LAB­O­RA­TORY Test Re­port

Australian HIFI - - ON TEST -

I mea­sured max­i­mum out­put lev­els from one of the head­phone out­puts in stan­dard (un­bal­anced) mode. Into a high in­put im­ped­ance (47kΩ) there was the tini­est amount of clip­ping at the 0dB out­put level at 100Hz, so I backed it down to –1dB and it was clean. The (ef­fec­tively) no load out­put was 8.74 volts RMS. Into a 295Ω test load, the out­put was 8.74 volts RMS. At least, it was with 1kHz and 10kHz test sig­nals. With 100Hz there was a touch of clip­ping, so I backed it off to –2dB to clean it up. That re­duced the out­put to 7.93V.

That works out to a 213mW out­put into high-im­ped­ance head­phones, or some 23dB higher than the sen­si­tiv­ity rat­ing. These days most head­phones are at least in the high 90dBSPLs for 1mW of in­put, so you can expect a good 120dBSPL if you want it. (You shouldn’t want it.)

Into a 15.9Ω load there was clip­ping again. At –5dB this was com­pletely gone. The out­put was 5.26 volts for an in­cred­i­ble 1.74 watts out­put. That’s 32dB higher than the sen­si­tiv­ity rat­ing. If the head­phones could cope. They prob­a­bly couldn’t.

I cal­cu­lated an in­ter­nal re­sis­tance of around 0.8Ω, so even head­phones with a widely vary­ing im­ped­ance curve shouldn’t pro­duce ma­jor fre­quency re­sponse changes.

As for the line out­put, if you set the RCA line out­put to ‘By­pass’—that is, the vol­ume

Graph 3. Fre­quency re­sponse show­ing ef­fect of FRMP fil­ter set­ting left chan­nel (white trace) ver­sus right chan­nel (green trace) us­ing 192kHz/24-bit test sig­nal.

Graph 2. Fre­quency re­sponse show­ing ef­fect of FRMP fil­ter set­ting (white trace), ver­sus SRMP fil­ter set­ting (green trace) ver­sus BRCK fil­ter set­ting (blue trace) vs Apo­dis­ing (pur­ple trace) us­ing 96kHz/24-bit test sig­nals.

Graph 4. Noise floor spec­trum show­ing noise when bat­tery-powered (white trace) and when mains-powered (green trace) us­ing 96kHz/24-bit test sig­nals.

Graph 1. Fre­quency re­sponse show­ing ef­fect of FRMP fil­ter set­ting (white trace), ver­sus SRMP fil­ter set­ting (green trace) ver­sus BRCK fil­ter set­ting (blue trace) us­ing 44.1kHz/16-bit test sig­nals.

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