Australian HIFI - - ON TEST -

Newport Test Labs mea­sured the out­put volt­age of the NA 6005 at just over 2 volts, as shown on the tab­u­lated chart, which is more than suf­fi­cient to drive any de­vice it might rea­son­ably be ex­pected to be con­nected to. Chan­nel bal­ance was ex­cel­lent, at 0.048dB, and the sep­a­ra­tion be­tween the chan­nels equally so, with a best re­sult of 140dB at 16Hz. Chan­nel phase was out­stand­ingly good, mea­sur­ing 0.02° at 16Hz, 0.01° at 1kHz and just 0.31° at 20kHz. Group de­lay was typ­i­cal at 180° and 5.27°.

The Marantz NA6005’s fre­quency re­sponse was also ex­cel­lent, just 0.09dB down at 16Hz, and only 0.32dB down at 8Hz. At 20kHz re­sponse was only 0.02dB down. You can see the graphed re­sult in Graph 10. Newport Test Labs’ re­sults show that un­like many man­u­fac­tur­ers, Marantz is still in­clud­ing de-em­pha­sis cir­cuitry for those sig­nals that re­quire it, and that the cir­cuit provided is ex­tremely ac­cu­rate, be­ing only 0.001dB out at 1kHz, 0.011dB out at 4kHz and 0.114dB out at 16kHz.

Over­all THD+N at 0dB was very low, at 0.011% as shown in the tab­u­lated re­sults. Dis­tor­tion at 0dB, as well as at lower recorded lev­els, is shown in the ac­com­pa­ny­ing graphs. Graph 1 shows the har­monic struc­ture of dis­tor­tion at 0dB. Other than a sin­gle even-or­der har­monic at –110dB (0.00031%), the har­mon­ics are all odd-or­der, with a third at –120dB (0.0001%), a fifth at –108dB (0.00039%), and a sev­enth at –122dB (0.00007%). Higher-or­der har­mon­ics are vis­i­ble, but are more than 130dB (0.00003%) down. The sig­nal at 15kHz is at –118dB (0.00012%) ap­pears to be a sam­pling-re­lated prod­uct rather than a har­monic. There’s a very slight rise in the noise floor around 20kHz, but since it’s more than 120dB down and oc­curs at such a high fre­quency, it’s of no im­por­tance.

At –6dB, al­most all the dis­tor­tion com­po­nents dis­ap­pear, with the ones re­main­ing be­ing the sec­ond har­monic at –126dB (0.00005%), the third at –112dB (0.00025%), and the fifth at –127dB (0.00004%), show­ing that the dis­tor­tion com­po­nents at 0dB were prob­a­bly in the ana­logue out­put stage, due to the high out­put volt­age, rather than re­lated to the dig­i­tal-to-ana­logue con­ver­sion.

The Marantz NA 6005’s fre­quency re­sponse was also ex­cel­lent, be­ing just 0.09dB down at 16Hz, and only 0.32dB down at 8Hz.

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