Tape Recording

JOHN M. CONLY is a former New York and Washington news paper man, now on the staff of High Fidelity Magazine. “They Shall Have Music" is a quarterly feature in the Atlantic.


TAPE recorders cost money. As recreational devices, they have found market, so far, among bird-song enthusiasts, sound maniacs, and cocktail-party gagsters. Now, however, that canny character, the living-room music listener, has begun to evince interest. As usual, in his wary way, he sprays the ground ahead with a barrage of queries.

Magnetic recording began twentyone years later than mechanical recording. Edison cut his first cylinder in 1877. Emile Berliner originated the disk record in 1888. Ten years later, a Dane named Valdemar Foulsen invented magnetic recording, using a steel wire passed between two 2-foot reels at tremendous speed. An electromagnet planted magnetic signals on it as it went (the idea was to record telephone conversations) in low fidelity, and any audio pioneer who crouched to inspect the winding of the reels stood in some danger of acquiring phony Heidelberg scars if the wire broke and lashed at him.

The basic theory behind tape recording is fairly simple, although some of its refinements are not very well understood even by the technicians who devised them. If a bar of iron is wound with a coil of wire, and electric current is passed through the coil, the bar becomes a magnet, with a “north” pole and a “south" pole. Much of the magnetism departs (especially in an iron alloy mixed for the purpose) when the current slops. This is an electromagnet. The recording head of a tape recorder is such an electromagnet, but bent into a circle so that the ends almost touch. Past it, touching both these ends, first one and then the other, runs the tape, coaled with a plastic paint full of iron oxide particles.

Just as a common horseshoe magnet magnetizes pins and nails, so the electromagnetic head magnetizes stretches of the passing tape — or, rather, of the iron oxide coating on the tape. The magnetization, of course, is governed by the current in the coil wound around the top of the ring magnet. When the current comes from a microphone, for instance, the magnetization faithfully varies in accord with the sounds which activate the microphone. The vibrations of a high-frequency treble tone will lay down a succession of almost microscopic magnetized areas — southpole, north-pole, south-pole, northpole— each under a thousandth of an inch long. Deep bass vibrations will stretch out the interval between N and S to nearly an inch. These areas stay magnetized until erased. (Incidentally, erasure can happen accidentally. Never store a reel near anything magnetic — like a loudspeaker, for instance.)

Playing the tape back depends on another property of magnetic force. Lines of magnetic force (called flux lines) like to form complete loops, head to tail, so to speak. Emerging from the N pole of a bar magnet, a flux line promptly executes a graceful curve, heads back down the length of the magnet, and curves again to re-enter at the S pole. Flux lines will do this through air, but they much prefer to travel through iron or an iron alloy.

The surface of a magnetized tape is alive with these little arcing lines of force. To put them to work, a reproducing head is placed near them as the tape moves past. The reproducing head is an exact duplicate of the recording head (sometimes the same head), except that no current is fed into the coil around its bent waist. As one of the tips of its gapped ring approaches an arcing flux line, the latter abandons the inhospitable surface of the tape and leaps up to complete its loop, momentarily, through the ring of permeable metal that forms the head.

Nature is full of helpful reflexive effects. Just as a current in an adjacent wire will temporarily magnetize a piece of iron, so will a brief magnetic impulse in the iron generate a current in the wire. The leap of the magnetic are from the tape through the iron of the reproducing head sends a tiny jolt of current out of the wire coiled around it. This travels to an amplifier, there to be built up and emerge from a loudspeaker as a glottis stroke by Perry Como or a drumbeat in Beethoven’s “Eroica.

To erase a tape, it is merely necessary to run it through what engineers call a “decaying” series of alternating impulses. The first, strong impulse magnetizes all the oxide particles in one direction. The next, slightly weaker, reorients nearly all of them the other way, and so on, until total, random confusion reigns among them —meaning that they are neutral and devoid of signal. This represents one of the great boons of tape as a recording medium. It can be erased and used over again.

