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34 Australian ON TEST W ith so many manufactur- ers now switching to using materials such as wood and plastic to build their ampli- fiers, it was reassuring to find that Arcam has stuck with its ‘Full Metal Jacket’ (FMJ*) [For alternate meanings of these three initials, see breakout box opposite] casing for its new A19 integrated amplifier. The result is that when you pick it up (not without some effort, because it’s also reassuringly heavy), you’ll find it feels rigid… a really solid piece of equipment. When you fire it up, you’ll realise there’s some pretty solid electrical engineer- ing inside it as well… engineering which in- cludes than a few really handy design fillips. THE EQUIPMENT As you can see from the photograph ac- companying this review, the Arcam is a true ‘slim-line’ component, as it stands just 85mm INTEGRATED AMPLIFIER Power Output: Single channel driven into 8-ohm and 4-ohm non-inductive loads at 20Hz, 1kHz and 20kHz. [Arcam FJMA19] Newport Test Labs Arcam FMJ A19 *What does FMJ stand for? Well, I maintain that the letters stand for Full Metal Jacket but in these politically correct, peace-loving days, Arcam insists they’re short for ‘Faithful Musical Joy’. You choose. It’s like the mystery about what the letters THX stand for. Do they stand for Tomlinson Holman’s eXperiment, or are they homage to George Lucas’s first feature film, THX 1138? Then there’s the DVD mystery—do the letters stand for Digital Video Disc or Digital Versatile Disc? (E.D.)

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Page 1: Arcam FMJ A19 - nextmediai.nextmedia.com.au/Assets/arcam_fmj_a19_amplifier_review_test... · avhub.com.au 35 arcam fmJ a19 integrated amplifier ON TEST motorised, so it turns if you

34 Australian

ON TEST

With so many manufactur-ers now switching to using materials such as wood and plastic to build their ampli-

fiers, it was reassuring to find that Arcam has stuck with its ‘Full Metal Jacket’ (FMJ*) [For alternate meanings of these three initials, see breakout box opposite] casing for its new A19 integrated amplifier. The result is that when you pick it up (not without some effort, because it’s also reassuringly heavy), you’ll find it feels rigid… a really solid piece of equipment. When you fire it up, you’ll realise there’s some pretty solid electrical engineer-ing inside it as well… engineering which in-cludes than a few really handy design fillips.

The equipmenTAs you can see from the photograph ac-companying this review, the Arcam is a true ‘slim-line’ component, as it stands just 85mm

integrated amplifier

Power Output: Single channel driven into 8-ohm and 4-ohm non-inductive loads at 20Hz, 1kHz and 20kHz. [Arcam FJMA19]

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Arcam FMJ A19

*What does FMJ stand for? Well, I maintain that the letters stand for Full Metal Jacket but in these politically correct, peace-loving days, Arcam insists they’re short for ‘Faithful Musical Joy’. You choose. It’s like the mystery about what the letters THX stand for. Do they stand for Tomlinson Holman’s eXperiment, or are they homage to George Lucas’s first feature film, THX 1138? Then there’s the DVD mystery—do the letters stand for Digital Video Disc or Digital Versatile Disc? (E.D.)

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motorised, so it turns if you decide to adjust volume with the remote control (included in the price… not an optional extra!), but the more important feature is that it’s not a standard volume potentiometer (variable resistor). Instead, it controls a stereo volume control integrated circuit, in this case a Texas Instruments PGA2311. Inside this PGA2311 IC are a resistor network, an analog switch array, and high-performance operational amplifier stages. The front panel rotary control is used to indirectly select taps in the resistor network that, in turn, determine the gain of the amplifier stage and thus the amplifier’s volume level. You can’t see where the rotary is set by looking at it, because there’s no pointer or engraving on it. Instead you need to look at the front panel display itself, where level will be indicated by a readout that runs from 00 to 99. (And flashes a welcoming ‘Arcam’ greeting whenever you power-up the amplifier.)

