therefore, our current suggestion is if you find a tape like this, do not rewind it and attempt to clear up the cinching unless you are also ready to transfer the tape, as there are no guarantees that it can be wound better after unwinding.

Please see this post for an update (2008-02-15).

While the Ampex Mastering Equalization is well documented on this site and at the MRL site, and standard equalizations are detailed at the MRL site on page 3 of this document, I am always amazed when I discover additional, supported tape equalizations. Certainly there have been proposals for alternate equalizations. Jay McKnight has published a paper (here) about this. This post is about something different.

Teac Corporation, with their X-2000M reel-to-reel tape recorder included a button called “Extra Efficiency” to be used with then-new tapes that had double the coercivity of standard reel-to-reel audio tapes. This changed the recording equalization (and the bias and possibly the reference levels) to better make use of the new tapes to improve the overall sound.

What was fascinating here is not that they used the IEC standard equalization of 35 μs at 15 in/s, which was standard in Europe, but that they also invented their own standard and used 35 μs at 7.5 in/s as well! Not content with that, they invented yet another standard of 50 μs for 3.75 in/s.

The NagraMaster and StellaMaster equalizations are also non-standard and were probably the most widely adopted equalizations after AME, but who knows how widely used this Teac EE equalization was and who knows what tapes are in archives that had this equalization incorrectly applied.

I have been informed that it was only intended for the consumer market.

A client phoned me and said a cassette he was playing started to shed in his machine and he stopped and took it out. He sent it to me and as I pulled a little bit of clear leader out of the middle of the tape, this is what I found:

Notice how the complete strips of oxide exist on their own, independent of the clear “leader” to which they previously were attached. (more…)

Demagnetizing tape heads and recorder parts is a ritual of magnetic recording. If any part that touches the tape is magnetized beyond a certain level it will begin degrading the tapes played on it.

While early machines may have had an issue with magnetization, most late-model machines rarely become magnetized. The source for real information on this is Jay McKnight’s Magnetic Reference Lab Web site. (more…)

The National Recording Preservation Board has made available a new document Capturing Analog Sound for Digital Preservation. It is an excellent summary document, and we’ve added it to our information page.

“Noise Reduction” is a potentially confusing topic, partially because it has come to be used to mean two different things.

1. Today, it means removing noise from a recording by means of a single-ended post-production device or plug-in, such as Noise Free Pro by Algorithmix that I use (among other tools).
2. Historically, the term was used for a double-ended process where the dynamic range of the program material was reduced in an unobtrusive way, transported by the noisy channel (be it tape or broadcast) and then expanded in a complementary fashion at the end/output of the noisy channel. These devices were generally referred to as companders (a contraction of compressor/expander).

When reviewing old tapes, they may be marked in various ways to indicate their noise reduction compression, or processing. As of this writing, there are no software plug-ins that accurately mimic the action of the hardware compander acting as an expander. We use actual companders from the original systems when restoring tapes made with these systems.

We currently handle nine different formats from four manufacturers and are always on the lookout for more. Most manufacturers sold a variety of systems tailored to the needs of different kinds of transmission/recording channels

See our special page under formats (click here) to see some of the information we’ve gathered about noise reduction techniques used over the years. Check back as we uncover additional formats and information.

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…)

You’ve been asked to digitize recordings in your collection and don’t have any idea where to start. There are several resources on this site which might be of use. 

What I use is shown on my facility page. That’s one of the main reasons it is there. If I’m using it, it’s because I like it or it solves a problem for me. If I’m not using it, either I don’t have an opinion about it, won’t spring for it, or don’t like it. (more…)

I received a phone call today from someone who wanted my opinion on a Tascam 238 8-track cassette recorder for recording his music.

This was like the person who wanted to know about the DCC recorder for the same purpose yesterday.

People keep hearing that “analog sounds great” or that this or that format “sounds great” and they want to buy in. (more…)

Audio levels (and their cousin loudness) has been an ongoing area of confusion and annoyances from the 1930s on. Adding digital to the mix has done little to simplify the situation.

Here we discuss some of the background and the relationship between the VU Meter, the Peak Programme Meter, and digital meters reference to 0 dBFS (Full Scale). (more…)