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#1
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Resilience of digital on video tape
I'm transferring all my PCM-F1 recordings (1984-1996) to computer via a PCM
601 processor with S/PDIF output. I'm amazed at how well these 20 year old tapes are tranferring. No significant dropouts in the first 18 tapes. Only a hundred more to go... I haven't gotten to the couple of tapes recorded at slow speed. I don't have much hope for those. I blew a whole $50 on a new VCR so I could read the VHS tapes with new heads. |
#2
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I'm transferring all my PCM-F1 recordings (1984-1996) to computer
via a PCM 601 processor with S/PDIF output. Might I ask which audio card you're using? My Santa Cruz doesn't have an S/PDIF input, and I'd consider replacing it to transfer my own PCM-F1 recordings. (I am fortunate to own the 601.) |
#3
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#4
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"William Sommerwerck" wrote in news:6IqdnWJWT-
: I'm transferring all my PCM-F1 recordings (1984-1996) to computer via a PCM 601 processor with S/PDIF output. Might I ask which audio card you're using? My Santa Cruz doesn't have an S/PDIF input, and I'd consider replacing it to transfer my own PCM-F1 recordings. (I am fortunate to own the 601.) Frontier WaveCenter (www.frontierdesign.com) S/PDIF and ADAT Lightpipe, but no analog inputs. |
#6
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Blind Hog wrote:
(Mike Rivers) wrote in news:znr1123445097k@trad: In article writes: I'm transferring all my PCM-F1 recordings (1984-1996) to computer via a PCM 601 processor with S/PDIF output. I'm amazed at how well these 20 year old tapes are tranferring. No significant dropouts in the first 18 tapes. Only a hundred more to go... In the past few months, I've dug out four and tried to play them. Two played fine. Two were so full of dropouts that they were quite unusable, at least on my VCR. These are all Beta format. I guess find a VCR with newer heads is kinda out of the question... Some of the newer professional Beta machines can play the old consumer Beta tapes, but they all have dropout compensation that you cannot disable. On the other hand, they also probably have much better S/N than those old consumer machines ever did when they were new. Parts Express still has a variety of head drums for consumer Beta machines, by the way, if you want to rebuild an old one. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#7
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Blind, just from curiosity, how are you dealing with the pre-emphasis
issue? The PCM-F1 always recorded with pre-emphasis (treble boost), so the S/P-DIF bitstream coming out of the PCM 601 will have this characteristic as well. But .WAV files don't have a standard way to indicate that this emphasis has been applied. As a result, when you burn CDs from the wave audio files, you always need to set the pre-emphasis flag on the CD tracks in the CD burning software, so that the pre-emphasis flag will be recorded on the CD. Only in that way can the CD player apply the compensating treble reduction. If you don't do something about this, all your CDs that come from F1 sources will play back with 10 dB of boost above 4 kHz or so. I use Golden Hawk's software for burning most audio CDs; its cue sheets include a way to signal that a track's source material has pre-emphasis. But pre-emphasis isn't used much any more, and I haven't seen this feature in other recent CD burning programs. That's why I'm asking--I'd like to know what other software supports this type of transfer. --best regards |
#8
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#9
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David Satz wrote:
I use Golden Hawk's software for burning most audio CDs; its cue sheets include a way to signal that a track's source material has pre-emphasis. But pre-emphasis isn't used much any more, and I haven't seen this feature in other recent CD burning programs. That's why I'm asking--I'd like to know what other software supports this type of transfer. Another way of dealing with this, and probably the more common one today, is to apply a de-emphasis filter in software once you've loaded the file. I've been doing this a lot, since I have a lot of tapes I recorded with a Tascam DA P-20, which had nondefeatable emphasis. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#11
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"David Satz" wrote in news:1123518322.687186.48960
