Eccentricity
I was glad to see the subject of poor record pressings taken up in your column for July, because the scratched and dirty condition of many of the records I obtain from domestic sources has led me over the last several years to import most of my purchases from England, Germany, and Japan.
If the difficulty with off-center records were due to an off-center hole, as your correspondent complains, both sides of the record would be off in the same direction and of course by the same amount; this has almost never been my experience, and I am plagued by records well enough centered on one side only.
How much eccentricity ought to be tolerated? It is easy to show (and easier to hear) that the effect on the pitch of the music is greatest at the end of a side, where the radius is at least 60 mm. Nowadays a turntable wow specification of 0.1% is respectable, and applying this as a standard would require records to be no more than 0.06 mm. off.
A record off by this amount will cause the pickup arm to oscillate over a distance of 0.12 mm. as the record rotates, and this is about the smallest motion which can be measured easily on fine pitch recordings. In my collection the records which meet this standard are the older ones and those made in Germany, with those made in England running a close second.
Which turntable manufacturer will be the first to provide a conveniently adjustable eccentric spindle?
-J. D. REED, Chicago
Eccentricity used to be more prevalent in England, but seriously, the problem lies with the record manufacturers and it should not be passed to the record player designers for a solution.
-ED.
Integrity
In the midst of all the electronic marvels of today and tomorrow at the EIA/Consumer Electronics Show, it was an unexpected pleasure to see that at JBL they still care about the guy who bought last year's model. Their new tuner will have interchangeable fronts, one of which will match their discontinued SA 600 integrated amp. That's a kind of integrity consumers seldom see. I appreciate it, JBL, I'll bet others do too.
--DAVID S. MONETT, Elmhurst, N.Y.
To JBL's President, Arnold Wolf--take a bow...
More on Doppler
I found the article on Doppler distortion by Roy Childs very interesting indeed. Little has been published on this subject-most experts apparently taking the view that Doppler distortion does not exist, or if it does, it is not significant.
As far as I know, Paul Klipsch is the only one who has really investigated the problem, but unfortunately his articles in the AES Journal and elsewhere are spoiled by his `blowing the trumpet' for horn systems. Perhaps you can persuade him to write a factual article without the propaganda?
--James Russell, Bridgeport, Conn.
Well, we did manage to persuade Paul to write an article for us although I must admit, the faint but persistent sound of a trumpet can be heard in the background! Years ago, most experts did tend to disregard the Doppler effect. The late Henry Hartley, one of the early pioneers said in a letter to me in 1961, "1 had a magnet design which avoided cross-modulation, mistakenly called the Doppler effect." He did in fact carry out a series of experiments which proved that certain spurious combination tones were caused by nonlinear voice-coil excursions relative to the magnetic field. The present interest in Doppler distortion--or as Paul has it, modulation distortion-is due to the advent of bookshelf speaker systems using small speakers which necessarily have large-amplitude cone movements to produce a reasonable base.
-ED.
===========
Editor's Review
Speaking at a meeting of the prestigious International Tape Association, Virginia Knauer, Special Assistant to President Nixon for Consumer Affairs, said "If the Tape Industry does not attempt to clean up its own shop, there will be a time when the option will no longer be yours" Strong words-which provoked swift replies from those who disagreed. Said Joseph Tushinsky, president of Sony-Superscope, "I don't think she knows what she's talking about." He went on to say that the industry has standardized already as far as tapes, microphones, and connectors were concerned. Jeff Berkowitz of Panasonic said the industry was almost completely standardized and that it was possible for anyone to buy a stereo 8 cartridge, cassette, or open-reel tape and play it on any manufacturer's machine. True enough, but when Virginia mentioned the lack of standardization for 4-channel and video tapes, she had a point.
Her criticism of poorly-defined warranties was probably justified but I am not certain I would agree that "there is a lack of information concerning recorders and service facilities are poor." Talking about standardization reminds me that very soon we will be confronted by a number of quadraphonic record systems-each with its own `black box' decoder to convert the two composite channels back to the original four. One of the latest to appear on the scene is from the Japanese Victor company ( JVC) and the leaflet makes the rather delightful statement, "The difference between two-channel and four-channel sound is the difference between a shower and a proper bath." Presumably, mono would be equivalent to washing under the pump.... Trouble, is-manufacturer A's Black Box will not work with manufacturers B's system and vice versa! Incidentally, the JVC system features carrier modulation with frequency modulated low frequencies and phase modulation above 800 Hz.
