VHS multitrack

[Farview]

Yes, no digital recording in a HiFi VCR. But it's not strictly "analog" either.
It works like FM radio.

Well, it's still analog. It's just not put to tape the way you would assume audio is put to tape.

Technically, anything recorded to a magnetic medium is analog. In the case of digital tape, the actual thing being recorded on the tape is an analog representation of the digital signal.

 

[Tim Gillett]

Well, it's still analog. It's just not put to tape the way you would assume audio is put to tape.

My point entirely!

I said it's not strictly analog. I even put quotation marks around my use of the word "analog".

I guess I just wasnt clear enough for you...Sorry.
Thankyou for your helpful clarification.

Cheers Tim

 

[Farview]

My point entirely!

I said it's not strictly analog. I even put quotation marks around my use of the word "analog".

I guess I just wasnt clear enough for you...Sorry.
Thankyou for your helpful clarification.

Cheers Tim

My bad. It was early. In my bleery-eyed state, I took it to mean something else. Oh well...

 

[Tim Gillett]

My bad. It was early. In my bleery-eyed state, I took it to mean something else. Oh well...

No worries. We all make them.

Actually I think Blue Bear hit it when he mentioned ADAT. If it hadnt been for that development, and what followed over the years I have a hunch there would have been developed some sort of analog multitrack format(s) using something like a Beta or a VHS or U Matic shell.

NR would have dealt with tape noise at slower speeds and narrower tracks just as it was used in open reel analog as well as portastudio formats.


You could speculate on say a VHS based fixed head analog multitracker running at 3.75ips, giving, on an E180, 45 minutes. Or on a U Matic KCS 60, 60 minutes but with more space for wider tracks or more of them.

On the U Matic 3/4" tape you could have got about 9 tracks with the same track width as on a standard 1/4" 2 track reel to reel format. At the end of the prosumer open reel days, EE tape was giving the same audio specs at 3.75ips as for normal tape at 7.5ips.
The potention for an excellent analog multitracker was there at least, in a videocassette type format.

Cheers Tim

 

[themaddog]

The potention for an excellent analog multitracker was there at least, in a videocassette type format.

Where were you four years ago to back me up! Just kidding.

-MD

 

[TransducerX]

The tape quality is the issue. The tape is formulated for video, not audio. The transport is not designed for the type of abuse that recording involves. That is why you always needed to buy an extra ADAT machine, one of them would always be in the shop.

The other thing is tape speed, there isn't enough tape in the cassette to do anything at 15 ips, much less 30ips. A VCR normally runs slower than 1 ips, so at 30 ips, you would get 4 minutes of tape.

VHS machines have been around for 25 years, multitracking has been around for 50. I'm sure this has been explored by no less than 3 companies, there is a reason why it never came to market.

It's half inch tape, so 8 or 16 tracks.

Thanks, Farview.

 

[Beck]

The transport is not designed for the type of abuse that recording involves. That is why you always needed to buy an extra ADAT machine, one of them would always be in the shop.

That's for sure... and maybe both in the shop; one from use and the other from sitting unused for too long.

 

[pianodano]

That's for sure... and maybe both in the shop; one from use and the other from sitting unused for too long.

Dang, you sure you guys aren't talking a Tascam DA-78 now? Out of the 5 of the darn things that I own, I can usually only (barely) keep 1 working. Seems to work out thusly:

1 in the rack -
1 on the way to the shop -
1 in the shop -
1 on the way back from the shop -
1 that never works no matter what -

 

[Farview]

Dang, you sure you guys aren't talking a Tascam DA-78 now? Out of the 5 of the darn things that I own, I can usually only (barely) keep 1 working. Seems to work out thusly:

1 in the rack -
1 on the way to the shop -
1 in the shop -
1 on the way back from the shop -
1 that never works no matter what -

I have 5 DA88's. Only 3 of them still work, but I only had 2 go down the entire 6 years I was using them all the time. I got them all 10 years ago. It's a shame that they aren't worth fixing.

 

[sweetbeats]

Out of the 5 of the darn things that I own...

Danny, have you always had 5? I thought you had 3. I guess it makes sense so you can have a more efficient rotation to the shop. Good thinking!

 

[Tim Gillett]

The tape quality is the issue. The tape is formulated for video, not audio. The transport is not designed for the type of abuse that recording involves. That is why you always needed to buy an extra ADAT machine, one of them would always be in the shop.

