GS1200 Speaker Removal

[Paul Adsett]

I have removed both speakers from one of my GS1200's. I have never used them and taking them out drops the weight by about 4 lbs and improves the cooling air flow through the electronics section.

[Graham Ritchie]

Paul

That's a good idea I will do the same, as I come to think of it I never use them

[Ed Gordon]

I am not familiar with the interior of a GS1200. Does removal of the speaker allow more air movement in/out of the case? The reason I ask is that if removing the speaker allows more air movement in/out, this would interfere with the air flow design. I have heard of problems introduced into computer cases when a user removes cards and does not put slot covers back on the case, which introduces over heating.

Do not remove unused expansion slot covers from a system case. The system case is a pressurized system, with carefully designed airflow that directs outside air across components and out of the case. When you remove the system cover or expansion card covers, you modify the airflow path, which typically reduces the cooling effectiveness of the system fans.

[Stuart Budd]

"pressurized system" This is probably a laptop or compact system such as Apple stuff. But see your point.

[Paul Adsett]

Ed you have raised a perfectly valid point. The only way to provide a definitive answer would be to do a fluid dynamic analysis of the GS1200 enclosure This can be done using CAE finite element analysis programs such as ANYS, which I used when I was designing for Northrop Grumman. The task would be to create a 3D solids model of the GS1200 interior using a CAD program such as CREO and then transfer the model into ANSYS for meshing. Such a task, even with computer power, would take hundreds of man hours to provide a definitive answer to your question. Another approach would be to mount thermocouples throughout the internal structure and measure temperature rise on the more critical components, with and without the presence of the speakers.
As of now I am going to assume that removal of the speakers, which sit over the top of much of the main control board, will be more likely to be beneficial, by opening up the interior and allowing more air to flow through areas that might have been stagnant or constricted.

[Graham Ritchie]

One thing I am going to look at is what I did with the 16mm last year, and that was to fit a small high speed fan, but this time on the inside where the speaker was, that will "draw in" more outside air. There are plenty of small very efficient silent running fans on the market.

[Steve Klare]

I think the side of the chassis where the speakers is low air pressure, low speed air, the high pressure, high speed airflow goes past the lamp and the speakers being there or not shouldn't make a significant difference.

Where it might make a difference is power semiconductors for the audio circuits. The good news is if you don't have speakers there, but are amplifying line-level signals externally, the power in these devices would be next to nothing and they will stay cool no matter what. Now, if there was going to be a problem, it would probably come if the amps directly drive external speakers with that altered flow. (I suppose you could block the speaker grills to keep the airflow through the inlets Elmo designated in the first place.)

This is one of the reasons I like amplifying the sound externally. It forces the device temperatures outside the projector into modern (and disposable) circuits. If I roast my Sony amp, I shed no tears: just go to Best-Buy and pick up another one!

[Paul Adsett]

I like Graham's suggestion for an additional fan is an excellent idea, mainly because he and I are both using 250w ELC lamps in the GS1200, albeit with the lamp totally powered from an external power supply. An additional 24vdc fan, could be powered directly from the existing 24vdc lamp socket in the projector which is no longer used to power the lamp. This would help dissipate some of that extra 50w of heat from the ELC.

[Stuart Budd]

Ed you have raised a perfectly valid point. The only way to provide a definitive answer would be to do a fluid dynamic analysis of the GS1200 enclosure This can be done using CAE finite element analysis programs such as ANYS, which I used when I was designing for Northrop Grumman. The task would be to create a 3D solids model of the GS1200 interior using a CAD program such as CREO and then transfer the model into ANSYS for meshing. Such a task, even with computer power, would take hundreds of man hours to provide a definitive answer to your question. Another approach would be to mount thermocouples throughout the internal structure and measure temperature rise on the more critical components, with and without the presence of the speakers.
As of now I am going to assume that removal of the speakers, which sit over the top of much of the main control board, will be more likely to be beneficial, by opening up the interior and allowing more air to flow through areas that might have been stagnant or constricted.

Wouldn't sound have an effect on cabinate air flow too? The speakers being active. Sound volume and frequency, mono and stereo, a push pull effect. Then component vibration too. Actually, if testing, probe silent then with volume. I'm slowly paddling towards the deep end here, out of my depth. One of the reasons Elon fired me.

It's funny how A/V appears to be one and silent projectors seem lacking the A bit. But as mentioned above and how they're captured. It would seem one box for both is just for convenience. Separating them again like the early Phonomatics seems a good idea. Just keeping the sound head. I really should get the GS out of it's box! Beginning to miss it.

[Steve Klare]

I've had similar thoughts: shouldn't the vibrating air inside the machine cabinet get to the film itself and maybe cause sound and image distortion?

-then again there is generally a side of the machine where the film is and a separate side where the machinery and speakers are.

-and No! My picture didn't improve when I went to external speakers (-sound sure did, for other reasons...)

[Paul Adsett]

One other note. When you remove the speakers from the back cover of the GS1200 you will see that a black mesh cloth is sandwiched between the speaker and the cover. These seem to be lightly tack glued to the inside of the back cover. I decide to remove these as well to provide even better flow of air through the metal grills. They just lift of real easy without any hassle.
A correction on my previous post. The power to the lamp in the GS1200 is of course 24vac not 24vdc, so an additional fan would need to be 24vac. Got mixed up with my 250w external lamp power supply which is actually 24vdc.

[Paul Adsett]

A further observation: what I thought was black speaker cloth looks in fact to be a very fine wire mesh. So it is possible that this mesh served the purpose of EMI shielding, as well as physical protection of the speaker cones. So far I have seen absolutely no adverse effect removing the speakers and the wire screens from the projector, and the machine does seem to run cooler, and the weight reduction is very welcome.