G90 Projector mounted on a custom made stand, and sounded proof. - AVS Forum
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post #1 of 9 Old 07-09-2012, 04:18 PM - Thread Starter
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Pictured are the G90 mounted on a custom made stand.

I had the G90 for a couple years now, sitting in a corner of the HT room along with my other 2 Electrohome PJ's not installed and used since I didn't want to keep the PJ on the floor as it will take up the best seat in the HT room, nor mount it onto the ceiling as it was too much of a hassle with the ceiling reinforcing required to mount the PJ, and then the repair work to dismount the G90 when it's time to retire it in the future. But I thought may be it's time to put this G90 to work before new video technologies render this PJ obsolete. My HT room is also a music room; and as such, I have to be able to sit in the front center seat in order to hear the music correctly. So, the coffee table was not an option as I used to do it with the two 8" & 9" Electrohome PJ's that I have. Besides, the G90 only had 1060 original hours on it in both standby and actual uses; so, it would be ashamed to waste this pristine PJ.

I contemplated this idea for 2 years now, but hesitated so much about doing it because of all the thinking involved and all the effort required doing it all alone. The final decision was made after I decided that I could build a tall 4-leg stand and mount the G90 upside down underneath it instead of to the ceiling directly. I didn't want the 2 front legs of the stand visible to viewers in the 2nd tear sitting; so, I designed a stand where all 4 legs were all behind the viewers with a "forward extended crane" hanging out to the front where the PJ would be mounted. The crane should be short and strong enough to resist the full downward 320-lbs pulling force of the G90 + the Chief mount. The final design looked like a side-way laying U-shape computer stand/table except that it will be very slender and very tall.

The 4-leg stand standed 7'8" tall and fit comfortable under an 8' tall ceiling. It's 4' wide and 16" depth (from the front to back legs); 3' forward at the top (the length of the cranes), 4' at the bottom (the 2 feet) to resist tipping forward. The stand will never tip backward because of the 320 lb weight at the front. The crane was built as a separate part and was bolted onto the top of the stand only AFTER the stand was moved into the HT room and set upright. This was done in order to build the tallest stand possible while still be ale to tilt it up (without the crane) from the laying-on-its-back position after we dragged it into the HT room. The bearing force will be upward for the back legs and the top-back bar due to the upward-lifting fulcrum effect of the cranes resting on the front bar; thus the back legs are non-load bearing. The weight bearing force is downward at the front legs, channeling down to the floor, and also downward along the 60-degree-sland triangle braces in front of the front legs. The end points of the front slant bars were actually the main centers of gravity for weight bearing. So, all the reinforcements to the entire structure were made based on this basic understanding of the directions of all the forces acting on the stand.

Everything was thought of to make sure that I can sit under the G90 and feel totally safe. Constructed out of 2x4, doubled-up 2x4, 4x4 and 2x12 wood bars and some very thick and strong plywood, glued and screwed through out. After all the slant wood/metal bracing/interlocking reinforcements, the cranes and the stand and the cranes can handle 400-500 lbs of load very easily without even the slightest hint of flexing. It was made to be lightest in weight to make it easy to move and least cost, while provided maximum load support, bent proof, tilt proof, swing proof and earth quake proof (I'm in CA!) This design allowed for a full 2nd tear normal sitting (can't recline though as the room is short, 15' W x 17' D).

It took 1 day to cut all the woods to the correct sizes from the final drawing plan, 3 days to assemble and finish the entire stand, 2 days to stain and satin coat it, 1 days to move it into the house, 2 days to mount the PJ underneath it (ran into some Chief hardware fit problems), and 2 days to power up the PJ and get a good picture out of it (ran into problems with the original G90 1.01 firmware). Time from PJ fine tuning doesn't count in this. The total elapsed time was just a little over 3 weeks. Hand/power tools used were the most basic. The wood working skill was basic and average. The total cost was less than $200 for everything including stain, paint and drinks in between. The stand weight around 150-170 lbs when finished, and 3 of us (all between 5' and 5'2" tall and thin) can move them into place with 2x4' wheeled platform. Not bad!

The screen was mounted 2.5' from the front wall to accommodate an older 61" full size TV behind the screen, for watching/listening to materials that don't need a PJ. Distance from PJ's green lens to the screen is 10', front tear sitting to the screen was about 9.5' reclined, and the optimal screen width was 7'8" wide (16:9 - the actual screen was 8'9" wide).

