E
ecc83
Well-known member
Best start an new thread, in noobs but give details of YOUR equipment and setup.
Dave.
Dave.
famous beagle
Well-known member
So I tried this. I made a patch chord with the shield disconnected on one end. The cable passed signal, so I know I wired the hot correctly, but there was no change with the hum issue.
Then, I tried a ground lift adapter just for kicks on the PC cord (the Behri cord is two prong already), and that didn't help at all. In fact, it made the hum significantly louder.
I don't understand, because I used this same system before I moved out here with no hum problem.
So I have no idea what to do now. I think I may just tear down the entire system and start completely over, listening as I plug in each piece of gear to hear when the hum occurs.
Then, I tried a ground lift adapter just for kicks on the PC cord (the Behri cord is two prong already), and that didn't help at all. In fact, it made the hum significantly louder.
I don't understand, because I used this same system before I moved out here with no hum problem.
So I have no idea what to do now. I think I may just tear down the entire system and start completely over, listening as I plug in each piece of gear to hear when the hum occurs.
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famous beagle
Well-known member
New development! I discovered the source of the hum!
Rather than tearing everything down and starting from the ground up, I decided I should just work backwards, leaving the PC and Behri plugged in and unplugging everything else systematically. It didn't take long at all. The third cord I pulled was for the CPU monitor. Once I did that, the hum disappeared.
(And wouldn't you know it .. I just got this monitor when I moved out here. And that explains why I didn't have this problem at my old place.)
Just for kicks, I tried a ground lift adapter on the monitor plug, and sure enough, the hum was gone. I tried plugging the monitor into a different outlet in the room (without the ground lift adapter), and the hum was still there. I know you said not to lift main earth (and I've heard that elsewhere too), so ... what other fix can I try?
Another development: If I disconnect the monitor from the PC, but still leave the PC plugged in, the hum goes away.
So it's the connecting of the monitor to the PC while the monitor is plugged in that's causing the hum.
This isn't tragic news for me, at least, because I bought this monitor (a flat-screen Samsung SyncMaster 170mp) used at a garage sale for $10. I did so because I wanted a monitor that I could use in conjunction with my camera in the studio so I could see what's going on from the control room (I can't afford to do the window). I bought this monitor specifically because it had both PC and TV outs, so I thought I could kill two birds with one stone. It works perfectly in TV mode as a monitor for the camera, so that's good, but when used with the CPU, it's flickering, and I can not get it to stop, regardless of what I try. (I've read up online for hours and tried every fix I could find.)
Annnnnyway, the good news is that I can still use this as a monitor for my camera, which is what I originally bought it for anyway. I'll just have to get another monitor for my music CPU, because I (prematurely, it seems) got rid of it when I got this one. (It was a cheapie.)
Knowing this new development, do you have any clue what's going on? (I'm wondering now if the monitor's flickering could be at all connected to the hum issue?)
Rather than tearing everything down and starting from the ground up, I decided I should just work backwards, leaving the PC and Behri plugged in and unplugging everything else systematically. It didn't take long at all. The third cord I pulled was for the CPU monitor. Once I did that, the hum disappeared.
(And wouldn't you know it .. I just got this monitor when I moved out here. And that explains why I didn't have this problem at my old place.)
Just for kicks, I tried a ground lift adapter on the monitor plug, and sure enough, the hum was gone. I tried plugging the monitor into a different outlet in the room (without the ground lift adapter), and the hum was still there. I know you said not to lift main earth (and I've heard that elsewhere too), so ... what other fix can I try?
Another development: If I disconnect the monitor from the PC, but still leave the PC plugged in, the hum goes away.
So it's the connecting of the monitor to the PC while the monitor is plugged in that's causing the hum.
This isn't tragic news for me, at least, because I bought this monitor (a flat-screen Samsung SyncMaster 170mp) used at a garage sale for $10. I did so because I wanted a monitor that I could use in conjunction with my camera in the studio so I could see what's going on from the control room (I can't afford to do the window). I bought this monitor specifically because it had both PC and TV outs, so I thought I could kill two birds with one stone. It works perfectly in TV mode as a monitor for the camera, so that's good, but when used with the CPU, it's flickering, and I can not get it to stop, regardless of what I try. (I've read up online for hours and tried every fix I could find.)
