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Old 24th Jul 2020, 2:48 pm   #21
Welsh Anorak
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Default Re: VHS HiFi - deterioration?

Far worse than the switching noise was the 'hi-fi, crackle, linear, crackle, hi-fi again' that happened with a poor tape or slightly worn heads.
When it worked, VHS hi-fi was, to my ears, preferable to the woolly muffle-fest that linear stereo gave (witness the Baird/JVC 8940 with Dolby). It might not be hi-fi as we know it, Jim, but was certainly a achievement in getting a quart out of a pint pot!
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Old 24th Jul 2020, 5:33 pm   #22
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Default Re: VHS HiFi - deterioration?

Ah yes, the dreaded linear/HiFi switching is irritating.

I stand by the fact though, to my (youngish, early 30's) ears that these tapes properly recorded and tracked, on a decent deck sound very good.

I'm listening on a humble setup (Tannoy 603s or Beyerdymanic DT990s with a Nad 3020i) so maybe a better setup would reveal something I'm missing, which I will freely concede.

I have a few where I can A/B with compact disc (Marantz CD65) and the sound is close if not on occasion (see my original post) better to my ears than the Compact Disc. This of course may be skewed by having one very good domestic video machine and one production quality unit.

It's just interesting that VHS HiFi with a near CD equivalent, near flat Frequency Response, an astonishing dynamic range and effective tape/head speeds in the meters-per-second is written off as 'passable' but categorically 'not' HiFi but an LP or Chrome Cassette 'is' HiFi.

Ultimately it's dead format, so it's not worth getting excited over and as said maybe my aural palate isn't as advanced as I'd like to think it is, but dang it sounds much better than passable in my humble opinion. It could be the DBX style companding doesn't irritate me whereas I know lots of people find it borderline sacrilege to music.

Yes, technologically it was a marvel, albeit I think from reserach taking heavy inspiration in operation from Betamax Hifi.

As said though, I've got a cooking model 350 Tascam PCM recorder next to me which would smash the whole lot of them in a sound quality test so it's probably still very average in 2020.
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Old 25th Jul 2020, 12:35 pm   #23
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Default Re: VHS HiFi - deterioration?

I think you have a very modest definition of humble...
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Old 25th Jul 2020, 1:45 pm   #24
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Default Re: VHS HiFi - deterioration?

Quote:
Originally Posted by arjoll View Post

The only dropouts I noticed were in just one video - for example at about 0:31,
1:22, 1:47, 2:19 here.
Yes they are complete dropouts of the HiFi track or at least a muting of it, and a default to the linear track. I've heard many YT uploads like that. Sometimes the flip/flop/flip/flop changeover happens many times. That can be more annoying than the quality difference between the two audio systems.

If the HiFi track cant be made to track better, the way to make the dropout as unnoticeable as possible is to optimise the linear track so that when it is inevitably exposed (which may only be for a second or so at a time) it sounds as close as possible to the Hifi track. That usually means azimuth alignment of the A/C head to the individual tape, and if necessary EQ and level adjust. When the programme is loud, often the increased hiss from the linear track is undetectable.

And even the switch from stereo to mono can be undetectable if for a short period. Even though the tape was recorded in Hi Fi Stereo, the source may still be mono. Sometimes choosing either left or right stereo tracks on a mono programme reduces the number and severity of switching clicks.

The fidelity of the linear track recording is not as bad as people often experience on playback. Azimuth misalignment between machines is potentially even worse than with audio cassettes. And when there is a lot of audible hiss, it's easy to assume it's tape hiss when it may be preamp hiss due to the fact that the tape to head alignment is so poor, or azimuth so badly off that the VCR's preamp hiss is completely exposed and has no competition.

Also I suspect that when the HiFi systems became more established in consumer VCR's, the designers werent as careful with the linear audio playback system as they assumed that all new recordings would be made and played back in HiFi. So on later model VCR's unshielded ribbon cable was more used from the audio head to the preamp, with the risk of noise in playback that isnt on the tape. I also suspect magnetic shielding of the A/C head sometimes became lower in quality.

Generally many analog recordings sound a lot worse than they actually are because not played back at their best. In pro audio production for reissue of older recordings there is sometimes a specialist job called Audio Transfer Engineer. The fellow may well do nothing else except replay and transfer various vintage recordings at their very best for the public's listening enjoyment, retrieving every wanted piece of information from it, and adding nothing unwanted in the process.

Sometimes people listening to a poor transfer of an old audio recording say, "Oh well it's an old recording. What more could you expect?" What more indeed!

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Old 25th Jul 2020, 3:13 pm   #25
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Default Re: VHS HiFi - deterioration?

