VHS Hi-Fi: The Mediocre, the Bad and the Crappy

[Ralf Stocker]

My father had one of these in the 80s. The rotating head drum gave a tape speed of, I think, 7 meters per second. That was unattainable for any tape deck or tape machine. The frequency response was linearly smooth. No wow or flutter.

 

[DrCWO]

Back in the very early 80s, Linn cut half an album (Dove Across The Water), one side using the analogue master and the other, the same take (unedited) cut from a Sony F1 system. The feedback was largely in favour of one particular side (the one with a little studio-talk between tracks) and this, to Linns apparent consternation as they told me, was the digital one... the analogue mix would have been to 30IPS two track on half inch tape with no noise reduction I suspect, although I have no proof

Interesting information. Where is the source you knew it from?

 

[DSJR]

Interesting information. Where is the source you knew it from?

First hand, as we were Linn dealers at the time

I have a copy of it somewhere. It's a Scottish folk group I think ('Ossian,' which still exists as a band apparently) and the music is light and not what I'd call 'heavy' or 'hard going.'

https://www.discogs.com/release/7155877-Ossian-AnalogDigital

 

[DrCWO]

First hand, as we were Linn dealers at the time

I have a copy of it somewhere. It's a Scottish folk group I think ('Ossian,' which still exists as a band apparently) and the music is light and not what I'd call 'heavy' or 'hard going.'

Very cool, I'm so curious to hear the difference. Ordered the LP right now. Thanks' for the hint

 

[Laniciffo]

Damn, that's unfortunate... Does stv2310 have some form of line time base correction? I mean, keeping every line's start&end timing the same. Typically used Philips SAA chips don't provide that(
I would greatly appreciate any info regarding the entire digitization process that's happening, especially if it was PAL

I was just in charge of the synchronization. The architect had chosen a line locked sampling which was unusual and probably an error. The usual way was to be locked on the chroma signal, when available. I suspect it might be easier to identify the several chroma subcarrier samples than the unique horizontal synchro pulse.
The chroma decoding was performed with the help of large fir filters. We decoded pal with a comb filter, requiring at least a whole line buffer (2d comb). I think another version even used a full frame buffer (3d comb), to benefit from the chroma phase alternances and therefore better discriminate whether the high feequency variations were luma or chroma. That's quite a challenge with composite video. SVHS and Hi8 and the old 12" video laser discs handled luma and chroma separately and that helped a lot.
I think PAL has a sequence of 8 different frames, depending on the chroma carrier phase vs the line's synchro pulse.

 

[ReDFoX]

I was just in charge of the synchronization. The architect had chosen a line locked sampling which was unusual and probably an error. The usual way was to be locked on the chroma signal, when available. I suspect it might be easier to identify the several chroma subcarrier samples than the unique horizontal synchro pulse.
The chroma decoding was performed with the help of large fir filters. We decoded pal with a comb filter, requiring at least a whole line buffer (2d comb). I think another version even used a full frame buffer (3d comb), to benefit from the chroma phase alternances and therefore better discriminate whether the high feequency variations were luma or chroma. That's quite a challenge with composite video. SVHS and Hi8 and the old 12" video laser discs handled luma and chroma separately and that helped a lot.
I think PAL has a sequence of 8 different frames, depending on the chroma carrier phase vs the line's synchro pulse.

Oh, a built in 3D comb filter... What was the reason ST dropped the development?
Line locked sampling means that this chip automatically corrects field geometry (i.e. has TBC capabilities)?
Sorry if I'm boring you with all these questions...
Maybe you know:
How chroma phase was obtained (and what was the amount of lines needed for initial phase detection)?
Am I correct to assume that front/back porch was used for setting digital levels?

 

[Haskil]

In its time, VHS Hi-Fi was a revelation. It was far, far better than linear tracks they had used before.

And it was the only way to record a full concert or a full opera without being there through programming and without having to turn over a 38 cm four-track tape if you wanted to record with a quality that preserved live FM so much better than 33 rpm...

 

[AnalogSteph]

Kinda off-topic, but a group of Russian enthusiasts reverse engineered PCM-F1 (if I'm not mistaken) and made a PLD-based (again, if I remember correctly) PCM decoder that works better than original one. They've built a PCM coder too...

That's awesome! I imagine something like this may come in super handy for folks suddenly finding themselves in need of archiving recordings made with a PCM adapter back in the day.

The encoder would arguably be quite a bit more niche as we're a bit beyond straight 16/44 recording to makeshift media at this point in time (even if being able to bypass the geriatric '80s ADCs definitely is a good thing in my book). I suppose its use would mostly be in validation and debugging the decoder.

 

[ReDFoX]

That's awesome! I imagine something like this may come in super handy for folks suddenly finding themselves in need of archiving recordings made with a PCM adapter back in the day.

The encoder would arguably be quite a bit more niche as we're a bit beyond straight 16/44 recording to makeshift media at this point in time (even if being able to bypass the geriatric '80s ADCs definitely is a good thing in my book). I suppose its use would mostly be in validation and debugging the decoder.

