Antec Sonata Case & PSU

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Antec, the biggest case & PSU brand in the US, moves towards quiet computing with the new Sonata case and True 380S power supply. Piano black finish, noise-reduced PSU, 120mm case fan, unique case flow, grommets for HDD mounting — how do they all add up? A 2-for-1 review: Antec Sonata Case / PSU and Antec True 380S PSU

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.

ProductAntec Sonata Case + True 380 PSU
(Separate True 380 PSU review here)
ManufacturerAntec Inc.
MSPUS$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.)

ANTEC TRUE380S PSU

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

LOAD
90W
150W
300W
380W
AC Power
139W
220W
406W
534W
Efficiency
65%
68%
74%
71%
V Fan
5.3V
7.0V
9.3V
11.2V
Noise (~1 cm)
42 dBA
44 dBA
47 dBA
49 dBA
Case Temp
30C
30C
29C
30C

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.)

IN ACTUAL USE: NOISE

The Sonata case was placed on top of a heavy steel desk which can resonate if there is enough vibration in a PC system. This quality was used to check the level of vibration emanating from the Sonata. For the most part, a dampening pad was placed under the case to eliminate interactive noise effects — they are too dependent on specifics.

Subjective comparative listening was done against the recently reviewed ARM Systems Stealth system as well as a self-built P4 system (quietest of all, with three 5V Panaflos and 2 elastic-suspended Seagate Barracuda IV single platter drives). Both use cases that are relatively modest in price but solid. The home-built machine is in a Landmark ATX-298U with grills cut away and some internal damping applied. The single-fan PSU has been modded with a Panaflo 80L fan swap.

Noise With Test Load

The first test was to simply power up the PSU on a test load, close the case covers and listen. The noise level was too low for any serious measurements with the old Heath SLM, and there was no opportunity to access the UBC anechoic chamber at this time.

1. PSU only: Up to ~100W power output, the Sonata + can be considered very quiet. There is no extraneous noise caused by air turbulence effects anywhere around the front bezel. The PSU fan is spinning too slowly for this to be a problem. A very small amount of noise escapes the small holes that form the name Antec across the sides, confirmed by blocking, then unblocking the holes. I would venture to say the difference is likely no more than 1-2 dBA. Most of the PSU fan noise is slightly turbulent midrange airflow, with a small amount of bearing noise — audible only if you get really close in a quiet room. There is too little vibration transmitted into the steel desk to cause any audible resonances.

2. PSU + 120mm fan: With the 120mm fan plugged into the fan-only voltage feed from the PSU, up to ~100W, the noise level is increased by about 1-2 dBA from one meter away. It is a smooth broadband noise similar to pink noise, where output drops with increasing frequency. There is little or no high frequency content in the noise of the 120mm fan, even at 12V.

Noise with Simplest Low Heat System Setup

The next tests involved the installation of a low-heat system.

Intel P4-1.8ARated at ~50W max
Thermalright AX478 HSVery good P4 HS
Panaflo FBA08A12L1A 80mm fan SPCR’s standard low noise fan, plugged into fan-only PSU output
AOpen AX4GE Max motherboardIncludes built-in VGA, LAN, and unique SilentBIOS & SilentTEK fan/thermal control features
256 MB DDR RAMSamsung 2100
Seagate Barracuda IV 40GSingle-platter, 12.8W max
Hitachi 16X DVD ROMDetailed specs unknown
Included 120mm Antec fanOn back panel

Given the component count, you might predict that there is hardly any difference in noise between this system and the dummy test load. You would be right.

The system draws 92-95W AC during long term 100% CPU utilization with 3 different software utilities. Given the ~65% efficiency of the True 380S at lower loads, this translates to 62W of delivered DC power. Yes, a few turn-on peaks of 120-130W were observed, but these were fleeting, mere bursts. A real VGA card, a couple of PCI cards, another strip or two of RAM and another hard drive — all these could add another 40-50W to the toal power load, but it would still be no more than about 100-110W long term maximum draw. The point is that the PSU fan speed would remain close to the default of 5V and thus remain very quiet.

3. PSU + Panaflo plugged into fan-only PSU output + HDD snugly screwed with grommets: There is a small increase in broadband noise from the Panaflo fan and the Barracuda IV hard drive. At one meter, the Heath SLM may have registered a 2 dBA difference; it is difficult to judge. Judging by ear, I believe it is no more than 2 dBA. The PSU fan remains most audible.

Seek / write of the hard drive could be heard quietly but plainly above the residual system noise, despite the rubber grommets. The HDD screws were just barely tightened to minimize mechanical coupling. Again, the difference is below the resolution of the Heath (and most affordable SLMs), but the seek noise is slightly more audible than with the EAR grommets in the ARM Stealth system. This noise sounds like soft thrumming. Placing the PC directly on the desk causes some amplification of the noise by the desk. Unless you are seeking silence, it is not objectionable or serious. Up to 3-4 dBA difference can be measured against direct HDD mounting without grommets; the subjective difference is much bigger than the measured 3-4 dBA. I personally do not put up with the noise of direct mounting of any HDD to any case.

4. PSU + Panaflo plugged into fan-only PSU output + HDD placed on grommets: The screws were removed, and the drive placed on top of the grommets, making sure the sides did not touch the mounting frame. The noise difference of this little adjustment is very difficult to measure but so easy to hear: The soft thrumming drive seek noise simply disappears. OK, maybe it does not completely disappear, but it drops enough that even with the PC directly in front of the keyboard I am working on, the seek noise is not audible. I have to get well under one foot or less to hear the noise. The PSU fan becomes the loudest noise again.