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In pro audio production for reissue of older recordings there is sometimes a specialist job called Audio Transfer Engineer.
Perhaps I missed my true vocation

I still have the original VHS tape of a friends 1986 wedding, it was damaged and causing head clogs, and I was asked to copy it.
There was not much I could do about the video quality going down a generation, but the so-called "professional videographer" at the venue was using a JVC over-the-shoulder machine with an azimuth maladjustment, so I adjusted my playback machine to match. The result was the sound was much better on the copy compared to the original, when played back on a correctly adjusted machine.

The other thing that people making A-B transfers of linear sound VHS, (and Compact Cassette come to that) don't appreciate, is that a direct connection between line-out and line-in is going to apply yet another dose of AGC dynamic compression to the already compressed sound. Unless your "B" deck has gain adjustments, you need a to attenuate the level, I used to use a 10k pot in a plastic film canister in the lead, so as not to overdrive the AGC action.

There were some stereo VHS machines with only linear tracks. Hitachi made one, and the track nearest the edge of the tape suffered more than its companion. This Hitachi also used miniature relays in the audio path and to say they were troublesome was a gross understatement.
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Old 26th Jul 2020, 3:35 am   #26
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Default Re: VHS HiFi - deterioration?

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Quote:
Originally Posted by TIMTAPE View Post
In pro audio production for reissue of older recordings there is sometimes a specialist job called Audio Transfer Engineer.
Perhaps I missed my true vocation

I still have the original VHS tape of a friends 1986 wedding, it was damaged and causing head clogs, and I was asked to copy it.
There was not much I could do about the video quality going down a generation, but the so-called "professional videographer" at the venue was using a JVC over-the-shoulder machine with an azimuth maladjustment, so I adjusted my playback machine to match. The result was the sound was much better on the copy compared to the original, when played back on a correctly adjusted machine.
Yes well done. Of course a good copy from original to digital looks and sounds as good as the original footage (no generation loss) and no more azimuth alignment worries.

This video was transferred from a player different to the original recorder. https://youtu.be/TlGtluiFdtY If azimuth aligned it would probably sound a lot clearer.


Quote:
Originally Posted by rambo1152 View Post
The other thing that people making A-B transfers of linear sound VHS, (and Compact Cassette come to that) don't appreciate, is that a direct connection between line-out and line-in is going to apply yet another dose of AGC dynamic compression to the already compressed sound. Unless your "B" deck has gain adjustments, you need a to attenuate the level, I used to use a 10k pot in a plastic film canister in the lead, so as not to overdrive the AGC action.
True. Overall though, the AGC was probably a good compromise for camcorders because it at least helped keep the quieter sounds above the tape noise while not saturating the tape on the loud sections.

Quote:
Originally Posted by rambo1152 View Post
There were some stereo VHS machines with only linear tracks. Hitachi made one, and the track nearest the edge of the tape suffered more than its companion...
Yes I have a Panasonic AG 7350 with linear stereo as well as HiFi Stereo. Tapes with edge damage can really suffer on the outer track (left channel) especially if the A/C head is worn or not perpendicular to the other tape guides. When everything is right though, it can sound quite reasonable, the main difference from mono being a somewhat higher noise floor.

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Old 27th Jul 2020, 9:32 pm   #27
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Default Re: VHS HiFi - deterioration?

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Originally Posted by TIMTAPE View Post
Yes they are complete dropouts of the HiFi track or at least a muting of it, and a default to the linear track. I've heard many YT uploads like that. Sometimes the flip/flop/flip/flop changeover happens many times. That can be more annoying than the quality difference between the two audio systems.
Just to clarify - when I've uploaded something it's normally ben because I haven't been able to find something with the equivalent video quality on Youtube already. I could have made the audio on this significantly better - either by editing the dropouts so they were less noticeable in level, or by replacing it entirely with the ripped CD track (I've got CDs of most of what I've uploaded, including that Rich Mullins track) and careful syncing with the existing audio - but I'm already violating copyright, so see no need to make it worse by including near-perfect audio.
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Old 27th Jul 2020, 11:54 pm   #28
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Default Re: VHS HiFi - deterioration?

I must have been easily pleased as I owned for several years one of the JVC/Thorn machines, branded a Netto model 8940. It had linear stereo with Dolby B. I was quite impressed with the quality when back then I connected it to my Sony TA1055 amp, especially watching movies with the stereo soundtrack I thought really added to the experience of watching the film. Of course I could only playback tapes recorded in stereo as the machine had a mono tuner, no Nicam stereo TV when it was made.

