Audio in General (Departments):
Audioclinic/Joseph Giovanelli; Tape Guide/Herman Burstein; What's New In Audio ; Audio ETC/Edward Tatnall Canby ; Behind The Scenes/Bert Whyte
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Audioclinic
by Joseph Giovanelli
Storage of Phonograph Records
Q. Please tell me what is the best way to store stereo LPs. I understand that storing them vertically is the best way to avoid warpage.
-Peter Bellavigna, Massapequa, N.Y.
A. The best way to store phonograph is vertically. This is to avoid having a lot of weight on the bottom of a pile of horizontally stored records.
Vertical storage can also have its drawbacks if discs are permitted to lean over at too great an angle. This would cause them to warp.
Intermittal Hum In a Record Player
Q. From time to time, while playing a record, a 60 Hz hum is heard from both speakers. It begins at a low volume and quickly increases in volume until it is louder than the music. By turning off the receiver for a moment, the hum is eliminated. I would like to determine the cause of this in order to eliminate this hum permanently.
-Rocky Strickland, Dallas, Texas
A. There are many possible causes for the intermittent hum in your equipment. Assuming the receiver is indeed at fault, the most logical possibilities are poorly soldered ground connections or cracked circuit board foils associated with the grounds for the phono input connectors or stages.
If you had said that the hum was 120 Hz, rather than 60 Hz, in frequency, I would then have had to consider the possibility that there were poorly soldered filter capacitor grounds or perhaps defective filter capacitors.
Other possibilities include poor contact between the shields of the phono input connectors and the plugs. Squeeze these connectors to be certain that they mate up tightly with the input jacks.
You might have a loose cartridge lug in the tonearm. Squeeze each one lightly with pliers so that they slide over the terminals of the cartridge with a bit of pressure.
If your tonearm is equipped with replaceable cartridge holders, check the contacts between the holders and the innards of the arm. Clean the contacts with suitable contact cleaner.
Depending on the design of the holder and contact strip, perhaps some mechanical bending is possible and desirable to insure good pressure when the holder is in its place.
Check solder connections on the cartridge slide lugs, as well as those which interconnect with fine tonearm leads with the heavier cable which plugs into the phono inputs.
The bearings, which pivot both horizontally and vertically as the arm traverses the disc, are often used to ground the arm. If these bearings are oxidized, intermittent hum can result.
I have found that WD-40 works well for cleaning these bearings.
Even though none of these factors deals with the receiver, turning the receiver off for a second and then turning it back on, can cause the hum to stop. This may have to do with the fact that the connections are shaken as you move near the equipment.
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Tape Guide
by Herman Burstein
Improving Response
Q. I have a tape recorder which is rather old but still has a lot of use in it, a Wollensak 1980. 1 am concerned about the playback response of this machine in comparison with two Sony’s I have. When I record a tape on the Wollensak and play it back on one of the Sony’s, it sounds very much like the record; but if I play it back on the Wollensak, it is definitely lacking some bass and treble. I don't think it is a case of worn heads; the Wollensak has never had the bass and treble response that the Sony machines have.
These machines are played back through a pair of AR-3 speakers; if there is any bass to be found, this system will find it. I would like to know if there is any way that I could get the Wollensak modified so that it will equal the Sony machines in playback.
-Robbin Hodge, Watertown, N.Y.
A. I think that a new head, with a narrower gap than the original one, would improve the treble response.
(Nortronics makes a wide line of replacement heads.) As for better bass, believe this would require an appropriate change in the playback equalization of your Wollensak. A competent technician, with the circuit of the Wollensak before him, should be able to quickly figure out how to increase the bass response, probably requiring only the replacement of a resistor or capacitor.
Recording "Stutter"
Q. I have a Philips open-reel, portable tape recorder. It is a fine machine and until recently has given very good service. However, of late the recording function seems to have developed a problem. There is a certain shakiness in recording. It is not flutter, because playback remains perfect. It sounds like poor tape-to-head contact, but after replacing the pressure pad and thoroughly cleaning the heads there remains a slight "stutter" in recording.
