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#1
October 9th 04, 06:22 PM
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"Cheapness," as per Frank Zappa.
Frank Zappa did a really funny bit about old horror movies long ago,
saying how much he liked "cheapness." You know, the bit about the plastic monster would be shoved forward into frame a bit too far and you'd see the 2x4 pushing it, that sort of thing? Well, I think 8 track recorders by Sanyo/Wollensak had some "cheapness" built in, also. Whether Zappa would 've appreciated it is subject for conjecture. The bias system in these things is amusing. A bias oscillator is transformer coupled to the "all in one" head assembly, which also has separate windings for an "erase head," per the schemo. There is NO record bias circuit at all. Evidently, the proximity of the erase gap to the R/P gap in the "all in one" head provides the bias for recording. Thus, if you decrease bias to get better top end on the tape, you lose erase efficiency...not a real problem, since I bulk erase them anyway. But, "cheapness", nevertheless! I remember Nortronics used to field an 8 track replacement head with separate erase gaps on the side of the head face, shielded from the R/P gap. Such a head wouldn't work on a Wollensak, since it seems that cross-coupling of the bias field into the R/P gap is what makes the Wollensak record at all! Of course, most people know that the record bias current is usually enough to erase most (not all) magnetism on a tape, even with the erase head disconnected, but there will still be artifacts left behind, especially in the bass region. Anyway, having a "real" erase circuit is of little concern to me while recording 8 tracks, since I bulk erase them. So, I fiddled with the erase bias current on my 8075, and voila...3 dB down at 12 KHz is a snap, with 10 dB down a bit past 15 KHz...pretty good, considering it's 8 track. Defeating the 19 KHz FM trap circuit on this model made it even better. This was on Scotch Dynarange, the old standby. BASF actually gave me even more top end (3 dB down at 14 KHz) but is noisier, and I had to crank the bias down even further to get that. Third harmonic distortion, of course, increases when this is done, so a judgement call has to be made between flatter frequency response versus audible distortion products...the same trade-off in ANY analog recording system. On peaks, the third harmonic was getting a bit nasty on BASF (that trademark "raspy" sound the technically unwashed refer to), so I bumped the bias back up to the "Scotch level", and it went away. So did most of that top end I'd gained. Oh well, everything in analog is a compromise. Next victims for testing: Memorex 90s, Ampex 84s and TDK SAs. I don't think I'll ever find some Scotch "Classic" ferrichromes..."unobtainium." One thing's certain...you can get lower THD at the same high frequency response on Scotch than with BASF. Later Radio Trash "Supertapes" are BASF with a different oxide; haven't tested them yet, but they seem bias hungry. Is this pretty much a standard biasing system on 8 track recorders for the consumer market? Inelegant, but it works. Next, as was discussed earlier, I did some serious disassembly of the DC can motor that drives all Wollensaks after the 3050, and did some judicious cleaning and lubrication. The wow and flutter, record/playback, turned out even lower after using a different drive belt, and measured .05% RMS weighted worst case...damned respectable for 8 track. Most cassette decks never got this good until the dual capstan Nakamichis and Akais started showing up in the '80s. However, a cheap or "stiff" cartridge (or one with a dirty or crappy pinch roller) will screw this up easily, as the tachyservo in the can motor can't keep up with the varying load presented by such a cartridge. This system does do one thing AC motors cannot...speed regulation, a necessity to someone like me who is cursed with perfect pitch. Most AC motored decks seem to run slow, while unadjusted DC decks inevitably are set a bit fast. Of course, one can fiddle with an AC powered deck to get better speed accuracy simply by shimming up (splicing tape works for this in a pinch) either the drive or driven pulley until the speed's dead on. I took a useless "polka hits" cartridge, precisely measured 187'6" of tape, spliced it with a foil strip, and measured the time between track changes...10 minutes was dead on, of course. It took a few runs to get it right, but now I can play a CD and 8 track of the same track and they GENERALLY turn out completely in sync. I ascribe those times when it didn't to different master