HF Nov12_020 Test Sunfire.indd
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1. 21 Sunfire Atmos Subwoofer Above the RCA input output panel is a subpanel that houses a crossover frequency control adjustable between 30Hz and 100Hz with a reference marking at 65Hz and a Bypass setting at its most clockwise setting a level control Min to Max with no intermediate calibration markings and a Phase control 0 to 180 with an intermediate calibration at 90 All three controls are rotary with a silky smooth action that is they re not click stop types Also in this subpanel is a tiny 2 5mm phone jack labelled Mic Input a tiny red Start pushbutton a chameleon LED marked EQ and a two position slider switch with positions for EQ Off and EQ On All are involved with the automatic room equalisation circuitry I mentioned previously The necessary measurement microphone is supplied with the Atmos and Sunfire also provides a really really nice little microphone stand Towards the bottom of the rear panel is a mains power switch and a standard three pin IEC 240V mains power socket Although there s only the single power switch the Atmos has automatic power circuitry that switches the subwoofer on when an audio signal is detected and off again when there hasn t been an audio signal for around five minutes This is a long enough delay that you re unlikely to have any false off triggers However speaking of triggers the Atmos also has a 12V d2. ON TEST Sunfire Atmos SUBWOOFER really don t think I am ever likely to see a subwoofer smaller than Sunfire s new Atmos It s so small I was very tempted to ask the photographer to put a match box alongside it to give you a sense of scale But to give you an idea the Sunfire Atmos is small enough to fit inside a basketball But it s not only small It s also packed with technol ogy including a compressor soft clipping and automatic room calibration circuitry THE EQUIPMENT You can t really miss the fact that there are two drivers on the Sunfire Atmos except that one isn t a driver it s a passive radiator When you re looking at the rear panel the Sunfire Atmos driver is on the right hand side of the subwoofer It s driven by an amplifier inside the Atmos that Sunfire rates as having an output of 1 400 watts into 3 3Q This driver s overall diameter is 183mm but its Thiele Small diameter is 137mm The actual cone diameter is 100mm but I put the word cone in inverted commas because there really isn t a cone as such the driving element is completely flat The driver itself is even more unusual because the material used as the flexible surround extends all over the driver so there is not the usual join between the surround and the cone I assume that there s a stiff flat circular plate underneath and it s this that s attached to the voice coil form
3. Sunfire also provides two pages of detailed instructions on how to use the automatic room equalisation circuitry As you ve probably guessed from the fact that it takes two pages to describe it the process isn t completely automated it requires a fair bit of button pushing and some attention to detail not to mention some careful listening on your behalf Indeed I found that on my il In terms of small subwoofers the Sunfire Atmos sets a new bar for low frequency performance both in terms of bass extension and clean undistorted SPLS Sunfire Atmos Subwoofer first attempts I could not get the circuitry to work in the way the manual told me it should work Even more confusing for me was that I could get the circuit to do something completely different more in line with the calibration procedures used for other subwoofers made by Sunfire Eventually after some to and froing between myself the Australian distributor and Sunfire in the USA which resulted in renewed attempts by yours truly I finally mastered the process And once I had the calibration process down pat I was able to calibrate the Atmos quickly and easily every time I needed to you only need to do so when you move the subwoofer without recourse to the instruction manual so it was obviously an issue with my understanding the instructions rather than that of the process or the instructions themselves and in real life if you run into p
4. c turn on trigger to allow integration with sophisticated automated home theatre or home audio systems Did I mention how small the Sunfire Atmos is It s just 216mm high 226mm wide and 257mm deep Despite these dimensions it weighs a substantial 14 5kg so it s no lightweight I also haven t mentioned the full model name of the 230 Volt version of the Sunfire Atmos because it s way too long and convoluted However for the record the precise model number of the model I reviewed is the Sunfire Atmos XTATM265230 IN USE AND LISTENING SESSIONS I have to say right at the outset that I just couldn t get over the size of the Sunfire Atmos in all the time I was reviewing it It s so small that I found that I actually had to position it out of the way in my listening room because if I didn t I or someone else in my family would always end up tripping over it However thanks to it being so small it fitted under every piece of furniture in my living room except the sofa 22 Australian hi fi The first thing I did was position the subwoofer in the best position in my listening room This in itself is interesting because there are several positions in my room that are acoustically the best but until I took the Atmos home for review not one of these positions was visually acceptable to my better half so where I have my subwoofers yes I take my own advice has always been a bone of domest
5. that people object to The size of the Sunfire Atmos means that finally it will be possible to place two or even more subwoofers in the same room without them intruding physically or visually on domestic living arrangements aka d cor The Slave input outputs are configured in such a way that when you add a second Atmos subwoofer there s no need to adjust the controls on the second subwoofer any adjustments you make to the controls of the main subwoofer will be automatically be sent to the slave subwoofer SUNFIRE ATMOS SUBWOOFER Brand Sunfire Model Atmos Category Powered Subwoofer RRP 1 999 Warranty Three Years Distributor Audio Products Pty Ltd Address Level 1 67 O Riordan Street Alexandria NSW 2015 N 1300 134 400 info www audioproducts com au Www audioproducts com au E Small size lit Room correction i circuitr E Z y Flat response Calibration process Lack of grilles LAB REPORT Readers interested in a full technical appraisal of the performance of the Sunfire Atmos XTATM265230 Powered Subwoofer should continue on and read the LABORATORY REPORT published on page 114 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 Ce ee L K L A avhub com au hifi
