Review: Smart Drive HDD Enclosure


by Mike Chin

Product: Smart Drive
Date: June 21, 2002
Manufacturer: Grow Up Japan
Supplier: Silicon Acoustics

The idea of isolating a noisy, whiny, annoying hard drive in an acoustically sealed box is not exactly new. Long before commercial products based on this idea began appearing, people who detest drive whining and chugging and clicking were stuffing them in cardboard shoe boxes, empty chocolate tins around socks, and wee wooden boxes with wood shavings... well, maybe not wood shavings.

With commercial and most DIY sealed boxes for hard drives, heat has been the Achilles heel. Hard drives get hot and need both conduction to the chassis and some airflow around them to stay cool. Deprived of these, they get much hotter than usual. Reports of premature hard drive failure due to overheating in quieting enclosures are not unusual. As hotter 7200 RPM drives have taken a large share of the market, the possibility of overheating is serious. The adage that data is the most precious thing in your computer rings true if you've ever lost a hard drive with real data on it.

Smart Drive seems to be a smarter realization of the seal-up-that-hard-drive idea. Silicon Acoustics, a great web retail shop for those seeking quiet PC products, kindly sent me a sample to review some weeks ago. I believe Silicon Acoustics is the only dealer in the U.S; my apologies for the long delay in getting this review out.


Made in Japan by a company called Grow Up Japan, Smart Drive is a nicely finished aluminum box with slightly rounded edges about the size of a typical CD drive. It's so stylish and slick-looking that it would not be out of place in one of those "side-windowed" showoff PCs that seem to compete with cars for young men's attention these days.

Smart Drive actually features two skins of aluminum with dense foam in between the inner and outer layers. The joining edges are finished with gasket rubber material for a very tight seal. The detail around the cable exit is well thought out, with a soft translucent plastic sleeve on the edges contacting the wires. Six flush mount screws keep the cover firmly in place. The fit and finish is top notch. Overall, appearance and attention to detail is impressive. It's just the kind of thing you'd expect in a high end Japanese camera or automobile.

The current price of the Smart Drive is US$65.

Drive goes in upside down in box but is right side up when Smart Drive is mounted normally; the cover is actually the bottom. The translucent soft plastic sleeves on either side of the cable exit molds around the wires for a good seal.

On first impression, the seeming lack of any metal-to-metal contact between outside and inside aluminum layers made Smart Drive's claim about keeping the drive cool seem dubious.

That's right: there appears to be no contact between the outside and inside layers of aluminum. The exposed anodized aluminum was scraped in a couple of spots to do a continuity check with a multimeter. There is no electrically conductive path between the inner and out layers of aluminum on the top or bottom of the case. This means any heat conduction between the hard drive and the PC case must occur through sandwiched foam layer.

Our understanding of the thermal characteristics of all kinds of foam comes from both theory and practical experience. The theory says basically that sound absorption occurs when air borne vibrations are converted to heat caused by the microscopic movement of the absorbing material. Practical experience says that foam retains body heat in beds, sofas, car seats, and so on.

It is possible, however, that layers of anodized aluminum are in contact with each other on the top and bottom layers, not passing electricity but conducting heat. Or that the foam passes enough of the heat to the outside aluminum layer to allow some degree of cooling to take place. It is not possible to tell without tearing the sample apart.


Listening Tests

A hard drive was put in the Smart Drive to hear what it does. A single-platter Seagate Barracuda IV drive was used on the test bench with a fanless power supply. The bare drive and the Smart Drive were each placed on 6" by 6" foam pieces half an inch thick to decouple them from the table. The test lab is a 10 by 12 foot room, with hardwood floors and only one virtually silent computer running during sound testing. The ambient noise in this room with the single PC running is approximately 32-35 dBA.