---
Doctor Van Kiunge of the Hague, Holland, has invented a loudspeaker system based on the human throat. Says the good Doctor, "The human vocal system is very efficient and it is logical to use the principles for a loudspeaker."
---The New York Audio Society ( 215 Adams St., Brooklyn, N.Y. 11201) announces an interesting meeting for November 11. The guest speaker is Martin Bookspan, of ASCAP and the place is the Dragon Seed restaurant, Jackson Heights, Queens.
Time: 8:00 p.m.
----
Harold Leak is of course well-known as one of the pioneers of Hi-Fi. In 1946 he designed an amplifier with the very low distortion of 0.1%-and so it was designated the Leak Point-One. A few months ago, Harold decided to retire and so he sold his business to the Rank-Wharfedale group.
Now I learn that Harold has bought himself a yacht which he has named-you guessed it-the Point-One. . . May he enjoy his retirement for many years. The same goes for Alexander M. Poniatoff of Ampex, who now retires at the age of 82.
He founded Ampex in 1949 and the name is taken from his initials, plus, he says-EX for excellence.
--- At the end of the magazine is a Reader Service Card ( known to the initiated as a "Bingo" Card) . Observant readers will note that some questions have been added such as "Do you want more record reviews? What kind? More technical articles? Constructional articles? and so on. You may not want information regarding X speakers or Y receivers at this time, but please take a few minutes to fill in the rest of the card-it will be appreciated.
----
Many readers have been annoyed by the asterisks in "Tape Guide" and "Audioclinic." This kind of thing: "I have been using a ---- machine with a ---- amplifier and...." Infuriating. From now on, we will print the names--so if you have a ----- tape recorder-you'll know it!
-G.W.T.
----JVC Four-Channel Decoder and Player
==================
ADs:
Sony
To call it an “amplifier" would be like calling a Porsche "Basic transportation”
There is unusual satisfaction that comes from fulfilling a prosaic task in a far from prosaic manner.
Hence this amplifying system: the Sony TA 2000 professional preamplifier and the Sony TA 3200F power amplifier. Together, they perform all an amplifier's standard tasks in a satisfyingly impeccable manner; but their 67 levers, switches, meters, knobs and jacks allow you to perform some interesting functions that are anything but standard.
Dual-purpose meters.
The two VU meters on the preamplifier front panel, for example, are no more necessary than a tachometer on an automobile. But they do serve the dual purpose of simplifying record level control when the TA-2000 is used as a, dubbing center, and of allowing you to test your system's frequency response and channel separation (as well as those of your phono cartridge) and to adjust the azimuth of your tape heads.
A broadcast/recording monitor console in miniature.
The TA-2000 resembles professional sound consoles in more than its VU meters. In addition to the 20 jacks and seven input level controls provided on its rear panel for permanent connections to the rest of your hi-fi system, the TA 2000 boasts a professional patch board in miniature on its front.
Thus, you can feed the inputs from microphones, electric guitars, portable recorders or other signal sources into your system without moving the preamplifier or disturbing your normal system connections in the least. And a front panel Line Out jack feeds signals for dubbing or other purposes into an external amp or tape recorder, with full control of tone and level from the front-panel controls and VU meters.
The tone correction and filtering facilities are also reminiscent of professional practice, allowing a total of 488 precisely repeatable response settings, including one in which all tone controls and filters are removed completely from the circuit.
The amplifier-no mere "black box" A power amplifier can be considered simply as a "black box" with input and output connections, a power cord, and an on/off switch; and such an amplifier can perform as well (or poorly) as the next one. But in designing the TA-3200F Sony took pains to match the amplifier's facilities to the preamplifier's.
Thus to complement the TA 2000's two pairs of stereo outputs, the TA-3200F has two stereo pairs of inputs, selected by a switch on the front panel.
Other front panel controls include independent input level controls for both channels, a speaker selector switch, and a power limiter (in case your present speaker should lack the power handling capacity of the next one you intend to buy). Circuitry unusual, performance more so The single-ended, push-pull output circuitry of the TA-3200F amplifier is supplied with both positive and negative voltages (not just positive and "ground") from dual balanced power supplies. This system allows the amplifier to be coupled directly to the speakers with no intervening coupling capacitors to cause phase shift or low-end roll-off (A switch on the rear panel does let you limit the bass response below 30Hz if you should want to, otherwise, it extends all the way down to 10Hz.) The individual stages within the amplifier are also directly coupled with a transformerless complementary-symmetry driver stage, and Darlington type capacitor-less coupling between the voltage amplifier stages.