The other thing is tape speed, there isn't enough tape in the cassette to do anything at 15 ips, much less 30ips. A VCR normally runs slower than 1 ips, so at 30 ips, you would get 4 minutes of tape.

VHS machines have been around for 25 years, multitracking has been around for 50. I'm sure this has been explored by no less than 3 companies, there is a reason why it never came to market.

It's half inch tape, so 8 or 16 tracks.

Dont quite agree here on a few things. I understand the tape in a normal VHS shell was similar to TDK SA, or a chrome or psuedo chrome, which is an excellent audio recording tape. The fact that they could run the linear audio analog track at half cassette speed (15/16ips) on a narrow track- admittedly not hifi- says it was a good tape on that score alone. That's a hard test.

Yes, video signal is a greatly different demand on the tape but they dealt with that by other means such as the fast rotating heads. No change in tape stock.



Also, if one of these machines was made purely for analog linear audio, the mech could be MUCH simpler than an ADAT machine, dispensing with the troublesome rotary head drum, motor and base. Similar to the Elcaset. Sure, the tape would need to be withdrawn from the VHS shell, but only to place it in a simple traditional tape path including 3 heads and a capstan.

Running at 30ips, even 15ips would be ridiculous in this format. If you could get acceptable sound using a similar tape stock on a Portastudio cassette running at 1.875 or 3.75ips, no reason you couldnt in a VHS or Umatic format. In fact your tracks could be wider for lower noise, you'd have better tape guidance from a properly isolated tape path as opposed to the compromise of the old Philips cassette (where the tape guidance was shared between the shell and the machine), plus you could use the same NR as on a Portastudio.
In the late 70's I worked with Umatic video machines and they had two linear audio tracks running at 3.75ips for an hour's program per cassette. The audio was not too bad. Better than standard audio cassette.

I think the VHS or Umatic or Beta cassette was far superior to the Philips audiocassette, and it needed to be for the higher demands video placed on it. For a start it used proper flanged reels which were cogged into the machine so that their height was controlled much better than on the Philips where the tape squeezed against slip sheets and jams and edge damage were a risk. Philips cassettes had that horrible pressure pad too which caused premature and uneven head wear. A video cassette was far superior for video AND audio.

As to the reason it never came on the market, I think that's already been covered: ADAT.
But as said, if it had come out, its transport would have been much more reliable than any system that used a rotating head drum.

Sticky shed is a problem with reel to reel tapes. The exact same tape on a rotating head drum is a disaster waiting to happen. For just a small amount of sticky shed with a rotating head drum machine, read: problems.
Even just a bit of dew or moisture in a rotating head shuts it down. Sticky shed? Forget it. The tape and tape path have to be near perfect.
That's one reason why restoration of old TV station videotapes is not simple.

In reply to the guy who started the thread, I reckon that had it not been for ADAT, we could have had some lovely multitrackers in videocassette formats.

Cheers Tim

 

[Farview]

You are starting with the premise that normal audio cassettes were good sounding. I don't agree. I guess that colored my opinion.

 

[TransducerX]

Dont quite agree here on a few things. I understand the tape in a normal VHS shell was similar to TDK SA, or a chrome or psuedo chrome, which is an excellent audio recording tape. The fact that they could run the linear audio analog track at half cassette speed (15/16ips) on a narrow track- admittedly not hifi- says it was a good tape on that score alone. That's a hard test.

Yes, video signal is a greatly different demand on the tape but they dealt with that by other means such as the fast rotating heads. No change in tape stock.



Also, if one of these machines was made purely for analog linear audio, the mech could be MUCH simpler than an ADAT machine, dispensing with the troublesome rotary head drum, motor and base. Similar to the Elcaset. Sure, the tape would need to be withdrawn from the VHS shell, but only to place it in a simple traditional tape path including 3 heads and a capstan.

Running at 30ips, even 15ips would be ridiculous in this format. If you could get acceptable sound using a similar tape stock on a Portastudio cassette running at 1.875 or 3.75ips, no reason you couldnt in a VHS or Umatic format. In fact your tracks could be wider for lower noise, you'd have better tape guidance from a properly isolated tape path as opposed to the compromise of the old Philips cassette (where the tape guidance was shared between the shell and the machine), plus you could use the same NR as on a Portastudio.
In the late 70's I worked with Umatic video machines and they had two linear audio tracks running at 3.75ips for an hour's program per cassette. The audio was not too bad. Better than standard audio cassette.

