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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>If I can put an RCA spin on this<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Quad errors are much faster than helical errors and so I would
not expect and external TBC expecting helical errors to respond to quad errors<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The TBC’s and servos also interconnect with error signal
called THF and THA ( RCA words)to keep these small window TBC’s in
the centre of their operating range.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>That was the TCR 100 problem two decks, two servos but only one
TBC it had to perform without THA to keep the TBC centered <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>It drifted and failed to lock the only answer frequent alignment<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Digital TBC’s <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The RCA TR 600 used digital error detection, but Analogue Error
correction, perhaps they had A to D problems, <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Trevor Brown<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>videovault@sky.com<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
quadlist-bounces@quadvideotapegroup.com
[mailto:quadlist-bounces@quadvideotapegroup.com] <b>On Behalf Of </b>Chill315@aol.com<br>
<b>Sent:</b> 08 December 2009 14:14<br>
<b>To:</b> quadlist@quadvideotapegroup.com<br>
<b>Subject:</b> Re: [QuadList] Time Base Correctors<o:p></o:p></span></p>
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<p class=MsoNormal><o:p> </o:p></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>TBC's are an interesting lot. The Quad ones were all analog
until the AVR 2 and 3. There are advantages to the use of the
analog type of TBC. <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>The video never is subject to the conversion to digital and
back. The conversion was not of a high quality in the early units.
Even the AVR 2 had issues and you had to tweak the converter to eliminate
stepping.<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>The AMTEC and Colortec are a very stable unit. The
experience that I had was that they never needed to be looked at. I would
do it anyway about once a year and never found them to be a problem.<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>The Velocity Compensator was the secret to a good playback.
It integrated the errors over a head pass and thus made the color hue constant
across the length of a line.<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Now what about a TBC. Merlin was able to make several units
work. Yes you get a very wide window. If the tape could not be H
locked, then there was a problem that the analog TBC could not handle.
(Unless you had an AVR 1.) Most after market digital TBC's can not
handle segmented scan and the head switch. This sudden jump in a line
placement is not what a TBC sees in every day life. The result is usually
a displacement of the line. There is usually a loop circuit to smooth out
the errors over several lines. That is the reason for the displacement. <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Most TBC's of the era were only 8 bit so the conversion is not as
clean as a 10 bit. I could walk up to an AVR 2 and see when the TBC
needed adjustment because of the artifacts that 8 bit put in. Just feed a
ramp in and it becomes very easy to spot. <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Would I change out the analog units? My answer is no as I do
not see that there are going to be any better results. The proper setup
of the original machine is the secret of a good playback. <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Now for a possibility to play back the REALLY TERRIBLE tape.
The machine can be played back in many different lock modes. If you can
not obtain H lock, what about taking the output of the AMTEC and then feeding
that to a TBC? Play the tape in any lock mode. The AMTEC takes care
of the segmented scan and any guide errors. Let a TBC external bring the
picture back into color and H lock. Velocity errors might be an
issue because the AMTEC might not have the error integration across the line.
Any thoughts or has someone tried this?<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'> <o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Chris Hill<o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>WA8IGN<o:p></o:p></span></p>
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