-Phil Hjemboe, Green Bay, Wis.
A. You can probably determine if your problem is poor tape-to-head contact by using a pencil or similar object to achieve good contact between the tape and record head; you can usually find a place where to apply the pencil in order to increase tension and thereby contact. If the cause is poor contact, it may be that your new pressure pad is of improper material or improperly positioned.
Check the pressure pads for the other heads. If poor contact is not the cause, some faulty component in the record electronics, including the bias oscillator, may be responsible. Also check the cable connections between your program source and the tape deck.
Treble Loss
Q. When I listen to either my tuner or my turntable, I get a pure sound. The same holds true when taping and monitoring the source. When monitoring the tape, the sound is pure from the tuner but muted from the turntable. It seems as if the highs drop out. I'm sure my recording procedures are correct. I've had the tape machine checked, and they said that with their instruments they couldn't detect any significant difference between tape and source performance.
Is there some sort of mismatch involved?
-Fred Hobson, San Francisco, Calif.
A. My guess is that you are overloading the tape with the sound from your turntable. The signal sent out by FM stations is usually compressed to a substantial extent. That is, the peak signals are reduced to prevent excessive modulation. Accordingly, in recording a tape you don't run into much danger that treble signal peaks will overload the tape. However, there may be substantially less compression in the case of a high quality phono disc. Hence, there are treble peaks which may overload your tape. Try recording at lower level from your phono discs.
Playback Volume Lower
Q. I have a Dokorder tape recorder and an Akai tape deck fed to my Kenwood receiver through a Pioneer reverb amplifier. I would like to know why my volume level is lower when playing back identical tapes through my tape recorder? It would seem just the opposite since my recorder has its own amplifier.
-Ronald Slakie, Tacoma, Wash.
A. Many recorder amplifiers have gain of unity or even less. Thus the term "amplifier" is somewhat misleading. What happens is that gain is consumed by equalization. To illustrate, the way we get bass boost is by first amplifying all the frequencies and then selectively reducing the treble tones, thus leaving the bass tones at a higher level than the rest, but not necessarily at a higher level than originally. This would explain the loss of gain when playing through your tape machine.
Tape Performance
Q. How do you feel about 1 1/2 mil vs. 1 mil tapes? I use the former for less print-through and greater strength. Some people say it is too stiff for proper contact with the heads. I am not concerned about recording time, for I am using 10 1/2-in. reels, and cost is not important. I am seeking maximum performance.
-Richard Minke, Woodville, Ohio
A. Where home recording is concerned, 1 mil tape seems to be entirely satisfactory so far as print-through is concerned, provided you stay within recording levels that do not cause excessive distortion (recording companies, at least in the past, have often gone above such levels in their desire to improve S/N and therefore have run into appreciable problems of print-through). As you have been informed, 1 mil tape has the advantage of being more limp and therefore conforming better to the head contour so as to preserve high frequency response. In the present state of the art, my vote is for 1 mil tape in home use.
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Audio ETC
by Edward Tatnall Canby
I DON'T intend to reopen the great Acoustic Suspension War-it was a long time ago.
But it has plenty of historical interest, now that things have calmed down.
This was a white-hot legal and engineering battle over speaker design and patents that raged between some big speaker companies and the then new and successful Acoustic Research, the vehicle for Edgar Villchur's radical AR speaker system. AR was fighting for protection. The others were busily challenging that protection while they developed excellent standby variants on the idea, just in case the patents didn't hold up. All very natural and to be expected in such a situation.
It was dog eat dog, and Villchur lost.
Tragedy? Far from id Later on, the man retired in triumph with one of the cosiest of all our big hi-fi fortunes, maybe not the size of Avery Fisher's-who knows? But Villchur was doin' OK, all right. If this proved anything, it proved emphatically that today you do not need to win exclusivity via patent protection in order to clean up in the hi-fi market. That was an earth shaker, I assure you, for a lot of our manufacturers. I doubt if there has ever been such a unique hi-fi success as the AR speaker, patent protection or no protection. Edison would even be amazed.