There're software encoder and decoder too. They were written by people from the same discord server btw.
I know (irl) a guy who has the biggest (AFAIK) collection of vintage PCM processors. Those type C machines I posted earlier are his...

 

[Ken1951]

For us the great thing about VHS Hi-Fi machines was that I could connect the cable input to it and then send the audio signal from the VCR to the receiver ( later a pre-amp) so we could hear TV audio through the main system. Haven't used "regular" sound from a TV other than the BR - and not even that now - for very many years.

 

[Herbert]

Did no one ever notice the rumbling noise under some audience’s applause on VHS-HiFi? It is the switching noise between the drum heads and can be easily spotted with this kind of signal. I guess this is why people like the „analog“, vinyl like sound of VHS-HiFi … I think, but I am not sure, that bass had to be cut at 50hz when mixing for TV and radio until broadcasting went digital, but I do not remember the reason why. At least in the late nineties, the mixes of the TV shows I edited were treated with this bass cut. Maybe one reason the switching noise was less audible.

 

[ReDFoX]

Did no one ever notice the rumbling noise under some audience’s applause on VHS-HiFi? It is the switching noise between the drum heads and can be easily spotted with this kind of signal. I guess this is why people like the „analog“, vinyl like sound of VHS-HiFi … I think, but I am not sure, that bass had to be cut at 50hz when mixing for TV and radio until broadcasting went digital, but I do not remember the reason why. At least in the late nineties, the mixes of the TV shows I edited were treated with this bass cut. Maybe one reason the switching noise was less audible.

Well, the bass cut is easily understandable since it eats away your headroom (domestic TV's speakers aren't capable of reaching even 50Hz). It's like rolling down everything from 25-30Hz in music, where only a few genres truly use full frequency range...

 

[SegaCD]

This was great! Thanks for taking the time to measure not only VHS Hi-Fi in general but to test a few different models to see possible variance between them. This confirms a bit of my suspicion that there is a lot of hardware variance & Hi-Fi starts to fall apart in higher frequencies. (I do a lot of VHS captures and have repaired/restored a number of decks.)
However, it does prove that, VHS Hi-Fi was a wonderful bonus for the average consumer compared to cassette. Performance superior to cassette while offering up to 8hrs of playback/record time per tape and using hardware I already own? Sign me up!

Speaking of which, I was a bit disappointed that different speeds weren't tested. I'd be interested to see if SP vs EP would make a measurable difference in any way especially since the track overlap increases significantly as speed decreases.

Also, I think it would be interesting to repeat this with some older NTSC decks as, by the period of manufacture of the tested decks, VHS decks were being made to hit a price-point (as DVD should have been out by the time of all of these models). It's a bit like testing late model budget cassette deck while a TOTL Nakamichi will measure much better.
If you go back to the early 1990's (during the peak bubble years), Japanese companies were making some audio-focused VHS decks. Decks based on the JVC Victor HR-20000 line (incl. the HR-Z1 and ultimate HR-W1), Mitsubishi HV-V7000, Toshiba A-L91, and many others were marketed for their "superior audio facilities." VHS Hi-Fi is a complex system with not only a separate set of heads and the general heterodyning/filtering of the signal to baseband audio, but a companding system, head-switching noise reduction circuit, and a whole video system (AKA high-freq. noise generator) next door to contend with. I would expect large variation depending on the model and circuit design.

I also 100% agree that anyone who is shilling VHS Hi-Fi as better than reel-to-reel is daft. Even the original white paper/theoretical specifications of VHS Hi-Fi don't exceed professional open reel decks. In the consumer space, it was a wonderful recordable format, but that's where it always stopped. Nobody wanted audio only VHS Hi-Fi albums...but live music where high-quality audio and video would be necessary was always great in Hi-Fi.

 

[DrCWO]

Back in the very early 80s, Linn cut half an album (Dove Across The Water), one side using the analogue master and the other, the same take (unedited) cut from a Sony F1 system. The feedback was largely in favour of one particular side (the one with a little studio-talk between tracks) and this, to Linns apparent consternation as they told me, was the digital one... the analogue mix would have been to 30IPS two track on half inch tape with no noise reduction I suspect, although I have no proof

I got this LP now via Discogs from England. Eight Pounds for the LP 12€ for customs
I can conform that the analog tape recorder was an „Otari MTR10 30 I.P.S. 1/2 inch.“ as noted on the LP.
Will listen to it during the next days with my ProJect RPM9 equipped with Sure V15 Type V-MR (original stylus) and make up my mind

Edit:
Was too curious so listened right now after washing the LP. Side B sounds much cleaner especially in the high frequency regions from the bagpipes. I like it more and the difference is clearly audible. Did not expect that

 

[rdenney]

...I'm a little sad everyone I know hopped off cassettes so fast. I don't know anyone with tapes or playback gear.

I have both tapes and playback gear. For reel-to-reel, too.