You can alter the brightness of this front-panel display (though only between ‘Dim’ and ‘Bright’) or switch it off completely, all via either the front panel pushbutton or the remote. Muting can also be activated or deactivated using either the front panel pushbutton or the remote. Whichever way you access the muting, Arcam’s implementation of the muting circuit is correct, because if you touch either the front-panel volume control or the remote’s volume control while the muting circuit is active, it will automatically de-mute, so you’ll never run the risk of accidentally damaging your speakers with an unwanted blast of sound.

ArcAm FmJ A19Integrated amplIfIer

Brand: arcammodel: fmJ a19category: Integrated amplifierrrP: $999Warranty: two YearsDistributor: Sennheiser australia pty ltdAddress: Unit 3, 31 gibbes Street Chatswood, nSW 2067

1800 648 628 (02) 9910 6700 [email protected] www.sennheiser.com.au

readers interested in a full technical appraisal of the performance of the arcam fmJ a19 Integrated amplifier should continue on and read the laBOratOrY repOrt published on page 38 readers should note that the results mentioned in the report, tabulated in performance charts and/

or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.

Lab Report on page 38

• Small and attractive• lots of inputs• Superb build

• remote control

laB repOrt

high, including its four rubber feet. (For the record, its other dimensions are 432mm (width) and 275mm depth). As it happens, it’s arguable that it was Arcam that pioneered the slim-line design ‘way back in 1976, with the design of its very first amplifier, the A60 (though back in those days, the company was known as A&R Cambridge—itself short for Audio & Recording Cambridge—before it eliminated the ‘&’ and dropped the ‘bridge’ to become Arcam… short and sweet). Also, as it happens, the original A60 didn’t have a ‘full metal jacket’. Its top and sides were made from slabs of solid timber. It also had rather ugly external heatsinking attached to its rear panel, but I’ll have more to say about heatsinks in a moment…

But before I do, let’s look briefly at the front panel. It’s so nicely and neatly laid out that you may not notice something quite flabbergasting, which is that the

A19 has EIGHT inputs, including a phono input. At a time when most other amplifier manufacturers are cutting down on the number of inputs in order to cut costs (an economy that sometimes results in their products having impractically few inputs) I was really impressed that Arcam is going the other way, which can only benefit users. It’s even given direct pushbutton access to each input, so it’s not only easy but also lightning-fast to select your desired source. Arrayed beneath the front panel display, these buttons are labelled Phono, Aux, CD, Tuner, Sat, BD, PVR, and AV. I think I can safely say that you’ll never need more inputs than are available on Arcam’s A19.

There’s a story behind the volume control you can see to the left of the display. Yes, it’s

(It’s amazing how many manufacturers overlook this important safety feature.) When you mute the sound the mute action is instantaneous (accompanied by a loud relay click) but when you un-mute it, the volume ramps up progressively (but very quickly), which I found particularly satisfying. When the amplifier is muted, the letters ‘MT’ appear in the front panel display.

Channel balance is implemented electronically, again using the TI PGA2311, and the display gives you calibrations from R01 to R012, and then from L01 to L012. The ‘balance’ mode will stay active for seven

Power Output: Both channels driven into 8-ohm and 4-ohm non-inductive loads at 20Hz, 1kHz and 20kHz. [Arcam FJMA19]

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Power Output: Single and both channels driven into 8-ohm and 4-ohm non-inductive loads at 20Hz, 1kHz and 20kHz. [Arcam FMJ A19]

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ON TEST arcam fmJ a19 integrated amplifier

seconds after you’ve implemented it, after which the volume control (which you also use to adjust channel balance) reverts to its normal function. Speaking of the volume control, I forgot to mention that it’s not a typical flat-sided control, but instead has a contoured surface, so it has a surprisingly nice ‘feel’ under your fingers if you use it in preference to the remote. As with many amplifiers, the Arcam A19 will always ‘remember’ the last input you used, as well as the volume level you were listening whenever you come out of standby.

