The review compares the noise from a AcoustiPack-treated Antec Sonata case versus a “bare” Sonata. Goes on and on… but lots of interesting things in there — other damping materials, what the stuff should do, and high quality MP3s for comparisons. A bonus for the uninitiated: One is of the Panaflo 80L at 12V at 1 ft.
February 11, 2003 — by Mike Chin
|Product||AcoustiPack – Deluxe / Standard|
|Selling Price||Deluxe: UK£39 – US$90 / Standard: UK£21- US$54 — Based on current QuietPC online catalogs. Prices outside UK greatly affected by high shipping weight / cost of products. Should drop as sea shipping is utilized.|
|Other Products considered|
Acoustic damping materials are virtually ubiquitous in the modern world. Fiberglass batting, foam, and all manner of specialized materials are used in an incredible range of applications to combat and control noise. In computers, however, it is not yet common. One place many SPCR readers may have seen it is beneath the metal protective cover of the Seagate Barracuda IV hard drive: a bit of blue foam is visible there. This foam helps to keep the Barracuda relatively free of high frequency whine. The fact that this quietest of all hard drives uses damping materials is probably significant. As far as I am aware, no other hard drives incorporate acoustic damping materials.
In my own systems, some damping materials are used — things like heavy carpet underlay and recycled foam from packing materials — but until now, I have never tried any of the aftermarket damping materials sold specifically for computer cases. There is little question that acoustic damping can help reduce noise.
The main question is,
How much money, time, and effort is required with acoustic damping materials to obtain what level of noise reduction in a PC?
Many PC silencers are of the opinion that using the quietest components and reducing the noise of components at their source makes damping materials unnecessary. This was generally my point of view, too. My perspective has been changed with exposure to the product under review.
This article began originally as a comparative review of four brands of damping materials marketed for use in a PC case. All share the common feature of being backed with adhesive on one side so that it is relatively simple to apply. They’re shown in the photo below (clockwise from top left):
Why this article turned into a review of just the one product will become clear as you read on.
TEST METHODOLOGY / PLATFORM
After a great deal of research into the question of how to analyze the effectiveness of these damping materials, I came to the unavoidable conclusion that there is only one practical way:
Apply the damping to a case as recommended by the manufacturer and compare it to an unmodified case of the same type, the same model, with the same noise sources (computer components) in it.
This conclusion took a long time to reach, mainly because it was the one I wanted most to avoid. Why was I so loathe to use this methodology?
Applying the damping looked like a mountain of tedious work, especially without at least one pair of matching cases. My hands were going to take a beating…
Fortunately, Antec came to the rescue by generously sponsoring another Sonata case, this time a pre-production black one to match the earlier beige sample used for the review conducted some weeks ago. This seemed a reasonable case to use as a test platform, as the Sonata is designed specifically as a reduced-noise case. Thank you Antec!
Still this meant applying four and removing at least two sets of the damping materials. Ideally, what I wanted was five identical cases. (Good thing I didn’t get them! As you know the review only focuses on one product.)
Before getting into the product details, it seems worthwhile to consider the challenge noise damping materials face in a PC. Here are some basic observations:
1. The main goal is to reduce noise — all noise. In a typical PC, there are high-pitched whirring noises from hard drives and small high speed fans, the mid/high frequency noise of fan turbulence, the lower frequency rumbling and clacking seek noise from hard drives. While we tend to identify the more annoying high frequency noises quickly, there are noises in every frequency band.
- The damping materials must be effective not in a narrow or limited bandwidth but across the entire audible frequency range.
2. The case is made of thin metal panels and plastics, which do not block, contain or dampen the noise inside well. The metal chassis and panels often vibrate, sometimes subtly, sometimes obviously, adding their own noise to the mix. This noise is usually lower in frequency, but their sympathetic vibrations add to the whole mix of noise.
- The damping materials must reduce or eliminate sympathetic panel resonances that contribute to the noise, and increase the noise blocking/containing capability of the case panels.
3. The case has air vents that allow noise to escape directly and easily. Sound becomes more directional higher in frequency, becoming more like narrow beams of light rather than waves from a splash in a pool (the behavior at lower frequencies). So in theory, it should not be that hard to minimize high pitched whining or whistling by eliminating direct paths to the ears. In practise, as most PC silencers know, high pitched noise is not easily eliminated by baffles alone, most likely because there are many hard and reflective surfaces that noises bounce off to find their way out the openings, regardless of frequency.