Annnnnyway, the good news is that I can still use this as a monitor for my camera, which is what I originally bought it for anyway. I'll just have to get another monitor for my music CPU, because I (prematurely, it seems) got rid of it when I got this one. (It was a cheapie.)
Knowing this new development, do you have any clue what's going on? (I'm wondering now if the monitor's flickering could be at all connected to the hum issue?)
E
ecc83
Well-known member
Heh!
In the hum/interference/humloop stakes top billing goes to laptop chargers when used with active (earthed) monitors.
Next come guitar amps when peeps play around with either "two amp" switching or "re amping".
A close last is visual monitors tho' the old CRT jobbies used to be notorious for spewing out crap! I have never had a problem with any FST monitor and in fact one of my two pc monitors is an LG 20" TV (probably not the last word in resolution for your hard nosed gamer but more than good enough for Cubase!) .
And you are correct, DO NOT LIFT MAINS EARTHS! Since you can sort the problem in other ways I would waste no more time on it. The hum issue and the flickering are probably not related but the TV probably had some design fault, I would let it lie. I guess it takes an IEC mains lead straight in? Most monitors run from a line lump and you can sometimes find a two conductor (fig 8) version sans earth, same goes for laptop supplies.
Dave.
In the hum/interference/humloop stakes top billing goes to laptop chargers when used with active (earthed) monitors.
Next come guitar amps when peeps play around with either "two amp" switching or "re amping".
A close last is visual monitors tho' the old CRT jobbies used to be notorious for spewing out crap! I have never had a problem with any FST monitor and in fact one of my two pc monitors is an LG 20" TV (probably not the last word in resolution for your hard nosed gamer but more than good enough for Cubase!) .
And you are correct, DO NOT LIFT MAINS EARTHS! Since you can sort the problem in other ways I would waste no more time on it. The hum issue and the flickering are probably not related but the TV probably had some design fault, I would let it lie. I guess it takes an IEC mains lead straight in? Most monitors run from a line lump and you can sometimes find a two conductor (fig 8) version sans earth, same goes for laptop supplies.
Dave.
famous beagle
Well-known member
Thanks for the info. So ... is there any way to know whether or not a monitor will cause this issue? I've used two before this current flat screen---one was the big old CRT type, and another was a different flat screen---and neither or them had a hum issue at all. I'd rather not get another monitor that has the hum issue. Is there any way you can predict this?
By the way, what does "FST" stand for?
Thanks
By the way, what does "FST" stand for?
Thanks
E
ecc83
Well-known member
There will always be some combinations of equipment that do not get on, PCs and Fussywire AIs is a very common one but in general we all have to take a bit of a risk. You could however look for a monitor with an earth free power supply? No promises mind!....WARNING! Hobby Horse about to be trotted out!
People get into this recording game thinking it is easy and they can buy everything they need. But one thing they cannot buy is a basic knowledge of electrical circuits and some simple electronics nonce. Things are fine until a problem crops up and it is very hard to fix things by remote control!
Ok, it's safe to come out now!
Flat Screen Technology.
Dave.
famous beagle
Well-known member
Yeah, I guess I've been lucky with regards to ground hum, because I've been involved with home recording for over 20 years using the most pedestrian of gear and can count the times on 2 fingers I've experienced an issue, including this one.
Just out of curiosity, what's the difference between a monitor with a two-prong plug and using a ground lift adapter on one with a three-prong?
Just out of curiosity, what's the difference between a monitor with a two-prong plug and using a ground lift adapter on one with a three-prong?
dgatwood
is out. Leave a message.
You can try star-grounding everything else. The most likely cause of this sort of problem is that the monitor is providing a path for some other noisy piece of gear's ground hum to flow to ground. The best way to fix that is to provide a shorter, much-lower-resistance path to ground from whichever piece of gear is noisy—one that doesn't flow through the shield of any of your audio cables.
Urgh. Yes. That suggests to me that either the monitor or your computer has a defective power supply that's noisy as heck. It's anybody's guess which one, but I'm kind of leaning towards the monitor, if you've never had problems with other devices. In that case, no grounding fix is going to help. You probably need to recap the monitor....
Then again, I'd be half-tempted, in your case, to do a mains lift on just the monitor (leaving the mains ground on the computer connected) and see if that helps, but I'd then want to get somebody else to touch some metal part on the back of the monitor with the back of his or her hand to make sure the case isn't hot....
