I've searched the other forums on this site but all of the information I find relates to other things or was not difinitive enough to lead me to an answer - they were all concerning diy components.
Simply put, I use my laptop to play the dvd's on the projector. I run the audio through the prologic sterio receiver. My cable is a heavier stereo cable with a stereo mini plug to the laptop and stereo rca's (red and white) to the reciever. The video to the pane is through the vga out.
I get a low end hum from the speakers. I've tried several things - positioning of the cable, trying the laptop on battery power rather than AC, etc.
Does anyone know right off hand the fix for this?
Lori
Simply put, I use my laptop to play the dvd's on the projector. I run the audio through the prologic sterio receiver. My cable is a heavier stereo cable with a stereo mini plug to the laptop and stereo rca's (red and white) to the reciever. The video to the pane is through the vga out.
I get a low end hum from the speakers. I've tried several things - positioning of the cable, trying the laptop on battery power rather than AC, etc.
Does anyone know right off hand the fix for this?
Lori
This sounds like interference from your projector... ie metal halide light or somthing like that. Also, some laptops i have had cause interferance with the soud card (i belive basically any computer will as long as it is an analog signal). One way to solve this problem would be to buy an external digital usb sound device that ouputs optical then run that to your reciver. This way the entire signal will be digital and there will be no interference (may be a little costly though 
). Aslo you might want to try a heavy sheilded cable.
). Aslo you might want to try a heavy sheilded cable.
OMG - This nearly killed me laughing
Immediately before I started this project, I had recently finished rewiring my whole house. This is a 1911 home which had only 1 or 2 outlets in each room. I specifically wired this room with craploads of outlets so I wouldn't have to use powerstrips or run extension cords for anything.
Nevertheless, the problem remains even if the laptop is running on battery power w/o the power adapter, so probably not the problem.
I hate to appear uninformed, but this is not a strong point of mine, so what is a "hum box" A link to purchase will suffice - to spare you having to explain.
Thanks
Immediately before I started this project, I had recently finished rewiring my whole house. This is a 1911 home which had only 1 or 2 outlets in each room. I specifically wired this room with craploads of outlets so I wouldn't have to use powerstrips or run extension cords for anything.
Nevertheless, the problem remains even if the laptop is running on battery power w/o the power adapter, so probably not the problem.
I hate to appear uninformed, but this is not a strong point of mine, so what is a "hum box" A link to purchase will suffice - to spare you having to explain.
Thanks
I'll find you a link... they are real cheap and should 'almost' kill the hum depending on how bad it is.
It's simply a little box that you wire the sound through. I'll post the link here as soon as I find one with good specs.
BTW... Does the laptop have an audio output or are you just using the mono phono output (should have a little picture of headphones). If your using the mono output that could also be a problem. You would then need a mono to stereo converter. Let me know.
-John
It's simply a little box that you wire the sound through. I'll post the link here as soon as I find one with good specs.
BTW... Does the laptop have an audio output or are you just using the mono phono output (should have a little picture of headphones). If your using the mono output that could also be a problem. You would then need a mono to stereo converter. Let me know.
-John
electrical interference
took this from a recording forum I peek in on every now and then and thought this might be of some small signifigance
"The insulation o a power cord is designed to protect you from shock, not to stop magnetic fields, so they are surrounded by an oscillating magnetic field at 60hz. Put that paralel to another wire for a significant length and it will induce a similar oscillating current in it at 60hz, or a bass hum."
took this from a recording forum I peek in on every now and then and thought this might be of some small signifigance
"The insulation o a power cord is designed to protect you from shock, not to stop magnetic fields, so they are surrounded by an oscillating magnetic field at 60hz. Put that paralel to another wire for a significant length and it will induce a similar oscillating current in it at 60hz, or a bass hum."
I had a similar problem with the sound output from my laptop when connecting it to the amp that I built. The problem ended up being a ground loop from the laptop.
To find out if grounding is your problem, unplug your laptop and run it from the laptop's battery only and see if the hum goes away. If it does, then a ground loop is causing the problem.
Brian
To find out if grounding is your problem, unplug your laptop and run it from the laptop's battery only and see if the hum goes away. If it does, then a ground loop is causing the problem.
Brian
She just said that the hum is still there with the laptop running on Battery power... so it's not a grounding issue.
I found a few hum boxes that should help... but before I recommend that you buy one I'd like to be sure it's needed. Lori, I just need an answer to my last question. How are you running audio from the laptop to the receiver? Meaning what output on the laptop are you using?
-John
I found a few hum boxes that should help... but before I recommend that you buy one I'd like to be sure it's needed. Lori, I just need an answer to my last question. How are you running audio from the laptop to the receiver? Meaning what output on the laptop are you using?
-John
Upon further inspection
I've always assumed stereo output. I have L/R balance, etc. I am sending audio out the headphone jack on the laptop, but I have settings for output to stereo headphones, 5.1 surround, 7.1 surround, regular surround, quad, etc.
I'm using a stereo plug.
I tried a few more things. Everything is fine until I plug the projection panel in and turn on the projector. I tried turning on/off the panel and projector independently of each other. Each of them produces a hum. When they are both on at the same time, the hum is amplified. I tried lifting the panel off of the projector, the hum remains. If one is off and the other is on, the hum is still there but not as loud.
Both the projector and the panel have ground plugs and I wired the circuits in this room myself. I know my polarity is right and I know my grounds are good at the receptacle.
Next?
I've always assumed stereo output. I have L/R balance, etc. I am sending audio out the headphone jack on the laptop, but I have settings for output to stereo headphones, 5.1 surround, 7.1 surround, regular surround, quad, etc.
I'm using a stereo plug.
