Cocoon Culture No.47



At the end of a road - System upgrade

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As my quest for silence approaches the end, some summary comments and measurements to wrap things up.

All that remains is to test the modified version of PSU(2). Results will be commented in document dealing with this.[ link ]

The system now has an average noise level far below +30 dB, when measured at the standard listening position.

I've done some final measurements, and recordings of the system as it is at the end. The PSU(3) is being used, as PSU(2) still haven't been tested as safe. The problems with high-pitched PSU noises still exists; and has infact increased in magnitude with time. Hopes to eliminate this rests on the outcome of the PSU(2) experiment, however the time has come to move on so this problem will be carried over to the new system. Note that the noise trap (prototype 4) has an super effect on trapping these noises.

As mentioned, the time has now come to move on to a more contemporary system, and both the CPU and motherboard will be upgraded. There is some excitement as to how well this will perform in comparison with the old system.  A report will be made, when I've tested this.The AOpen AX5T-2x and Pentium 233 MMX, will be swapped for an ABit BX133-RAID and a Celeron FC-PGA 700 .

Final Measurements

The system is measured at 5 point, 1 centimeter sound pressure level from chassis. These are :

  • Front : Center of cabinet front, Immediately below the 3.5" floppy drive.
  • Side : Center of cabinet leftside (relative to viewed from the front)
  • Rear 1 : Center position of cabinet rear.
  • Rear 2 : Noise Trap (4) air-outlet.
  • Rear 3 : Center of PSU Fan. (Noise Trap removed of course)

3 different modes of operations, are also measured :

  • Idle ( HD spun down i.e. OFF) ,
  • Average ( HD idle, Normal use : testing using winamp 2.7 playing files : 60 % idle as reported by waterfall)
  • Load (HD working, CPU full load : tested using CPUIdle & winamp 2.7 playing mp3's),

Also possibly throw in some sound recordings of the different scenarios.

Note ! due to the limitation of the sound-meter range some levels could not be measured. These are marked as sub +28 dB.

Another note ! The only sound generators in the system now is the PSU and the HD. In the Idle state, only the PSU.

One more ! Wind-cap on meter in all measurements.

state\pos Front(dBA) Front(dBC) Side(dBA) Side(dBC) Rear1(dBA) Rear1(dBC) Rear2(dBA) Rear2(dBC) Rear3(dBA Rear3(dBC)
Idle (1) 31.5 39.2 32.3 41.3 42.3 44.1 45.2 53.2 51.5 58.8
Average 32.0 40.9 34.4 43.8 41.9 47.7 50.0 57.0 55 62
Loaded 36.5 46 38.5 49 47 51 54 60 59 66
Idle (2)* 29.3 36.4 30.6 37.7 36.2 42.1 40.2 48.9 50.5 55.8

Unmodified version of PSU(3) used in the above measurements. Noise-trap on (Cardboard box type), except where noted.

* Idle (2) - Second opinion, Idle (1) measurements where made with lots of background noise from the room above. Ambient sound level for the recordings where : 28.4 dBA and 33.7 dBC. The actuall sound level are probably less than that wich is recorded, but as the noise-level recorded near the cabinet approaces the ambient sound level, things are looking good.

Conclusions, closing comments on the old system (1) :

With the assumption (rather optimistic) that the modified version of PSU(2) manages to eliminate the high-pitched noises, the system will be virtually silent in it's idle mode of operation. Some modifications to the cabinet ventilation and fan control will still be needed though. But the odds are looking great for a completely silent system. Pity that the CPU has become outdated. Maybe a dilemma of the modern age, just as "a thang" reaches maturety it becomes obsolete.

Final results of system (1) :

The MB have been removed from the cabinett, and will be tested externally together with PSU(2). An update will follow here at some point. [ Late december 2000 ]

The external testing of the system was successfull. It is completely silent, as there are no fans and the high pitched PSU noise is also gone. The only noise present is that of the HD, but the Noisebox made for this takes care of this. I expect that I will have to do major improvements in the natural ventilation of the cabinet, but I will check it out without modefications first. This will provide a refrence as to the effect of the modifications. [ Late January 2001 ]

Absolutely final results for system (1) - Absolute Silence :) my-star.gif (1965 bytes)

After modification of cabinet and sucsessful testing of psu, everything was put back together for a reality test. The system was completely silent, with the exception of drive noise (which has been dampened by a noise box). Some minor problems were encountered, see psu(2) investigation doc for details.

Happy happy :) [ Early Febuary 2001 ]

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Copyright 1999-2002 Cocoon culture no.47 . All rights reserved.
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