AR was not able to keep that revolutionary speaker principle for itself, if I am right, because of that complex of early basic audio patents which to this day still makes it extremely difficult to protect a "new" idea in speakers, or in any other audio area. A patent can be so basic that it is omnipotent. And audio, after all, is still young. The basics were developed only yesterday in real time.
"Gray Flannel" Speakers
Even so, hi fi marches on and the AR lesson was a salutary one. AR, of course, is far from out of the running even now, in spite of recent trends away from its long-familiar format.
But in its early success days, the words Acoustic Suspension were fighting terms among the many AR challengers who understandably took a dim view of the enormous AR success.
People are human, even in hi fi. I once had to write an article about "gray flannel suit" speakers-that being the conventional business costume of the time-a piece that had more double talk in it than I care to think about. The gray flannel was AR's sound, of course, and the more colorful suitings were, uh, the other speakers, the ones with that lovely coloration, so prized by many a listener.
Not by me. Luckily, most readers couldn't figure out what I was talking about, which was just as well. It was a fighting time for all of us.
I've already sketched in the nearly forgotten earlier place of the R-J speaker enclosure (last month) because it was in fact the first of its sort, the modern small speaker with big bass. But AR, soon to overshadow R-J, went much further into the fundamentals. Where R-J remained strictly conventional in certain respects, AR broke loose with sensational new impact in the same areas.
First, R-J offered in the standard manner of the day an empty speaker enclosure minus speaker. You bought that separately, to choice. True, the R-J box did new and good things for almost any speaker's sound, if it was the right size to fit inside. But there was not yet the concept of a permanent matching between speaker and cabinet, for a speaker system.
There could have been, surely, and much to R-J's advantage. But it was too soon-by a hair.
Secondly, R-J went along with the standard concept of a loudspeaker as a separate unit, able, so to speak, to stand on its own feet, that is, constructed with a normal cone and spider suspension, solid and springy enough to propagate sound, pumping in and out like a piston, yet remaining exactly centered in the circular voice-coil slot without outside aid or support. The speaker spoke, on its own, and you diddled, via cabinet or baffle, with its output signal. The enclosure-any enclosure-was built following this assumption; the thing simply made use of the radiated acoustic signal, hopefully with a minimum of cancellation and enforced distortion. R-J did exactly this, and did it quite well in a newly small space.
Bass Only Boxes
Not so AR. The initial model, AR-1, as all subsequent models to this day, was built uncompromisingly with the sound generator unit, the speaker, sealed inside as a part of the system. You bought the works. You have ever since. At the time, that was radical, even courageous in a business sense.
Though, curiously, the earliest prototype if I remember rightly was not a full range system but only a woofer, in an enclosure. You provided your own high end. That is, until AR saw the light and added an upper range as well in the AR-1. Just shows how the prevailing thought ran. The new AR principle involved only the bass; therefore it was normal thinking to leave the rest, the top end, for your own optional choice.
We still see occasional separate tweeters today but we are rarely offered a woofer in a box, complete and ready to go in all its muffled glory! Like an Add-A-Part record. You add the melody.
It was indeed the bass end which impressed in the AR. It was the innovative part, both in the method of production and in the sound itself, low, clean, and totally boom-free.
Sensational, and only later did AR make modifications towards a more imaginative high end, to match its fine bass via such improvements as the little dome-type tweeters-leading to those intriguing AR model conversions with the exponential names-AR 4ax. (Even now there are continued improvements in the AR high end, such as the new flush surface to avoid cavity distortions.) In all of this, every single AR system has had its built-in set of driving speakers, straight from the start. After awhile, after AR, the old cabinets in all their empty prolificity began to fade from the market and so did the loose speaker units that once had filled up the stores and the hi-fi displays. AR killed them. A really big change, you must admit.