I tried a few more things. Everything is fine until I plug the projection panel in and turn on the projector. I tried turning on/off the panel and projector independently of each other. Each of them produces a hum. When they are both on at the same time, the hum is amplified. I tried lifting the panel off of the projector, the hum remains. If one is off and the other is on, the hum is still there but not as loud.
Both the projector and the panel have ground plugs and I wired the circuits in this room myself. I know my polarity is right and I know my grounds are good at the receptacle.
Next?
I have experienced something similar to your "humming" problem with the computer to stereo hookup, which has only been a problem when my monitor is close to the audio cable. What has always worked for me is to keep the computer volume and program volumes (i.e. winamp) down very low, and turning up the volume on my receiver. I don't know why/how it works, but it has worked well for me. Good luck!
Hello Everyone.
I've tried a hundred things to no avail. I would still like the link to the "hum box" you referred to.
I am still finishing this room and in the last few days have pulled and routed all of the audio video cables and installed all of the jacks so I will finally be able to sheetrock and finish the room.
My husband cracked the fresnel last night since I still don't have the enclosure built for the thing and he was trying to help by cleaning the lenses and fresnel before we watched a movie, so now to deal with that. Is there any other source than DIY labs because as long as it took to get the triplet lense from them, I'm really not inclined to order from there again.
The humming got too much for me last night so I stopped in the middle of the movie, effectively irritating everyone in the household. Strange how little things don't cross your mind, but I decided maybe it was a ground problem afterall, so I searched the house for a 3 to 2 plug (which I'd packed away now that the house is rewired and we actually have ground and outlets w/ ground plugs). Popped the 3 to 2 on the QA 1650 power cord, plugged it in and NO HUM! Disappeared instantly. I don't know what the ramifications of running it long term this way may be, so if that would help determine what I really need to do to fix the problem directly, I'd love to hear it.
Thanks for all the suggestions. I appreciate your responses.
I've tried a hundred things to no avail. I would still like the link to the "hum box" you referred to.
I am still finishing this room and in the last few days have pulled and routed all of the audio video cables and installed all of the jacks so I will finally be able to sheetrock and finish the room.
My husband cracked the fresnel last night since I still don't have the enclosure built for the thing and he was trying to help by cleaning the lenses and fresnel before we watched a movie, so now to deal with that. Is there any other source than DIY labs because as long as it took to get the triplet lense from them, I'm really not inclined to order from there again.
The humming got too much for me last night so I stopped in the middle of the movie, effectively irritating everyone in the household. Strange how little things don't cross your mind, but I decided maybe it was a ground problem afterall, so I searched the house for a 3 to 2 plug (which I'd packed away now that the house is rewired and we actually have ground and outlets w/ ground plugs). Popped the 3 to 2 on the QA 1650 power cord, plugged it in and NO HUM! Disappeared instantly. I don't know what the ramifications of running it long term this way may be, so if that would help determine what I really need to do to fix the problem directly, I'd love to hear it.
Thanks for all the suggestions. I appreciate your responses.
Lori are using the laptop with the charger plugged in?...that will create noise
and running the laptop with that adaptor wont hurt anything....its there to protect the equipment
and on a note those stereo mini jacks are herrendous for noiseI wired up some rca jacks on my comp but I know thats not feasible with a laptop.....maybe think about a cheap comp
and running the laptop with that adaptor wont hurt anything....its there to protect the equipment
and on a note those stereo mini jacks are herrendous for noiseI wired up some rca jacks on my comp but I know thats not feasible with a laptop.....maybe think about a cheap comp
Been there, done that. I previously tried all of those suggestions.
It's not the laptop power supply that is causing the hum. The hum only appears when the 1650 is plugged into the laptop. What eliminated the hum was not plugging the laptop adapter into the 3 to 2 plug, since the laptop charger doesn't have a ground plug to begin with. What stopped the hum was to plug the QA 1650 in using the 3 to 2 adapter. That is what killed the hum. I just want to be sure I won't be causing long term damage to the the panel or leaving the laptop wide open to something hitting it through the connection to the QA 1650
At some point, I will build a compact computer that will fit into the cabinetry for this room strictly for movies and audio. I've got several cases that would fit the bill, and it won't take much since I can pull music off one of the servers, but I have other projects right now. I've got 7 other machines running + 4 other peoples computers here to be repaired and I'm more than a little burnt on the computers right now.
The laptop is going to have to do the job for probably at least through the winter, because I want this project done right without wires running all over the place, or computer cases cluttering up the room. I have lot of work ahead of me before it's complete, so right now, I just want to use it as it is when we need a distraction or time out from the work to relax and watch a movie - without the hum... and I don't think I could go back to watching movies on the television after having had a taste of this.
Lori
It's not the laptop power supply that is causing the hum. The hum only appears when the 1650 is plugged into the laptop. What eliminated the hum was not plugging the laptop adapter into the 3 to 2 plug, since the laptop charger doesn't have a ground plug to begin with. What stopped the hum was to plug the QA 1650 in using the 3 to 2 adapter. That is what killed the hum. I just want to be sure I won't be causing long term damage to the the panel or leaving the laptop wide open to something hitting it through the connection to the QA 1650
At some point, I will build a compact computer that will fit into the cabinetry for this room strictly for movies and audio. I've got several cases that would fit the bill, and it won't take much since I can pull music off one of the servers, but I have other projects right now. I've got 7 other machines running + 4 other peoples computers here to be repaired and I'm more than a little burnt on the computers right now.
The laptop is going to have to do the job for probably at least through the winter, because I want this project done right without wires running all over the place, or computer cases cluttering up the room. I have lot of work ahead of me before it's complete, so right now, I just want to use it as it is when we need a distraction or time out from the work to relax and watch a movie - without the hum... and I don't think I could go back to watching movies on the television after having had a taste of this.
Lori
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