- The damping materials must reduce the noise and reflections within the case by absorbing it as much as possible. Coverage of as much internal surface area as possible is likely desirable.
4. Other desirable qualities.
- Nonflammable — Acoustical or soundproofing foam is most often made from polyester, polyurethane, or some other poly-something or other, all of which have a tendency to be at least somewhat flammable.
- Doesn’t smell — Nasty smells have been reported to emanate from damping materials, especially as the computer case heats up. It is not clear whether this smell is accompanied by any toxic outgassing or is simply unpleasant.
How do the contenders fare on the points under NOISE CHALLENGES?
2 – 40 x 34, 2 – 40 x 17
2 – 30 x 24
1 – 25 x 25
1 – 25 x 25
3 – 49.5 x 39.5
2.8, 12.5, 19
high / very high
5 – 49.5 x 39.5 (more)
The Akasa Paxmate is far too light, way too thin and has too low a density to meet any of the criteria set above. Its total area coverage is the only way that it passes — just barely, but it is a minor 1 out of 4. It is simply not worthy of a serious look. It also smells terrible, although one user mentioned it seemed to go away after a few days. It is unlikely that applying this product could have any significant impact on the noise of any PC in any case. Anyone with the least bit of understanding of acoustic damping will come to that conclusion in a 30-second examination. Not recommended.
The Cooler Master Pro-Studio comes in a really nice lime green translucent plastic case with handles and snap locks. It’s the nicest part about this kit. It is too light, too low in density, and covers way too little surface area to have any affect to noise in a PC. If 4 or 5 kits were purchased and their entire contents applied to the interior of a PC case, there would probably be a small decrease in high frequency noise. Not recommended.
As the above profile of the 1″ Wispermat by Muffled Computing shows, this is a composite of 3 materials. The thin grey strip in the center is a dense vinyl layer. The acoustic foam on either side of the vinyl layer is considerably less dense. The thicker outer layers seems stiffer and more coarse, while the inner layer closest to the adhesive seems both softer and finer. Its weight and density is very close to that of the Acousti Products Acoustic Composite sheet (see below). Wispermat is thick enough, dense enough, and heavy enough; alas only one 1/2″ sheet and a 1″ sheet were provided. Not nearly enough to conduct a full review. They were excluded from this roundup only for that reason, and will be the subject of a review in the near future.
AcoustiPack Deluxe: 4.6 kg (over 10 albs) of 4 different types materials
Acousti Products, based in the UK, are relatively new to the market. They offer two kits, a standard and a deluxe version, the latter offering more materials, and more types of materials for a larger case. The variety of materials in the deluxe kit indicates an approach that is considerably better thought out and more sophisticated than others. Both kits easily meet all the above criteria.
Referring to the photo above, starting with the materials on top and moving down, the Deluxe AcoustiPack contains…
Each of the 5 sheets measures a substantial 495 x 395mm (19.4″ x 15.5″), which is large enough to cover the entire side cover of almost any tower case. The total weight of the package is substantial, at 4.6 kg (10 lbs).
The Standard AcoustiPack has 3 Acoustic Composite sheets (same size as in the Deluxe kit).
Acousti Products’ web site has extensive details about these various materials. It provides the most comprehensive information of all the PC damping materials referred to above. It even includes this graph showing lab measurements of the materials’ damping qualities. All this is impressive, as it suggests a carefully studied approach to development, rather than the typical marketing-driven, me-too approach.
Acoustic Foam — AP use a semi-open cell, polyurethane foam. This is approx. 65 kg/m³ – unusually dense compared to alternative noise-reduction foams. The advantages claimed for high density foam:
- Improves sound absorption efficiency at lower frequencies (sub-1KHz) – said to be critical
- Helps to maintain a low flammability performance, and
- Withstands being manufactured into thin ‘low-reflection’ layers for dual-layer composites
“The acoustic foam is certified UL94, ISO 3582, FMVSS 302 and DIN 4102 for low flammability, and can be operated normally within the temperature range -40°C to +120°C.”