As you can see over near the push-button mains power switch on the far right, Arcam has provided both a front-panel headphone output and a front-panel Aux input, both implemented in the form of 3.5mm stereo phone jacks. The front-panel Aux jack is very clever: just plug in your iPod (or any mobile device with a line output) and you’re instantly listening to music stored on it, rather than your system. As for that headphone output, although I would have preferred it to be implemented via the larger 6.35mm phone socket, I was gratified to find that the circuitry behind the socket is a proper headphone amplifier, using discrete components, with an output impedance of less than 1Ω, so not only it will drive any headphones you care to use, but it will do so rather better than most outboard headphone amplifiers.

Around the back you’ll find not only all the necessary inputs and outputs you’ll ever need (almost all of which, including the ground terminal, are gold-plated), but also a direct, isolated, fully-regulated source of 6V power that can be used to power any ancillary component that needs a stable 6V supply. It has obviously been designed to encourage the use of Arcam’s own products that require such a supply, for example its rSeries outboard DACs. Using it won’t affect the A19’s performance: it’s completely separate from the power supplies used inside the amplifier. The loudspeaker terminals are ‘economy’ multi-way (but gold-plated) types that will accept banana terminals, stripped

wire, spades and lugs. The A19 has a set of pre-amplifier output terminals, so if you ever decide you need more power than the A19 can deliver, you can use the A19 as a pre-amp and connect it to a higher-powered power amplifier.

Open up the amplifier (which I don’t recommend you do yourself: you’ll not only void the warranty, but will also expose yourself to dangerous voltages) and you’ll see that Arcam has opted for a Class-A/B output stage (using a pair of LM3886T ICs), the rails for which are supplied from a large toroidal transformer backed up with 18,000µFs-worth of capacitance (four 4700µF 63V electros), all of which allows Arcam to rate the FMJ A19 with a power output of 50-watts per channel

both channels driven into 8Ω. (Arcam also claims an output of 90-watts in some brochures, but this is into a 4Ω load, and with only one channel driven, so it doesn’t really count.) The heat generated in doing this is dissipated by an internal heatsink (and it’s a real one, not one of the ‘fake’ ones found in amplifiers from some other famous manufacturers I won’t name), but because it’s internal, you’re going to have to make sure the ventilation holes above and below it are not obscured if the amplifier is to remain cool during high-power operation.

The remote control supplied with the remote is, ahem… ‘serviceable’. It has the advantage of being small (145×40×15mm) and has square sides and ends, so you can stand it on its end or on its side on your equipment rack or coffee table, but it’s not exactly attractive. Something more streamlined, sculpted and shinier might have been more appropriate, simply because it

would be more in keeping with the look and quality of the amplifier itself. The remote powered by two AAA batteries that I’d recommend you immediately discard (they’re very ordinary carbon ones) and replace with high-quality alkaline leak-proof batteries.

in use and LisTening sessionsThanks to the editor pre-loading me with products for review, I was in the position of having not just my own turntable available to try with the Arcam FMJ A19, but three other high-quality vinyl-spinners, so its phono stage got quite a work-out… not least because, to my complete surprise, the Arcam A19 is equipped with a very decent phono stage optimised for a fairly standard load of 47kΩ/100pF, which suits a wide range of moving-magnet cartridges.

Whilst checking to see if the Arcam’s phono stage could be internally switched to suit it for use with a low-output cartridges (it can’t), I discovered that if you don’t want to use a turntable, you can very easily convert the phono input into a standard line-level input… no soldering required. (Not only is there no soldering required, but you don’t even have to ‘pop the lid’: just press the ‘Balance’ and ‘Phono’ buttons simultaneously and the job’s done.)

