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I'm Building a hush box for the HS10

Discussion in 'Projectors, Screens & Video Processors' started by John_N, Jan 29, 2003.

  1. John_N

    John_N
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    Well

    After living with the HS10 for a few weeks now I've noticed that the fan noise is indeed very temperature dependent. Because my unit is sited near the ceiling, it seems to start cool and quiet and then by the end of the movie it's definitely louder.

    So. I've ordered some soundproofing barrier from these people:
    http://www.diysoundproofing.co.uk/soundbarriermats.htm

    It's about £75 for a 1metre * 900mm piece which is enough.

    This is different to acoustic foam. The one that I'm buying is the 'sandwhich composite' - 32mm thick with a lead core. Basically it's a lead sound barrier with acoustic foam surround. Designed to be fixed to the enclosure to provide soundproofing. Quite heavy - weighs 6kg per metre.

    The next job is to fabricate the enclosure itself.

    The enclosure is going to be built into the house wall - sticking out of the wall by about 15mm and going into the thickness of the house wall by about 15mm. The protruding parts of the enclosure are going to be made from thick MDF faced with plasterboard and plastered. The internal area of the box is going to be lined with this 32mm soundproofing barrier.

    The box will have passive air intake and forced exhaust (ie there will be air inlet ducting and forced exhaust via a fan. The box will have temperature monitoring inside it.

    The projector will initially shine through a simple hole in the front. If this proves too noisy, the hole will be glazed with optical glass but we shall cross that bridge when we come to it.

    External to the box will be a power switch for the projector and fan speed switching (off / low / high).

    Yes. It's a lot of trouble. But quite an interesting project.

    I shall be getting a sound pressure meter for the before and after measurements.

    My electric Projecta Procinema electrol arrives this week. I'm looking forward to it after watching a picture on my grainy grey wall (too rough). I'll post the info on it when it happens.

    J
     
  2. WebLoader

    WebLoader
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    weird.. i too had decided to build a hush box.
    i wasnt going to use the lead lined material, just straightforward sound deadening foam.

    My projector is wall mounted, and we sit directly underneath it. Therefore my plan is to build a simple box, open at the front which will encase it on 4 sides (the wall encloses the '5th' side) . I am considering forcing air in at the top of the box using a panaflow quiet fan, just to keep things moving in there. I also think John that having positive air pressure around the body of the projector should be more effective, as when you have the unit ceiling mounted the vents underneath (now on top!) act as intakes.

    I convinced myself it was worthwhile a I have found that just holding a reasonable size cushion underneath the unit (therefore between the seating position and the projector) makes a significant difference to the amount of noise reaching us.

    by the way - i have had a proper wall bracket custom made for the HS10 (my brother in law own an engineering company), if anyone is interested I will be posting some pics up. The company that made it for me have said they can make some more if there is sufficient interest.

    cheers
     
  3. Markatlarks

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    How about a drawing
    ___________________________________________________

    I am impressed – You have obviously given this a lot of thought and energy. As a potential HS10 owner I would be fascinated to see a cross-section and elevational drawing of your proposed baffle-box. I await with interest.

    As a matter of interest – what happens if you lose you ‘external fan’? Would the HS10 be able to pull the air through the box?
    Good Luck
    Marko
     
  4. John_N

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    Hi

    I had a long chat with the soundproofing guy. He said that normal acoustic foam absorbed reflected sound but sound would pass straight through it. He thought I would need a heavier material (hence the lead barrier in the foam) to actually be a sound barrier and reduce the noise significantly.

    I've been looking at thick optical glass - the same glass as is used in commercial projector ports in your local cinema - because obviously the thicker and heavier the case the less sound will travel through it.

    According to my research, to make a wall reasonably soundproof involves at least three layers of plasterboard on EACH SIDE (ie 6 layers thick) in order to give the wall enough mass. In the world of soundproofing - mass is everything.

    I've ordered the foam and I'm going to make a prototype box I think using thin plywood as an inner, lined box. This will house the projector. If this doesn't result in enough sound insulation then the structural phase will begin where I effectively build a thicker MDF / Plasterboard cubicle sticking out of the wall - possibly glazed with thick optical glass - and the inner plywood insulated box can go inside that. If there is enough left I might be able to stretch to two thicknesses of the sound foam.

    At this stage, the design is not finalised. I'm waiting for the foam, MDF, plywood etc and then I can try a few ideas (including leaving the front 'open') to see what difference it will make.

    I really like the idea of ducting cool air into the enclosure and sucking the hot air out because up near the ceiling of my TV room there is a surplus of hot air rising from the central heating, the projector etc. My other half likes the room warm and is currently complaining that I've turned the radiator temperature right down in that room... Hence the cool air duct plan.

    I'm planning to dry the air using dessicator cans so that I'm blowing cold dry air into the box. This air will come directly from outside via a duct.

    I intend to monitor the humidity and temperature inside the projector hush box with one of those little digital gadgets you can buy. I'll be able to see it through the 'window'.

    Let's wait for the foam to arrive...
     
  5. RASH PATEL

    RASH PATEL
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    Hi Webloader,

    I would be interested in the custom ceiling mount.Any idea of the price?

    Rash
     
  6. WebLoader

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    hi rash

    prices are unknown at the moment, it will be cheaper than the sony mount though.

    by the way it is a WALL mount rather than a ceiling mount.

    i am putting some pictures up this evening..

    cheers
     
  7. Markatlarks

    Markatlarks
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    I think there is an alternative. Have you come accross soundproofing plasterboard and foam sandwiches?

    (I am in construction) We have to deal with these noise problems all the time. The use of insulated accoustic plasterboard is a good alternative. It comes in 8x4 sheets - enough for the whole job and doubled up using LiquidNails or gripfil as your adhesive should do the job.

