Precision reels on eBay (SPAMISH post)
- Thread starter Blue Jinn
- Start date
sweetbeats
Reel deep thoughts...
I think some of it might have to do with the slower transport speed and the fact there are no lifters. Like, that’s my experience when I happen upon open reel tape that’s gone sticky, if it’s just starting to go, it’ll happen during fast-wind…you start to hear the squeal. But then I might be able to hit PLAY but if I put my ear up to the tape path you can hear the drag against the static tape path elements. And most of my experience is at 15ips. But cassette at 1 7/8ips or 3 3/4ips doesn’t have the same degree of heat from the friction…like, this is totally unscientific…but I feel like in those situations I describe above, the transport overcomes the stiction of the sticky tape, but as it passes at high speed over static lifters and guides there is an increase in temperature and that causes the friction coefficient to head in the wrong direction…downward spiral. And then sometimes it’s in PLAY…when the tape is a little worse condition. But a cassette…no lifters, no static guides…there are rolling guides in the shell. And the slower speed maybe there isn’t that same increase in temperature. I’m not saying the cassette tape might not be sticky, but the same triggers that set things sideways with open reel tape aren’t as present with cassette tape. I’m just hypothesizing here. The bottom line is cassette tapes aren’t immune at all. I just think it is less common or evident, a higher percentage of the cassette community may be unaware of SSS at all and if they have a bad tape might just be like “well that sucks”, toss it and move on. We also know different formulas of tape are more or less prone and it’s possible cassette tape formulas may generally be less prone like certain open reel tapes. But you can do a web search of cassette sticky shed and get hits that discuss the issue generally but also include cassette tape in the mix.
Blue Jinn
Rider of the ARPocalypse
Are cassettes even back coated? I can't recall from all those times had to pull out the pencil, or fix that one mixtape . . .
sweetbeats
Reel deep thoughts...
No they’re not, but back-coating is only one element of a complex problem with sticky and/or shedding tape. I think there is a some misconception that SSS only affects back-coated tape and that’s just simply not true.
jamesperrett
Active member
3M made back coated cassettes in welded shells that tended to jam up very easily. I've also had cassettes that shed but they've mostly been obscure brands like Racal (a very well known UK industrial electronics company who decided to dip their toes in the consumer market without much success).
I received the case of tape today. It came in a Quantegy cardboard box with one of the labels dating it to 2003. The tape itself came in individual plastic cases. There are 7 total. Im ready to do some "logging" but I won't be able to test it for a few weeks, until I get my capstan motor repaired. The tape looks good though, definitely NOS. Years ago, I got a hold of some 2" 3M 966 tape, which is the same as 996 but is only 1ml thick and it worked fine. So Im not concerned about this Quantegy tape being 1ml, especially at 1/2".
Blue Jinn
Rider of the ARPocalypse
Please keep us posted. The specs look OK, it looks like you need to bias for Quantegy 499/GP9, RTM 468, but don't hit it as hard. I don't know if there's something different about the formula.
rob aylestone
Moderator
eh? You've baked a tape and are going to use it for new recordings? Why did you bake it? I'm really confused by what you've done here?
sweetbeats
Reel deep thoughts...
So there’s nothing exceptionally thin with the logging tape. As mentioned earlier in the thread it’s a 1mil spec tape…like LPR35 or 407/457…so if it’s slipping on your transport then yes either your pinch roller pressure is off, your pinch roller is hardened and needs replaced, your takeup tension needs adjusted, or some combination of those factors. It doesn’t mean the tape is bad or impossible to use. Your MTR-12 should have no issues properly running 1mil tape…sophisticated gentle transport. I just want to put that out here for other readers to avoid folks thinking 1mil tape is bad. I still have concerns about the tape’s usability for audio production use due to the lower operating level and intended application of low-speed voice capture, but the thickness of the tape shouldn’t be on anybody’s primary list of concerns AFAIC.
On some tape machines, there need to be adjustments between the capstan roller in order to handle thinner tape stock.