The phono stage on the FMJ A19 is so good that I spent quite some time enjoying it, while at the same time marvelling at the incredibly good sound of the LPs in my collection. And I am not kidding when I say ‘marvelling’: I play far more CD (and SACD and DVD-A… not to mention WAV and FLAC) than I do vinyl, not least because there’s an enormous catalogue of work that simply is not available on LP, and I think all the non-vinyl sources I’ve mentioned sound fantastic (otherwise I wouldn’t play them!), but I still find that every time I spin up an LP of something I also have on CD, I prefer the sound on the LP! One great example is Billy Joel’s 52nd Street, which I just got brand new on the Impex label, on 125gram virgin vinyl (for $45, ouch!). The sound is just so much

The phono stage on the FMJ A19 is so good that I spent quite some time enjoying it, marvelling at the incredibly good sound

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ON TESTarcam fmJ a19 integrated amplifier

better than it is on CD… the LP’s sound is warmer, fuller, richer… more organically real. So my new purchase will certainly be my preferred method of listening to 52nd Street until I accidentally scratch the LP, or the groove wears down so much the highs start getting fuzzy, or the inevitable clicks and pops that creep in over the years get too pervasive, after which it will be back to one of the digital delivery modes for me. But, until that happens—and it will unfortunately, inevitably occur—vinyl rules!

One CD that got a lot of play time on the A19 over the festive season was the latest instalment in the ‘Punk Goes’ series from Fearless Records. Of course it was ‘Punk Goes Christmas’ with its offerings from New Found Glory, All Time Low, Real Friends, Man Overboard, The Summer Set, Crown the Empire, Yellowcard, Issues, The Ready Set, Set It Off and William Beckett. Other than the track This Christmas, performed by the Summer Set, which I didn’t like because of its staccato production values, I found this CD not only hilarious, but great fun. There are also some great sounds and performances (notably Christmas Lights, as performed by Yellowcard, but there are others nearly as good). You should now be able to pick up the CD really cheaply, because not only was it streamed over Christmas, but the album got some terrible reviews, which I think were completely unjustified. So my advice is to buy a copy now, so you’ll have it around when next Christmas comes around! (And whatever you do, don’t miss listening to Set It Off’s This Christmas (I’ll Burn It To The Ground)… which the late, great Frank Zappa would have loved.)

For my super-serious listening sessions I mainly used high-res music files (all 24-bit at 48kHz or higher) of solo instruments and small ensembles, as well as some full-blown orchestral works converted from digital by an rDAC powered from the rear of the A19 for improved performance. My listening sessions also involved using moderately high-efficiency speakers, because while running the A19 in with some very old and very inefficient loudspeakers I use specifically for this purpose (i.e., burning-in electronic components) it quickly became apparent that I’d have to use moderately high-efficiency speakers to extract the most from the A19’s rather modest 50-watt-per-channel rating. As a result, all of the speakers I used while preparing this review had SPL ratings of 88dBSPL (1w/1m) and higher.

Once the sessions started, my most immediate impression of the A19 was the detail I could hear in the sound. It was as if

the amplifier were cutting away extraneous noise and letting only the musically significant information through to the speakers. While I wasn’t hearing details I had not heard previously with other amplifiers, I did seem to be hearing them more easily and more naturally. The detail wasn’t ‘etched’ either… it was perfectly consistent with the flow of the music, not ‘louder’ or ‘harder-sounding’. This detailing was evident at all normal volume levels, and no matter what type of music I played. The only time the detailing disappeared was when I played music at extremely high volume levels. I was particularly impressed that the detailing remained at low volume levels. Often, when listening at very low levels, I sometimes get the impression I am missing on detail, which I resolve by turning the volume a little higher than I really want it to be. Listening to the Arcam late at night, with the music so low as to not disturb my partner, I never once thought I was ‘missing out on detail’, so the Arcam is a real winner in this regard.

I am sure that at least a part of this detailing ability was due to the amplifier’s lack of background noise. Even with the most efficient speakers I used I found I could stop a track half-way through playing then walk up to speakers and bring my ear close to a tweeter and hear nothing at all—no hiss. Moving my ear down the front baffle of the speakers to hear the woofer up close, I couldn’t hear any mains hum either. Excellent performance in this respect.

