8mm Forum: Running Projector Through A Stereo System

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Posted by Roger Shunk (Member # 2836) on February 02, 2012, 09:24 AM:

Hello,
I don't know alot about electronics but I would like to hook up my stereo through my projector for better sound reproduction. I have a Elmo ST-800 and the on the back of the projector it has a AUX OUT to run a mini jack with two RCA plugs that go to the stereo receiver. Do I have to get a mono jack from the projector because if I get a stereo jack won't only one channel
work because I pluged my stereo headphones into the headphone jack of the projector and the sound only came out one side of the headphones.
If anyone can shed some light on the subject I would appreciate it!

Thanks,
Roger

Posted by Martin Jones (Member # 1163) on February 02, 2012, 09:40 AM:

Quite right, Roger. The output is a MONO socket, so you must use a MONO plug.
You then have two options...
1 If your Stereo Amplifier has a MONO position on its selector you can use a MONO lead plugged into either left or right input.
2 If not, you will need to use a "3.5mm Mono Jack to 2 x Phono" lead, which will convey the same MONO signal to both inputs.

This will undoubtedly give you better sound than the internal speaker; however, the AUX socket on this projector carries exactly the same signal as the speaker feed, so all the amplifier noise/hum will be there as well, so do not expect HI-FI!

Martin.

Posted by Steve Klare (Member # 12) on February 02, 2012, 09:57 AM:

Where to Begin!

This has been my pet project for a long time and it's going nicely (Wife may say it's actually getting out of hand...)

I can tell you this can work quite well, but there are some issues.

You need to get together some wiring to plug the monaural aux output into the stereo amp. Radio shack probably has what you need. What you run into very often is because the projector and your Amp aren't grounded well, you'll get a ground loop and pretty severe hum.

If it's practical, you can plug the projector and amp power cords (and grounds) into the same outlet. This isn't practical for me because my projector and stereo are 20 feet apart and my amp is grounded to my TV, which is grounded to my cable box, which is grounded through 75 feet of coaxial cable to the service entrance out in my garage.

I built a circuit to kill this problem, but Radio Shack also has a ground loop eliminator if you aren't up to building one..

-you may need that too.

The reason you only got one channel is the monaural jack on the ST-800 only contacts the tip(Stereo channel left or Mono) and the base (ground) of the stereo plug. A stereo jack has a third contact to touch the third contact in the middle (Stereo Right) which is absent from mono connectors.

Posted by Roger Shunk (Member # 2836) on February 02, 2012, 09:57 AM:

Thank you both for your suggestions! I was wondering if it would be possible to run a battery wireless hook-up with a transmitter? No speaker wires to deal with.

Roger [Confused]

Posted by Steve Klare (Member # 12) on February 02, 2012, 10:47 AM:

I thought about doing this too. It would certainly take the ground loop out of the equation. (-and the cables running around the room...)

One of the deciding factors is I don't have an FM antenna! (I almost never listen to radio at the house.)

I built my settup mostly for the satisfaction of solving a problem. Saner folk can certainly find easier and quicker ways to do the same thing.

-It's the same "logic" that leads some to building ships in bottles!

Posted by Osi Osgood (Member # 424) on February 02, 2012, 12:47 PM:

I tend to use (for a mono super 8 track), my Dolby Surround sound processor from the 1980's, as it has a switch for "simulated stereo", and that gives a very nice sonic quality to the sound reproduction.

Posted by Steve Klare (Member # 12) on February 02, 2012, 01:19 PM:

My amp has a "surround" function which I think is just a slight reverb. It works nicely with CDs but it just makes my movie tracks kind of muddy.

If I have my head in the game, the first thing I do when I don't like the sound I'm getting is check to see if that LED is dark.

Posted by Paul Adsett (Member # 25) on February 02, 2012, 01:27 PM:

I connect a 10 band graphic equalizer between the projector and the stereo amp. You can then adjust the levels of each of the bands to notch out mains hum, low frequency rumble, and high frequency hiss. It greatly improves the quality from a lot of pre-recorded films.
I have tried the wireless connection, but it was not very satisfactory, the audio quality was definately inferior to a wired connection.

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