Acoustic Barrier Mass — This quote is from AP:
“Manufactured from a flexible polymeric material incorporating additional mineral fillers to increase mechanical strength, durability and fire resistance. The material is not bitumen-based, and does not give off undesirable odors when warm. This material is very dense at approx. 2000 kg/m³. It is designed to add mass to computer casing, for example, sheet aluminium, steel, alloys and non-glossy plastic surfaces. The material mass acts as an acoustic absorption barrier, significantly reducing noise transmission and reducing any natural resonance frequencies.” It is considerably more effective at sub-1000Hz frequencies than the acoustic foam.
“The acoustic barrier mass is certified to ISO 9772, DIN 75200, ISO 3795 and FMVSS 302 for low flammability, and can be operated normally within the temperature range -25°C to +120°C.”
They recommend combining the Barrier Mass with the Acoustic Foam whenever possible — for example, on the main left side cover. This ensures the best broadband noise reduction. Their Acoustic Composite sheet, which is not described in detail, is a composite of these two materials. The photo below shows the profile of the composite sheet; the thin lighter gray layer is the heavy barrier mass:
Adhesives: Acousti Products use water-based, nonflammable adhesives. They say these are
“less odorous than solvent-based adhesives in some similar products… and can be operated normally within the temperature range -20°C to +150°C. If a mistake is made during the application of acoustic materials, our adhesive allows for the materials to be peeled off and then reapplied.”
“Although the range of operating temperatures stated above are those published by the manufacturers of the raw materials – we strongly recommend that materials are not placed directly against hot components. This is to ensure that products are installed with optimal safety in mind and to help maintain hardware longevity. Always read the printed instructions with each product prior to installation.”
APPLYING THE DAMPING
The biggest challenge to applying the AcoustiPack materials to the Antec Sonata is that the right side of the case is not removable. The gap between the motherboard tray and the right side panel is too small for any material to be applied to either, as shown in this photo below, taken from the PSU location looking towards the front of the case.
After careful study of the available spaces and access to various portions of the Sonata case, I decided to use the Deluxe AcoustiPack. I wanted the flexibility of its wide range of materials.
I consulted Acousti Product’s fitting instructions, included with the kit, as well as these resources on their website: well-illustrated instructions and FAQ recommendations. Here is the approach I decided to take:
1) Antec Sonata case on operating table (dirty floor rug).
2) Measure twice… cut with sharp utility knife and/or scissors.
3) Top piece for right side panel.
4) Between step 3 and this one, there were actually about 3 dozen steps, but you don’t need to see them.
5) Some slightly sloppy cutting for Acoustic Composite material behind the front door. A photo was not taken, but a layer of Acoustic Composite material was similarly applied to the inside of the plastic bezel intake vent.
6) The right panel with Mass Barrier sheet on bottom and convoluted Acoustic Foam on top.
The installation process took more than two hours. (It would go faster if you were not stopping to take photos or make notes.) One and a half sheets of the Acoustic Composite sheet, one Acoustic Barrier sheet and almost all of the Acoustic Contour sheet were used. The total weight gain was about 8 pounds.
The adhesive is very sticky, but can be pulled off and reapplied at least once to get the alignment right. (I actually did it a couple of times with a few pieces.) None of the materials smells much. Finally, the 3 foam blocks for drive bays were added. They friction-fit into place easily.
The True380S PSU in each Sonata case was used to drive various fans, and do A/B comparisons. It made for a relatively simple series of listening and measuring comparisons.
After trying a number of different fans for noise makers, I concluded that the greatest difference was most easily heard and measured with the loudest noise sources. Rather than present an exhaustive set of data about different noise sources, the loudest, most dramatic one is detailed here.
Both listening and acoustic measurements were conducted in the main test lab, a converted kitchen with no carpeting and very live acoustics. The ambient noise was estimated to be around 20-25 dBA. The cases were placed on the top of a very heavy steel office desk. It did not contribute any resonance noise when the loud fans in the cases were turned on. The Sonata’s PSU is too quiet to contribute to the overall perceived or measured noise in this setup.
Main test instrument: Heath AD-1308 Real Time Acoustic Analyzer / Sound Level Meter. Note: This machine is not calibrated and very old. Its accuracy is somewhat questionable, but above 40 dBA, it seems to jibe with both what I hear and with other more accurate instruments.
