TEST METH­ODS AND EQUIP­MENT

Sound & Vision - - SPEAKER CABLES -

Both parts of the lis­ten­ing test, the open and the con­trolled, were per­formed in a sparsely fur­nished liv­ing room mea­sur­ing 18 x 11 x 28 feet. The hard­wood oak floor is cov­ered with a Persian area rug, and sheet-rock walls and large glass win­dows rise to a “semi-cathe­dral” ceil­ing. Acous­ti­cally the room is very live, with a re­ver­ber­a­tion time of about 1 sec­ond.

High-end equip­ment was used through­out the test setup. The sys­tem in­cluded an Ac­cuphase AC-2 mov­ing-coil car­tridge (sty­lus wear ap­prox­i­mately 75 hours), a Mag­nepan Uni­trac 1 tone arm, and a Linn Son­dek LP-12 turntable (Val­halla mod­i­fi­ca­tion, of course). Other sig­nal sources in­cluded a Tand­berg TD-20A open-reel tape deck (spe­cial equal­iza­tion model) run­ning at 15 inches per sec­ond and a Mag­navox FD 1000SL dig­i­tal Com­pact Disc player. The Mark Levin­son ML-7 stereo pream­pli­fier that served as the con­trol cen­ter was equipped with L-3 mov­ing­coil phono sec­tions. Levin­son sil­ver in­ter­con­nect ca­ble ran from the ML-7 to the power am­pli­fier.

Dur­ing the open lis­ten­ing ses­sions a num­ber of high-qual­ity power am­pli­fiers were used, in­clud­ing an Elec­tro­com­paniet Am­pli­wire 1, a Mark Levin­son ML-9, and a Per­reaux PMF 2150B. Each of these high-power units had been tested pre­vi­ously and found to be in per­fect work­ing or­der. For the con­trolled lis­ten­ing tests we chose the Per­reaux unit (more than 200 watts per chan­nel).

The speak­ers were in­stalled 6 feet apart along the room’s short wall and about

2 feet out from each side wall. In­fin­ity RS-3A, Spen­dor BC-I, and KEF 105.2 sys­tems were all em­ployed in the early trial ses­sions and dur­ing the open lis­ten­ing phase. Only the KEF’S were used dur­ing the con­trolled tests be­cause of their built-in over­drive pro­tec­tion. Each lis­tener was al­lowed to set the vol­ume level to his taste at the be­gin­ning of his part of the con­trolled lis­ten­ing test; the vol­ume was then left at that level for the en­tire test ses­sion. For one of the Mon­ster Ca­ble/24gauge com­par­isons the two ca­bles were matched in gain level within 1 db us­ing a po­ten­tiome­ter con­nected be­tween the pream­pli­fier and power am­pli­fier and an Ivie IV-10 spec­trum an­a­lyzer.

Pro­gram ma­te­rial for the open lis­ten­ing tests in­cluded a wide range of sources and mu­si­cal styles. Among the record­ings used were the pink-noise band from Te­larc’s “Om­ni­disc” test al­bum (Te­larc DG-10073/74), Mozart arias from Philips 9500 098, per­cus­sion in­stru­ments from Harry Patch’s Delu­sion of the Fury (Columbia M2 30576), Karla Bonoff’s Rest­less Nights (Columbia JC 35799), Ber­lioz’s Sym­phonie Fan­tas­tique (Ref­er­ence Record­ing R-11), and two se­lec­tions from a Philips CD sam­pler disc (801 027 2), El­ton John’s ren­di­tion of “Blue Eyes” and “Once Upon a Time in the West” by Dire Straits.

The pro­gram ma­te­rial for the con­trolled tests was re­stricted to only two se­lec­tions. The 3-minute pink-noise band from the “Om­ni­disc” was cho­sen by the panel as most re­veal­ing of sub­tle sonic dif­fer­ences. Cho­ral mu­sic sung by the 300-voice Jay Welch Cho­rale (Varese Sara­bande VSD l000) was cho­sen be­cause of the disc’s un­usual de­gree of stereo sep­a­ra­tion and the vo­cal res­o­nances in the male cho­rus.

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