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Tip #5: Basic acoustic treatment is not rocket science

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  • Avatar
    Marcel Villamil

    Nice tips! Very useful.

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    Angela Serrano

    I'm glad you liked them Marcel! 

    Any other topics you'd like us to cover are more than welcome, so don't hesitate on letting us know what type of content you'd like to see here!

  • Avatar
    Stafford0

    Angela

    In the tradition of "hang clothes, blankets, cushions" a quick, easy and cheap reflection filter can be made by visiting a nearby fabric and sewing supply store where you can purchase various kinds of foam.  "Egg crate" foam (sometimes known as "mattress topper" foam) is best for absorbing sounds as you will see in the commercial products, two-inch foam is usually enough for this cheapy version.  Next, off to the school supply store where you purchase a 3-fold presentation foam board (used by us nerds at science fairs and other places we display projects from schools). Cut the foam and foam board to match in size (typical size of a foam board presentation display is about 36" x 48"), cutting the foam board down to somewhere in the 20" to 24" height should do for most cases (48" is the width of the center panel plus both wings folded out).  Spray the foam board with glue, apply the smooth side of the egg crate foam and allow to set/dry. Voila, a reflection filter.  A weight along the bottom might be needed in some cases or a score that permits another fold at the middle to make a 4-sided enclosure can make a more stable reflection shield.

    I hope this will help someone.

    Sincerely,

    Stafford "Doc" Williamson

     

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    Angela Serrano

    Hey Stafford!

    That's such a GREAT idea! I do remember the foam boards from school. Oh, the memories of my nerdy science projects. This is a great solution 

    This is such a great solution when getting started! I even want to try it myself. Hopefully, someone does and lets us know how it worked :) 

    Thanks for your insights, Doc! Feel free to pitch in any time on any of our articles. 

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    Duane Doherty

    Any feedback on how to quiet your PC would be very helpful.  Other than the obvious of removing it from the room...that's not really an option for me.  I've added acoustic treatment to my room but that PC is making my life reeeally difficult.  Thank you for your feedback!

    Duane

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    Stafford0

    Duane,

    Regarding silencing your PC, I have a couple of suggestions. Keep in mind that some pretty talented engineers have given a lot of thought to designing your PC (esp. if it is a brand name with no user modifications) and is a relatively delicate instrument overall. Please use great caution in attempting to apply any of these suggestions.  I cannot be held responsible for your ability to execute any of these. I have been using PC's for well over 30 years and still don't consider myself an expert, even though fixing them and modifying them was sometimes part of my job description.

    Your voice is vibrations of the air that in our case you want to record. Noises from the PC are vibrations you don't want to record, even the air whooshing from your heating or air conditioning need to be silenced or otherwise treated to avoid unwanted sounds. So, first thing is to be sure your PC and microphone are not resting on the same surface (shelf, desk, etc.) so vibrations are not transmitted directly.

    Next, wherever your PC is, make sure it is not transmitting its vibrations into whatever it is resting on. I don't know if them even make them any more, but they used to sell sound dampening dense foam pads to put under typewriters. Putting your PC on one of these will help isolate it. Mouse pads are better than nothing, the dense kind of foam would be best so that the weight of the PC doesn't compress soft foam down too much. In any case, check out the air flow through you PC's box. Make sure this (or any of these suggested "fixes") do not block any of the vents or decrease the air flow through the box.

    One of the next best suggestions is to increase the air flow through the PC. I still have a rather large and nearly silent fan sitting on a shelf behind me that did not fit a previous (homebuilt) PC. It needs a 12V power supply but takes on about 1.5 watts of power and runs at the near silent level of 15dBA. You can mount this outside the PC over the existing exhaust fan (rubber washers are included with mine to be sure that it is not passing vibrations into the PC case) although connecting it to the 12V power source inside the PC should only be attempted by very advanced amateur PC users with experience in such operations.

    Again, air flow is a major consideration, but isolating the PC by putting it in a "box" of some kind would/could be a significant help in "hiding" the vibrational noises from the PC.  These days most of the sound comes from cooling fans mounted directly to the CPU or the GPU (graphics processing unit). Turning them off, or even slowing them down would be a very bad idea. Overheating "fries" the chip.  However, a box, made of plywood, perhaps, with adequate openings to allow lots of cooling air flow, placed on a dense foam pad that isolates the box itself and probably another pad inside that isolates the PC from the box. Obviously, the box will need openings for power cord and other connectors, so aiming those opening away from the microphone and not too close to any walls or windows (even if the walls have been treated with foam or other sound absorbents) would help too. And lastly, keeping the PC as far from the microphone even with good sound insolation will likely help. Extension cords are available for power, of course, but also for USB and most other kinds of PC cables as well.

    Oh, yes, one of the less frugal solutions is to buy a laptop with the laptop CPU that doesn't need a cooling fan to use that specifically for recording (only?), then transfer the recording via some portable medium to your regular PC for editing or any other processing which requires more power and more sophisticated software.

    It is not an easy problem and depends a great deal on your individual circumstance so good luck.

    Sincerely,

    Stafford "Doc" Williamson

     

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    Duane Doherty

    Great info!  Thank you, Doc!!

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    Duane Doherty

    Here's one for ya....to increase cooling/airflow without having to replace the stock fans, would it make sense to remove the case of the computer before encasing it in ...whatever box/soundproofing dealio you choose??  No case = no enclosure = more efficient heat distribution.   ??  Of course still doing all the sound reduction measures that you mentioned. 

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    Stafford0

    Duane,

    NO !!!! Don't even think of a naked PC. ** Electrical insulation/isolation of components is essential. You might get away with putting the guts into one of those "all grillwork" (rather pretty) PC cases, but even different models from the same manufacturer are often different motherboards, daughter boards, internal connection to external gauges (i.e. temperature). Still not a good plan.

    If anything, you might go in the opposite direction and wrap the entire PC (except the airflow vents) in that heavy foam material I mentioned so that internal vibrations are not transmitted through the case. Remember, though it is almost entirely CPU/GPU fan noise we are concerned with so some of that is going to be in the air passing through the case as cooling "fluid".

    ** I bet the first thing that came to mind was a "naked PC".  It's like saying, "Don't think of an elephant."

     

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    Duane Doherty

    HAHA!  

    ...and THIS is why I'm as literate as a bucket of spit when it comes to technical...stuff.  THANK YOU!

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    Thomas W. Johnson

    The best thing you can do with a computer is remove it from your recording space. A quality mic will pick up its fan and hard drive noise. Move the computer out and run cables to your monitor/s. Wireless keyboards and mice are easy to install often by simply plugging in a USB device. The computer will be happier out of your booth, too, as the temperature can vary greatly during a long recording session.

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    Dale Wilcox (Edited )

    You can also eliminate the computer altogether by using a dedicated recorder made by ZOOM, TASCAM, or others. They’re available with XLR and USB inputs, record to SD cards and are completely silent. At $200 and up they are cheaper than another quieter computer. (You would of course need an adapter to read the SD card and do your editing in your main computer.)

     

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    Angela Serrano

    If you let me pitch in here! I don't recommend the ZOOM or TASCAM devices for professional recordings. Their AD/DA converters are usually not designed for professional audio recording to the level we require. These devices are more for on-the-go recording and outside recordings, but they usually lack fidelity and have a high noise floor for pro audio.

    I'd stay away from them and get an interface. There are ways to isolate your mic from the computer or to lower the comp's sound. I personally have a desktop in which I installed a liquid cooling device and also make sure I clean it once a week to avoid it over heating and making more noise. 

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