Antec Sonata Case & PSU

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December 17, 2002 -- by Mike Chin

Dec 18, 2002 -- Minor edits and clarifications on some details were made in response to readers emails and forum comments.

Product Antec Sonata Case + True 380 PSU
(Separate True 380 PSU review here)
Manufacturer Antec Inc.
MSP US$100~125? To be announced before release to market in January 2003

The Sonata case by Antec was first previewed here in Part 2 of our Report from the Fall Intel Developer's Forum. A visit to Antec's headquarters near San Jose led to that little scoop; the product was initially named Tranquility. Now, after a few more months of development and a name change, SPCR is pleased to bring you another news scoop: the first review of this new case. The Antec Sonata is meant specifically to form the basis of a noise-reduced PC with optimized case airflow.

Black Sonata photo courtesy of Antec; review sample is white.

The standard finish, as shown above, is described as piano black. That description might be a bit of a stretch, but there is little question that for a PC, it is a very nice finish. At first glance, the front bezel looks like a complete departure from Antec's popular and ubiquitous Performance series, but this is a bit of an illusion. The top hinged cover opens to reveal the same type of 5.25" bay covers. The bottom bezel molding is considerably different, however, abandoning the distinctive bold slotted grill in favor of something more subdued and smoothly contoured. The metalized curved cover over front USB and audio ports is a classy touch.

Unique Airflow Setup

Antec says this modest sized (17"H x 18"D x 8"W) steel case is quite different in terms of the case airflow pattern. One of those differences is easily visible: both side panels have a pattern of small holes, about 3/16" (~1/2 cm) diameter, that form the word Antec across the top. This is cosmetic, no? Well, yes, but consider that there are 91 holes on each side, each hole with an area of 0.2 cm2. That calculates to a total area of 18 cm2 or ~2.8" square per side. Although edge turbulence effects in these little holes keeps the effective vent area somewhat lower, they definitely represent a significant intake airflow path.

What are the holes for then? They are meant to act as cool air intake vents for the PSU. Because the PSU fan is the closest, Antec says the air that comes in through these holes get drawn mostly into the PSU. The PSU thus runs cool, even though it has only one fan. Would the cool intake air not go down into the CPU area and below? If it does, this will help CPU cooling, which may be an even better benefit.

It's an interesting concept, isn't it? The question is whether the holes also allow much noise to emerge.

The back panel has a perfectly open grill vent for a 120mm fan, which is supplied. It has an Antec label, but is made by Dynaeon Industrial of Taiwan, and is said to be a custom fan rated at 2000 RPM / 12V. The closest Top Fan match is a DF1212BB, rated for 2200 RPM, 87 CFM and 39 dBA. The latter numbers are a bit too high, judged by listening and feeling the airflow on the skin. This fan is meant to be driven by the reduced fan-only voltage feed from the PSU. At the default drive voltage is 5V, the fan spins slowly enough that all the mechanical noise is in the lower frequencies, very low in level. The predominant noise is air turbulence, which is also very low in level.

Front Bezel: Airflow without Noise

The photos here begin with the fully covered bezel on the left below. On the right, the hinged cover and bottom bezel are removed to expose the sub-bezel, for want of a better term. The right photo shows the cover and bottom bezel removed. The power and reset buttons lie behind the hinged cover. Power and HDD activity LEDs are visible even with the cover closed. The door must be opened to gain access to the power button, however. The vent slots in the sub-bezel, for want of a better term, are not very generous.

The images below shows what lies behind the sub-bezel. A screen filter on a slide-in frame, much like mosquito netting, keeps dust from clogging up the innards of the PC. The round holes behind the filter represent only about a third or quarter of the available area for air intake. The final outside bottom bezel molding divides up the intake path into 3 -- the sides and the bottom. All of these convolutions in the airflow are meant to eliminate direct paths for sound to escape the case. They may have gone a bit too far; the intake airflow could be significantly improved without additional noise exposure. Some of this front venting plastic invite cutting and slashing. It is such a contrast to the 120mm back panel vent, which is so wide open.

There are three 5.25" drive bays that use plastic rails with metal clips for fast in/egress. The purple plastic and metal rails themselves are stored clipped on the inside of the drive bay covers. Once the drive is installed, it can be removed by simply pressing on either side into half-round finger-depressions to release the clips. (See two photos up, on right) Very slick! It isn't new; the same system is used in Antec's Performance series.

Just below the 5.25" drive bays are two 3.5" bays with access to the front panel for floppy or ZIP drives and the like. A metal slide-in bay is used, again very convenient.

90° Rotated Drive Bays: A Touch of Genius!

Four 3.5" hard drive bays are situated directly behind the front intake vents. The bays have been rotated 90 degrees horizontally so that the drive's length runs across the width of the case. The power and data cables can be routed on either side of the drive (left or right side of case). Positioning the cables on the right side of the case makes it easier to keep them from blocking the airflow path if you have many drives. To install the cables on that side, they must be inserted into the drive before it is slid all the way into the bay.