I used that machine till about 2001 when I replaced it with a new Aiwa machine, 6 head Nicam/hifi stereo model. Had twin VU level meters, and a handy 3 step BBE function that basically would brighten up dull sounding audio on old tapes. Being a Nicam machine I was finally able to record in stereo, and I did many concerts etc from live TV. I did suffer with the drop outs though as others have mentioned. I still have some recordings I did on that machine and they still play fine, well audio does. Picture wise not too good thanks to using long play, and using the cheapest blank tapes I could buy.
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Old 15th Sep 2020, 5:38 pm   #29
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Default Re: VHS HiFi - deterioration?

Interesting point on NICAM.

I've not experimented much with NICAM (well, I didn't at the time); out of interest did NICAM machines simply decode the data to linear baseband and-or HiFi or was the NICAM data encoded on to the tape and decoded on playback?

Sorry if that's a silly question. RR
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Old 15th Sep 2020, 5:48 pm   #30
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Default Re: VHS HiFi - deterioration?

NICAM audio was always demodulated back to conventional 20 to 20kHz analogue audio and then recorded as such using the standard FM depth modulation technique on VHS.

I used to have a NICAM Sony C9 Beta that I made a small plug in NICAM module for. Geez, (and for the second time this month on here)... I must have been keen back then. Pity it only had the linear audio tracks and not true FM HiFi.
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Old 15th Sep 2020, 6:09 pm   #31
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Default Re: VHS HiFi - deterioration?

Thanks @Mooly - that solves that, I'm very much of the DVD generation but I have an appreciation of NICAM etc and it just crossed my mind how that may have worked in relation to recording.

Now, here's on maybe somebody can riddle me.

As part of this video I was going to feed in 20hz-20kHz from a WAV file in to my recorder, go "Oh look, it's squeaky clean up until x, here's the 3dB point but it's pretty damn good."

Trouble is, when I try this experiment what comes back from the tape is squeaky-clean until about 8kHz, noisy until about 12kHz until it just breaks down in to absolute garbage and noise all the way up progressively, a total drop-out about 17kHz and fading back in until the end of the experiment.

I used a 0dB 1000Hz tone at the start of the test file for dialing in 0dB on the machine (this is a professional Panasonic AG-7350 with VU meters and manual gain adjustment with clean heads and new quality tape-stock) - I've also tried -6dB/-10dB but yields the same results. I'm satisfied the meters are precise as 0dB in sits bang on the detent on the gain adjustment when playing-in the 0dB file.

Playback level precisely matches recording level, so it seems to be efficiently transferring to tape.

Go back to recording music, and it sings perfectly.

I'm guessing here my experiment is faulty, any suggestions as to what I'm doing wrong? I didn't expect a perfectly linear response but I might have hypothesized reasonable results....

Where am I going wrong? Oh I'm definitely talking about HiFi, the linear tracks actually act precisely to spec' and have the lovely slope that matches the technical spec near enough.

Cheers,RR
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Old 15th Sep 2020, 7:19 pm   #32
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Default Re: VHS HiFi - deterioration?

Were your results similar to "Belmont's" in this post?

http://www.digitalfaq.com/forum/vide...-response.html
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Old 15th Sep 2020, 7:42 pm   #33
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Default Re: VHS HiFi - deterioration?

I can't ever recall testing a HiFi VHS deck tbh and so have no base line for comparisons although the headline specs suggest it should cover the 20-20k range.

I'll be honest and say that I came to regard the system as flawed and very flaky and temperamental as we had lots and lots of issues with certain machines. Upper cylinders (heads) and lower drums were changed like they were going out of fashion on some models and still there was little 'give' in the system and little tolerance for normal wear and tear before issues showed up again. Ferguson (JVC)... I can't remember the model number now... were one of the bad ones which was a shame because the picture quality was outstanding.
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Old 15th Sep 2020, 9:37 pm   #34
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Default Re: VHS HiFi - deterioration?

https://youtu.be/quXQKPE7CmY

Can videotape experts just have a look over this for me, just to check I've not made any glaring technical errors.

Please ignore the janky first animation, that was just a quick sketch and will be changed for a detailed animation in rendering.

I'm not called RobustReviews for nothing, I don't think this contains much foul-language but you've been warned. This is just an except from the full 15 minute video but this covers the basic technical aspects of VHS.

Cheers,
Andy (RR)

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Old 15th Sep 2020, 11:39 pm   #35
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Default Re: VHS HiFi - deterioration?

I think most of the problem with VHS Hi fi, compatibility/inter-deck alignment issues aside, was down to the tape.

For accurate reproduction of the FM audio, higher coercivity tape was required. Unfortunately the tape used in a number of distribution places seems to be only a step up form the pound shop/market stall no-name stuff that was abundant back then. I suppose they imagined that shortcomings probably wouldn't be noticeable on a typical consumer-grade VCR playing through a typical CRT television, especially through an RF connection. Which let's face it is what most people used until the late 90s or so.