Tape has other vital assets, too. It can he cut and rejoined (patched with sticky tape or heat-welded) very easily. This makes editing extraordinarily simple, even for amateurs. Tape recording’s mechanical frictionnoise doesn’t get into the recorded signal or sound, since it isn’t magnetic in its nature. This produces eerily quiet recording background. Tape can be played over and over without loss of definition, whereas disk recordings, even played with the finest and most compliant jewel styli, do always lose, through abrasion, I some of their high treble frequencies; the corners of the smallest, sharpest groove-turns are simply rubbed off. Moreover, even if grit gets into a reel of tape and scratches its surfaces, no clicks or pops are heard when it is played — a point which will be appreciated by collectors of today’s fine but vulnerable vinyl microgroove phonograph disks.

To offset these advantages, tape has had, until recently, a number of dubious qualities. Foremost among these has been its tone range or, as it is commonly called now, fidelity. High frequencies could he recorded but, from reels spinning at less than the professional speeds of 30 or 15 inches per second, they couldn’t be reproduced. The high overtones of a violin, for example, would leave on the tape magnetic impressions which were actually shorter than the gap in the recording head. Naturally these couldn’t send flux lines around the playback head’s ring; they wouldn’t reach. As recently as two years ago, it was estimated that at a tape speed of 71/2 inches per second (a common homerecorder speed) the high-fidelity ceiling was about 7000 cycles per second, approximately the same as a pre-war phonograph record.

Greater tape speed could obviate this trouble, of course. With the tape going twice as fast, the fiddle overtone’s impression was spread out twice as far, and the gap in the reproducing head could easily pick it up. However, true professional tape recorders cost upward of about $500 each, had to use big, 10-inch reels, and often weighed upward of 100 pounds. They weren’t living-room equipment. (They did become standard equipment in the LP phonographrecord industry, however, so that their benefits reached home listeners at second hand. Virtually all phonograph records now are recorded initially on tape.)

True, there were a few semiprofessional machines available, offering two speeds — 71/2 and 15 inches per second. Most popular were the $345 Concert one and the slightly more expensive Magnecordette. People who wanted to tape music — and couldn’t wait — bought these, in substantial quantities. They have had no cause to regret, it; these are fine, flexible machines. People who wanted nonmusical parlor playthings or secretarial devices bought slowspeed, low-fi, home-style recorders,

A good many people, however, weren’t satisfied with this choice. They held out, in the hope that one of two things would happen. Either someone would make a low-cost, high-speed recorder, or someone else would make a high-fidelity, low-speed recorder.

They were wise. The second development is the one that took place in 1933. There are now on the market at least a half-dozen recorders which operate at 71/2 inches per second (some offer a talk-speed of 33/4 inches as well) and can record, when new, out to 13,000 or 15,000 cycles per second, which is as high as the average ear can hear. They can do it cleanly, too, with little flutter or other vibratory distortion. They range in price from $199 to $299, the lowest price being that of the Crest wood 401, which comes, like a professional recorder, without amplifier or speaker — just the recorder and its necessary preamplifier, to be plugged in and used with existing sound-systems.

The improvement which made this possible was not especially dramatic. To begin with, the recorder manufacturers had arbitrarily divided their customers into two groups: professionals, who wanted expensive, heavyduty, precision machines, and laymen, who wanted low-fi parlor gadgets. In disagreement with this division, that valorous corps, the hi-fi dealers, set up a tremendous squawk. Thereupon, the manufacturers began polishing and squeezing their recorder-head gaps and smoothing their tapes until 71/2inch-per-second machines could pick up musical frequencies as high as 15,000 cycles per second — when new.

The repeated qualification “when new” introduces another tape-recording problem, and may as well introduce a leading proponent, experimenter, and spokesman for tape — Dr. W. W. Wetzel, sound-tape research chief for Minnesota Mining and Manufacturing Company, which makes more than half the tape used in the United States. Wetzel, after teaching physics at Colgate, Chicago, and Minnesota universities, got into magnetic development work during the war, devising anti-magnetic-mine protections for ships. Like many another devotee of hi-fi music, he gravitated to sound-research because he was dissatisfied with pre-war phonographic equipment.

