The sound - MuleSlow Services

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smaller type face) mid-frequency power capability, wh ich is listed at 75 watts per channel. We actually measured 77 watts of output per channel at 1 kHz with both channels driven, into 8 ohm loads, before the 0.25 % rated THO figure was reached, as shown in Fig. 5. At the nominal "FTC power" of 60 watts per channel, THO measured below 0.1 % for this mid-frequency. 1M distortion in our sample was a bit higher than specified, reaching 0.3 % at the nominal 60 watts output, and 0.45 % at 75 watts output. The reason for the lower (60 watts) rating over the entire audio band becomes clear when you examine the distortion-versus-frequency graph of Fig. 6. At 20 Hz, with 60 watts delivered from each channel, THO reaches the specified 0.25 % . All of these measurements were made after first preconditioning the receiver for one hour, during which time it delivered continuous power of 20 watts per channel into 8 ohm loads. ~ 0 z 0 r- oc 0 r- CI) 0 0 .7 0.6 0.5 0.4 0.3 0 .2 0 .1 o 0 . 1 _./ ./1 ALL CHANNELS DRIVEN a-OHM LOADS INPUT : 1 KHz I I IIII I 75W@0.45%IM I 1 11 11 1 ....... 77W@0.25%THD II I I 11 111 1 I I IIIII 1.0 10 100 1000 POWER OUTPUT/CHANNEL - WATTS Preamplifier Control Section Measurements Phono input sensitivity was identical for both sets of inputs and measured 2.8 mY. Maximum signal input at 1 kHz before overload distortion became apparent was 125 mY. RIAA equalization accuracy was within 1 dB from 30 Hz to 15,000 Hz, and frequency response for high level inputs was flat to within 1 dB from 5 Hz to 38 kHz, with the 3-dB roll-off point occurring at 70 kHz. Figure 7 is a 'scope photo of sequential traces made by our spectrum analyzer from 20 Hz to 20 kHz and depicts the full range of all three tone controls of the RS4744 receiver. Bass boost and cut range is greater than we normally find on receivers, with nearly 20 dB of boost and cut available at the 50-Hz point (each vertical division of the 'scope graticule is equal to 10 dB of amplitude). The action of the extra mid-range tone control is exactly as expected and is centered at around 1.5 kHz as claimed. In Fig. 8 we plotted action of the loudness compensation circuit from full volume to a -50 dB setting in approximately 10 dB steps and, as can be observed, action involves bass emphasis only. Action of high- and low-cut filters is shown in the 'scope photo of Fig. 9, and a comparison with maximum attenuation of the bass and treble controls (Fig. 7) shows the advantage of these 12-dB-per-octave filters in eliminating noise and rumble with least degradation of musical frequency response. Fig. 5-Harmonic and intermodulation distortion characteristics. t!- Z Q r- oc 0 r- CI) 0 0.5 0.4 0.3 0 .2 ...... 0.1 o 10 100 IK a-OHM LOADS BOTH CHANNELS DRIVEN 60 WATTS ICHANNEL 10K / 20K FREQUENCY - Hz Fig. 6-0istortion vs. frequency. Fig. 8-Loudness control action from full cw setting of volume control to -50 dB below full volume. Fig. 7-Control range of base, mid-range, and treble controls. Fig. 9-Action of high-cut and low-cut filters. 50 AUDIO. FEBRUARY, 1976
Four questions you must ask about any lnultiple-playturntable. 1 2 3 4 Does it perform. as well as any single-play turntable? • There are some who believe that a single-play the arm rest and shuts off the motor-is turntable is somehow inherently better than a completely disengaged during record play. A multiple-play unit. All right- the Z2000B is a 2-position control sets the proper vertical single-play turntable. Its capacity to function tracking angle for single or multiple play. The as a multiple-play unit offers convenience with Z2000B can truly be called the automated, no compromise of performance. The auto- single-play turntable with multiple-play matic mechanism which gently indexes the capability. arm, lifts it at the end of play, returns it to Does it have belt-drive and variable speed? • Garrard engineers have attained remarkable pressive specifications achieved. A variable results by combining the world famous speed control corrects out-of-pitch recordings Synchro-Lab motor and an inventive belt/ idler and an illuminated stroboscope provides drive combination. A 5 lb. , die-cast, dynami- optical confirmation. The