Okay, on topic: VHS HiFi was revolutionary when it was introduced. For field recordings, prior to that technology, we had cassettes and open-reel tape decks. I used both. The best I was able to achieve with portable (read: 7" reels) consumer gear was using a Teac 4010S. It was pretty good, but it clearly sounded like a recording. SNR was perhaps 55 dB real-world performance, and it takes a fairly sophisticated cassette deck in perfect condition to perform that well. With either, we were limited to 30 minutes of recording without having to flip the tape.

I could have done better with a half-track open-reel deck, like a Tascam mix-down deck, but I couldn't afford it. And even at 7-1/2 IPS, a Revox would outperform that Teac any day, but I couldn't afford that, either.

My Teac A4300 is a step above the 4010, but it performs about the same. I've recently repaired it and ran it through REW to see how it would do. Frequency response was 20-22KHz, +/1 2 dB, when the signal is at -20 dB from the "reference" level (per Teac's test procedure).

I used the 4010 for field recordings of the orchestra I played in, but it was a pain in the rear.

Then, I acquired a Mitsubishi VHS deck of "better" quality in the day, the day being about 1986 or so. It had the innovative HiFi sound, and I tried that out for doing those field recordings, having been impressed by the frequency response on display from movie tapes that used it. For the first time, ambient room noise (when the music was not being performed) sounded real in headphones. That's the first time I'd heard recorded voice that truly did not sound recorded.

I conclude that the 70 dB SNR that HiFi could deliver was good enough. And four hours of recording meant that I could start the tape and just let it run for the whole concert, and that was transformative given that I also had to perform in the group.

Where that system broke down was attempting to cue tapes for editing and such.

The first field digital technology I attempted (and could afford) was Sony Minidisc, which really worked quite well, though adjusting levels was a pain in the rear. PCM processors on video tape or DAT were much too expensive for me. I did observe the use of a Sony DAT machine for recording a symphony orchestra in which I was subbing on on occasion, and was impressed. That would have been late 90's. In the early 2000's, the systems I saw in use recorded directly onto CD's.

For plain video playback, the first movie sound I heard at home with realistic thunder sounds used HiFi sound, played back on a decent system that use Genesis speakers. I think it was the silly movie Romancing the Stone, but it was the first time I heard realistic (albeit distant) thunder on a home system.

Rick "stuff used to be difficult" Denney

 

[DSJR]

I got this LP now via Discogs from England. Eight Pounds for the LP 12€ for customs
I can conform that the analog tape recorder was an „Otari MTR10 30 I.P.S. 1/2 inch.“ as noted on the LP.
Will listen to it during the next days with my ProJect RPM9 equipped with Sure V15 Type V-MR (original stylus) and make up my mind

Edit:
Was too curious so listened right now after washing the LP. Side B sounds much cleaner especially in the high frequency regions from the bagpipes. I like it more and the difference is clearly audible. Did not expect that

Linn had an ATR 102 for playing the analogue tapes into their Scully lathe, I remember. Does the 'better to you' side have slight talking in between tracks?

 

[Curvature]

My Teac A4300 is a step above the 4010, but it performs about the same. I've recently repaired it and ran it through REW to see how it would do. Frequency response was 20-22KHz, +/1 2 dB, when the signal is at -20 dB from the "reference" level (per Teac's test procedure).

This is with test tapes?

I posted a link with a few FR graphs of these machines: https://www.audiosciencereview.com/...-bad-and-the-crappy.64209/page-5#post-2355041

 

[rdenney]

This is with test tapes?

I posted a link with a few FR graphs of these machines: https://www.audiosciencereview.com/...-bad-and-the-crappy.64209/page-5#post-2355041

Yes. I have a thread about that somewhere. (searching...) Okay, here it is. It described the test tape that I purchased and used, but it's a long read. The test tape I used was supposedly identical to the TEAC test tapes, made by a guy in Germany who has a good reputation on Tapeheads.

The link starts at Page 3, so you don't have to follow along my learning curve.

R

'old, crappy tape deck advice...'

May 14, 2021

So, I inherited several bins of old open-reel tapes from my father, who passed away recently. These bins are recordings of lectures from half a century ago that I consider to be irreplaceable, and personally deeply important. So, naturally, I wish to preserve them in a more sustainable form. Many are recorded at 1-7/8 inches/second, which was acceptable for voice, but there are a some music tapes recorded at higher speeds. Most good decks don't go that slow, but I'm figuring (without having actually explored the matter) that cutting the speed in half in software will be trivially easy and...

• rdenney
• Replies: 93
• Forum: Audio Electronics and Hardware

• 

Note that this was 20 dB down from the reference level used by TEAC, per their specifications and service manual, so noise at full scale will probably be lower than this. (But distortion will probably be higher.) As I understand REW, when noise dominates distortion, the distortion plot turns gray--I see that in the dips of the second harmonic around -60 dB in the vicinity of 100 Hz. That is not a good noise test, however.

Rick "has a much better 'bench' nowadays" Denney

 

[Addicted to music]

Thnk god for the digital revolution