6. EST RESULTS The frequency response measured by Newport Test Labs of the Sunfire Atmos XTATM265230 was better than the manufacturer claimed with the top most red trace in Figure 1 showing that it was measured as extending from 28Hz to 129Hz 3dB That s not only better than specification it s a truly excellent response for a subwoofer in its own right As you can see from the trace the Atmos deliv ers maximum output at 56Hz and is so flat ul This is an impressive and very well designed subwoofer either side of this frequency that it s comes in at 37Hz to 90Hz 1dB Note that all three traces were measured after the Sunfire s cir cuitry had been equalised for flattest response in an IEC listening room environment Figure 2 and Figure 3 show the nearfield responses of the individual drivers located either side of the Atmos You can see that one peaks at around 65Hz and the other 10Hz lower at 55Hz For this measurement Newport Test Labs reset the automatic EQ and ran the Atmos in its Bypass mode so you re boost looking at the raw unequalised responses of the drivers each time for three different settings of the crossover frequency control dBSPL Newport Test Labs 30Hz 65Hz and 100Hz It s clear from these graphs that Sunfire is using the equalisation circuit to attenuate the output of the drivers to produce the best response which is a far better solution than trying to use additional Figure 4 shows
7. e sub bass area So I really can t agree with Sunfire s claim that the Atmos provides and I quote as il Sets a new standard in linearity across its performance band its frequency response is superbly flat much bass as you could get from several 15 inch drivers mounted in a cabinet the size of a small refrigerator unquote However how many people do you know who d buy a subwoofer the size of a small refrigerator irrespective of how many 15 inch subwoofers might be fitted in it That said my jaw did drop when I heard the depth and volume of sound the Sunfire Atmos was able to deliver in my listening room In terms of small subwoofers it set a new bar for low frequency performance both in terms of its bass extension and as regards the clean undistorted sound pressure levels it can deliver It also sets a new standard in linearity across its performance band its frequency response is superbly flat so no one frequency is emphasised at the expense of any others The lack of distortion also meant that the low bass was remarkably tuneful Most of the small subwoofers I ve auditioned previously had such high levels of distortion that it s difficult to easily follow low bass lines on instruments such as for example an electric bass So long as I kept the volume at reasonable levels I had no such difficulties with the Sunfire Atmos That said there s no doubt that the Atmos performs at its best with music w
8. er but I couldn t remove the driver to check Sunfire itself says of the design that An extra large magnet and long throw mechanical design yield very high back emf The result is extraor dinarily high operating efficiency that is more acoustic output for each watt of input This high back emf is significant according to Sunfire because it means that the current flowing in the voice coil is lower that it would otherwise be which in the company s words is the singular property of the driver that allows the subwoofer to be approximately ten times more efficient that a subwoofer this size would normally be However even with high back emf limiting current flow in the circuit using an amplifier capable of delivering 1 400 watts means that Sunfire has had to include sophisticated protection circuitry to prevent damage to the driver in the event that some unwitting consumer does something silly The first line of defence is a compressor circuit that kicks in if the input signal level reaches a voltage that would overload the driver If the input signal level exceeds the capability of the compressor to control it the Atmos second line of defence is a soft clipping circuit that Sunfire says allows high volume levels but prevents poling or to use Sunfire s exact words produces extremely high sound pressure levels in your room without the driver banging against the mechanical stops The passive radiator w
9. hen it s reproducing music that has only two or three instruments in its passband drums bass guitar double bass and electric piano synthesizer for example just as there s no doubt it performs better at low to average in room sound pressure levels than it does at high sound pressure levels But given the incredibly small size of the Atmos it s a wonder that it performs as well as it does During my auditions I found that my jaw dropped so often and so far that it ached Another reason for the Atmos superb performance is that Sunfire has not attempted to over reach the design in that it essentially operates only at frequencies lower than 100Hz around G 2 on a standard piano keyboard which means that for best integration with main speakers those speakers should be capable of operating down to at least that frequency CONCLUSION Did I mention the size of the Sunfire Atmos And that it sets a new standard for perfor mance for a subwoofer of its size I certainly know that I raved about its jaw dropping performance Basically the only conclusion I can draw after experiencing it is that if you re in need of a small subwoofer for either music or home theatre applications or both you really owe it to yourself to check out the Atmos but do prepare to be amazed greg borrowman 24 Australian hi fi LAB REPORT ON PAGE 114 CONTINUED FROM PAGE 20 iy N i a 2Ol Sunfire Atmos Subwoofer T