The venerable Heath AD-1308: OK above 40 dBA…
This Thermake fan is the noisiest fan in the lab. It is used on the Thermaltake Volcano 7+ heatsink. Measured noise:
While it can be categorized as broadband noise, there is a marked peak of 5-6 dBA at 4-8 KHz, centered at ~6 KHz. It makes quite a screaming racket, with lots of whine and whoosh — wind turbulence noise.
The fan was placed on the bottom center of each case in the frame used to mount it to the Volcano 7+ heatsink. In the undamped case, a thin piece of closed cell foam was used to keep the fan from chattering and vibrating against the metal case floor.
|Heard||The overall noise of the fan dropped a lot compared to having it outside the case. There was much less whine, and maybe a bit more lower frequency noise. The latter could have been caused by both cavity resonance as well as case vibration, which could be felt with the fingers. This is so loud I would toss it out the window in 20 minutes if I had to work with it.||The whine became much more subdued than in the undamped case and the overall noise dropped further. There was less case vibration, and somewhat less low frequency noise. It became more wind noise than whine, but was still too loud. Most of the sound emanated from the outflow vent on the back panel. In comparison, there was very little noise coming through the top, sides or front of the case.|
|Measured 4″ from front panel mid-height*||55 dBA; 6 KHz peak no longer visible. Highest peak now around 500 Hz.||48 dBA; 6 KHz peak even less visible. Highest peak around 400 Hz.|
|Measured 2″ from back panel exhaust hole*||63 dBA; 6 KHz peak almost unchanged from free air. 500 Hz peak also in evidence.||56 dBA; 6 KHz peak clearly visible but less pronounced. Highest peak around 400 Hz.|
*These distances are ~10″ from the fan — albeit through panels and grills. It is about the same distance as the first free-air measurement above and thus directly comparable to consider the impact of the case.
The data indicates that an undamped case has a fairly significant noise reduction effect simply by enclosing the noise source. The improvement measured from the front of the case was 9 dBA. The AcoustiPack-treated Sonata improved on this by a further 7 dBA for a total of 16 dBA noise reduction, which is very dramatic.
Sounds really good? Keep reading; the story does not end here.
Another listening comparison and measurements were done. This time, the fan vent in the back panel of both cases was blocked completely with some scrap composite Acoustic Composite material. Naturally, there were still many small holes and gaps where some sound could emerge, but now the exhaust fan hole for the PSU became the largest opening on the back panel.
|TEST 2 – back panel sealed|
|Heard||The overall noise was lower than in Test 1. There was less whine. It was still so loud I would toss it out the window if I had to work with it. Maybe not in 20 minutes, but half an hour?||The whine became even more subdued than in Test 1 and the overall noise was lower again. Low frequency noise. There was also less wind noise, but it was still too loud.|
|Measured 4″ from front panel, mid-height||56 dBA; 6 KHz. peak no longer visible. Highest peak around 500 Hz.||48 dBA; 6 KHz. peak even less visible. Highest peak around 400 Hz.|
|Measured 2″ from back panel, mid-height||58 dBA; 6 KHz. peak no longer visible. 500 Hz peak also in evidence.||50 dBA; 6 KHz. peak even less visible. Highest peak around 400 Hz.|
Keep in mind that the above test is completely artificial. In a real system, the exhaust vent could not be sealed without components overheating inside. But it does show dramatically the effect of the noise coming out through that back vent.
So what does all this mean?
MP3 NOISE SAMPLES
My musician friend Adri has a nifty Sony portable minidisc recorder and a high quality stereo microphone she resorts to when “shooting on location”, so to speak. Adri graciously agreed to help me capture some PC noises with her audio gear for the benefit of SPCR readers. The goal for making these recording was so that you could hear an approximation of the noise that I heard and am discussing and measuring here.
We first listened to the Volcano 7+ fan in the two cases in her living room. Adri marveled at how anyone could stand to have such a noisy fan in their computer. I must have become deafened temporarily; I could only marvel at how much softer the noise was in her carpeted living room compared to the hard live test lab.