The pictures are from the HT room in the middle of all the moving and rearranging of furniture and equipments, and (failed) firmware upgrade attempts; so, it looked totally disastrous and horrible, and didn't show the stand at its best yet, but you should be able to get the idea. Better pictures will be posted once the HT room is in its final shape and finished... whenever that may be.

Before starting on the stand, I sounded proof the G90, not with the posted fan mod (I rather have more air flow), but by using a product called "B-Quiet Ultimate". This product was typically used to line car's internal metal surfaces to cut down the road noises, to make the car interior more quiet, even more quiet than a Lexus. It can also be used as back lining for enclosed speaker driver installations similarly to Dynamat but cheaper, and it can be used under the feet of stereo equipment (double up the thickness for a max weight of about 60-70 lbs) for more noise dampening. I guessed that this material would produce very similar result to the Dynamat, and also similar to those expensive flat rubber sheets made to add under the stereo equipment's feet to dampen vibrations, but the later sells for $10 for a 10 square inch sheet while this product costs $54 for a 12' x 1' roll. The material has to contact and stick firmly to a surface in order to be able to dampen the vibration passed through it. I bought 12' of this material on eBay, shipped from Canada. It's like a thin sheet of black rubber, 1.5mm thick lined with aluminum foil on one side and adhesive on the other.

To judge how many layers to use, I tap on all the surfaces with the front edge of a plastic spatula and listen to the sound. If it sounded more hollow, louder or more ringing, I would double the layer. If it sound more muted and/or solid, I used only one layer.

To start, I opened the PJ and removed all the back fans, put this material around the fan itself, inside the fan holding casing, all the flat surfaces in front, below and outsides around the fan, in various trenches and inner side wall surfaces of the PJ internal. Maximum of 2 layers can be used to ALMOST DOUBLE the VIBRATION DAMPENING effect. The material can be cut with a scissors. The adhesive on this sheet is very sticky and strong but was still peal-able off the metal surfaces with some persistent tugging and pulling force; so, it's best to peel off a smaller part of the far end(s) of a cut-out shape, position it and verify the final placement before pealing off the rest, and pressing gently along to be sure of a full surface contact with no bubbles. Only apply full force when you are sure since it won't be removable after that. I used a spatula and scraped forcefully onto the silver side surface until it became shinny.

Then, I removed the top-back plastic cover of the G90 and double lined the whole top metal surface, cut around screws and keep 1" from the back edges. Do not glue this material near the back edge as you won't be able to close the top-back plastic cover back down flushed with the sides. I also used the sharp edge of the spatula and scored deep trenches onto the silver side of the material where the plastic support bars under top-back plastic cover left their imprint marking. This helped the top-back cover to stay totally flat when reassembled.

I then removed the front plastic housing below the lens and double layered this material all around the perforated metal case in front of the front fan, all the plastic tops and sides, on all solid surfaces. After that, I cut out dense foam pieces to shape and jam them all around the lens cavity.

I also put this material on entire the top metal lid of the case, including the cutout holes for the 3 lens. I ended up using almost the entire 12' roll at the end.

I also opened both plastic sides and stuffed thin flat acoustic foams into the cavities. Don't over stuff as the side will be pushed out after the covers are reassembled. On both sides, the middle of the lower metal frame had more ringing to it; so, I put some of the dampening material there. On the right panel looking from the front to back, there was a small flat plastic tab stick out near the end of the side cover. Make sure that the screw right around this tab is tight enough, as this tab will push an invisible internal electrical contact inward and that enabled the G90 to power on. Failed that, and you will hear some constant clicking sounds and the G90 will not turn on.

Once done, I tapped the entire lightly PJ with my knuckles and the echo was a very solid and dampened sound all around, a very good sign. Once the G90 was turn on, the result was a very well dampened sound all around, lesser in decibels and more importantly, it cuts out some of the higher pitch noises that was more of an audio irritation than anything else, and the smaller front fan was far worse at this than the back 4 big fans. The G90 was quiet enough now that it was no longer bothering me even without the fan mod. For those of you who did the fan mod, this will make it even more whispering quiet. I thought the Electrohome's that I used before were much more quiet than the G90 initially when I first fired up the G90; but now the G90 was definitely even more quiet than the Electrohome as I remembered.