In fact I remember reading somewhere that they used to use the absolute cheapest tape for childrens' cartoons: few dark scenes to show up the white dropouts, garish colours to mask the lack of detail, and above all least critical viewing audience!

For this reason manufacturers started making high grade tape that worked more consistently with Hi fi decks. TDK E-HG is one I like. BASF was always very good too. Fuji was superb, we used to use that in the edit suite at uni. Of the big names Sony was the most disappointing as was scotch/3M. Anyway, the point being, you can't just use any old tape and expect Hi Fi to work consistently.

A similar thing can be seen with S-VHS. That system placed even higher demands on the tape. You can try drilling a small 'S-VHS detect' hole in a standard VHS tape, and you will see the dropouts vary from brand to brand!

I must dig out some of my old prerecorded music videos and see how they play. I have some Santana and Jaco Pastorious stashed away somewhere...
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Old 16th Sep 2020, 1:45 am   #36
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As part of this video I was going to feed in 20hz-20kHz from a WAV file in to my recorder, go "Oh look, it's squeaky clean up until x, here's the 3dB point but it's pretty damn good."
I seem to remember doing this around 30 years ago with my Philips Hifi VHS recorder when we were thinking about the possibility of using it for recording 30kHz sonar at work. My memory is fairly hazy but I seem to remember the -3dB point being around 30kHz with usable output up to around 50kHz and a very small signal still there at around 90kHz. It must have been sufficiently impressive as the people doing the project bought themselves an Akai machine (my Philips was long discontinued).

It was only superceded when 96kHz sampling rate digital audio recording came along.
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Old 16th Sep 2020, 8:39 am   #37
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Default Re: VHS HiFi - deterioration?

I soon learnt that selling and repairing Hi Fi VHS machines was nothing but a nightmare. Drop outs, poor sound quality, incompatibility and head wear were just some of the problems to say nothing of customer moaning.
I think it was a feature we could have done without. It was after all Video Home System and not designed for frills. John.
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Old 16th Sep 2020, 12:08 pm   #38
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Default Re: VHS HiFi - deterioration?

I used to advise people who wanted the best and most archivable results, to avoid dual-speed machines, because even in SP they laid down a narrower track and therefore there was less flux to be replayed. And to avoid 4 hour cassettes, because they were an afterthought with a thinner substrate.

I don't remember including avoiding FM Hi-Fi in my advice, but I think machines that offered it were usually multi-speed anyway.
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Old 18th Sep 2020, 6:17 pm   #39
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Quote:
Originally Posted by jamesperrett View Post
Quote:
Originally Posted by RobustReviews View Post
As part of this video I was going to feed in 20hz-20kHz from a WAV file in to my recorder, go "Oh look, it's squeaky clean up until x, here's the 3dB point but it's pretty damn good."
I seem to remember doing this around 30 years ago with my Philips Hifi VHS recorder when we were thinking about the possibility of using it for recording 30kHz sonar at work. My memory is fairly hazy but I seem to remember the -3dB point being around 30kHz with usable output up to around 50kHz and a very small signal still there at around 90kHz. It must have been sufficiently impressive as the people doing the project bought themselves an Akai machine (my Philips was long discontinued).

It was only superceded when 96kHz sampling rate digital audio recording came along.
I have purchased a sealed TDK archival tape (XP Pro S-VHS) to repeat my experiment, I'll let you know how it goes.

One bit of data I'm struggling to get info on is Hifi head geometry, does anybody know the angles for Hifi heads, in my video above I erroneously claim they're offset 90 degrees from the video heads but clearly aren't, the audio heads sit fairly close to the video heads.

Cheers,. RR
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Old 18th Sep 2020, 11:09 pm   #40
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This is interesting stuff RR. It appears different manufacturers "did their own thing", instead of adopting a standard!

Excerpt from a post by LeoB1955 taken from:

http://www.tapeheads.net/archive/ind...0video%20heads).




Finally, the first JVC-based Hi-Fi VHS models use audio/video head pair angle of 138 degrees (audio heads are preceeding their respective video heads).

But early Panasonic models (and some other brands) opted for a 120-degree A/V head angle. Some European-made Grundig VHS machines even went for a 90-degree A/V head angle.

These deviations may appear trivial, but they can cause irritating compatibility problems when playing back tapes with less than perfect FM audio signals.

When the PB tracking control is set for best picture quality, the FM audio signal may become riddled with excessive head switchover noise, or get muted altogether.




You couldn't make it up, could you!

It would follow that the the best way to digitise a Hi-Fi tape would be a two pass process, first get the optimum video, then adjust the tracking to get the maximum FM signal from the audio heads, and mate the digital video and audio together in an editing application.
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