    Have you considered cooker extractor conduit to 'feed' you cool air? Iam a bit concerned about importing 'cold moist air into your room. You should use a heat exchanger - using the cold outside air to cool the internal air. This way you wont get moisture problems.

    Let me know how you get on

    Product Details:

    1200X600 X17 MDF (9mm MDF 8mm Insulation)£13.00+ VAT
    2400X600 Chipboard (18mm Chipboard 8mm Insulation) £20.00 plus VAT

    Please note these are trade prices so you are likely to pay more.

    Phone Sheffield Insulation for more details.
     
  8. John_N

    John_N
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    Hi

    The heat exchanger is a good idea although obivously it makes things a lot more complicated.

    I could use a spare 'condensor' from a condensor tumble dryer because this is effectively an air-air heat exchanger. Or possibly an old turbo intercooler. even an old car radiator might work. Yes I have thought about extractor fan ducting for the air. I was hoping that using a dessicator would remove enough moisture to prevent condensation issues. I might have to do an experiment or two!

    I'll have a further think.

    My present challenge is the rather mundane task of getting the DVI cable and the SPDIF cable from my study into my TV room without ruining the decor. Once that is done and dusted I'll be back on track with the hush box..

    Cheers
    John
     
  9. vulkan75

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    hey John any chance you could get some pictures of your project posted up i really do need things mashed up for me.....ha:eek:
     
  10. Kase

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    JohnN, have you made any progress on your hush box yet? I'm about to start building one for my HS10, having made a number of cardboard mock ups to work out air flow etc..

    My projector will be ceiling mounted and I have found two major issues with air flow so far. Firstly, the heated air rising from the front vents gets sucked into the intake quite easily when the projector is upside down, increasing the fan speed really quickly, but adding a deflector just behind the adjustable foot stopped this happening. Secondly, I can see the heat haze from the hot air, so I have placed thin physical barriers between the lens and the fans.

    I plan to completely encase my projector, and use acoustic foam for the sound deadening, but leave the box open to the ceiling, and have cool air intakes at the back/bottom. However, the whole thing needs to be really easy to close up as small as possible when the projector is off, so that I can recess it between the joists in the ceiling, dropping on a scissor lift, making the whole thing invisible when it is not in use.

    Anyone else managed to design a hush box that they want to show off?
     
  11. John_N

    John_N
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    Hi

    No I haven't started work yet :-( - I have the sound deadening foam and I've found some 18mm MDF that I plan to use doubled up to 36mm thickness for the box.

    Before I could start, I needed to tidy the garage which I've done - and I need a workbench - which my other half said I couldn't buy this month! So I've put it on hold for a few weeks.

    I'm very interested to hear the bit about sucking in hot air from the fron fans. That's a very good point and probably what is happening to my machine when it gets louder and louder.

    I might put an air deflector up there and maybe a temporary wall vent to provide cool air to the HS10. That by itself might help matters... Have to see.

    When I make some more progress I'll post it - like I said - expenditure at the moment has been limited by "her indoors" who is fed up seeing money being spent on projectors, screens and other 'gadgets'.... :)
     
  12. John_N

    John_N
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    Sigh.

    I built my hush box. It worked very well in the garage. However "her indoors" went mental when she saw it and wouldn't allow me to fix it into the viewing room.

    So it's back to the drawing board.

    For anyone interested in this design, I basically used a pine bedding box as the outside cavity and lined it first with felt rubber (wooden floor underlay material) and then with 40mm sound barrier mat (composite with a lead shield in it).

    I mounted the projector firing left to right - ie along the long side of the bedding box and mounted a mirror to bend the light through 90 degrees and out the side of the box. In the prototype I used just an ordinary household mirror - didn't want to spend the cash to get a front silvered mirror.

    The box was unvented in this prototype because it only ran for 2 mins at a time. In the final version it was going to be fan vented.

    Like I said... Back to the drawing board... The new idea is a piece of furniture with it built in instead... Maybe that would work...

    On my HS10 - I was going to swap it but I've only actally had 1 false start and it seems OK now and after seeing the competition I'm not sure it's worth the extra £1000 outlay..

    J
     
  13. Klippie

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    John_N,

    When you say the fan noise from the HS10 bothers you is the volume down low on your sound system when watching films, the reason I ask this is my HS10 sits right above my head in a small room and I cant hear anything from it once the movie sound gets going. I can hear the fan but only in very quiet scenes not enough to annoy me though.

    Maybe try not listening for it all the time and I am sure you will come not to notice it as much.

    Just a thought....

    Klippie.
     
  14. MrSafety

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    I have a large understairs cupboard which is next to the room containing my PJ - you know the type, door in and then the cupboard slopes down under the stairs to nothing. I could put a hole in the wall and project through it using a mirror to deflect the picture onto the screen. One question: would I need ventilation/cooling for this? I guess it would be acting as a large hushbox (in which case I guess I should add ventilation) or as a small room (in which case maybe I could get away with it). The issue of where such ventilation would come from/go to is a different story.

    Anyone done anything similar or have an opinion on this?
     
  15. John_N

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    Hi

    I suspect you will need to suck the hot air out of the cupboard. Otherwise the unit will be sucking in hotter and hotter air and the temperature in the cupboard will rise quite a bit. If you think about the volume of air in the cupboard and the CFM of the fans in the HS10, it won't take long for all the air in the cupboard to effectively go through the HS10.

    If I was you, I would suck air out of the cupboard and blow it under the floor space (if you have a suspended wooden floor). You can also suck cool air IN from under the floor.

    If you have concrete floors then I would blow air out through a vent in the wall somewhere near the top of the stairs fed by a flexible air duct into the cupboard.
     

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