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Quietening a Barco 808

Discussion in 'Projectors, Screens & Video Processors' started by ShinObiWAN, Jun 21, 2004.

  1. ShinObiWAN

    ShinObiWAN
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    I was wondering if it would be possible to lower the noise levels from my Barco 808.

    I can't use a hush box because the projector is floor mounted. I was thinking more along the lines of replacing the fans for some quieter ones. I've noticed that the PC modding community has a wealth of low noise and moderate air flow fans.

    Can I use 12cm 12v pc fans inside my barco?

    And does anyone have any suggestions or recommendation for a particular brand?
     
  2. Phil Hinton

    Phil Hinton
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    Roland has done a lot of work on quieting 808 PJ's so have a word with him.
     
  3. chrisgeary

    chrisgeary
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    why can't you use a hush box? it should be easy peasy for a floor mounted PJ. ive had great success with a modified IKEA table, some MDF panels, acoustic foam and some temperature controlled 12v fans mounted in acoustic foam superglued to the roof of the table. IIRC, Roland found no fans better than the ones barco supply.
     
  4. ShinObiWAN

    ShinObiWAN
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    Thanks for the advice,

    Any chance you have pictures of your hush box?

    Would be interested to see how it could be done and still look tasteful. I did consider just boxing it in and then carpet the whole thing so it matches in with the floor. But I think this would look pretty rough.

    Its currently under a table so I suppose I could box that in, but would prefer to look at replacement fans for now.
     
  5. Roland @ B4

    Roland @ B4
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    It's true I have done some extra quietening on 808 PJs.
    But you have to be very carefull.
    I have seen mods that just slow the fans down either by, by-passing the original circuits or just by wacking in some resistors to slow down the fans.
    Both of these are potentially fatal for the projector as they make no consideration for increase in temperature in the machine or even in the suroundings.
    Adding resistors will work to start with, but I have found machines where the voltage has been too low to start the fan spinning and as the 808 has no feedback from the fans this will cause big problems later.
    There are a few mods going around that use a timer to spin the fans fast at start up and slow them down but they have no sensor to cope with temp build up. It is all too easy to do a mod that is designed for sensible use then some pratt wants to use 2000x1600 resoloution (well beyond the sweet spot) and overdrive the tubes. then complains that a tube has failed.

    I have so far replaced about 40-50 fans and have come to the concusion that the original NBM fans are amongst the quietest around, so there will be no magic quick replacement formula there either.

    I have found it neccessary only to replace noisy fans when the bearings are going.

    Any mod I do now has a sensor to increase the speed of the fans to cope with temperature change.
     
  6. ShinObiWAN

    ShinObiWAN
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    As always Roland your input is greatly appreciated.

    You've kinda scared me off the thought of modding things myself. I'd hate to have to replace a tube(s) because I just wanted a few dB's less.

    My quick fix of exchanging the fans obviously isn't going to gain me any extra credit either, since you state the standard fans are of a high quality.

    All in all, I think its better and safer to just put up with the noise for now, afterall its quieter than any digital I've heard. I'll have to start some research into floor mounted hush boxes.

    Thanks for all the advice everyone!
     
  7. Roland @ B4

    Roland @ B4
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    A few quick end user things that can be done.

    The fans are on rubber mounts give them a good strong wiggle to reduce any noise transmision.

    Make sure the fans are clean good blast with compressed air (take it down to your local service station or buy a can of dust off)

    I haven't tried it my self but I have heard that if you clean the fans with polish then that will reduce some of the noise. ( please don't just spray Pledge into the back of the projector) but wiping with a cloth with the polish on it should do the trick. (if you pick a sented version you should get smellavision too)
     
  8. ShinObiWAN

    ShinObiWAN
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    The inards of the projector are spotless including the fans.

    When I bought the projector back in December 2003, it had been completely dismantled, serviced, cleaned and the reassembled.

    Really I'm being a little picky here, the projector is quiet but I just wanted it silent for those quiet moments in films.

    Guess a hush box is the safest and most economical way of doing this, though I'm all woodworked out after my latest DIY escapades. Though its definitely on my to-do list.
     
  9. chrisgeary

    chrisgeary
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    here is the thread talking about my hushbox:
    http://www.avforums.com/forums/showthread.php?t=89774

    in there is a link to my site which shows the official home cinema shots. but here are some more detailed shots taken early on, the basics are the same, but i've refined the cooling system since.

    http://www.christophergeary.co.uk/ht/

    no mods were done to the projector. IIRC, i was recording over 50db of noise at the seated position, during movies it was quite intrusive. after the hushbox was used, the noise was unmeasurable using the radioshack meter, and i barely notice it these days.

    total spent on the hushbox was less than £50 (although the fans and controller were about £100)

    hope this helps!
     

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