A dark-haired, vigorous, cordial man of fifty, Wetzel is enthusiastic but honest about tape and tape recorders as home-music media. One tapetrouble problem, he and his laboratory crew have already solved. The 1940 German tape, coated with black iron oxide, was rough and uneven. It generated unpredictable variations in loudness, clouded the air dramatically with black sand as it shot past the reproducing head, and wore the tips of the head down so that their effectiveness waned rapidly. Wetzel and his associates tested hundreds of powdered oxides and came up with a red oxide which could be ground much more finely and applied more evenly. Now that this is standard, they have moved onward, discovering a green oxide which yields a much louder signal, lessening the proportion of random background noise and in general cleaning up the reproduced sound.

So far, Minnesota Mining is sole keeper of the secret of green highoutput tape, though this probably won’t last long. M-M-M’s competitors, though much smaller, are very brisk outfits. Next biggest is Audio Devices (Audiotape), which retains the services of the redoubtable C. J. LeBel, erstwhile president of the Audio Engineering Society. Hard on its heels comes Reeves-Soundcraft, which does some of the finest custom recording work anywhere.

Next, says the insatiable Wetzel, someone should perfect and market a thinner tape, so that 2400 feet of it can be wound on a home recorder’s 7-inch reel, yielding a good two hours of music per twin-track reel. He himself has been caught at the end of a half-hour reel when an orchestra, broadcasting by FM, was about to begin the last movement of a symphony. No one, he says with feeling, should have to move that fast.

Moreover, even the thinnest, smoothest tapes are still abrasive, and they wear recording and reproducing heads down. When a reproducing head has been ground down past a certain point, it suddenly suffers a drastic loss in tone range and must be replaced. In home use, this isn’t much of a problem. The useful hi-fi life of such newly designed heads as the Shure “Golden” or the Brush BK-1090 — call it 1000 hours — compares very well with that of a diamond phonograph stylus. And replacement cost is not exorbitant — between $15 and $30.

Most present heads are made of an alloy called Mumetal, very permeable to magnetic impulses but softer than I the tape that rubs against them. Wetzel points out that there exists another possible head material, which is harder than the oxide tape-coating: a baked magnetic ceramic called ferrite. Ferrite heads cannot yet be mass-produced, but Wetzel’s men have handcrafted a few for theaters to use on their multichannel 3-D sound tracks, and they have outlasted metal heads three to one. At a venture, ferrite replacement heads should hit the home market in about two years.

It may be pointed out here, as a warning, that not every recorder can accommodate a new, improved recording head without internal adjustment. The major complication is a thing called “bias.” Bias is a veryhigh-frequency signal, fed into the recording head along with the audio impulses. Its function is to shake up the tape’s oxide particles, sensitizing them to even the weakest of the radio signals, which otherwise they tend to throw off. Not all recorders apply the same bias, and substituting a different-type head may produce distortion in the recorded sound. It may not be amiss to point out here that any head will produce distortion if it gets dirty or is pushed askew. For the exacting home recordist, a useful acquisition is a set of alignment-test tapes, which help him to get his recording and reproducing heads in exactly the right position for best performance. (One of the best sources is the L. S. Toogood Company, Chicago.)

Among the new crop of hi-fi 71/2inch recorders, several have brought in enthusiastic recommendations from users—notably the Revere T-10 ($235), the Ampro 756 ($240), the Brush “Soundmirror” 455P ($289), the Webster-Electric Ekotape, and a new Webster-Chicago (Webcor) with three small loudspeakers. Perhaps most-mentioned are the new Crestwood paired units: the 401 ($199), which consists of tape mechanism only, and the 402 ($100), a matched amplifier-loudspeaker assembly. All the other makes mentioned above have built-in amplifiers and speakers, though they also can be used with existing hi-fi equipment. In a slightly different category come the assorted Magnemites put out by the Amplifier Corporation of America. These are tiny devices, driven by smooth spring motors and powered by batteries, so that they may be carried and used anywhere. One of them, beloved by bird-call fanciers, has a 15-inch speed! They are not inexpensive.

