[LarryV]

Just installed RecordNow9 Music Lab and hooked up a high quality cassette deck and tried to digitize the analog signal to HD. Before starting the recording, the volume scales showed some fluctuating sound coming through, though I could hear nothing. Did the recording, which sounded nice, but there is a low frequency hum in the background that is very annoying. How do I either avoid picking up the hum or remove it once the digitizing is complete? Thanks. LRV

[Brendon]

I used to get a terrible hum when recording. The way I got rid of it was to clip a wire between the frame of the computer and the frame of the amplifier, to ground one to the other.

[LarryV]

I used to get a terrible hum when recording. The way I got rid of it was to clip a wire between the frame of the computer and the frame of the amplifier, to ground one to the other.

Thanks for the suggestion. Actually, there is no amp connected. The input wires to the computer are coming straight out of the cassette deck. So, no amplifier. Also, I see that even with the cassette deck turned off, when I go to the LP/Tape page in Music Lab, the input volume scales show fluctuating sound levels coming in from somewhere (R somewhat more than L) when the input volume is put high. The only way to reduce this mysterious input volume is to turn the input volume levels way down. Same result even with the computer's sound system turned off. Might this be from some 60 cycle power cord, etc? Thanks. LRV

This post has been edited by LarryV: 09 July 2009 - 10:21 AM

[LarryV]

Further to my problem. I've even unhooked both the sound input and output connectors and the mystery input still registers on the input meters. So, am I correct in assuming that the problem lies inside my computer? If so, what do I do to get rid of the problem? Thanks again. LRV

[Brendon]

Hard to say without having your computer on the bench to test, however if your input is 'floating' you might be picking up some of the plentiful hash which is present in your computer. Grounding your deck [which contains the amp] to your computer and using proper shielded audio cables should reduce any 60 Hz hum.

[LarryV]

Hard to say without having your computer on the bench to test, however if your input is 'floating' you might be picking up some of the plentiful hash which is present in your computer. Grounding your deck [which contains the amp] to your computer and using proper shielded audio cables should reduce any 60 Hz hum.

I tried grounding the computer to the cassette deck, but no change. Talked to some friends who speculate that it's 60 cycle background from the power wires, etc. I turned off the room lights, turned off unnecessary electronic equipment, etc., but no change. Other than enclosing the computer in a lead lined box, how does one get rid of such interference? If there is no internal "defect" in my computer, doesn't this happen to other users of this (and perhaps other) sound using programs? Thanks.

[Brendon]

Sorry, all I can say is that this worked on my machine.

It won't be 'background noise' that's getting into your machine. If you are feeding your machine on 60 Hz mains power the machine itself will be generating a zillion times more 60 Hz hum than anything else in your room, and the steel case is designed to keep the hum IN so the machine can get FCC approval.

If you're grounding your equipment at a common point and using shielded audio cables then any residual hum is being caused by poor filtering or poor design in your machine. From here on it would probably require a technician to rebuild parts of your computer. I'm sorry I can't suggest anything simpler.

[ogdens]

You are plugged into the Line In jacks on your sound card, correct. I am not familiar with RecordNow9 Music Lab, but does it have a Sound Editor application, if so, do you get the same problem using it.

This post has been edited by ogdens: 12 July 2009 - 05:01 PM

[LarryV]

You are plugged into the Line In jacks on your sound card, correct. I am not familiar with RecordNow9 Music Lab, but does it have a Sound Editor application, if so, do you get the same problem using it.

Thanks for the suggestions. However, the problem persists. Tried grounding the cassette deck to the computer. No luck. Using Sound Editor shows the same problem with "floating" inputs even without any signal being sent to the computer from the cassette. Weird that the floating inputs show the L line slightly higher than the R line for all input alternatives except Mic where the R input is higher than the L. Computer is an HP Pavillion 751 running XP Pro. Don't have a separate sound card. Just plugging connections into the line input on the mother board. Not sure about the properly shielded cables. Using typical cables one would use with stereo equipment, RCA jacks out of the cassette into small stereo pin into the line in jack. Checked the grounding and wiring of the power outlet used and it's fine. Again, I still get the floating inputs when everything but the monitor is unplugged from the computer. I guess it could be the internal power supply. Help! LRV

[Brendon]

Cabling is worth checking, else it can be a problem. I was recently faced with several sets of triple cables [Left audio, Right audio, and Vid] which were doing strange things. Finally in exasperation I got the multimeter and found that none of them had ground continuity. Each set connected only the center pins at each end, and the outer connector of the RCA plugs was unconnected.

One thing which might help you is to turn down or mute all other inputs but the one you're actually using so you're not getting hum from an unused floating input. Apart from the things we've mentioned, there's not much you can do to combat poor design, I'm sorry.

[LarryV]

Cabling is worth checking, else it can be a problem. I was recently faced with several sets of triple cables [Left audio, Right audio, and Vid] which were doing strange things. Finally in exasperation I got the multimeter and found that none of them had ground continuity. Each set connected only the center pins at each end, and the outer connector of the RCA plugs was unconnected.

One thing which might help you is to turn down or mute all other inputs but the one you're actually using so you're not getting hum from an unused floating input. Apart from the things we've mentioned, there's not much you can do to combat poor design, I'm sorry.

Well, I believe i have determined that the source of the hum and floating inputs is internal to the computer. I moved this computer and hooked it up in a different location in the house and it showed the same floating inputs. Then I hooked up a different computer in the location where the one with the problem was originally set and the different computer showed no floating inputs and was able to record fine with no hum. Speculation is that the internal power supply may be putting out the hum in the first computer. Not sure how to confirm that or if replacing the internal power supply is a simple or big task. Any thoughts? Thanks for all your suggestions. LRV

[Brendon]

Replacing the internal power supply is very simple, so long as you get one with the same connectors. I've done it slowly inside 15 minutes.

I still think it's a design fault rather than a faulty PSU in your first computer, but swapping the PSU will be the acid test.

Best of fortune.