Not only does it make more efficient use of space, this novel orientation improves installation and removal of the drives -- so much that it feels like a revelation. To install, screw metal rail to drive, slide rail into place till locked, then insert power and data cables. To remove, reverse the process.

It is as easy as it sounds. In fact, the Sonata's HDD mounting arrangement is so much superior to the normal convention of mounting drives lengthwise that once you've seen it and used it, you can't help asking, Why hasn't it always been done this way!? When other case makers see it, there may be a mass migration to this 90 degree rotated HDD setup. There ought to be!

The drive rails, shown above, integrate 4 rubber grommets and come with longer mounting screws to attach to the bottom of the HDD. The grommets are meant to decouple the hard drive from the case and reduce the noise caused by mechanical vibrations. This is the greatest source of HDD noise, so Antec is right to tackle this problem at its source. The rubber grommets are not quite as viscous as the EAR grommets used in the ARM Systems Stealth PC. They're much better than direct mounting, for sure, but could be improved upon.

The final touch is a set of mounting holes for a 120mm cooling fan on the frame just behind the hard drive bays. It goes to the left of the drive bays in photo above. If all four of the bays are full with hot HDDs, this may be a useful feature indeed.

Fewer Pieces, Fewer Joins

The top, right side, and bottom case panels are formed from a single U-shaped piece of sheet steel. Fewer joins usually mean a more rigid and stronger construction less prone to rattling and vibration. It also means lower cost. The front and back panels are attached with rivets. A reinforcement bar runs from front to back and supports the PSU as well.

Only the left side panel is removable, and the motherboard tray is not removable. It came with brass screw inserts for a standard ATX motherboard. The plastic slide latch used on many Antec cases is pressed into service here for the removable left cover. The fit is little sloppy; screwing the side panel down stopped it from rattling when nudged.

Antec opted for hard rubber feet of ~1.2" diameter instead of the paddle style plastic feet used in many of their cases. Softer feet would help to reduce mechanical coupling to the floor for noise reduction. There is a small gap between the cover and the end of the front bezel, as shown in the photo above right, which appears designed to allow some air to flow into the case. This assumes a higher rather than lower level of airflow. There was no obvious evidence of sharp edges anywhere. (In other words, I received no cuts from the Sonata case.)


The included PSU is not identical to the Antec TruePower 380 in that it has only one 80mm fan. The second 92mm fan common to the TruePower line has been omitted, and the intake air vents on the inside of the PSU have been doubled in area.

There is a reason for the 1-fan configuration: It is quieter than two. It is not clear whether this PSU will be offered separate from the True Power 380. It shares many of the features of the TruePower line. Rather than delve into the details, the Antec True 380S PSU is fully covered in a separate review; please read that review for a more complete analysis of the PSU.

There are seven 4-pin Molex connectors and two floppy drive power connectors on three sets of cables, the longest of which is 33" long. The main ATX cable has a mesh cover to keep it tidy, and P4 12V cable are on ~18" cables. There is also a fan RPM monitoring output that plugs into any 3-pin motherboard fan header.

Under the Hood

There are no vent holes in the cover. The heatsinks are bigger than those in the 2-fan Antec PSUs. Quite simply, there is more room because the 92mm fan is not protruding in. The exhaust fan has an Antec label; one assumes it is made by Dynaeon Industrial of Taiwan like most fans used by Antec. At the minimum 5V level, the fan speed is ~1350 RPM.

Antec True 380S PSU Test Summary

AC Power
V Fan
Noise (~1 cm)
42 dBA
44 dBA
47 dBA
49 dBA
Case Temp

The overall measured performance was very good, with all of the lines showing tight 1% regulation at all power levels. The efficiency does not reach 70% till above 150W. The optimization point for power efficiency seems high. 74% at 300W is very good, but the 65% and 68% numbers at 90W and 150W are a touch low.

Noise was measured ~1 cm from the edge of the PSU fan exhaust, not in the airflow path. At all power levels ~100W or lower, fan voltage remained around the minimum of 5V. Measured to be 42 dBA, it is about the same noise level exhibited by the Zalman at the 90W power level. Several alternatives among the Recommended PSUs are quieter at the same power level -- by 2 to 7 dBA @1cm, which probably translates to no more than 3 dBA @ 1 meter. The competitors drop to slightly lower noise levels as power output declines from the 90-100W range. This Antec does not; its fan voltage stays at 5V from turn on at any temperature to ~100W power level. The noise level at 150W is audibly higher than at 90W. At full power, at 49 dBA, it is not bad even though >11V is being fed to the fan.

The test platform Case Temp did not change between 90W and 380W, which means the PSU fan control does a very good job of keeping itself cool. The temperature would have climbed if the light bulb wattage was changed to match the output power at all times. (See full PSU review for details.)

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