As a result, in part, of this unique approach, the TA-3200F produces 200 watts of continuous (RMS) power at 8 ohms, across the entire frequency range from 20 to 20,000 Hz; IHF Dynamic Power is rated at 320 watts into 8 ohms (and fully 500 watts into a 4-ohm load). But more important by far is the quality of the sound; intermodulation and harmonic distortion levels are held to a mere 0.1% at full rated output, and 0.03% at the more likely listening level of one-half watt. The signal-to-noise ratio is an incredible 110dB. And the full damping factor of 170 is maintained down to the lowest, most critical frequencies (another advantage of the capacitorless output circuit). The companion TA-2000 preamplifier also boasts vanishingly low distortion and a wide signal-to-noise ratio, but this is less unusual in a preamplifier of the TA-2000's quality (and price). What is unusual is the performance of the phono and tape head preamplifier circuits; for though they have sufficient sensitivity (0.06mV) for the lowest-output cartridges (even without accessory transformers), these preamplifier circuits are virtually immune to overload even with input signals 80 times greater than normal.
Their sole vice: they are hardly inexpensive Of course, at a price of $329.50 (suggested list) for the TA-2000 preamplifier, and $349.50 (suggested list) for the TA-3200F power amp, this system cannot be considered other than a luxury. But then, it was intended to be. For there are those to whom fulfillment of prosaic tasks is unfilling. And among them are not only many of our customers, but also many of our engineers. Sony Corporation of America, 47-47 Van Dam Street, Long Island City, New York 11101. SONY
------------------
SONY Model 366 Tape Deck
We have received the following comments from Fred Tushinsky, Superscope's Director of Marketing: "Your Equipment Profile on the Sony 366 was extremely thorough and generally complimentary but the importance of several of the features was somewhat neglected. For example, the automatic total-mechanism shut-off is, in our opinion, a great advance in single-motor recorder design because it eliminates the possibility of forming a flat spot on the pinch roller, a common fault of recorders which merely shut off the a.c.
automatically. Also the absence of pressure pads (Ilse of hyperbolic heads) is very unusual in recorders costing $200-$250. The Record Equalization Selector Switch is another unusual feature which aids both the economy and quality of home recording. This feature received minimal attention in the review despite the fact that the results of this switch together with SLH tape produces an almost incredible 57 dB signal-to-noise ratio." In reply, we can only say that all of these features were mentioned, but possibly not stressed sufficiently. We felt they were so obviously advantageous that they did not need additional comment. At $229.95, it would be difficult to find a better deck.
------------------
Thorens TD-125 3-Speed Electronic Transcription Turntable
Superb performance and reliability go hand in hand in all Thorens turntables. The TD-125 carries on this fine tradition. But then, you expect unexcelled quality from Thorens. And you get it.
The powerful, 16-pole synchronous motor of the Thorens TD-125 is lonely. It has been completely isolated (from the tonearm mount and turntable assembly) along with the controls, on a separate, but integrated chassis. This power source, operating at very low speed 250 rpm at 331/3 rpm platter speed assures constant and smooth in-phase precise speed. Further, rumble is reduced to an absolute minimum,-48dB, through the action of the long and resilient drive belt system which functions as a filter between the motor pulley and the large diameter flywheel of the turntable. This trouble-free motor is one of the reasons High Fidelity (Sept. '69) proclaimed the TD-125 "as the best three-speed manual we've yet tested." Here are a few other reasons: Wien bridge oscillator for precise speed control... Tonearm mounting incorporated in shock mounting of platter... Interchangeable tonearm mounting board... Controls independent of shock mounting... Dynamically balanced 7 lb., 12-inch non-magnetic platter... The World's Finest Transcription Turntables THORE5 Thorens-Franz AG., CH 5430 Wettingen, Switzerland U.S. Distributor: ELPA MARKETING INDUSTRIES, INC., New Hyde Park, N.Y. 11040
------------------
Studio-Tape Recorder Magnetophon M 10 A
Technical Highlights on magnetophon M 10 A with Amplifiers V 396/ 397.
Top model meeting highest demands in Radio and Television Studios.
Extremely low changes in high frequency.
Signal to noise ratio ? 75 dB. Electronic switch to compensation network.
Amplifier with silicon-type transistors on plug-in circuit boards.