This ability on the part of the Arcam meant that solo stringed instruments (acoustic guitar, for example), sounded absolutely stunning! So too did human voices, solo or accompanied. In fact, the detailing worked for all music, right up and including complex orchestral works. One particularly enchanting work is the most recent album from Joseph Tawadros, ‘Chameleons Of The White Shadow’, for which he won an ARIA award (‘Best World Music Album 2013) which features him on Oud together with Béla Fleck (Banjo), Richard Bona (Electric Bass), Joey DeFrancesco (Hammond Organ) and James Tawadros (Req’ and Bendir). The synergy between Tawadros (one of the world’s best Oud players) and Fleck, (ditto, but on Banjo) is breathtaking.

Another album that should be on your ‘must-buy’ list is ‘Pure Heroine’ by Ella Maria

Lani Yelich-O’Connor (who very sensibly assumes the stage name of Lorde). It’s great, musically and sonically, but be warned that the tunes on this album are so catchy that you’ll never get them out of your head. Barely a day went by when I didn’t play Pure Heroine on the Arcam, yet I never tired of it. Lorde’s vocal technique is unique, and the A19 delivered it perfectly.

ConCLusionArcam’s A19 is a neat, well thought-out pack-age that is wife-friendly in size, looks high-class, is beautifully built and a real joy to use. Partner it with high-efficiency speakers with a nominal impedance of 6Ω or more and the music you’ll hear will make your final buying decision very easy. Ernest Denman

Arcam’s A19 is a neat, well thought-out package ... that looks high-class, is beautifully built and a real joy to use...

laB repOrt On page 38

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LAB REPORT

LaboraTory TesT reporTWhen measured by Newport Test Labs us-ing its standard test conditions, the review sample of Arcam’s FMJ A19 exceeded its rated power output when driving 8Ω loads by de-livering 62-watts [17.9dBw] per channel, both channels driven, at all frequencies from 1kHz up to 20kHz. Driving just a single channel, power output increased by just under 1dB to 75-watts [18.7dBw] per channel. However, you can see from the tabulated results and the accompanying bar graphs that when the test frequency was dropped down to 20Hz (still into the 8Ω load), power output dropped to 56-watts [17.5dBw] (both channels driven) and 71-watts [18.5dBw] (single channel driven). It is presumably because of this low-frequency power limitation that Arcam rates the output of the FMJ A19 at 50-watts per channel.

Newport Test Labs also measured the Arcam FMJ A19 when it was driving 4Ω loads, with the Arcam delivering 100-watts (20dBw) into both channels from 1kHz up to 20kHz. However, maximum continuous output at low frequencies (below 250Hz) was just 25-watts. The lab assumed this measurement was being affected by the Arcam A19’s protection circuitry and Nick Clarke, Chief Engineer at Arcam agreed. He advised by email: ‘there is a protection circuit and this is looking for clipping, over-current and thermal rise of the amplifier and its reaction to any of these would be to gracefully mute the output and restore it once the trigger condition has passed. I

would suspect it’s reacting to thermal rise in your test case.’

The protection circuit also interfered with Newport Test Labs testing into 2Ω loads, though this time the circuit was no doubt detecting an ‘over-current’ trigger condition, so tests into 2Ω loads were suspended. It was noted by lab technicians, however, that the over-current protection was very ‘graceful’, because the amplifier would simply mute itself when volume level increased, then automatically demute when it decreased. Many amplifiers with similar circuits go into total shutdown, requiring the volume to be reduced and then the amplifier be turned off completely, after which it has to be turned on again in order to reset the protection. Arcam’s implementation is far more elegant.