Subjectively, the noise of the Barracuda IV can be described as slight whirring with little high frequency content (whine) and some low frequency components. The Barracuda IV is rated by Seagate for 20 dBA in idle. We have no way of verifying this because measuring such low levels requires highly sophisticated, expensive test equipment and a super quiet environment. There is little reason to doubt this claim, however. The drive is quieter than any 20dBA-rated fan in our lab. Subjectively, a Panaflo 80L12A rated at 21 dBA is audibly louder at 12V. The Panaflo is quieter at 5V; it is roughly at the same volume level at 7V. The bare Barracuda IV on foam is difficult to hear 3 feet away. From 6 feet, it is inaudible.

Enclosed in the Smart Drive, the Barracuda IV noise is muffled evenly across the frequency range. It is a very audible difference, but only if the distance is under 2 or 3 feet. The noise reduction may be more easily audible in a quieter room. In the Smart Drive, the Barracuda IV noise becomes inaudible at around 4 feet rather than 6.

With an IBM DTLA 703045 (otherwise known as the infamous sudden-death-afflicted 75GXP). a 3-platter 45G model rated at 31 dBA, the noise suppression achieved is more dramatic. Bare, the IBM is audible anywhere in the room. Enclosed in Smart Drive, it is about as quiet as the bare Barracuda IV. Seven feet away, it can hardly be heard.

The test was repeated with a 7200 RPM, single platter, 20G Western Digital WD200BB rated at 32 dBA, with results similar to the the IBM. Smart Drive is more impressive with both the IBM and WD hard drives, probably because they are both fairly noisy and easily audible. SD drops the noise level down into the whisper threshold. With the Seagate, the default noise is already at whisper level.

Approximate Distance (in feet) to Subjective Inaudibility
Bare Drive
In Smart Drive
Barracuda IV - 40G
IBM 75GXP - 45G
Western Digital WD200BB


While we don't have highly sophisticated, expensive test equipment and a super quiet environment to measure soft noises with high accuracy, we can actually measure the difference in noise between the bare drive and in the Smart Drive.

A picture is worth a thousand words, they say. How about a picture with words?

It's a filing cabinet in the test lab. The half-full bottom drawer is lined with foam to minimize reflections. The microphone is a cheap omni. The hard drive is placed on the bottom foam and powered remotely with an extension from an external PSU. The mic feeds into a SBLive! sound card and is recorded as a WAV file using the very powerful Cool Edit 2000 audio recording, editing and mixing software by Syntrillium. The sonic isolation provided by the drawer is just 3-4 dB, comparing the mic output inside and just outside the drawer. (A little isolation is better than none.)

Does this "recording drawer" setup looks familiar? Not surprising. It's the same one used to measure the noise reduction of the hard drive sandwich.

The mic is not calibrated, nor is its frequency response known. This does not matter, however, as the only real significant data is the difference between the red and blue curves, which represents the actual noise reduction effected by the Smart Drive. The vertical scale on the graph as been positioned only for convenient display; there is no absolute reference. In other words, 0 here is not 0 dBA. The dynamic linearity of the microphone is never challenged; it is not an issue here.

The curves show the averaged frequency spectrum (21 to 22,000 Hz range) of two WAV files 30 seconds long. The red line is the bare drive; the blue line is with the drive in the Smart Drive. On average between 440 (middle A on the musical scale) and about 12,000 Hz, the noise improvement is about 3-4 dB. With the IBM 75GXP, the recorded level was more than 10 dB higher than with the Barracuda drives; but the noise suppression achieved was very similar: about 3 to 4 dB.

Given the complexities of sonic measurements, these measurement cannot be guaranteed to be repeatable elsewhere; take them as a guide to the Smart Drive's noise reduction, not absolutes.

Red is the bare 'cuda drive; blue is the 'cuda in the Smart Drive.


Test Platform

Silent PC Review's Fanned Reference Standard PC, otherwise known as Silent P3, was used to test the Smart Drive. Silent P3 is extremely quiet, inaudible from the operator position except late at night when the ambient noise drops to ~32 dBA. At that point, a tiny hum can sometimes be heard emanating from the Silent P3. Its single hard drive, a Seagate Barracuda IV 40G, is normally suspended in elastic in a 5.25" drive bay.

