LAB­O­RA­TORY TEST RE­PORT

Australian HIFI - - ON TEST -

Newport Test Labs mea­sured the out­put volt­age of the bal­anced out­puts of the Bryson BCD-3 as be­ing a bit over 4-volts (see the ta­ble for the ex­act volt­ages), with of course the un­bal­anced out­puts com­ing in at half this volt­age. The dif­fer­ence in volt­age be­tween the two chan­nels put the chan­nel balance at an out­stand­ingly good 0.051dB. Chan­nel sep­a­ra­tion was so good that the guys at the lab were asked to dou­ble-check their re­sults, but they re­ported that they were right the first time: 150dB at 20Hz, 157dB at 1kHz and 137dB at 20kHz. I am fairly cer­tain that those are the best re­sults Newport Test Labs has ever recorded for a CD player.

Re­mem­ber, too, that this is or­di­nary Red Book CD test­ing! In­ter-chan­nel phase was also out­stand­ingly good, com­ing in at 0.01° at 20Hz, with a ‘worst’ re­sult of just 0.81° at 20kHz. THD+N was a van­ish­ingly low 0.002% at 1kHz at 0dB and the dis­tor­tion spec­trum is shown in Graph 1. You can see there’s a sec­ond har­monic dis­tor­tion com­po­nent at –118dB (0.0001%), a third at –95dB (0.0017%) and a fifth at –123dB (0.00007%). That’s it! What’s more, the over­all noise floor is sit­ting down at –140dB, with the low-fre- quency noise at the ex­treme left at around –120dB. If you look at the tab­u­lated re­sults, you’ll see that Newport Test Labs mea­sured the over­all sig­nal-to-noise ra­tio at 116dB un­weighted, and 123dB A-weighted. This means the Brys­ton BCD-3 is go­ing to be a lot qui­eter

than any elec­tron­ics you use to am­plify its sig­nal. At a recorded level of –10dB, which is more like what will be peak level on a typ­i­cal com­mer­cial CD, only two har­mon­ics are vis­i­ble, a sec­ond at –132dB (0.00002%) and a third at –112dB (0.00025%). The low-fre­quency noise has dropped a lit­tle, so even that lit­tle noise at 0dB was likely caused by the max­i­mum sig­nal level… which would not be present on a com­mer­cial CD.

At –40dB recorded level, there’s no har­monic dis­tor­tion vis­i­ble at all, just ‘grass’ on the noise floor be­cause of the lack of dither­ing on the 1kHz test sig­nal. (If the sig­nal had been dithered, the ‘grass’ would dis­ap­pear.) You can see this on Graph 6, which shows the Brys­ton BCD-3’s re­sponse to an un­dithered 1kHz test sig­nal recorded at –91.24dB com­pared to Graph 7, which shows the Brys­ton’s per­for­mance with a dithered 1kHz test sig­nal at –90.31dB. The dis­tor­tion com­po­nents dis­ap­pear en­tirely, and the noise floor be­comes uni­form across the au­dio spec­trum… though slightly higher in level. How­ever, since that noise floor is still sit­ting down at –140dB, it’s not an is­sue. You can read an ex­cel­lent ar­ti­cle about dither at www. tinyurl.com/magic-dither.

Newport Test Labs mea­sured in­ter­mod­u­la­tion dis­tor­tion (IMD) us­ing two dif­fer­ent tech­niques, CCIF (Graph 8) and SMPTE (Graph 9) and the Brys­ton BCD-3 re­turned su­perb re­sults in both cases. On Graph 8 you can see the two test sig­nals at 19kHz and 20kHz around the cen­tre of the graph. There are only two side­bands, both down at around –105dB (0.0005%) and the un­wanted 1kHz dif­fer­ence sig­nal is down even fur­ther at –126dB (0.00005%). The sig­nals above 20kHz are IMD prod­ucts re­lated to the sam­pling fre­quency, but other than one at –117dB (0.00014%) they’re all 120dB (0.0001%) or more down. All these IMD prod­ucts would be com­pletely in­audi­ble. On Graph 9 the test sig­nals are at 60Hz and 7kHz (in a 4:1 ra­tio) and you can see some side­bands on the 60Hz sig­nal that are around 110dB (0.00031%) down, plus some dis­tor­tion around 16kHz that’s more than 120dB down (0.0001%). As I said: su­perb re­sults.

The Brys­ton BCD-3’s fre­quency re­sponse is shown in Graph 10 and even a cur­sory glance shows that it’s ruler flat, par­tic­u­larly when you re­alise that the ver­ti­cal scale of the graph has been ex­panded so far that each hor­i­zon­tal di­vi­sion rep­re­sents a dif­fer­ence in level of only 0.2dB. This means the re­sponse is within 0.01dB of ref­er­ence up to 5.2kHz, af­ter which it ‘rolls off’ to be down 0.21dB down at 20Hz. So nor­malised, the fre­quency re­sponse mea­sured by Newport Test Labs was 20Hz to 20kHz ±0.11dB. In other words, su­perb. The re­sponse be­low 20Hz is not shown on this graph, but it ex­tends equally flat all the way down to 2Hz (the lab’s mea­sure­ment limit).

The Brys­ton BCD-3 showed some slight de-em­pha­sis er­rors (0.16dB at 1kHz, 0.84dB at 4kHz and 0.34dB at 16kHz) but these are small and no com­pact disc man­u­fac­tured in the past 30 years will be em­pha­sised any­way, so de-em­pha­sis would not be re­quired. If any­thing, Brys­ton is to be con­grat­u­lated for in­clud­ing a de-em­pha­sis cir­cuit at all—many modern CD play­ers don’t have one.

Lin­ear­ity er­rors were very low, as you can see from the tab­u­lated re­sults, with no er­ror at all at –60dB and –70dB and a worst-case er­ror of just 0.11dB, at –80.70dB. This means sounds will be re­pro­duced at the cor­rect level, ac­cord­ing to their recorded vol­ume.

Im­pulse test­ing showed that the AKM DAC ap­pears to use a min­i­mum-phase re­con­struc­tion fil­ter, so there’s no pre-ring­ing at all—all the ring­ing oc­curs af­ter the im­pulse. The square wave shows iden­ti­cal per­for­mance.

The qual­ity of the sig­nal from the dig­i­tal out­puts was out­stand­ing, with ul­tra-low jit­ter, at just 1.5 nanosec­onds (peak-to-peak) and ex­cel­lent eye-nar­row­ing char­ac­ter­is­tics at both 200mV and zero-cross.

Power con­sump­tion when the Brys­ton was play­ing was about what I’d ex­pect for a CD player, but the standby power con­sump­tion of 2.07-watts is about twice what I’d ex­pect from a modern hi-fi com­po­nent, with the Aus­tralian gov­ern­ment ex­pect­ing standby con­sump­tion to be less than 0.5-watts. That said, 2.07-watts isn’t go­ing to im­pact on your power bills, but to be green, you should turn the player off when you’re not us­ing it.

Over­all, su­perb per­for­mance from the Brys­ton BCD-3 CD player. This is a state-ofthe-art com­po­nent. Steve Hold­ing

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