The Air Spring
But that was not all. The striking thought that hit the inventive Edgar Villchur was to build a speaker /driver as a part of the cabinet, specifically, to replace the standard independent springy system of sturdy cone and spider with a different elasticity, an air spring. It was produced, an infinitely elastic restoring force, by sealing up the space behind the speaker as it had never been sealed before, airtight.
And instead of the old self-sustaining cone he mounted a new limp, flabby thing which would derive its springiness almost entirely from the air pillow behind it. That air had to be carefully calculated in volume-the problem was not to make the box small but to make it big enough to work in this fashion. Do I remember how that impressed me! (Am I hearing faint echoes of the War again? Don't bother arguing, folks. Worrying about acoustic suspension today is a bit like fighting Eleanor Roosevelt. If I've got things wrong, don't blame AR, blame me.) So the limp speaker took over and so did the newly clean, astonishingly low and uncluttered bass that came out of this one-sided system, the back wave swallowed up and suppressed, the front wave smoothed out and extended 'way down, into the Klipschorn range. Yes, people said and still say that no limp-speaker bass will ever sound like the solid stuff from a horn enclosure and they may be right. But the point is academic. There simply is no comparison in a living room sense between a big horn and a small box.
The miracle was that we could get any sort of clean low bass out of a bookshelf speaker, even if no bookshelf was ever devised that would hold one of them, let alone two.
Wasn't it Klipsch himself who in the end capitulated a bit and came out with a smallish thing he called the Heresy? Honestly put! It was no horn.
Reminds me somehow of the AM Gremlin, so curiously named.
Heat & Efficiency
Power, now, was to be the new name of the hi-fi game, to cope with this one-sided speaker inefficiency, and power came out of tubes. AR-type speakers needed very heavy pushing to make them work. By the time we got into stereo, with everything doubled including AR, power began rather ominously to be translated into heat. Even now, I can warm up my living room via the old Fisher 300 stereo, or the hefty Dyna 70, the egg fryer. I have an old borrowed H. H. Scott Type 208, too, its considerable warmth from seven tubes gently irradiating one side of my turntable, catching me up with surprise-we don't expect heat like that any more. This matter of efficiency grew more important as the new AR speakers began conquering much of the hi-fi world, and still more when other companies swung over to similarly inefficient speakers.
But the answer to low efficiency, the solid-state amplifier, was a long time in coming. During those numerous years when tubes were receding and high power from solid state was still decidedly impractical, the acoustic suspension speaker spread ever more surely as the standard for good quality hi fi sound. The definitive AR-3 and then the 3a, with better highs, bulky for any bookshelf (and much too heavy-just try lifting one!) were everywhere, and still there was a power problem. Obviously a LOT of amplifier was now needed to drive these things, more than we had ever thought would be necessary. And that power had to be cool, as only the solid-state amplifier could make it. No go! Again and again I was told that transistor circuitry allowed only a maximum of around 30 watts output (averaging the various watt rating systems). That was not enough.
In the end, of course, the big solid-state breakthroughs came and all of a sudden we had power and to spare--as I quickly discovered via a beautiful white solid-state job which shall be nameless (I forget the name) that arrived in my house, produced really superb low-efficiency speaker sound for awhile, then quietly liquified itself all over the floor while lazy smoke arose to assail the nostrils. A replacement, heavily redesigned, played somewhat longer but one day that, too, blew up with a puff and all the fuses out. Quite a time passed before we got solid-state power and reliability-with heat sinks and circuit-breaker protection. The next such amp I got to use was a Crown and that one is still going strong. Absolutely unflappable.
Now we have gone further, into really potent solid state, in a geometric power progression that has taken us up into the hundreds of watts per channel and onwards. At last we have the power we need to drive all the low-efficiency speakers you could ever want, and maybe burn them out at that! Wouldn't you know it, then, right now is the time we start back, towards the old high efficiency speakers that don't need much power! Crazy.
Not hard to explain, though. The low-efficiency speaker really spoiled us for good, convenient low bass, given the power to get it out of the box.