Intel PIII - 550 (SECC2 casing) - overclocked to 733 MHz; undervolted to 1.45V

GlobalWin VOS32 heatsink run with Panaflo 80mm L fan at 5V
Generic 17" Tower Case

Generic PSU 250W, modified with Panaflo 80mm L fan at 4V

MSI BX-Master (MS-6163) motherboard. Built-in RAID not used.
512 MB PC133 SDRAM by Infineon (2 - 256 MB sticks)
Matrox G550 dual head video card (32 MB)
Seagate Barracuda IV IDE hard drive, 40G capacity; normally in elastic suspension in 5.25" drive bay.
Realtek Network Card 10/100
SCSI card interface for scanner
USRobotics 56K modem, hardware PCI
SBLive! sound card
Removable Drive Rack in top 5.25" bay switched between Iomega ZIP drive and second Seagate Barracuda IV drive used for periodic backups of main drive.

When using the Smart Drive, it was mounted in place of the CD drive that normally sits in the second 5.25" drive bay. To ensure best cooling, a small air gap was left between the front of the drive bay and the Smart Drive.

Noise in Actual Use

Listening comparisons were made between normal drive mounting of the Barracuda IV, the Smart Drive, and the original DIY elastic suspension. The seated listener/operator position is about 3 feet away from the PC under the desk.

Smart Drive
Softly audible
Normal 3.5" Mount
Softly audible
Elastic Suspension

Does it heat up the hard drive?

Maximum HD Temperatures for Seagate Barracuda IV recorded over 6-8 hour stretches for each type of mounting. Ambient room temperature: 23-24° C. DTemp software was used to monitor the internal S.M.A.R.T. temperature diode of the Seagate Barracuda IV.

° C
normal 3.5" bay
Smart Drive
Elastic Suspension

The worry about heat seems to be for naught. After several hours of working on this web page with Dreamweaver and Photoshop while keeping half a dozen other applications open, its internal temperature is 42C. This is actually 4°C cooler than when the drive is suspended in elastic and only a degree hotter than normal mounding in a 3.5" bay. Through the course of an entire day, the highest temperature recorded was 44° C, after a long series of hard drive intensive work.

When touched, the outside of the Silent Drive feels warm. Not hot, but warm. That means heat is conducted from the drive to the outside aluminum layer. This allows further cooling via conduction from the outside aluminum layer to the steel drive bay. Plus, there is some air convection as well.

A Systran / Babel Fish Translation of the Japanese web page describing Smart Drive gave me this snippet:

heat generation is extreme as a feature of the turning at full speed HDD, the above necessity heat the basket and others is designed to be the structure which is not by designating the material of the product as the aluminum.

As to what this means, your guess is as good as mine. All I can conclude is that the foam used as acoustic insulation in the Silent Drive has some of thermal conductivity which allows the outside aluminum casing to benefit from both conduction and air convection. This is a good thing.


Smart Drive is a useful addition to the arsenal of tools for battling PC noise. While the price makes it more than a casual purchase for most buyers, there is considerable noise reduction with only a small increase in temperature compared to normal drive mounting. It combines many of the benefits of decouple-mounting and DIY sandwiching without mess or fuss. The degree of benefit will naturally vary with your ambient noise level, specific drive and the overall noise of the PC.

Pro Con
Reduces drive noise by 3-4 dB Seek noise remains slightly audible
Little effect on drive temperature US$65 price
Excellent fit and finish

With louder drives (>30 dBA), Smart Drive can bring the noise level down enough so that it is no longer identifiable as a primary noise source in the PC. With already quiet drives, it can virtually silence them. When used with the Barracuda IV drive, Smart Drive is about as effective as decouple-mounting using either elastic suspending or a foam bed and keeps the drive several degrees cooler. The only minor downside is slightly higher seek noise, due to closer mechanical coupling to the case.

Our thanks again to Silicon Acoustics for the review sample!

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