Demagnetize Heads of Reel-to-Reel Recorder

Video Transcript

"For Expert Village I'm Kurt, chief engineer at KGB Studios. We're continuing our series on how to restore a 4 track reel to reel tape machine. Okay, remember this device here, this is the head demagnetizer with a nice soft rubber tip as you can see here. Hopefully the profile's good in the middle of your screen. What that's for is that it doesn't rub or scratch the heads. What I'm going to show you now is how to actually demagnetize the head in this session. So we've got the record head here and we've got the playback head here. Now, I'm not touching it and I'm not going to touch it with this but I'm going to show you the process for head demagnetization next. Off we go. Alright, the first thing we're going to do is after we've cleaned the heads we do the demagnetization. This is a Nortronics head demagnetizer here. It's kind of a weird instrument and it's very difficult to hear unless you've got pretty good hearing. Sometimes you can feel the vibration patter from it but I've used this on 8 track, cassettes and reel to reels. And the thing that really stands out to me that I know that this really works. Even though the controversy says it doesn't. Is that for high transient information like drum cymbals or harp sounding or instrumentation that has high harmonic content, I use and have really heard the difference in my studio monitors with head demagnetization verses non head demagnetization. So I'm sold. And this is the one thing that this thing does. So, the 2nd thing it does is that it takes away any residual magnetism that is stored up or collected over time over the head. Now it's not a digital world. This is an analog world so the way the audio signal is arranged is on the iron filings on the tape itself. And that is how you hear what you hear off of the tape. Now, lets go through and go through the procedure. So we're going to go off camera a spell and basically what I'm going to describe to you is that I align it to the tape head over here on the right hand side and then I come in at about 2 inches per second. And this is after I turn it on because if you do it the other way it starts magnetizing the head. So follow me here. As you can see, I'm going up and down on the head. And then I'll make a little circular path relatively slow. And I keep it at about the same distance away from the head. You don't want to touch the head. So you get really close but you don't touch the head. And then you slowly egress away at about 2 inches per second, about the same speed. You don't turn it off and you leave the head demagnetizer of until you reach about 4 to 6 feet. And then you'll let it go off. Now the same thing is true of this other head. And I'll also of course hit the tape paths in that time. So I'm coming in here. And as you see I'm moving in relatively close and then I do the up down motion over the tape gaps or the tape heads. Then I do the side to side and I stop in the middle and then slowly egress out of the path there of the head until about 4 or 6 feet. Then I shut it off. I do the same thing for erase heads as well as this left hand sides with the tape path and the guides and of course the caps. And as you can see me over here on the right hand side. I do those three at once and then as you can see I do those three when I do the erase heads on that side. Remember, now you want to egress out and in at about 2 inches per second and then power on or power off depending upon in or out. That's how you do head demagnetization with this Nortronics head demagnetizer. The other thing you need to be aware of is that if you have any tape stock or anything that has recordable media like video tapes or reel to reel tapes you want to make sure that that has been removed. Otherwise you can magnetize it or erase it. You can really scramble the signals and there's nothing you can do. You're going to have to re-record whatever you put on there so be careful of that. Move that out of the room if it's in the room. So that's the process. That's head cleaning and head demagnetization. Join us next time when we actually are going to do the head lubrication of the head and the tape paths. And that's what we only do maybe once or twice a year so join us again. On Expert Village this is KGB Studios."