In the earlier period the more efficient speaker systems, bass reflex and so on, were for the most part haphazardly assembled out of separate components, usually untuned to each other. They inevitably boomed and blurred. Good tuning, for a properly clean bass, was a rare, half-accidental accomplishment. Aside from the big horns, then, only the acoustic suspension speakers could guarantee us a smooth, clean low bass and so these speakers moved in the thousands into homes everywhere. It was worth the sacrifice in efficiency just to have that sort of sound conveniently available, in small packages.
Computer Design
Now we have calculators and computer techniques to design and precisely predict an optimum shaping for those old-fashioned ports and back-wave escape tubes. But most of all, we can design new high-efficiency systems as integrated units, even down to the simplest, the speaker and enclosure permanently matched. Result, a far better sound, right down the line, than in the old days of empty boxes and free speaker choice. With all this going for us, is it surprising that we should now begin to back away from the low-efficiency speakers even though we have plenty of power to drive them? The new speaker systems play louder, easier, and they now sound just as good, bass and treble, give or take a bit for the argument.
We now have some lovely power options. We can simply play louder, and LOUDER, as plenty do. Better, we can play our music at reasonable levels and yet have the reserve to cover the most exquisitely extensive transient peaks which, we know, are momentarily far more potent than the lowly average level shown by the VU meters. We like this new power headroom. We can hear it. We want more and more power. More speaker efficiency, too. We can use them both.
Yes, we will be seeing a lot of modest four-way speaker installations in these coming years; the idea is too good to drop and music will not let it fail. We will need small speakers for this, four for two, inconspicuously.
(With four, bass is not a great problem.) I see headroom needed, everywhere. Small speakers, efficient, yet smooth in the bass end. Four-way amplifiers with a lot more power, modestly presented, than most of our present showy quadraphonic receivers now offer. Too little! What we will want is a reasonable 50/50/50/50 and on upwards to 100 x 4 and more. Not louder! Cleaner. That's the headroom. More headroom at every level of price. Power to spare, along with simplicity and spareness of controls.
Super hi-fi? There's always a place for that, at any price. So let's go straight forward on our present track-to amps rated as 1000/1000, common as chickens used to be, and superb new speakers the size of a house, or at least a chicken coop, which respond to one watt of power (electrical) with a roar you can hear a mile away. Now that'll be headroom for you.
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Behind The Scenes
IN THE AUGUST, 1974 issue of Audio, I reported that at the 48th convention of the Audio Engineering Society in Los Angeles the BASF tape people had introduced their "Unisette." This was a scaled-up version of the Phillips compact cassette-some 40 per cent larger
-which used quarter-inch tape and operated at a 3 3/4 ips tape speed.
Among its claimed advantages, aside from the obvious benefits of wider tracks and higher tape speed, were openings in the cassette shell to accommodate erase, record, and separate playback head for true monitoring capabilities, the option of singleor dual-capstan tape drive, and a method of tape tension control. Very significant was the fact that tape guidance was a function of the playback machine, rather than the cassette, as is the case with the current "compact cassettes." Thus accuracy of tape guidance remained invariable for all Unisettes, with the advantages of stable azimuth and low wow and flutter.
BASF envisioned the Unisette in such applications as high-quality automated radio programming, language laboratory machines, "audiophile quality" cassette recording...they even had a track layout for quadraphonic sound in their technical manual. It was reported that the first Unisette machines would be built by Willi Studer and that negotiations were "under way" with Sony and TEAC to produce Unisette recorders.
It is now close to two years since the introduction of the Unisette, and the anticipation of an early entry of this product into the audio market seems to have been overly optimistic.
I have checked with the BASF people a number of times in these intervening months on the progress of the Unisette, but they had little to report.
Ultimately at the March AES convention in Zurich this year, Willi Studer did show a prototype Unisette machine which was obviously slanted towards the professional market and priced accordingly. As far as the audiophile segment of the potential Unisette market was concerned, nothing seemed to be forthcoming from any quarter.