However, most folk who buy hi-fi home recorders intend to use them mostly to copy phonograph records (unethical as this may seem to record manufacturers) or to tape radio broadcasts, which can be very rewarding in major cities, where excellent live musical programs are regularly transmitted on high-fidelity FM. Anyone planning to assemble a hi-fi rig incorporating a tape recorder, to billow these practices, is hereby advised to make sure that his amplifier has a tape-output socket. It will simplify his monitoring substantially. Others may have to do a modicum of tinkering to feed their recorder from phonopickup or radio tuner — and listen themselves at the same time.

There is, of course, prerecorded tape. As yet, however, it must be admitted that most of it is not cheap and not reliably good. Briefly, Magnecord published tapes duplicating Vox record releases, but at 71/2 inches in days when 7^2 was low-fi. A-V Tape Libraries, in New York, have been duplicating Remington records, on 71/2inches-per-second tapes which usually sound better than their counterpart disks. Westminster has definite plans to begin issuing tapes itself, later this year, and there are rumors that Columbia may commit a “select library" to tape. Up to now, prerecorded tapes have cost somewhat more than disks per minute of music —about $8 an hour. This is cut somewhat when selections arc offered on twin-track tape as well as single-track, as many are. It is probably safe to predict that most prerecorded tape will come out on twin-track, which indicates the desirability of getting double-track heads on recorders when there is a choice.

So far, only one small entrepreneur. Concertape, has put prerecorded binaural tape on the market. It requires double, playback-heads, two amplifiers, and two speakers. Without doubt, there will be more 3-D tape before long.

There are people, not given to loose talk, who say that the days of the classical phonograph disk are numbered. None of them care to pick a number, but there is reason to think that they are right.

Record Reviews

Beethoven: Symphony No. 6 in F, “Pastorale” (Willem van Otterloo conducting Vienna Symphony Orchestra; Epic; 12” LP). Epic records are issued by Columbia from the stockpile of their new Dutch affiliate, Phillips. Some early Epics suffered from a strange hollow sound. This one, contrariwise, has easily the best tonal quality of any “Pastorale" on disks — rich, limpid, delicious. Otterloo sets a gracious pace for music he obviously loves and understands. It all adds up to a very, very fine new Beethoven Sixth, perhaps the best.

Brahms: Sonatas for Clarinet and Piano, Op. 120, Nos. 1 and 2 (Leopold Wlach, clarinet ; Georg Demus, piano; Westminster; 12” LP). Oddly, this is only the second LP recording of these unsurpassed works for the effective team of clarinet and piano. The Kell-Horszowski (Mercury) version has some intriguing subtleties, but nothing like the impressive sonic realism of Wlach and Dennis’s fond, relaxed performance.

Columbia Literary Series (Truman Capote, John Collier, Edna Ferber, Aldous Huxley, Christopher Isherwood,Somerset Maugham, Katherine Anne Porter, William Saroyan, Dame Edith, Sir Osbert, and Sacheverell Sitwell, John Steinbeck, reading from their own works: Columbia: six 12” LPs in black calf attaché case, with hard-cover booklet by Goddard Lieberson, producer. $100). Absolutely engrossing as this set is, there must be few people willing to pay $28 for the carrying case — and it is a good bet that Columbia will release the disks separately later on. They are treasures, not a one negligible. The writers read beautifully. When you can, sample Truman Capote’s brittle, hypnotic tale of Miss Bobbitt, Sir Osbert Sitwell’s drily hilarious account of a family’s (his) sitting for a group portrait by Sargent, the restrained horror of Katherine Anne Porter’s “Flowering Judas,”William Saroyan’s impatient leafing through his own plays, some of which mystify him utterly. All lastingly lislenable.

