5196105870

AUDIO_______ _

New uipment Repo

Preparation supervised by Robert Long, Michaeł Riggs and Łdward ). Foster.

Laboratory data (unless otherwise noted) supplied by Diversified Science Laboratories

t

X Marks the Yamaha

Yamaha B-6 power amplltier. In metal cm Otonenatona: 11 % inchea tqu#r* (at b*u oi pyr amid). 7 Inchet high Prtce: S9S0 Warianty “llmKed." Iwo year* parli and la-bor Manulacturar: NlpponOakkł. Japan. U $. dittribu-tor: Yamaha International Corp.. 6600 Orangethorpe Ar* . Buena Park. CaUf 90C20

RATED POWER 23 dBW(?00 MrattS). channol

OOTP\jT AT CLlPPlNG(tx>th chano*ls<Ji iven)

8-otvn ioad    24 Y> dBW (28? watts)/cnann*

16-onm load    22 dBW (l S8 watts)/chan net

(not rated tor 4 onm loadft)

DYNAMłC MEAOROOM (8 ohms)	I % dB
HARMONC OlSTORTlON<THO. 20 H/ ?o 20hM/>
at 23 dBW (200 watts)	• 0 027\
at 0 dBW < \ wam	0 0l\
PREOUENCYRESPONSE
♦ 0. -VkOB, •	10 H/ to 53 kH/
“3<J0 «it 320 kM/
SENS*TIVlTY (reOOBW)	i00mv
S N RATlO(A-*e»ghte0)	101 dB
DAMPINGFACTOR (at 50 M/>	280

The \vori> "ri\oi itionary" is frc-quently oscrused. and it would bc streichingu point loapply it to Yamaha'* ”X" anipliliers-of whieh the B-6 is the premier model-thoueh the point is mu-tincly stretched much further. Yet "evo-lutionary" scems toi» tepid a word lor a design that makes so signilicant a break with the past Mam umplilicr designs al-ter tramistor hiasing on a signal-dcmand hasis to increase overall capahilitics in some respect: the X design (and the (*arver “magnetie” amp. under whosc patent the X amp is manufacttiied) runs its enlire power supply on signal de-mand. «leveloping its fuli output only w hen transient peaks eueed its normul-state capacity. Antong other ihings. this perntiis a smaller power transformer than is rcquircd b\ conventional designs of similar wattage. and therefore smaller. lighter. and potentially less ex-pensive umplificrs. loranolher. ii means less power is consumed front the wali sockei. whether idling or at luli ery. Whilc other **rcvolulionarv“ circoils are lowering distortion b\ antotints whose audibilily is. at best. u subject for debatę, thisapproach to power-supply design of-fers advantages you ean lakę to the bank or invest in a better system than you might otherwise have been able to affitrd.

The B-6. though it may not lit your concept of what a power amplitier

shotild look like (it ccrtainlv isn't de-signed for stacking). looks tcrrific. The front faec of the truncated black pyra-ntid sports iwo red LKDs. one for on and one for proif< iion (whieh mdudes a turn-on cvcle lastmg a fcw seconds). Fhefe is an on/olf switeh hidden bclow. hut the iwo-prong pług on the AC cord makes it easy to run the B-6 off a switched eonvenience rcceptaele on your preantp. Speaker eonneelions (spring-litaded elips), inpul eonneelions (pin style), a ground binding post. and a srt \kirs on/olf sw iteh are all reccssed helów the back face of the pyrantid. whieh is a sentilation grille. (As adver-tised. the heat generated by the amp is. to the touch. eonsiderably less than you might expect 1'rom so hefty an amp.) rhafs it: arguably the most elegant design to hit the stereo cquipmcnt market in vears.

As the l)iversiiied Science I abora-tories measurements show. performance is linę. In the conicxt of today's amps. thal's anything bul famt praise. Al 0 dBW (I wali), distortion is bclow the 0.01% threshold of our reportorial eu-riosity (and well be Iow the threshold of audibilily): at fuli power. distortion be-eomes measurable. with the third harmonie predominaling over the morę be-mgn sccond. bul still at very Iow (and quile inaudible) levcls. The 8-ohm dynamie hcadmom (1% dB) means that

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HIGH t lDt LITY