I think the VHS or Umatic or Beta cassette was far superior to the Philips audiocassette, and it needed to be for the higher demands video placed on it. For a start it used proper flanged reels which were cogged into the machine so that their height was controlled much better than on the Philips where the tape squeezed against slip sheets and jams and edge damage were a risk. Philips cassettes had that horrible pressure pad too which caused premature and uneven head wear. A video cassette was far superior for video AND audio.

As to the reason it never came on the market, I think that's already been covered: ADAT.
But as said, if it had come out, its transport would have been much more reliable than any system that used a rotating head drum.

Sticky shed is a problem with reel to reel tapes. The exact same tape on a rotating head drum is a disaster waiting to happen. For just a small amount of sticky shed with a rotating head drum machine, read: problems.
Even just a bit of dew or moisture in a rotating head shuts it down. Sticky shed? Forget it. The tape and tape path have to be near perfect.
That's one reason why restoration of old TV station videotapes is not simple.

In reply to the guy who started the thread, I reckon that had it not been for ADAT, we could have had some lovely multitrackers in videocassette formats.

Cheers Tim

How fast would you suggest running the tape? 15 ips?

 

[TeyshaBlue]

Doesn't the fact that it uses a rotating head give it a higher overall tape speed by several factors? 15ips on a static head is not the same as 15ips on a rotating head....

And as Dave said, if you're dealing with a deck with Auto Level Control, you won't be happy with the end results.

 

[pianodano]

Danny, have you always had 5? I thought you had 3. I guess it makes sense so you can have a more efficient rotation to the shop. Good thinking!

Sweetbeats,

Yep, I did have 3 for a number of years. But because 1 or 2 was always down, I bought (duh, what was I thinking ?) 2 more that had pretty low hours on them last year. Not one of my better ideas I guess.

Danny

 

[Tim Gillett]

How fast would you suggest running the tape? 15 ips?

Well the faster the speed, the better punch in precision. But things could be improved for slower speeds by designing the erase head as close as possible to the record head. So halving the distance between those two heads would give you the same punch in precision at 7.5ips as at 15ips on open reel.

I guess, thinking about it, 15ips would be fine so long as you were prepared to accept the playing time limitations of maybe 12 minutes on an E180. But all things considered, I would have thought 7.5ips a good compromise for home or small studio use.

Having it on a cassette means you could have changed over to a fresh tape much quicker than with a 10.5" reel, especially since you wouldnt strictly have to rewind the tape onto one reel before removing it from the machine.

Cheers Tim

 

[Tim Gillett]

Doesn't the fact that it uses a rotating head give it a higher overall tape speed by several factors? 15ips on a static head is not the same as 15ips on a rotating head....

And as Dave said, if you're dealing with a deck with Auto Level Control, you won't be happy with the end results.

Yes, the rotating head allowed video recorders to capture in the megahertz range. That made video as well as digital audio recording possible.

Sure, many VHS consumer machines (at least for the linear audio track) used auto level and for good reason, but we're talking here about a dedicated multitracker for small studio use, designed from the ground up, even though using a standard videocassette format. You'd assume a separate level meter for each track.
Auto level for each track? Well, if that's what the customer wanted and was prepared to pay for it, no reason it couldnt be an option. But that applies to any recorder.


These days, with modern tapes though, 15ips even with a static head, can record well above audible frequencies. A good audio cassette could do 20khz at 1.875ips, so at 15ips the same tape could do 160khz, if needed. Industrial instrumentation recorders captured well above audio frequencies using tape speeds that we might have considered only good for the audible range.

As audio tapes and machines got better, high linear tape speed came to be more necessary for clean punch ins than for frequency response.

Cheers Tim

 

[Tim Gillett]

You are starting with the premise that normal audio cassettes were good sounding. I don't agree. I guess that colored my opinion.

Well not quite. I said that given acceptable sound from say a Portastudio at the same tape speed and tape stock, you could get the same with a VHS tape. That's hardly debatable.