Why is magnetophon M 10 A the Tape Recorder used in all Studios of German Radio Stations? The answer: Top fidelity and reliability.
Please consult us; no obligation on your part.
Our address is: AEG-TELEFUNKEN Department for Technical Information 775 Konstanz, Postfach 154 West Germany
Studio-Tape Recorders by AEG-TELEFUNKEN
--------------
King of Turntables
The only record playback system engineered for stereo cartridges that can track as low as 0.1 gram.
New Troubador Model 598
HERE is a turntable system designed exclusively for the new low tracking force cartridges-the long players that won't wear out your records.
This unbelievable. record playback device exceeds every broadcast specification for professional playback equipment.
Driven by the world's finest turntable motor (hysteresis synchronous type) the system reaches full speed in less than 1/3 of a revolution, locks in on A.C. line frequency and maintains speed accuracy with zero error, (built in strobe disc and pitch control provided). The 12 inch turntable platter and massive balanced drive fly-wheel are both coupled to the drive motor by a precision ground flexible belt.
Empire's excusive pneumatic suspension combines pistons and stretched springs. You can dance, jump or rock without bouncing the stylus off the record.
The Troubador will track the world's finest cartridges as low as 0.1 gram.
With dead center cueing control the tone arm floats down or lifts up from a record surface bathed in light. Pick out the exact selection you want-even in a darkened room.
The extraordinary Troubador system features the Empire 990-the world's most perfect playback arm.
This fully balanced tone arm uses sealed instrument ball bearings for horizontal as well as vertical motion. Arm friction measures a minute 1 milligram. Stylus force is dialed with a calibrated clock main spring, (more accurate than any commercially available pressure gage).
-Calibrated anti-skating for conical or elliptical stylii. Exclusive Dyna Lift automatically lifts the arm off the record at the end of the music. With the arm resonance at an inaudible 6 Hz, it is virtually impossible to induce acoustic feedback in the system even when you turn up the gain and bass.
TECHNICAL SPECIFICATIONS
3 speeds--33-1/3, 45, 78 rpm Push-button power control
Built-in 45 rpm spindle Rumble-90 dB (RRLL)
Wow and flutter .01% Overall Dimensions (with base and dust cover): 17-1/2" W. x 15-1/8" D. x.8" H. Dimensions (without base and dust cover): Width 16",'Depth 13-1/2". Height above mounting surface: 3-1/4" Depth required below base plate 3-1/2" Swiss ground gold finish.
Troubador 598 playback system. $199.95 less base and dust cover.
Satin walnut base and plexiglas cover combination $34.95.
The 990 playback arm also available separately, $74.95.
For your. free “1971 Guide to Sound Design", write: Empire Scientific Corp., 1055 Stewart Ave., Garden City, N.Y. 11530
EMPIRE
---------------
Altec's new 714A receiver.
It's built a little better.
With 44/44 watts RMS power at all frequencies from 15 Hz to over 20 KHz (at less than 0.5% distortion). Most receivers meet their power specifications in the mid-band but fall way short at the critical low and high frequencies. The above curve shows the typical low distortion at all frequencies from the new 714A receiver at 44 watts RMS per channel. For comparison purposes, we also rate the 714A conservatively at 180 watts IHF music power at 4 ohms. This means that the 714A will handle everything from a full orchestration to a rock concert at any volume level with power to spare.
With 2 crystal filters and the newest IC's. Ordinary receivers are built with adjustable wire-wound filters that occasionally require periodic realignment.
And unfortunately, they are not always able to separate two close stations. So we built the new 714A with crystal filters.
In fact, 2 crystal filters that are individually precision aligned and guaranteed to stay that way. To give you better selectivity. And more precise tuning. The new 714A also features 3 FET's and a 4 gang tuning condenser for high sensitivity.
And with a lot of other features like these. Separate illuminated signal strength and center tuning meters on the front panel. A full 7 inch tuning scale and black-out dial. The newest slide controls for volume, balance, bass and treble. Positive-contact pushbuttons for all functions. Spring loaded speaker terminals for solid-contact connections.
Altec's new 714A AM/FM Stereo Receiver sells for $399.00. It's at your local Altec hi-fi dealer's. Along with all the other new Altec stereo components--including a new tuner pre-amp, new bi-amp speaker systems and all-new high-performance music centers.
For a complete catalog, write to: Altec Lansing, 1515 South Manchester Ave., Anaheim, California 92803.
Built a little better.
(Source: Audio magazine.)
= = = =