Z2000B combines cally balanced platter is rotated via a flexible all of these elements to achieve the main goal belt. Not only are the tiniest fluctuations of of Garrard engineering: superior performance speed smoothed out. but an extraordinary at reasonable cost. -64dB rumble is only one example of the im- Does it handle records gently? • All responsible turntable manufacturers are both directions. The ingenious built-in autoconcerned with protecting your records. With matic record counter keeps track of how many Garrard, it's an obsession. The Z2000B boasts LP sides the stylus has played. And unlike an array of features designed solely to prolong some of the highest priced changers that supthe life of your records. In addition to the port records only at the center hole, the exclusive, articulated tonearm, it incorpo- Z2000B supports them at the hole and edge, rates an exceptionally accurate magnetic anti- and the release mechanism operates at both skating device. Cueing is viscous damped in points. Protection for your records indeed! Does it eliminate tracking error? • The grooves of a record are cut by a stylus compromise was unacceptable in the Z2000B. that travels in a straight line. Conventional What Garrard engineers did about it was sumplayback tonearms move in an arc. The dif- med up by High Fidelity Magazine which ference between these two paths is called described the Zero Tracking Error Tonearm "tracking error." Simply stated, tracking error as "... the best arm yet offered as an integral launches a cycle of distortion and record wear. part of an automatic player:' The Z2000B is In good design, the error is averaged over the the only automatic turntable in the world withrecord so that distortion is minimal. But such out tracking error. The Garrard Z2000B. Yes. Yes. Yes. Yes. For your free copy of the New Garrard Guide. write to Garrard. Divisio n o f Plessey Consumer Products, Dept. C , 100 Co mme rcial St.. Plainview. New Yo rk 11 803 Check No. 17 on Reader Service Card The Automatic Choice
Page 2 and 3: Actual , unretouched photo of an os
Page 4 and 5: The $750 alternative. Audioclinic 0
Page 6 and 7: ,~T~E PROBLEM SOLVER Tape Guide Her
Page 8 and 9: What~ ew in Au • 10 Phase Linear
Page 10 and 11: I.r • i. is .rli. Richard C. Heys
Page 12 and 13: Audio ETC I T'S GETTING to be a gam
Page 14 and 15: THE COLOSSUS by KUSTOM ACOUSTICS (G
Page 16 and 17: THI GOlD-PlATID RlllABlllTY fACTOR.
Page 18 and 19: Behind The Scenes Bert Whyte Autumn
Page 20 and 21: In cred ible. How else would you de
Page 22: Dear Editor: Another Sage Down Unde
Page 25 and 26: cilloscope is a voltage measuring i
Page 27 and 28: through Rll provide local negative
Page 29 and 30: Check No. 25 on Reader Service Car~
Page 31 and 32: not everyone could build a stereo k
Page 33 and 34: OUR FLAT RESPONSE TO HIGH PRICES. .
Page 35 and 36: New from Acoustic Research The New
Page 37 and 38: TWICE AGAIN, HISTORY REPEATS ITSELF
Page 39 and 40: TOSHIBA CASSETTE DECKS PLAY GREAT M
Page 41: Dual concentric, clutch-type bass,
Page 45 and 46: nnouncing The Infinity FET Preampli
Page 47 and 48: Every Dual, from the 1225 to the CS
Page 49 and 50: The Rule: "Only separate components
Page 51 and 52: Laboratory Measurements Noise and T
Page 53 and 54: The look of denim. The Sound of Kos
Page 55 and 56: The great Sansui equation For those
Page 57: ACCUSOUND'S 80A OUTPERFORMS THE LAR
Page 60 and 61: ! " Section Bac:k Panel Asmby. Fron
Page 62 and 63: knobs were at 12'oclock. The kit in
Page 64 and 65: Let's Be Fair To Our Favorite Compo
Page 66 and 67: it lead to the first of his many ne
Page 68 and 69: 0111 ~ Box 176A' lJ,UlJ~ 0 Pe terbo
Page 70 and 71: ---- "".n-,;-' enbacker guitar. The
Page 72 and 73: of the unity of man in a coadunate
Page 74 and 75: differences" and "to find God," or
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Page 78 and 79: Canby~ Capsules Ravel: Daphnis and
Page 80 and 81: J. E. SUGDEN & CO. LTD. AUDIO EQUIP
Page 82 and 83: Crown TheKnown Value •.. at an un
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Page 86 and 87: SPECTRO POWER! THE SUPER CLEAN SPEC
Page 88 and 89: Our gimmick is no gimmicks at all.
Page 90 and 91: Tape & Turntable Bert Whyte Tale Sp
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