After some preliminary listening and testing, Adri determined that a small bathroom on the main floor was the best, most isolated location — equidistant between the distant traffic noise from the north windows and the hum / buzz of her server bank in the upstairs landing. All the recordings were made with the Sony DAT recorder gain at maximum, and the mic positioned about a foot from the fan.
|Recordings of PC Noise (MP3)|
|Thermaltake Volcano 7+ fan, FD12702598-2F at 12V, 12″ Warning: This is very loud, but if you turn the playback volume down too low, you may not be able to hear the Panaflo without turning the volume back up, thus spoiling your comparison.|
|Volcano fan in undamped Sonata case, mic in front|
|Volcano fan in damped Sonata case, mic in front|
|Volcano fan in undamped Sonata case, mic in back|
|Volcano fan in damped Sonata case, mic in back|
|Panaflo FBA08A12L fan at 12V, 12 inches When played on a reasonably good pair of speakers or headphones, this recording gives you a good idea of the smooth quality of the Panaflo 80mm Hydrowave bearing fan noise and why it remains SPCR’s reference. Comparing between this and the first (Volcano fan) recording is really educational.|
WITH LOW NOISE COMPONENTS
Thus far, the testing and analysis has focused on a “system” whose noise level would be considered ridiculously loud by SPCR standards. This was necessary in order to work with easily measurable and recordable levels. But what about with a system whose components have been carefully selected and optimized for low noise?
This question required a third test, of course. There are no measurements offered here, only my listening observations, because the noise level is far too low for the Heath SLM.
This test was run with the Panaflo at 12V, and then again at 7V. The fan was placed on its side the bottom of the case.
|TEST 3 – Panaflo 80L fan as noise source|
|Panaflo 12V||The overall noise was low. A bit of whine could be heard from the Panaflo but it was modest. From the rear exhaust vent, the Panaflo fan noise became more audible. The fan noise from the PSU made more low frequency noise than the Panaflo. The hard drive seemed to contribute a bit to the low frequency noise as well, but it was difficult to separate out.||The overall noise was lower than with the undamped Sonata. Virtually no whine could be heard from the Panaflo inside, except when listening right at the back exhaust vent. The fan noise from the PSU became the bigger noise source. The hard drive noise was even harder to identify|
|Panaflo 7V||The overall noise was very low, not much different than the Panaflo at 12V in the damped Sonata case. The Panaflo could not really be heard. Most of the noise came from the rear, from the PSU fan exhaust. The hard drive seemed to contribute a bit to the low frequency noise as well, but it was difficult to separate out.||The overall noise was the lowest of all, but not by a big margin. The PSU fan exhaust seemed to be the only source of any noise. The hard drive noise was very hard to identify|
In Test 3, it became clear that with the Panaflo fan at 7V, the PSU became the limiting factor in noise reduction. The damping materials can do little to reduce the noise of the PSU because its noise source, the fan, is located on the back panel, virtually on the outside of the case.
The 12V Panaflo is louder than the PSU fan, but when inside the damped Sonata, gets to about the same volume level. While the damped Sonata with the 7V Panaflo is the quietest, its advantage over the undamped case is not nearly as big as before; much less than the 7 dBA estimated with the loud fan earlier.
You’re a trooper if you read through all the above to get here. If you did a quick jump and scroll to get here, instead, I don’t blame you. It’s been a long review for me too!.
The Deluxe AcoustiPack by Acousti Products represents a thorough and effective approach to dampening materials for computer cases. The variety of damping materials supplied, and the various functions they perform, as well as the comprehensive information for the end-user — all these bespeak of a carefully researched solution not evident in other damping products.
There appears to be two main potential uses for AcoustiPack.
For SPCR diehards, there are three ways to consider AcoustiPack:
Whether you consider AcoustiPack damping a necessity or a luxury really depends on the approach you take to PC quieting, and on your noise standards. Regardless, Acousti Products have clearly come up with a useful tool to add to the PC silencer’s toolbox. Recommended.
* * * * *
Much thanks to Acousti Products for the review samples, and to Antec for the extra Sonata case for this comparison, and our apologies to Muffled Computing for not being on the ball about obtaining more samples to do a review. And great thanks to my friend Adri for her creative, expert approach to the audio recording challenges.
* * * * *
As we were “going to press”, word came from Acousti Products that they have nearly finished developing a new pre-cut kit for the Antec Sonata case. They say it should be available soon. Antec may also offer it directly.
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