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Author Topic: Quadraphonic tapes  (Read 3911 times)

Offline Guglielmo

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Quadraphonic tapes
« on: April 12, 2011, 06:36:06 AM »
Hi to all.

Please an information: may the "discrete quadraphonic" open reel pre-recorded tapes be played on 2 tracks RtR? Obviously without 4phonic effect but simply in stereo?

Thanks!

Cheers,

Guglielmo


Offline zaphod

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Re: Quadraphonic tapes
« Reply #1 on: April 12, 2011, 09:03:24 PM »
Hi to all.

Please an information: may the "discrete quadraphonic" open reel pre-recorded tapes be played on 2 tracks RtR? Obviously without 4phonic effect but simply in stereo?


hi,

you might get some weird effects, (backing surrounds up front) but it might just be a blast :)
Lance Bailey
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walk gently. leave a good impression.

Offline steveidosound

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Re: Quadraphonic tapes
« Reply #2 on: April 12, 2011, 10:02:48 PM »
The short answer is yes. Results will not be optimal however. The left channel of the 2 track head will read both the left front and rear tracks somewhat equally and "mix" them together. The right channel will do the same for right front and rear. But the head is not centered on either track so some odd phasing effects or frequency response anomalies might occur. You will at least get an idea of what is on the tape but perhaps not the mix balance that was intended.
Steve Williams

you don't want to know what equipment I listen to...

Offline Guglielmo

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Re: Quadraphonic tapes
« Reply #3 on: April 13, 2011, 09:44:18 AM »
Thanks to all for useful contribution. Actually I was in the occasion to get some quadra-tapes but I was in doubt whether these ones could be played on 4 tracks machine...

Please another clarification dealing with tape tracks: is it normal than when I listen to original pre-recorded 2 tracks tapes on a 4 tracks machine the volume in the channels is not the same. This happens with all 2 tracks tapes so I have to increase the right channel to get a good balance... Obviously the S/N on this channel is dramatically increased...

Thanks for clarification.

Guglielmo

Offline ironbut

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Re: Quadraphonic tapes
« Reply #4 on: April 13, 2011, 11:47:35 AM »
Hi Guglielmo,

I checked your past posts and noticed that you have a ReVox A77. In one of your posts, you referred to it as a 4 track machine. As far as I know, Revox only built the A77 in either the 1/2 or 1/4 track configuration (I've owned both).
If your machine has 2 VU meters, it's 2 channel in either of the above mentioned track configurations. It's a little confusing but there's an excellent post in the "Beginners Guide" that's located in a sticky above the General Forum.
This would explain why the channels aren't equal in level when playing 2 track (1/2 track) tapes.
steve koto
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Offline jeri

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Re: Quadraphonic tapes
« Reply #5 on: April 13, 2011, 03:02:23 PM »
Hi Guglielmo,

Steve is on the right, er, track.

It's normal that the two channels don't balance when listening to 2-track tapes with a quarter track machine.

You might think that quarter track heads would line up with half the width of the recorded tracks of 2-track tapes, but they don't.

The reason is that there are unused guard bands between the recorded tracks.  In the case of 2-track tapes, the guard band is almost as wide as each recorded track, so the tape is essentially divided into thirds.  The outer quarter-track lines up pretty well with one of the 2-track tracks because it is near the edge of the tape, but the inner quarter-track (track 3) is off quite a bit.  This is shown in the attached sketch.

If you run the numbers for actual track widths and positions, it turns out that about 87% of one quarter track head gap covers recorded material on a 2-track tape, but only 41% of the other gap covers recorded material.  With less signal, there is less volume.  So it's no surprise that one channel is louder than the other on playback.
Jeri

Offline Guglielmo

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Re: Quadraphonic tapes
« Reply #6 on: April 14, 2011, 10:00:56 AM »
Thanks Steve, thanks jeri for helpful contribution.

Finally I understand why my Revox is always unbalanced with 2 track tapes! I wrongly guessed that something was to be realigned! Now it is OK!

Cheers,

Guglielmo