5. PSU + Panaflo and 120mm fans plugged into fan-only PSU output + HDD placed on grommets: As in scenario #2, the noise level is increased by about 1-2 dBA from one meter away. The 120mm fan is a smooth, broad increase in sound, not really objectionable or very significant. Some low frequency noise accentuation may occur of the system is placed on a resonant structure.

Noise Performance Summary

The Sonata combinations is a bit noisier than the ARM System Stealth. My guesstimate of anechoic chamber readings for the Sonata system, based on the 22-23 dBA @ 1 meter for the ARM Stealth, is about 26-28 dBA @ 1 meter.

The primary limitation is the fan in the Antec True 380S PSU. In free air, with both fans at the Antec’s 5V default voltage, it is louder than the Panaflo 80L, the fan in the PSU of the ARM Stealth and my own home-assembled PC. With the added accentuation of lower frequency noise in the PSU due to acoustic impedance effects, the Antec PSU is the loudest component. Keep in mind, however, that the Antec’s ability to keep itself cool at high power load is definitely superior, as its fan is rated for almost 40 CFM airflow at 12V, compared to the Panaflo’s 24 CFM.

The noise of the 120mm fan off the PSU fan-only output is unobtrusive. It does add noise, mostly a kind of lower frequency hum, but the quality is such that it hardly seems to, especially with the masking effect of the slightly noisier PSU fan. Given its proximity to the CPU, it would be a simple matter to rig up a duct from the 120mm to the heatsink, and eliminate the fan on a top-ranked HS. Unless you are overclocking and overvolting a very high power CPU, this is probably a perfectly viable cooling solution.

No part of the bezel opening could be identified as a source of noise; almost all the noise came from the back of the case where the fans are. The drive seek noise could not really be isolated to its source. It seems to emanate from the entire case. Softer, larger grommets — perhaps in combination with soft plastic screws — would help improve the effectiveness of the HDD noise reduction.

The holes that form the word Antec allow a small amount of noise to emerge. That noise is relatively modest but tends to be somewhat higher in pitch, perhaps because of the proximity to the PSU, which emits some very low level buzzing. Blocking the holes from the inside is a simple way of reducing the noise if so desired.

COOLING PERFORMANCE

Three points were monitored for temperature during CPU stress testing:

  1. CPU diode with Motherboard Monitor (MBM5)
  2. PSU fan exhaust (with thermal probe and DigiDoc2 from online retailer SVC as shown below)
  3. HDD with Dtemp software

DigiDoc monitoring PSU exhaust; HDD mounted low in drive bay to take advantage of convection.

The PSU exhaust monitor was simply to ascertain whether the 120mm fan lowers case temperature enough to make a difference in the PSU temperature. The unusual external 4-pin DC power output on the Antec PSU came in very handy here, as you can see in the photo above.

120mm fan
OFF
ON
CPU Stress
idle
max
idle
max
CPU temp
29C
59C
28C
56C
PSU exhaust
30C
39C
30C
33C
HDD
35C
38C
34C
34C

FAN voltages (for both Panaflo on HS and 120mm fan) remained at 5V throughout testing, as the PSU never got hot enough to push the fan any higher. Ambient room temperature was at 20C throughout.

The results are clear:

  • The P4-1.8A stays cool enough with the Thermalright AX478 / Panaflo at 5V, with or without the 120mm fan at 5V, although the big fan does drop the max temps a bit.
  • PSU exhaust air temp drops by a significant 6C with the 120mm fan on, so if your system runs hotter than this one and pushes the PSU fan voltage up, the big fan will help it run cooler and quieter.
  • The HDD temp stays perfectly safe with or without the 120mm fan. Anything below 40C is just coasting. The HDD location just behind the front bezel vents always ensures at least a small amount of airflow, enough in this system to keep it cool.

The holes on the sides that form the word Antec appear to have some cooling effect. Blocking them with duct tape raised all temps by a few degrees.

CONCLUSIONS

In the SPCR forums and elsewhere, I have often repeated the line that how quiet a case is not that important, it’s how cool a case will let components run that’s more interesting. The concept is simple: if the components can be run quietly enough and still be cooled effectively, then there is so little noise that the ability of a case to damp noise is irrelevant. Of course, this is probably only true if you don’t run cutting-edge, burning-hot components.

The Antec Sonata incorporates no damping at all, so if it is being marketed as a quiet case, it is on the basis of its ability to run components coolly, and therefore, quietly. Like all cases, by simply enclosing the components, the Sonata provides a degree of noise reduction.

For those seeking simplicity in a quiet home-built PC, the Sonata is a good choice. Buy a Sonata case / power supply. Pick out the Barracuda IV or V drive(s) of your choice, CPU, motherboard, VGA, RAM, optical disks, etc — and any top ranked HS from our recommended list with a Panaflo 80mm L fan. Assemble everything and run both the Panaflo and 120mm from the fan-only output of the PSU. Make sure the CPU HS fan protection switch in the BIOS is turned off. Power up. Voila: you now have a quiet computer.

  • the convoluted sound path through the front air intake vent,
  • the noise-reduced, single-fan PSU (Antec’s quietest, as far as I know),
  • the PSUs reduced-voltage fan output,
  • the quiet high-airflow 120mm case fan,
  • HDD mounting grommets
  • and the unique (and cool) HDD mounting setup

… these are the many features that allow a quiet system to be built around the Sonata with little effort. Given the modest size of the Sonata, it may not be for power-crazed gamers. In the hands of an imaginative or experienced silent PC devotee, it could easily be made extremely quiet. The HDD mounting system alone is worth the purchase price if you are a hardware hacker like me. Oh, let’s not forget — that black piano finish looks pretty slick, and it is a handsome unit.

The Sonata is Antec’s first foray into quiet computing. As such it is a very respectable effort. Recommended.

Much thanks to Antec for the review sample and their kind support.

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