The better Portastudios were not set up not for "normal' tape, and in fact worked poorly with them for that reason, but for the better type II tape, running at double normal tape speed, and often with the benefit of Dolby B, C or dbx.


The contrast between a "normal' cassette at normal speed, and a Portastudio using type II tape, running at double speed (3.75ips), and often with NR is also hardly debatable. It was a huge difference.

A VHS tape being much wider than a 4 track Portastudio cassette tape could fit maybe 14 tracks and at that same sound quality. At double that speed (7.5ips) your editing would be tighter and sound quality even better, but with the same recording time as a Portastudio.

Besides we're not talking about top end studios but small and home studios on a budget. And VHS cassettes became really cheap because they were virtually universal.

Cheers Tim

 

[themaddog]

Well the faster the speed, the better punch in precision. But things could be improved for slower speeds by designing the erase head as close as possible to the record head. So halving the distance between those two heads would give you the same punch in precision at 7.5ips as at 15ips on open reel.

I guess, thinking about it, 15ips would be fine so long as you were prepared to accept the playing time limitations of maybe 12 minutes on an E180. But all things considered, I would have thought 7.5ips a good compromise for home or small studio use.

Having it on a cassette means you could have changed over to a fresh tape much quicker than with a 10.5" reel, especially since you wouldnt strictly have to rewind the tape onto one reel before removing it from the machine.

Cheers Tim

The problem I would imagine 15 or even 7 1/2 ips is the durability of the tape. I'm just not sure that VHS tapes are durable enough, particularly within a thin 180 minute tape.

-MD

 

[Tim Gillett]

The problem I would imagine 15 or even 7 1/2 ips is the durability of the tape. I'm just not sure that VHS tapes are durable enough, particularly within a thin 180 minute tape.

-MD

Interesting question.

I've just got out my old TDK booklet on their audio and video cassette range around 1990.
TDK list the E180 as having a total thickness of 19.5 u meters. But the C90 audiocassette is listed as having a total thickness of only 12.5 u meters!


So as far as I can tell, the VHS E180 videotape was actually thicker based than the C90 audio cassette.

Interesting too that their shorter videotapes like E 120 and E 60 used exactly the same tape stock, not thicker ones. Just shorter lengths.
You'd think that if there was a durability advantage from thicker tape bases they'd have gone for it in the shorter lengths where there was room in the shell for it. But to be fair, maybe with the delicate setup of a videotape where tolerances are pretty tight, a different thickness tape might have caused more problems than it was worth. I'm only guessing.

I think the main stresses on the videotape were related to the rotating drum and things like staying in pause mode for extended periods when you could literally scrape the coating off the base. Possibly the reason for the apparently tougher tape than with audiocassettes.

In any case those extra stresses on the videotape would not apply in a deck with no head drum.

So that's my reasoning. If a tape can survive a rotating head drum, it can surely survive stationary heads. I dont think we should assume that just because it was a videotape as such that it was fragile. Rather, video required the rotating heads and that was probably the achilles heel of the thing.

I guess the same would apply to DAT tapes and these days to mini DV camera tapes which I use myself, but, I admit, with some trepidation! Three years and so far, so good, but I transfer the data as soon as I can just in case.
Interestingly, DAT tapes are notoriously problematic and arent trusted as archival media. Again, a rotating head configuration.

You mention 7.5ips or 15ips as possibly stressful for the tape. I doubt it would be. For example good quality standard audiocassettes can happily be high speed duplicated at 30ips.

And that's duplicating in the actual cassette shell. Commercial pre recorded recordings could be high speed duplicated serially on pancakes running at over 100 times play speed! So the limiting factor for speed was not the tape but the mechanical abilities of the cassette housing or shell. Cassette tapes couldnt be duplicated much faster than x100 because above that the tape would to "fly", meaning the trapped air between the tape and the record head would lift the tape off the head just enough to reduce recording clarity! We're talking a tape speed approaching 200ips!

From everyday experience we know that VHS, Beta, Umatic and other tapes survive REW and FF at speeds far in excess of the design play speed. And that's not capstan controlled, the preferred method for ideal tape wind.
I dont have a VHS spec list but found an old Beta one. On an L500 tape the average rewind speed (which in a Beta machine meant fully engaged with the head drum) was 46.8cm/sec which translates to well over 15ips (38cm/sec)

Anyway, my thoughts FWIW.

Cheers Tim