Ironically, just a few weeks after I made one of my periodic checks with BASF about the Unisette, rumors began to circulate that several Japanese companies would soon be introducing Unisette machines. On April 21st, Panasonic/Technics invited the audio press corps to a preview of some new cassette decks (about which, more at a later date), with Mr. Toshio Morimoto, chief engineer of the tape recorder products division on hand. After a run-through and demonstration of the new decks, we had luncheon, and then the bombshell was dropped. ...instead of verifying the rumors about the Unisette, it was announced that Sony Corporation, Matsushita Electrical Industrial Company (parent company of Panasonic/Technics), and TEAC Corporation had jointly developed a new audio recording system known as the "Elcaset"...meaning large cassette. It was also announced that the Aiwa Company and JVC (Victor Company of Japan) had agreed to adopt the Elcaset system.
Another Format
What is the Elcaset system? Simply put, it variation on the Unisette theme, with modifications and embellishments which the Japanese feel have significant advantages. Like the Unisette, the Elcaset uses standard quarter-inch magnetic tape at a speed of 3 3/4 ips. The Elcaset measures 152 mm wide by 18 mm in height by 106 mm in depth...approximately 40 per cent larger than the standard compact cassette. While the width of the Elcaset tracks are naturally greater than those in the cassette, since it uses quarter-inch tape, the disposition of the tracks is the same as the cassette for mono/stereo compatibility. However, in between the two pairs of stereo tracks are two narrow "control tracks," which can be used for such purposes as automated programming, slide changing, etc. A prototype Elcaset shell was circulated among us, and we were furnished diagrams explaining the functions of the many holes and openings in the shell.
There are large "positioning" holes, and openings that obviously are for dual capstan tape drive. As with the Unisette, once the Elcaset is inserted in the recorder, it remains rigidly fixed in place. Unlike the Unisette, in use, tape is pulled out of the Elcaset shell and is transported on what is essentially an open-reel drive system.
This allows the use of separate erase, record, and playback heads, permitting monitoring in normal open-reel fashion. This stationary shell/open-reel transport system assures accuracy of tape guidance and independence from irregularities and imperfections in the Elcaset shell which could affect azimuth and wow and flutter. The Elcaset will be available in three different types of magnetic tape material including (rather surprisingly, in view of the 3 3/4 ips speed), chromium dioxide. There will be LC60 (30 minutes each side), and an LC90 (45 minutes per side) Elcasets available. Some special "holes" in the Elcaset shell afford automatic "code" selection of proper bias and equalization for the three tape types, as well as automatic Dolby selection. The time constant of the Elcaset tapes will be 3180 microseconds, plus 70 microseconds, and the reference recording level will be 185 nWb/m, as in normal 3 3/4 ips open-reel tape. As a comparison of tape thickness...regular cassette is 0.012 mm in a C90, 0.013 mm for an Elcaset LC90, and 0.038 in open reel. Performance claims for the Elcaset system include full spectrum frequency response, wide dynamic range, and greater "head room," plus lower distortion because of less possibility of tape saturation.
What Will It Cost?
Needless to say, we all found this Elcaset announcement quite surprising but nonetheless very exciting. Mr. Morimoto graciously divulged as much information as he could, including the fact that quadraphonic Elcasets were a distinct possibility. As to cost, while specific figures were not given, a "ballpark" estimate is that a typical Elcaset recorder would be around the 700-800 dollar mark, with blank Elcasets at about 25-20 per cent higher than the equivalent open-reel tape. Recorded music Elcasets would seem a natural consequence, especially with JVC in the picture.
Why did the Japanese choose to develop the Elcaset system rather than adopt the Unisette? A good guess would be that the mechanism needed for the Unisette concept would have been too expensive to produce...so much so as to preclude it from the consumer audio market. Perhaps there were licensing problems with the Unisette. It may simply be national pride or that ever-present attitude called "face." Whatever the reasons, I am bound to say, with all due respect to BASF for their pioneering work on the Unisette, that with the considerable "clout" of the five Japanese companies currently committed to the Elcaset system, the future of the Unisette ... at least in the consumer audio market...is uncertain.