10. hich is on the left side of the Atmos when you re looking at it from the back looks identical to the driven cone but of course it does not have a magnet or voice coil and is not connected to the amplifier It s driven simply by variations in air pressure inside the cabinet that are caused by the movement of the driven 20 Australian hi fi Sunfire Atmos Subwoofer cone on the opposite wall This is why this particular type of driver is often referred to as a drone cone The first thing I noticed on the rear panel was that the Atmos doesn t have speaker level inputs but I guess that given the small amount of space available this would have been difficult without providing some form of custom connector However I also noticed three pairs of gold plated RCA terminals which was also unusual It turned out that the top most pair is for left right line level input also LFE The pair underneath can be used to copy the signal that s presented at the line level inputs or it can be used to send a high pass filtered at 85Hz further down your signal chain Essentially this connection allows you to relieve your main front loudspeakers of the responsibilities for handling low frequency signals at least frequencies below 85Hz However in practise you would ONLY use this if your speakers were not capable of handling signals below 85Hz which would be all small bookshelf loudspeakers The thi
11. ic disharmony The size of the Atmos meant that all of a sudden I not only had several acoustic best positions to put it but also a choice of visual best positions including not visible at all As discussed previously locating the best position for a subwoofer in the room is fairly complicated so we ve loaded the information on our website here www tinyurl com subwoofer placement As it happens the Owners Manual that comes with the Atmos gives almost identical advice to that on our website though Sunfire adds the information that it designed the Atmos to be placed in a corner and suggests you start your location search with at least two corners before trialling other positions in the room I was extremely pleased to find that Sunfire also includes advice on how to set the crossover frequency and phase controls except that rather than re invent the wheel the company simply reproduces with permission a calibration procedure recommended by Dr David Rich at the time he was a contributing editor to The Audio Critic a US audio magazine that is no longer published though it still maintains somewhat sporadically a web presence Rich s advice is excellent but does require you to purchase both a test CD and an SPL meter If you use Rich s method you ll quickly find that it would have helped a lot if Sunfire had provided calibration markings for the level frequency and phase controls on the Atmos
12. rd set of RCA terminals the bottom most pair are labelled Slave Input and Slave Output They re designed to simplify operation when you are using more than one Atmos subwoofer Why would you use more than one Atmos The main reason is that the output of a subwoofer any subwoofer is hugely affected by a room s acoustics so it s entirely possible that depending on where you position a subwoofer in your room there may be certain locations in that room where you will hear almost no sound at all at certain frequencies This is not a fault with the subwoofer it s simply that reflections from the walls and other surfaces of your room cancel those frequencies The ONLY way to correct this other than rebuilding your room is to add a second subwoofer and place it in a different physical location in the room such that its output will fill in the dead spots where the other subwoofer s output has been cancelled Many acoustics experts right around the world including the famous speaker researcher Floyd E Toole have long championed the use of multiple subwoofers in the home environment but their sage advice hasn t gained much traction probably because so few people like having even a single subwoofer in their home that the chance of talking people into having two subwoofers in the same room is incredibly small However that s because most subwoofers are very large and it s only really their size
13. roblems you ll be able to get your friendly local Sunfire dealer to demonstrate the calibration process to you However after you have correctly initiated the first step of the process correctly the second step requires that you be able to hear a tone with a frequency of 35Hz and that s something that I suspect some older people over 65 years of age will be unable to do at least at the low level the tone is being generated by the Atmos during the calibration process So if you fall into this age bracket I d suggest that when you re initiating the calibration process you should actually watch the driver cone or feel the cabinet for the tell tale vibration that will tell you the subwoofer is performing the 35Hz calibration Additionally I feel the manual should note that if as I did when I first tried to calibrate the subwoofer you hear a frequency sweep with ascending tones running from low to high rather than just a single fixed frequency you should reset the subwoofer using the reset procedure outlined in the manual and start all over again I ve said it before and I ll say it again here and most likely in many future subwoofer reviews that no matter how much high tech you throw at a subwoofer you will ultimately be bound by the inviolable laws of physics which dictate that there will always be limits on the sound pressure levels that can be delivered at any particular low frequency particularly in th
14. sation circuit Sunfire Atmos Sub 114 Australian hi fi
15. the four test tones generated by Sunfire Atmos s equalisation circuitry and you can see despite the low resolution of the filters Newport Test Labs used to isolate the signals that the tone frequencies are positioned at 35Hz 48Hz 62Hz and 80Hz meaning that the equalisation circuitry will only be able to correct the Atmos s response at and around these frequencies This is an impressive and very well designed subwoofer AN Steve Holding Newport Test Labs 55 20 Hz 30 40 50 60 70 B0 90 100 200 Figure 1 Pink noise frequency responses smoothed at 2 0 metres with crossover frequency control set at 30Hz black trace 65Hz green and 100Hz red Sunfire Atmos Newport Test Labs 55 20 He 30 40 50 60 70 3090 100 200 Figure 3 Near field frequency responses right driver only with crossover frequency control set at 30Hz black trace 65Hz green and 100Hz red Sunfire Atmos Newport Test Labs 20 Hz 30 40 30 60 70 B0 90100 200 Figure 2 Near field frequency responses left driver only with crossover frequency control set at 30Hz black trace 65Hz green and 100Hz red Sunfire Atmos 20 Fz 30 40 50 60 70 20 90 100 7200 Figure 4 Frequencies of tones generated by equali
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