Frequency response was more than adequate, but not extended, with Newport Test Labs measuring the FMJ A19’s response as being 1dB down at 9Hz and 37kHz, and 3dB down at 5Hz and 57kHz. Within the audio band, the accompanying graph shows that the response was 0.3dB down at 20Hz and 20kHz, for a normalised response of 20Hz to 20kHz ±0.15dB, when the amplifier was driving a standard 8Ω resistive test load. Interestingly, the Arcam’s response improved slightly when it was driving a simulated loudspeaker load, with the normalised response extending out to 25kHz within the same decibel envelope. The response into a simulated load is shown by the red trace, which shows a very slight rise at around

Arcam FmJ A19 Integrated Amplifier – Test resultstest measured result Units/Comment

frequency response @ 1 watt o/p 9z – 37kHz –1dB

frequency response @ 1 watt o/p 5Hz – 57kHz –3dB

Channel Separation (dB) 66dB / 65dB / 50dB (20Hz / 1kHz / 20kHz)

Channel Balance 0.032 dB @ 1kHz

Interchannel phase 0.52 / 0.01 / 0.33 degrees ( 20Hz / 1kHz / 20kHz)

tHd+n 0.01% / 0.007% @ 1-watt / @ rated output

Signal-to-noise (unwghted/wghted) 77dB / 86dB dB referred to 1-watt output

Signal-to-noise (unwghted/wghted) 91dB / 98dB dB referred to rated output

Input Sensitivity (Cd Input) 28mV / 195mV (1-watt / rated output)

Output Impedance 0.15Ω OC = V

damping factor 53 @ 1kHz

power Consumption 0.45 / 22.7 watts (Standby / On)

power Consumption 47.3 / 210.4 watts at 1-watt / at rated output

mains Voltage Variation during test 241 – 243 minimum – maximum

Arcam FmJ A19 Amplifier – Power Output Test resultsChannel load (Ω) 20Hz

(watts)20Hz

(dBW)1kHz

(watts)1kHz

(dBW)20kHz

(watts)20kHz (dBW)

1 8 Ω 71 18.5 75 18.7 75 18.7

2 8 Ω 56 17.5 62 17.9 56 17.4

1 4 Ω 25* 13.9 115 20.6 107 20.3

2 4 Ω 25* 13.9 100 20.0 100 20.0

note: figures in the dBW column represent output level in decibels referred to one watt output.

*protection limits output at frequencies under 300Hz when driving loads of 4Ω or lower.

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LAB REPORTarcam fmJ a19 integrated amplifier

200Hz and 4kHz, but the difference between the two responses is far less than I’m used to seeing, which means that the FMJ A19 will ‘sound’ the same irrespective of the speakers you connect to it, so long as the impedance of both is over 6Ω.

Separation between the left and right channels was measured at 20Hz, 1kHz and 20kHz as being 66dB, 65dB and 50dB respectively, all results that are far in excess of what’s required to deliver excellent stereo imaging, but that I’d personally typify as being ‘good’ rather than ‘excellent’. Channel balance, on the other hand, was certainly excellent at 0.032dB at 1kHz. Interchannel phase errors were also extremely low… below levels of human perception.

Graph 1 shows output distortion when the Arcam FMJ A19 was delivering 1-watt into an 8Ω load and you can see that although there are harmonic distortion components visible (all odd-order, save for the second harmonic, which is even-order), the levels of the individual components hover around –110dB, which is equivalent to 0.0003% THD and so low as to be completely inaudible, so could have no effect on perceived sound quality. Look also at the noise floor, which is more than 120dB below reference except down at very low frequencies (extreme left of graph) where you can see components that are 90dB down. This, too, is superb performance.