Finally, I will quote an article from 1997 which can be found here: https://www.soundonsound.com/techniques/analogue-tape-machines
This is a well known issue that is not something that I just made up. Take care and good luck.
Before we look at how the tape recorder works, perhaps it's worthwhile to spend a few moments considering the actual recording medium — the tape. Recording tape is coated with a metallic compound capable of storing a pattern of magnetisation. This magnetisation is varied in strength and direction to represent the original sound waveform. In other words, the magnetisation pattern is analogous to the air pressure variations of the original sound.
Modern tape formats use polyester as the tape base, with a suitable magnetic coating. Polyester has the ideal combination of strength and flexibility, such that it will not snap or stretch under normal usage. The thickness of the backing material is important: if it's too thin, the tape transport may have difficulty in handling it (the C120 cassette being the most obvious and notorious example). If it's too thick, the amount of tape which can be wound on to a given spool is limited, reducing recording and playing times.
Typical 'Standard Play' open‑reel tape is about 50 microns thick, with a full 10‑inch reel of tape (the standard professional size) lasting a little over 30 minutes at 15 inches per second, or ips (a common speed for a professional machine). However, other thicknesses are available, notably the 'Long Play' version, which is only 35 microns thick. This type of tape is most commonly used on machines with particularly twisty tape paths, or where the spool size is restricted, the most obvious example being the infamous Nagra tape recorders used for location sound recording. In its portable mode, the Nagra will only accept 5‑inch spools, and its tape path involves a couple of very sharp 90 degree bends, so Long Play tape is the ideal choice.
Most modern tapes are 'back coated', which means that they have a slightly matt and rough‑feeling surface, as opposed to a shiny, slippery one. The back coating is to improve how the tape winds (by offering improved friction between layers) and to exclude trapped air during fast winding. Neat and even winding is important in avoiding edge damage to the tape — the most common cause of drop‑outs and poor head‑to‑tape contact. On the subject of edge damage, a correctly wound tape should not touch either spool flange but should sit between them, and any tape spools which are bent, so that they rub against the tape during recording or playback, should be thrown away and replaced with new ones immediately!
Depending on the requirements of the tape, the detail of the magnetic material used to make up the magnetic coating may vary, but is usually either a metal oxide or metal alloy compound. The most common material is gamma‑ferric oxide (gamma referring to the shape of the ferrous particles) but chromium‑dioxide formulations are also used. In the early to mid‑'80s, metal‑particle tapes were developed, primarily for compact cassette recorders, but few machines were equipped to make best use of the formulation, as metal tapes need extremely high levels of magnetisation (they have a high 'coercivity', which is the ability of the tape to become, and remain, magnetised). The majority of domestic cassette machines simply could not achieve the required field strengths, although those that could benefited from better distortion and signal‑to‑noise ratios. In fact the metal‑particle tape has become far more commonly used for digital audio and video recording, where its very high recording density is ideally suited to the high‑frequency requirements of digital formats. It should be noted that tapes intended for digital recorders have radically different compositions to those for analogue recorders, because the nature of the recorded information is entirely different — never use digital‑formulation tapes on analogue machines!
Fundamentally, recording tape is little more than a highly sophisticated rusty ribbon, the nature, shape and depth of the 'rust' particles bestowing the combination of properties the manufacturer is seeking.
The magnetic properties of recording tape are far from linear, and, if used 'raw', would produce very quiet but heavily distorted recordings. To 'linearise' the medium, a high‑frequency signal (typically about 150kHz) called bias is used. The amount of bias needed to produce optimum results depends largely on the precise construction of the magnetic layer, and will affect output level, noise, distortion and frequency response. This is a point I'll return to later.
Another characteristic of recording tape is that high‑frequency signals tend to be retained by the top surface of the magnetic layer, whilst lower‑frequency components tend to be recorded throughout its full depth. This has a bearing on the requirements of the recording heads and the longevity of recordings.
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