Auto-reverse cassette recorder query.

[toshiba tony]

Ok. A very simple one but due to dementia it's got me. Imagine, auto reverse cassette deck. (2 header) in normal record mode first the tape is erased then new music laid on. So when it's in reverse mode the tape runs past the r/p head first then the erase head. So how does that work. Daft things you think about when your mind gets confused. Ta, anyone.

[Refugee]

I have got one that turns the head over to play the other side.
The erase head is also part of the assembly that turns over. There are two azimuth screws for the two sides of the tape.

[IanBland]

I'm fairly sure you could only record in the forward direction, auto reverse just did playback. Otherwise you'd need two erase heads..?

[Refugee]

Originally Posted by IanBland

I'm fairly sure you could only record in the forward direction, auto reverse just did playback. Otherwise you'd need two erase heads..?

Have a look at post#2.

[dave walsh]

I did have a really brilliant auto reverse recording deck once [might have been Panasonic but not sure]. Most decks that did that left a gap at the turn around point but this one was instantaneous-amazing! I think it auto reverse recorded both decks in sequence. Never got another one like it. When it failed I bought an apparently similar model but there was a gap-it was so disappointing. Feeling very overwhelmed at one stage, I stupidly ditched a lot of high end auto reverse machines thinking they couldn't be repaired. Then I found the Forum If the current cassette revival continues all the redundant machines we are hoarding may spring into life [like Radiograms et] and we can expect another onslaught from new "enthusiasts". "Stand by/buy".

Dave W

[TIMTAPE]

The fanciest auto reverse dual cassette deck I've seen was the professional Tascam 122RMkII. It had a reversible combo head for off tape monitoring ("3 head"), two erase heads, one for each recording direction, and data connections to another 112RMkII. When one machine completely filled up one cassette it started recording on its other cassette. When both those cassettes were filled up, it signalled the other machine to start recording on its two cassettes. So I guess a total of 6 hours recorded on 4 C90 cassettes.
Because it had to be dual capstan for reverse, the erase heads had to fit in the two small windows either side of the cassette's central large window.

[TonyDuell]

Originally Posted by IanBland

I'm fairly sure you could only record in the forward direction, auto reverse just did playback. Otherwise you'd need two erase heads..?

My Uher CR210 records in the 'forward' direction only (it's autoreverse in playback mode) for exactly that reason. Just one erase head, and a 4-winding record/playback head.

['LIVEWIRE?']

My TEAC W-600R has two decks, oneautostop, Playback only, and one Auto-Reverse, which plays and records in both directions, which I thought was fairly common. The combined play/record/erase head assembly rotates as the direction changes. I also recently repaired a Sony machine in which both decks were auto reverse, and both are recorders, although tape dubbing can only be done from deck A to deck B.

[toshiba tony]

Refugee gets it. Both my decks do recording in both directions. Don't know how to make a pot of tea but certain things still come into my head, and that was one.
The erase head is on the rotating assembly. Thanks.

[toshiba tony]

Sorry, a few of you helped.

[8 Tracker]

There is another way. Have a look at the Akai GXC-65D Invert-O-Matic, which physically turns the cassette over to play the other side. Total madness, but fascinating to watch.

Video here

Mark.

[Refugee]

The one I have got and shown in post#2 is a JVC.
It does record in both directions and can make tapes from CD.

[dave walsh]

Does it leave a gap though? I recall that the people in the Dealership didn't really understand that extra bit of sophistication, re the model I had. When I asked why they weren't available any more I was told "no demand" but I think they actually had "no idea". The superior machine detected and acted upon the actual end of the magnetic tape material to switch over [as opposed to using the tension at the end of the leader and reversing back back from there, hence the delay . I don't recall how the heads were arranged but you could hear the mechanism go over so fast that I never noticed any interruption in the recording. I wondered, at the time, why they weren't all like that? It couldn't have been that complex or expensive to build in Maybe it was like the introduction of Mini Disc Long Play-a great improvement but not really promoted enough. Anyway, I'll do my best to try and find out what that cassette recorder was?

