I received a cassette from a client and he complained that the previous recording was audible as well as the new recording.

There are several ways this can happen:

• The erase head can be dirty—this usually leads to high frequencies being erased and lower frequencies still audible
• The erase head can be misaligned—this often provides a partial erasure, but careful use of track selection can find a section of track with less crosstalk.
• A similar problem occurred on quarter-track reels with misaligned record heads where recordings from the opposite direction would invade the tracks for the forward directions. Again, a specially adjustable narrow head usually solves this.
• A completely non-functioning erase system—this is what we suspect happened with the current project. There were no track dissimilarities nor any other way we could find, including looking at the tape with the 8-track cassette recorder to separate the underlying, unwanted recording from the wanted one.
• A totally unrelated mechanism that may sound the same is if the microphone or tape recorder picks up a broadcast or other radiated signal and records that along with the desired signal.

We opted not to proceed with any noise gating as it would not improve the overall audio quality for listening and may actually impede transcrption.

While not a success, we were able to confirm to the client that there was no way that could preserve the fidelity of the desired sound and remove the undesired sound. The desired interview was completely intelligible and could be transcribed. It was just distracting to listen to.

“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…)

I received a phone call today asking if I knew where to get DCC blank tapes. The person had purchased a used DCC machine on eBay or someplace like that because he “heard that they sound good.”

Audio mythology is growing. DCC is a perceptually coded format with bit reduction. Like MP3. Like the ATRAC system used on Minidisc. Not as advanced as MP3, probably (it’s older). Not as advanced as Windows Media (it’s older). (more…)

I got a call today from a friend who said the hum shields on a friend’s APR-5003 were not working.

I recalled this had happened to one of my machines in the past.

Removing the cover surrounding the heads will expose the mechanism—of course the heads and pinch roller need to come off first.

Cleaning and lubricating the rods and other parts of the linkage should make all well again.

I used Zoom Spout Turbine Oil.

The 20 kHz bandwidth of CD audio media may cause truncation of some material. Here is an example of a small amount of energy above 20 kHz in a symphonic recording. It is interesting to note that this is a 7.5 in/s recording done on 1970s prosumer equipment. I’ve said in my presentations for some years, most 7.5 in/s tapes are well-suited to 44.1ks/s 16 bit transfers, but there are exceptions. This shows one. (more…)

Remember, this transfer that you (or I) are about to undertake may be the last time (and hopefully the best time) that the original is transferred. Here are some suggestions: (more…)