Tape formats

Open reel tape comes in different sizes, formats and speeds so it’s a good idea to get to grips with some of the key variants, not least to ensure that the tape machine you buy can actually play the tapes you want to listen to.

As with most things, there’s inevitably a trade-off between performance and cost. The wider and faster the tape, the better the fidelity and quality of the recording. But obviously this uses up more tape and so the higher the cost.

Much will also depend on the age of the tapes and of the vintage decks you’re dealing with, since different eras had different technologies and ways of doing things. What’s more you’ll find significant variations between hardware and processes made for professional versus domestic use.

These are all things to bear in mind when investing in a tape machine and when buying tapes for either playback or recording purposes.


Tape width

¼” tape

Open reel tape comes in ¼-inch, ½-inch, 1-inch and even 2-inch widths. Broadly speaking, ¼-inch tape was the norm for domestic mono or stereo tape machines, while professional mono, stereo and multi-track tape recorders used any of ¼-inch, ½-inch, 1-inch or 2-inch tape. More tape width means more information storage capacity so the wider the tape, the better the potential fidelity. But unless you’re recording professionally, chances are you’ll almost exclusively encounter ¼-inch tape. Which is good news since you’d need a whole different machine (with different tape heads, guides, etc) to play broader width tapes.

Takeaway points
¼-inch tape is the norm for both vintage tapes and current master tape copies.
If buying a vintage tape deck, make sure it takes ¼-inch tape.


Reel size and format

5″, 7″ & 10.5″ reels

Tape reels come in two main types, NAB reels and CINE reels. NAB reels were typically used in studio and professional settings while CINE reels (also known as Trident) were the norm in domestic applications. However the vast majority of tape decks, whether designed for professional or domestic use, tend to come with CINE hubs, for which you’ll need a NAB adaptor.

The more important consideration is reel size since your choice of machine could potentially limit the tapes you can play. The most commonly-used reel sizes were 5, 7 and 10.5 inches in diameter (though the latter is often abbreviated to 10”). Most domestic decks were designed to play commercially-released 5 and 7-inch tapes, whereas 10.5 inches is the norm for master tape copies. To play 10.5″ reels (or larger) you’ll need a higher-end vintage domestic deck or a professional one.

Takeaway points
You’ll need CINE hubs to play vintage commercially-released tapes and NAB hubs to play current master tape copies. Look for a deck with CINE hubs and get a NAB adaptor.
For master tape copies, make sure your deck can take 10.5” reels.


Tape recording formats

When it comes to tape recording formats, again there was typically a difference between professional and domestic use. In the case of stereo recording, professional studio machines were usually two-track (also called half-track), which means that the left channel occupies one half of the tape width and the right channel the other half. Two-track/half-track tapes record in one direction only, there’s no B side, so once you’ve finished playing the tape, you have to rewind it to listen again.

Domestic machines, in contrast, were usually four-track (also called quarter-track) in that they recorded in both directions, providing double the amount of recording/playback time by allowing you to flip the tape over between side A and side B – though remember we’re not actually talking about two physical sides as with vinyl, since tape only has one recordable magnetic surface. So a four-track/quarter-track tape records two channels in one direction and two in the other when the tape is turned over, each track occupying a quarter of the total tape width. (The compact cassette tape was a development of four-track tape but the tape width was halved from ¼” down to ⅛” and the speed halved down to 1⅞ ips).

Technics RS-1500 showing two-track & four-track tape head options

It’s a rare tape deck that can play both two-track/half-track and four-track/quarter-track. In most cases it’s either one or the other. Exceptions we’ve come across include the Technics RS-1500 and 1506, the Otari MX-5050BII and the Teac X-1000M.

Most vintage commercially-released tapes are four-track/quarter-track while pretty much all current master tape copies are two-track/half-track. So your options are basically: (a) make a choice, (b) track down one of those rare decks, (c) save up for two tape decks or (d) get someone with two tape decks to copy your old four-track/quarter-track tapes onto new two-track/half-track tape!