@g43g2000cwa.googlegroups.com: Blind, My apologies to all readers. I've changed ISP's and newsreaders, put up a bogus name during the conversion, and forgot to remove it before beginning normal conversation again. Message from the old blind hog are from me. --Carey Carlan |
#12
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Blind Hog wrote:
(Scott Dorsey) wrote in news:dd82tn$aet$1 : David Satz wrote: I use Golden Hawk's software for burning most audio CDs; its cue sheets include a way to signal that a track's source material has pre-emphasis. But pre-emphasis isn't used much any more, and I haven't seen this feature in other recent CD burning programs. That's why I'm asking--I'd like to know what other software supports this type of transfer. Another way of dealing with this, and probably the more common one today, is to apply a de-emphasis filter in software once you've loaded the file. I've been doing this a lot, since I have a lot of tapes I recorded with a Tascam DA P-20, which had nondefeatable emphasis. What does that curve look like? "10 dB above 4kHz or so" sounds pretty vague. EIAJ has 15 and 50 microsecond time constants as I recall. This would give you: ================================================== ===== kHz 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -dB 0.0 0.0 0.0 0.1 0.1 0.1 0.2 0.2 0.3 ================================================== ===== kHz 1 2 3 4 5 6 7 8 9 10 -dB 0.4 1.3 2.4 3.5 4.5 5.4 6.1 6.7 7.2 7.6 ================================================== ===== kHz 11 12 13 14 15 16 17 18 19 20 -dB 8.0 8.2 8.5 8.7 8.9 9.0 9.2 9.3 9.4 9.5 ================================================== ===== (chart shamelessly stolen from Tom McCready, but there is a copy of this in the Tascam DA-30 review in the July 1991 issue of Studio Sound) --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#13
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#14
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Blind Hog wrote:
I'm listening to the digitally-transferred recordings and don't hear anything like that kind of rise in the signal. +3.5 dB at 4K should be pretty obvious, and, with only a -54 dB noise floor in the mic preamps, I should be getting intense amounts of hiss. Don't hear that either. The effect is not subtle, really. Could the 601 be doing de-emphasis out the digital port? How could I find out? Guess I could record a sweep or pink noise. I don't think the 601 does it, but it's entirely possible whatever you have plugged the digital signal into is doing it. The data coming out of the 601 has consumer subcode with the emphasis bit set, and so whatever is reading it may well have dropped a digital de-emphasis filter in there automatically. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#15
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(Scott Dorsey) wrote:
I've been doing this a lot, since I have a lot of tapes I recorded with a Tascam DA P-20, which had nondefeatable emphasis. What does that curve look like? "10 dB above 4kHz or so" sounds pretty vague. EIAJ has 15 and 50 microsecond time constants as I recall. This would give you: ================================================= ====== kHz 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 -dB 0.0 0.0 0.0 0.1 0.1 0.1 0.2 0.2 0.3 ================================================= ====== kHz 1 2 3 4 5 6 7 8 9 10 -dB 0.4 1.3 2.4 3.5 4.5 5.4 6.1 6.7 7.2 7.6 ================================================= ====== kHz 11 12 13 14 15 16 17 18 19 20 -dB 8.0 8.2 8.5 8.7 8.9 9.0 9.2 9.3 9.4 9.5 ================================================= ====== (chart shamelessly stolen from Tom McCready, but there is a copy of this in the Tascam DA-30 review in the July 1991 issue of Studio Sound) One can calculate the theoretical pre-emphasis curve frequency response from the following relationship: y = 10log(A/B) where y = dB output at a frequency of f Hz A = 1 + (L x L) B = 1 + (H x H) H = (2 x pi x f x t(H)) L = (2 x pi x f x t(L)) t(H) = high freq. time-const, in sec (= 0.000015) t(L) = low freq. time-const, in sec (= 0.000050) For de-emphasis, reverse the sign of y. A clunky, but exact, formula - just layer it into a spreadsheet to cobble up a quick 'n dirty graph. Certain software de-emphasis plugin presets, e.g. Waves, sound OK but don't measure all that closely to the theoretical curve. I'm unaware of any soundcard which de-emphasies an incoming s/pdif stream and stores to 'straight' straight wav -all done in the digital domain. But rme cards can detect pre-emphasis flags and apply de-emphasis in a DA stage - so that you can at least monitor 'straight' while writing the still-emphasised wav to hard disk . Tom McCreadie Live at The London Palindrome - ABBA |
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