It was a semi-professional product and was sold for something like 900 USD. The "ES" is the label for the high-end product from SONY. It was the top of the range products. CD players and other devices hold that "ES" label too.
It had to be placed between the sound source and a video recorder. While recording, the video recorder acted like a storage device. And while listening it acted like a playback device.
One could use VHS videotapes, or Betamax videotapes, one of the two major consumer videosystems. VHS offered less reliability over time than Beta, since VHS video signal has a poorer quality from the beginning. Dropouts occurence occured more often with VHS than with Betamax. The V2000 consumer videosystem from Philips and the U-Matic professional video worked well too.
The 501ES does not need that the videorecorder be hifi-stereo in order to record stereo digital sound. As sound from the source is converted into pictures while recording, and pictures from the tapes converted back again into sound while listening. The soundtrack on the videotapes is left blank and is not used at all while recording or playing back.
Although digital duplicating of recorded tapes was possible with the 501ES, through a re-generated video signal output (available through the "COPY out" RCA plug at the back of the 501ES, there wasn't a standard digital output on that device. 601ES added that digital output. There wasn't any digital input either. Anyway CD players did not offer digital output at that time.
501ES sound quality was 16-bit/44,1KHz.
14-bit encoding was possible to bring compatibility with the Matsushita Technics PCM adaptor.
DAT, the replacement for the PCM adaptor, were released in year 1987. It offered better sound quality, 16-BIT/48KHz. But the cost of the DAT tapes was 12 times higher than VHS! So 501ES was still a good option for those interested in archiving, or radio stations… in LP mode, with a 5 hour VHS tape (an unuasual length, 4 hours being more standard), one could offer a 10 hours program of non-stop mixed music!.
About year1988 hifi-stereo video recorders were released. They offered video with stereo sound. But for recording sound only, 501Es offered a better sound quality.
I owned three of these 501ES devices back in the eighties. I still have two of them on a top of a shelf. The third one has been stolen!
I have about 500 videotapes with PCM signal which I transfered onto cd in year 2003.
The thing I can say is that the sound of this device is not extremely good, for the ears of the audiophile which I became, but at that time it offered a very very good price/quality ratio, compared to better recording devices like the DAT (which appeared 4 years later than the 501ES).
One thing to know is that the sound is better when using two of these devices along : you plug the video signal from the VCR into the "video in" of the PCM #1, you push the copy buttton, you take the "copy out" signal and put it into the "video in" of the PCM #2. Then the sound is better.
Still, in year 2003 I had to use, with some tracks, an equal curv (I used Nero at that time) in order to get an even better sound quality, and sometimes a barely audible reverb effect (something like 0,003 second).
Another thing to know is that you shouldn't record too close to the zero db, I mean too close to the saturation level. Why? Due to the technical concept, the more the sound is loud onto he recording, the thinner the lines are on the video signal image, that means that it is more likely to have "drop outs" when recorded loud.
That leads us to the other problem with these devices: dropouts! Any problem on the videotape and it's a mess during one or two seconds in the recording. That's why I always made copies of my videotapes (using the "copy out").
I used the devices with my synth's. I didn't had a multiple track analog recorder, so I programmed my 16k computer to play the synth, recorded it onto one PCM, then changed computer programming to play once again the synth, played back the recording while mixing it with the synth, recorded it onto the other PCM of course, and so on, 3, 4, 5 times, maybe more. In order to keep sync, I always had to play back the recording in the same VCR that recorded it, otherwise the speed changed… one VCR do not play exactly at the same speed from another ! Of course that wasn't very convenient, as the only option was to get rid of the last layer of synth by reverting to the previous recording. Getting rid of one of the first layers of synth simply wasn't an option.
These are the tracks that I made 20 years ago! http://www.electrobel.be/artist/5337#songs
Understand me well, I mean the sound of these 501ES devices is not bad at all, but it's a little bit less good than the sound of a cd.
Nowadays I use a TASCAM DV-RA1000 DSD recorder in order to backup and sound process my vinyl collection : recordable CD is not good enough for my audiophile ears.
How a PCM adaptor works
High-quality PCM audio requires a significantly larger bandwidth than a regular FM-modulated analog audio signal. For example, a 16-bit PCM signal requires an analogue bandwidth of about 1-1.5 MHz (compared to about 15-20 kHz of analog bandwidth required for an analog audio signal), and, clearly, a standard analogue audio recorder could not meet that requirement. The obvious answer, at that time, was to use a video tape recorder, which is capable of recording signals with this high bandwidth, to store the audio information. Such an audio recording system therefore includes two machines, namely the PCM adaptor and the video tape recorder. A PCM adaptor has the analogue audio (stereo) signal as its input, and translates it into a series of binary digits, which, in turn, is coded and modulated into a NTSC (or PAL)-standard monochrome video signal.
This video signal can be stored on any ordinary analogue video tape recorder, since these were the only widely available devices with sufficient bandwidth. This helps to explain the choice of sampling frequency for the CD, because the number of video lines, frame rate and bits per line end up dictating the sampling frequency one can achieve. The sampling frequency of 44.1 kHz was also adopted in the Compact Disc, as at that time, there was no other practical way of storing digital sound than by a PCM Converter & video recorder combination. The sampling frequencies of 44.1 and 44.056 kHz were thus the result of a need for compatibility with the NTSC and PAL color video formats used for audio storage at the time.
Most video-based PCM adaptors record audio at 16 bits quantisation, and a sampling frequency of 44.1 (or 44.056 for NTSC) kHz. However, some of the earlier models, such as the Sony PCM-100, recorded 16-bits quantization as well, but used only 14 of the bits for the audio, with the remaining 2 bits used for error correction, in case of dropouts or other anomalies being present on the videotape.
A PCM adaptor can only store a single stereo signal, and is not capable of studio multi-track recording.
Models of PCM adaptors
The Sony PCM-1600 was the first commercial video-based 16-bit recorder (using a special U-matic VCR for a transport), and continues in its 1610 and 1630 incarnations. The 1600 was one of the first systems used for mastering audio compact discs in the early 1980s by many major record labels.
Several semi-professional/consumer models of PCM adaptor were also released by Sony, including:
The PCM-F10 (the first consumer-marketed model),
The PCM-F1 (which was sold with a companion Betamax-format VCR, the Sony SL-2000 or SL-F1, for recording & playback),
and the PCM-701.
Technics also made a portable PCM adaptor as well, the SV-100, and a version with a built-in VHS videocassette transport, the SV-P100. Nakamichi as well manufactured a PCM adaptor, the DMP-100.
dbx, Inc. also manufactured a PCM adaptor, the Model 700. It differed from the above listed models in the fact that it did not use PCM, but rather delta-sigma modulation. This resulted in a higher quality digital recording with more dynamic range than what standard PCM modulation could offer. Like a standard PCM adaptor, the Model 700 also utilized a VCR for a transport.