Oh and there are also some old commercially-released mono tapes out there. In the early days of tape, mono recordings were either one-track (a single-sided recording occupying the full width of the tape) or two-track (a double-sided recording where the recording occupied half the width of the tape, which was turned over to read in the other direction).

Takeaway points
Most vintage commercially-released tapes are four-track (aka quarter-track) while pretty much all current master tape copies are two-track (aka half-track).
Very few tape decks can play both so it’s usually a case of one or the other (or of stretching to two decks).

Tape speeds

Studer A812 with three speeds

Like vinyl records, open reel tapes can be recorded at different speeds and obviously need to be played back at that same speed. Tape recording speed is expressed in inches per second, abbreviated to ips. In general, the faster the speed, the better the reproduction quality.

You’ll typically come across four or five main speeds. 3¾ ips and 7​½ ips were the speeds used for the majority of consumer market releases of commercial recordings. Most domestic machines therefore had speed settings of both 3¾ ips and 7​½ ips. Some also offered a third, slower speed, 1⅞ ips. (3¾ ips was also the speed used in 8-track cartridges and 1⅞ ips in compact cassettes).

The usual professional speeds for quarter-inch tape were 30 ips and 15 ips. 7​½ ips was only occasionally used in studio settings, perhaps for a quick preview or demo recording.

Takeaway points
Most vintage commercially-released tapes were 3¾ ips or 7​½ ips while all current master tape copies are 15 ips or (occasionally) above. Make sure your deck of choice offers the range of speeds you need.


Studer A812 showing both EQ options

Like vinyl with its RIAA curve, tape uses an equalization when it’s recorded. This needs to be undone at playback. The two most common equalizers are NAB and CCIR (the latter is also known as IEC1). Typically, Europe favoured CCIR and the USA went with NAB. CCIR is the more modern of the two and is what most currently produced master tapes copies use. And yet again it’s a different story for most vintage commercial releases, which usually tend to use NAB.

Most tape machines are one or the other, but some machines can be switched between the two (again, the Otari MX-5050BII is a good example). But if you find yourself with a machine that can’t, fear not since you still have options. A handful of hi-fi manufacturers are now making external tape amplifiers which, like a phono stage, allow you to upgrade an old tape deck by taking a direct feed from the tape head into a modern, high quality head amplifier. Some of these devices also add on switchable NAB/CCIR equalization. If you’re buying one, be sure to have the direct feed from the tape head fitted by a knowledgeable engineer.

Note: You can physically play NAB tapes on a CCIR-calibrated machine and vice versa, but you won’t get the optimum sound quality. A NAB tape played on a CCIR-calibrated deck will sound dull and bass heavy, while a CCIR tape played on a NAB-calibrated one will sound bright with diminished bass weight.

Takeaway points
Most vintage commercially-released tapes use NAB equalization while the majority of current master tape copies use CCIR.
Since tape decks typically offer one or the other, you might need a switchable add-on.

Tape operating level (aka ‘reference fluxivity’)

Studer A812 VU meters

Tape operating level, or reference fluxivity, is a term used to describe the strength at which the recording head ‘prints’ the signal onto the tape. For the recording engineer or the record label, the choice of operating level is made to minimize tape hiss and maximize dynamic range and resolution, so basically it’s all about balancing the signal/noise ratio. Tape operating levels are measured nano-Webers per meter (eg. 250nWb/m).

Over the years the typical standard operating levels used for recordings changed, as tape manufacturing improved and audio electronics became more advanced. So again, there’s the issue of which decks were manufactured at the time of which operating level standards, and what can and can’t be adjusted to current standards. It’s quite a complex issue to wrap the head around – for more details check out our dedicated blog on the subject: Tape operating level aka ‘reference fluxivity’: what’s it all about (and why should you care)?

Takeaway points
There are two key contexts in which you need to consider operating levels. First, when choosing a deck, make sure it has adjustable output levels so that you can enjoy tapes with varying operating levels without compromising on sound quality. Second, when having your deck calibrated during initial set-up and subsequent servicing, you need to decide what operating level to calibrate it to. See the above-mentioned blog for full details.