When driving 4Ω loads at a power level of 1-watt (Graph 2), the distortion remains almost the same as it was with an 8Ω load (slight increases in most distortion components, but all still more than 105dB

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Graph 4: Total harmonic distortion (THD) at 1kHz at rated output (90-watts) into a 4-ohm non-inductive load, referenced to 0dB. [Arcam FMJ A19 Amplifier]

Newport Test Labs

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Graph 1: Total harmonic distortion (THD) at 1kHz at an output of 1-watt into an 8-ohm non-inductive load, referenced to 0dB. [Arcam FMJ A19 Amplifier]

Newport Test Labs

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Graph 5: Intermodulation distortion (CCIF-IMD) using test signals at 19kHz and 20kHz, at an output of 1-watt into an 8-ohm non-inductive load, referenced to 0dB. [Arcam FMJ A19 Amplifier]

Newport Test Labs

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Graph 6: Frequency response of line input at an output of 1-watt into an 8-ohm non-inductive load (black trace) and into a combination resistive/inductive/capacitive load representative of a typical two-way loudspeaker system (red trace). [Arcam FMJ A19 Amplifier]

Newport Test Labs

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Graph 4: Total harmonic distortion (THD) at 1kHz at rated output (90-watts) into a 4-ohm non-inductive load, referenced to 0dB. [Arcam FMJ A19 Amplifier]

Newport Test Labs

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Graph 2: Total harmonic distortion (THD) at 1kHz at an output of 1-watt into a 4-ohm non-inductive load, referenced to 0dB. [Arcam FMJ A19 Amplifier]

Newport Test Labs

below reference, or 0.0005% THD), but the low-frequency noise rises a little, and there’s more ‘hash’ on the low-frequency noise floor, indicating that the power supply is working harder than it does when driving 8Ω loads.

Distortion at rated output into 8Ω (50-watts), as shown in Graph 3, is interesting for several reasons. First, the level of distortion has increased, as you’d expect, but the dominant harmonic components are now all even-order, with a 2nd harmonic at –60dB (0.1%), a fourth at –72dB (0.02%) and a sixth at –78dB (0.012%). Second, the mid-to-high-frequency noise floor has risen to an average of around –116dB, whereas I would have expected it to stay around –120dB. It seems this is a function of the volume control schema used by Arcam.

When driving a 4Ω load at 90-watts (Graph 4), the output distortion spectrum was almost identical to that into 4Ω, which is good. As with Graph 3, most of the distortion components are more than 90dB down, equivalent to 0.003% THD. Overall THD+N measured as being excellent, as shown in the tabulated figures: 0.01% at an output of one watt, and 0.007% at rated output.

Signal-to-noise ratios are also tabulated, and you can see that the results are good, with the one-watt figures coming in at 77dB unweighted and 86dB A-weighted. Referred to rated output, the test results were 91dB unweighted and 98dB A-weighted, with this latter figure coming in just a little shy of the magic three-figure S/N mark. So, overall, excellent performance in this area as well.

Intermodulation distortion (CCIF-IMD) was superbly low (Graph 5).

The two test signals (at 19kHz and 20kHz) rise from a –120dB noise floor, with all high-frequency sidebands more than 100dB down (0.001%), and the regenerated 1kHz component at –105dB (0.0005%). Again, a superb result on this test.

Square wave tests show graphically the performance of the Arcam A19, with the 100Hz test showing the amplifier’s low-frequency roll-off and its excellent phase performance. The 1kHz square wave is essentially textbook, while the 10kHz wave shows the limited high-frequency response noted previously. The performance into a capacitive load shows a very minor overshoot and very quickly damped ringing, which is consistent with amplifiers that are rated as having ‘good sound’ in subjective tests… valve amplifiers usually do very well on this test, for example.

Overall, Newport Test Labs’ tests show the Arcam to be a very well-designed amplifier, with excellent measured performance. It could be argued that the amplifier’s protection circuitry could be relaxed to enable higher continuous low-frequency power levels into low impedances, but in practise, music signals are highly unlikely to trigger the protection, even if you’re playing at loud volume, so I can see why Arcam has taken this ‘err on the safe side’ approach. To ensure maximum power is always available at low frequencies, and to avoid any issues at all with thermal or over-current triggering, simply use speakers with a nominal impedance of 6Ω or higher and make sure the amplifier’s ventilation holes are completely unobstructed. Steve Holding

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