Dave W

[julie_m]

There were three common ways of providing automatic end-of-tape detection. The first was by a metallic foil spliced between the recording tape and the leader, which completed a circuit just before the end of the oxide. The second was by means of a tension finger in the tape path, which was pushed out when the tape pulled taut at the end of the leader. The third was by sensing the rotation or not of the take-up spool; either mechanically, or electronically -- often by means of a magnetic or optical sensor linked to the tape counter (which is why as a general rule, if a hi-fi cassette deck will not stay in play or fast wind, the counter belt is one of the first things to replace). Again, this senses the leader.

Perhaps the quick-turn-around machine was able to detect a special tape with metallic foil (at the beginning of the leader, which has not yet reached the centre window with the heads; so the only unrecorded portion would be for the time it took to reverse the travel and swivel the head assembly) using a sensor on the counter pulley as backup in case you were using a normal, foil-less tape?

Another method would be to rely on the leader transmitting light, while the recordable tape is opaque. This too would be nearly seamless, but might not work with every brand of tape (some leaders might not be transparent enough, or a mended cassette might have the recording tape joined straight to the spool) so would require movement-sensing backup for a reverse cycle at end-of-leader.

[ben]

Somewhere I have a late-70s Pioneer CT-F750 ( think) auto reverse unit that has a fixed 4 track head and two small erase heads which fit into the smaller gaps to the left and right of the usual head gap in a cassette.

I also have a Sony TC-WR735S dual well deck which records auto reverse on both wells.The heads are rotary on that (as is the case with all the newer ones it seems). The benefit of a fixed head is that the azimuth is always the same, not the case with rotary ones.

[dave walsh]

Thanks Julie and Ben. The only metal foil in tape system I've seen was reel to reel. The tension finger was also commom on reel to reel. I don't recall that the "quick flip" cassette recorder I had required any special type of cassette tape
They certainly stopped before the end of the leader!

Dave

[julie_m]

I've definitely seen early Sony Cassette-Corders (apparently, the Sony people figured that "re" means "again", so the process of laying the first-ever signal on a brand-new tape must be called "cording") with contacts for detecting a piece of metal foil spliced between the tape and leader, and I once even saw a cassette belonging to someone else that was fitted with such foils; I don't remember if it was a Sony. But these were very old machines. By the 1980s, they were no longer using the foil-type auto-stop. The problem of building a semi-automatic single play turntable with a belt as opposed to an idler drive was already solved, and the mechanical auto-stop sensors work on basically the same principle: something has to move a certain distance within one turn of a wheel (or not) to trip it into the next state.

If your (Panasonic? Sounds just like the sort of thing they would do) didn't need a special tape, then it could have been using optical sensing. Most tapes did have clear leaders, though some were coloured and might not have worked properly if the source was monochromatic such as an LED -- green or blue would not let much red through, for instance. (A good designer would have accounted for this, and also sensed the tape motion or tension.) If it was packing three heads into the reversing assembly, then it could detect that it was not recording on the leader and trip the reversing cycle. Sensing recordable tape vs. leader by some magnetic method might also have been possible, but likely to damage existing recordings -- so not much use on playback, when you would want to hear the near-seamless reverse.

You have got me intrigued as to how they actually did it, now!

[emeritus]

My Sony music centre has a rotating head assembly as per #2. I haven't tried recording in auto reverse mode. Not sure about azimuth adjustment.

[paulsherwin]

Most autoreverse decks which can record in both directions have two erase heads. They don't add much to the manufacturing cost - decks with this functionality aren't going to be cheap in any case.

[Welsh Anorak]

A more prosaic one was the Aiwa midi-system popular in the late Nineties. It usually had a 3-CD changer in the top of the unit and twin cassette tapes, one of which was auto-reverse.. As mentioned in post #2, the 'head' was in fact two side by side - erase and record/play - that rotated 180 degrees by a gear system when reverse was initiated. Amazingly, the system worked well with the azimuth staying pretty true. Besides belt troubles, the main source of trouble was the fine wires fracturing. As you can imagine, replacement was a tricky job - the wires were produced through a small tube and anchored to a PCB. Repeated rotation of the heads inevitably led to their demise. Luckily the deck assembly was easy to remove complete.