Inevitably, we get to the question..."who needs it?" What is the Elcaset in aid of? Why still another tape configuration to further complicate the market? As seen by the Japanese backers of the Elcaset system, it is primarily intended to satisfy the demands of those people who want higher audio quality than the cassette, but are too fumble-fingered to use or are intimidated by open-reel recorders. The Elcaset would appear to bridge the gap between upper-end cassette machines at about the 500600 dollar range and the open-reel machines from 1000-1200 dollars upwards. Whether it is called the Unisette or the Elcaset, my feeling toward the concept of a quarter-inch tape/3 3/4 ips "jumbo" cassette hasn't changed ... I think it is a commercially viable product, that will fill a distinct need, as well as create an entire new market. I look too at the potential of the Elcaset...for example, with a two-speed capstan motor, one could operate at 7 1/2 ips speed for still greater sound quality...or conversely at 1-7/8 ips speed for 90 minutes of recording per side on an LC90. The possibilities for bringing true discrete quadraphonic tapes to the audio consumer at moderate cost is particularly attractive as well.
As to availability, the folks at Technics by Panasonic hedged a bit, but allowed as how they might have a machine ready for the market sometime this fall. A later press release, however, from Superscope, tells us that two models from the Sony line, both front loaders, will be previewed at the June Consumer Electronics Show in Chicago. The release goes on to say that the Elcaset system will find its way into both the Superscope and Marantz lines by early 1977. We'll keep a close watch on developments with this Elcaset concept.
Headphones and Amps
As a rule I don't do very much listening to music via headphones ... maybe because I did so much of it in my binaural experiments way back in 1950-53. Be that as it may, I have had reason to do a lot of headphone work recently in conjunction with some cassette experiments...which will be reported on in due course. I have quite a collection of headphones, but decided to try the new Yamaha HP-1 model which was recently sent to me.
These headphones are of a rather unusual design. The diaphragm is a gossamer-light polyester film, to which is bonded (in some fashion) a voice-coil of flat aluminum wire wound in a spiral so as to drive the entire area of the diaphragm. Two discs of ferrite magnetic material, with holes punched in them to permit transmission of sound, "sandwich" the diaphragm. The phones are open-backed, but appear to have more isolation than usual with this construction. As an added bonus, the HP-1 phones are very light, and easy to adjust. I am reporting on these phones, because I was singularly impressed with their performance.
Overall response was very smooth and wide, with obviously low distortion. The sound was very clean, with exceptional transient response. But what really raised my eyebrows was the superb bass response...solid, clean, well-damped bass that certainly extended well below 30 Hz. It was possible to hear a distinct "attack" and "skin-tone" on tympani and bass drum, and contrabassi had a most natural sound both pizzicato and arco.
Speaking of headphones, it appears that there are quite a few high-quality pre-amplifiers and amplifiers, which do not have headphone input jacks.
According to some designers there are some very pertinent reasons, in matters of added distortion, why these units do not have this facility. If you want to use these amplifiers for headphone listening, you will have to interface your phone plug with either a screw barrier output strip or wrestle with banana plug outputs. There is the added problem of coping with high wattage output from these amplifiers, as most of these units which do not have headphone jacks, do not have volume control pots either. If the kind of people who own these fancy units want to do some high quality headphone listening...what to do? At their friendly Crown dealer they will find a most versatile slim-line amplifier, the D-60. This 32-watt per channel unit is widely used in biand tri-amplification set-ups and, increasingly, for headphone listening. It has a headphone jack whose output impedance is perhaps half an Ohm and will handle phones of the 8 Ohms and higher values usually found in con sumer models. The input is 25 k-Ohms, and left and right control pots are furnished. Not cheap at $289.00, but the answer for high quality headphone listening, when there just aren't any facilities on the main units.
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(Audio magazine, 1976)
Also see:
Equipment Profiles: E88 "Eclipse" Model 2240 Electronic Crossover/Leonard Feldman; Garrard Model 86SB Turntable/George W. Tillett
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