Copland:Appalachian Spring; El Salón Mexico (Serge Koussevitzky conducting Boston Symphony Orchestra; RCA Victor: 12" LP). These are labeled as “Treasury" items, indicating reprints. If they are madeovers from the 78 albums M-1046 and M-546, some magic has been wrought, for the fidelity is exemplary. The performances, of course, are agelessly famous; no others extant can remotely compare.

D’Indy:Symphony on a French Mountain Air with Saint-Saens: Concerto No. 5 in F (Fabienne Jacquinot, piano; Anatole Fistoulari conducting Westminster Symphony Orchestra; M-G-M: 12” LP). In a way, perhaps the month’s best buy: ideally paired recordings in which absolutely everything went right. No philosophical implications — just a sensation of soaring effortlessly through an aerial sea of enchanted sound. Try it!

Eliot, T. S.:Murder in the Cathedral (Robert Donat and the Old Vic Company; Angel: two 12" LPs in album with illustrated program). Faultless and deeply stirring presentation of Eliot’s first important play, dealing with the murder of Archbishop Thomas a Becket. The Grecian-style use of spoken chorus is particularly effective via phonograph. So is the terminal technique of having the murderers explain themselves to the audience. Wonderful.

Haydn: String Quartets, Op. 76, Nos. 1 and 2, “Quinten,” 3 and 4, “Emperor” “and Sunrise,” 5 and 6 (Schneider Quartet; Haydn Society: three LPs, boxed or separately). The hard-worked adjectives fall away, and all I can find to say is that here is music I will truly love until death do us part, and that I think I have never heard it so well performed before, and certainly never so well recorded.

Strauss, Richard: Don Quixote (Clemens Krauss conducting Vienna Philharmonic Orchestra; Pierre Fournier, cello solo; London: 12" LP). There is a fairly good Fritz Reiner version of this on Columbia cut-rate “Entré,”and an elderly, authoritative Decca with the composer conducting. However, Krauss has a peculiar affinity for Strauss, and the London engineers for Strauss-sounds (remember Zarathustra?). Here the brass and the acid lyricism are beautifully balanced in scrupulously maintained perspective. Very nice indeed.

Thomas, Dylan: Selections from the Poetry of Dylan Thomas, read by the Poet, Vol. 2 (Caedmon: 12" LP). The creative talent and untimely death of Dylan Thomas are treated of elsewhere in this issue, but the issuance of the second disk of his readings brings to mind another of his accomplishments. A true Welshman, he was a declamatory artist of extraordinary gifts. Beautifully recorded here, he reads eight poems, including “A Winter’s Tale,” “Death Shall Have No Dominion,”and “If I Were Tickled by the Rub of Love.”

Vivaldi: Chamber Concertos and Duo Sonatas (Jean-Pierre Rampal, flute; Pierre Pierlot, oboe; Robert Gendre, violin; Paul Hongne, bassoon; Robert Veyron-Lacroix, harpsichord; Haydn Society: 12" LP). A gem of unfailing melodic variety, played with zest and mastery, and recorded with just the degree of intimacy such music should have. Vivaldi liked his instruments (some of them newly invented then) to sound out, and they do here.

Speed the Parting Guest (Jimmy Carroll conducting nine men playing twenty-three percussion instruments and one U.S. Coast Guard Quoddyhead foghorn; Cook Laboratories: 10" LP). Subtilled “Hi-fi Bull in a Chime Shop,”this proves that Emory Cook, the Sounds of Our Times maestro of the locomotive and the 20-cycle thunderelap, has a sense of humor. The central objective is sheer, horrendous noise, but the end result also embodies an odd and elfin charm. This opus slew audiophile visitors to the 1953 New York Audio Fair, but it also will serve as an infallibly entrancing children’s record.

Voodoo — Authentic Music and Rhythms of Haiti (Emy de Pradines conducting Haiti Danse Orchestra and Chorus: Remington: 12" LP). Hardly half of this has any relation to voodoo ritual; the rest is assorted folk music; but it’s all very good listening. The drum portions are hi-fi excitement of a high order, and at least one of the songs, the nostalgic love-ballade Choucoune, is one of the prettiest things you ever heard in your life. Price: $2.99, and well worth it.