S-VHS ET: How Exactly Does This Technology Work?

D Page

Standard Member
Does anybody know exactly how the S-VHS ET (Super VHS Expansion Technology) video format works?

I have been a user of the S-VHS format since the early nineties and, although I have progressed to DVD recorders, now, for video recording, I have a couple of S-VHS ET recorders (for playback of my large S-VHS tape collection), and I have recently bought my Father one, through eBay. My Father will continue to use S-VHS and VHS with this machine (for recording and playback), and I was curious about the S-VHS ET feature.

I have tried to find out about the S-VHS ET technology, and any detail regarding how it actually works seems very limited. All I know is that it enables you to record to S-VHS format using regular VHS tapes (High Grade tapes are recommended).

I remember, when S-VHS was the highest quality domestic recordable video format available in the UK in the 1980s and 1990s (I'm excluding ED-Beta in that statement!), there was information flying about that, by drilling the S-VHS tape identification hole in a standard VHS cassette, in order to 'fool' the machine into thinking the inserted tape was an S-VHS tape, this would permit you to record in S-VHS mode on VHS tape. However, the following issue would arise:

“In attempts to record S-VHS content to a VHS tape, picture quality is somewhat better, however, after several months the quality drops dramatically to a point of severe graininess or video noise in dark areas in the images. This is due to the standard VHS tape's lack of coercivity that the S-VHS format requires, causing the stronger magnetization of the tape provided by a S-VHS deck's recording heads to not be fully retained by the magnetic oxide particles of the VHS tape over time, producing a weaker signal on playback.
Eventually, the recording becomes unwatchable (although it may be copied to another more suitable media while still in usable condition). The original tape itself can be reused for standard-format VHS format recordings without problems (as the oxide media itself remains physically undamaged).”


(an excerpt from wikipedia's S-VHS page)

How does the S-VHS ET technology work? What extra circuitry is inside S-VHS ET recorders to enable S-VHS recordings to be made to VHS tapes, without them rapidly deteriorating in the way described above, with regular tapes? I haven't experimented to find out whether S-VHS ET recordings onto VHS tape actually do rapidly deteriorate, or not, with repeated playings, but I assume they must not, otherwise S-VHS ET would actually be nothing more than the recorder allowing you to record in S-VHS mode with VHS tapes (in other words, to simply ignore whether there is, or isn't, an S-VHS identification hole in the cassette shell, and nothing more than that).

I have heard many reports of there being vastly different picture quality obtained, depending on tape brand, and also incompatibilities when attempting to play S-VHS ET recorded tapes played back in other S-VHS ET machines, even machines of the same brand. Because of these issues, irrespective of what the S-VHS ET technology intales (which I have yet to find out about), it appears, to me, to have been quite a desperate attempt, by JVC, to keep the S-VHS format alive, by allowing its use with cheaper tapes that everybody could get hold of, and afford (but which, ultimately, contained a quality of videotape just, probably, not up to the job, in reality).
 
Last edited:

bow79

Active Member
I think it sort of pushed harder to record higher freqenceys and hence more detail presumabley tape formulation amongst other things had developed over the years.
 

Gavtech

Administrator
S-VHS ET was developed in 1998 by JVC... but they never did release full technical details of how the system worked.

The components and elements that made it possible were a high performance video head used in combination with an improved pre-amplifier and a new signal emphasis system.

These permitted a wider bandwidth signal to be recorded onto standard VHS tape (160% wider)

The S-VHS ET specification was very close to the S-VHS specification with the exception that the ET spec has a slightly lower white clip level.... and the system has a poorer signal to noise ratio compared to true S-VHS.

At the time of the ET launch, JVC reported that the ID hole in cassettes fell into disuse almost immediately after the launch of S-VHS.

Later machines use the signal waveform to determine tape type and ignore the presence or absence of an ID Hole.

Hi Grade VHS is recommended in ET machines.
 

The latest video from AVForums

Star Wars Andor, Woman King, more Star Trek 4K, Rings of Power & the latest TV, movies & 4K releases
Subscribe to our YouTube channel
Support AVForums with Patreon

Top Bottom