speeds at the dupe plant. Many cheapo dupe plants used old Ampex 300s for master decks, and although the best at low wow and flutter, they were notorious for speed inaccuracy. Speed accuracy on LPs was never that much of an issue, except for some of MCA's lousy "best of..." and "twofer" re release series, where they sped up the masters a bit to cram another track on each side. AM top 40 radio did this ad nauseum in the '70s to get more commercial spot time, something that used to drive me nuts. Now, they just digitally "nibble" at parts of a cut, and although the tempo is irregularly faster, pitch sensitive folks aren't as offended. Another bitch about MCA LPs...high regrind content vinyl, making surface noise horrid. All LPs got crappy in the '70s, but MCA led the pack, for certain, in the relentless pursuit of profit over quality. Now, with bias adjusted and wow and flutter a non-issue, I dubbed some LPs and CDs and listened to them a few hours later. My gut reaction is that 8 track, when everything's working right (which is seldom) is as good as 3.75 IPS RTR...no better, or course. Using Dolby "B", however, dropped the noise floor nominally 10 dB, making it better than Dolby encoded cassettes of the same era, due to lower wow and flutter and seemingly a bit more headroom. Of course, later on, cassette wound up besting the best of 8 track on high frequency response (if you wanted to spend the money) and even on wow and flutter. But one area in which 8 track will always be superior to cassette is bass response...more of it, flatter, less response "humps" caused by bass self-erasure, an occupational hazard of recording at 1.875 IPS. Try as they might, they were never really able to ameliorate this problem with cassettes. Popular misconception has been that the difference is in the tape, but I don't believe that to be true. It's simply that the tape moves too slowly across the gap to avoid this phenomenon. Verification of this were the Denon "two speed" decks which could record cassettes at 3.75 IPS, giving flatter bass like an 8 track and more top end than RTRs at 7.5 IPS. Philips claimed this was as violation of their licensing agreement, and Denon eliminated this feature about two years after it showed up. I think Akai had a two speeder at one time, too, which disappeared shortly after Philips squawked. Philips, of course, had an agenda...the audio CD, which was invented in the US in 1965, was in the works for mass consumption at the time by both by Sony and Philips, and they wanted to keep cassettes "crummy" to sell more CD players after their introduction in 1984. And they most certainly did.... Anyway, enough 8 track fiddling for now. I actually have to get some work done! dB 
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#2
October 10th 04, 01:33 AM
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Some interesting stuff, dB.
You might try using a thicker drive belt on the AC units to pick up some speed. Zappa Rules! Dan 1.5
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#3
October 10th 04, 03:47 AM
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#5
October 11th 04, 04:14 PM
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I've a couple of "Classics" if interested. More willing to trade.
hit me off board if interested. PEACE! Dan DeserTBoB wrote in message . .. I don't think I'll ever find some Scotch "Classic" ferrichromes..."unobtainium." One thing's
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#6
October 12th 04, 03:23 PM
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zzzzzzzzzzzzzzzzzzzzzzzz.....................
snok, snore... ZZZZZZzzzzzzzzzzzzzzzzzzzzzzzzzzz........
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#7
October 12th 04, 05:38 PM
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#8
October 12th 04, 11:25 PM
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Next, as was discussed earlier, I did some serious disassembly of the
DC can motor that drives all Wollensaks after the 3050, and did some judicious cleaning and lubrication. The wow and flutter, record/playback, turned out even lower after using a different drive belt, and measured .05% RMS weighted worst case...damned respectable for 8 track. You are totally incorrect here, ROUND BELTS and THICK BELTS are readily available online from the proper suppliers. As many as you want, and any length you want. Also, WTF is a "Wollensak 3050" ?? Man, that is one RARE deck dude, esp. since WOLLENSAK NEVER MADE A 3050 !!
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#9
October 13th 04, 01:02 AM
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