The stand and all the sound proof done with the B-Quiet Ultimate material that I added to the G90 tamed down the high pitch loud noises from the G90 greatly and made it very acceptable both visually and audibly for all viewers.

After everything was done, I will mount a curve 4' wide and 4' tall 1/8" thin board starting from under the middle of G90's back (now upside down) down toward the back side of the stand. then I will fix/glue 6 sheets of very dense 2' x 6' x 1" foam sheet (from fabric stores that sell furniture refinishing materials) to the back side of the board, making it a 4'W x 6'H x 3"D barrier on the back side. This will cut down some more of the noise still coming out of the back side of the G90, and it will also channel all the hot air off the back of those sitting in the 2nd tear.

I hoped this helps inspire somebody with their project.
DT999.
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post #2 of 9 Old 07-10-2012, 10:47 AM
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wow, what could have been a 2 or 3 hours job for a carpenter with a 30 minute dry-wall patch turned into a huge woodworking project. It's amazing how people can turn something so incredibly simple into so something so complicated.


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post #3 of 9 Old 07-11-2012, 12:39 AM - Thread Starter
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I am very happy with this choice as it gave me more freedom to experiment with various setups. This "complicate project" already paid off nicely so far since I was able to move the stand around a bit to test for different viewing angles as I was not sure how I wanted the room to be. I am a tactile and visual person; so, I make decisions better with direct experiments rather than just imagining or guessing. Simple questions such as should I face the PJ outward or inward, leave it more in the middle or more to the left or right of the room, what screen size is better and how far the PJ should be for such screen size, how about adaptability to future equipment and room changes are a few to name. It's not convenience nor economically to cut a hole in the ceiling and patch it up and cut another hole just to find out if a setup is good or not, or after I changed my mind about a setup or wanted to try something else. I needed the full mobility of the stand to explore those possibilities. This HT room was also not for movies only, and thus it gave me more flexibility to accommodate many goals I had in mind for this room.

So, yes, it seemed more complicate as it might appear to some people, but it is simpler and easier for me (minus the initial effort) to manage in the long run. There are also other personal reasons that benefited me so much more than just having the PJ up and running alone by doing this project personally. People have different reasons to make their choices. If we make choices to seek approvals from others rather than to make ourselves happy personally, then… well… good luck with that!

Cheers.
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post #4 of 9 Old 08-18-2012, 06:48 AM
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I truly believe this is a great solution.Maybe not the right one for a lot of people that managed in a different way but it is an amasing solution for some type of situations. smile.gif
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post #5 of 9 Old 09-08-2012, 12:33 AM - Thread Starter
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Per members' requests, I posted the plan of the stand for those who want to try their own construction. It took me a week to complete the whole thing, about 3 days worth of real wood work plus rest time in between waiting for the glue/paint to dry, doing it alone for the most part. Two persons would make it go much faster. It was built with earth quake proof in mind, and we had 2 light earth quakes so far and all were well. The total weight of the G90 plus the mount was about 320 lbs, but this stand can bear 400 lbs worth of weight easily; so, a Marquee 9500 would do much better at about 50 lbs less in total weight. wink.gif

Projector stand Plan.
Projector Stand Design.xls 99k .xls file

Construction notes.
Projector Stand Design.doc 49k .doc file
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post #6 of 9 Old 09-08-2012, 09:57 PM
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I really appreciated it ,you made and incrdible work with descritpion. This is stupid proof and that's exactly what I was looking for!
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post #7 of 9 Old 09-09-2012, 01:08 PM
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Interesting solution. Another way to do it is to mount the pj vertically behind the couch with a mirror. Pjackso did this and may still be using this configuration.

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post #8 of 9 Old 09-09-2012, 05:10 PM - Thread Starter
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This would work if the PJ projecting distance is much longer than the seating distance. For my 8' wide screen (110" diag), 9.5' projecting distance from the front of the lens and 10' seating distance felt best for me; and as such, the main seating area was right below the PJ, overlapped by a foot or so.
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post #9 of 9 Old 09-11-2012, 07:42 PM - Thread Starter
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I corrected one drawing error on the "V" bars on the lower back of the stand, to show the correct cut angle of the top of the bars.
Projector Stand Design.xls 99k .xls file
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