Bill Firebaugh: The Well-Tempered Innovator Page 4
Holt: What you see is essentially all the release of the stored energy.
Firebaugh: Yes. An impulse contains all frequencies, and its duration is so short in comparison with the time it takes for the system to release the energy from the pulse that it stores, that all you read is the system's response. That's how the FFT works. It allows you to suppress the input pulse so all you read is what happens after the pulse. It's almost like having an output signal with no input.
Once I saw how unstable the arm was, even with that modicum of damping, I knew that there wasn't enough of it. I knew I would have to use a fluid with better viscosity characteristics. The thing about tonearm damping is that you want a lot of friction when the arm is moving fast and very little when it is moving slowly. And when it is hardly moving at all, you want as little friction as possible. That's the trouble with mechanical damping—pure friction. You get the same amount of friction at all motional speeds. The proper damping fluid cleared up most of the arm's misbehavior.
Holt: You haven't mentioned the sand.
Firebaugh: Even after I got the damping coefficient correct, as evidenced by these impulses, piano and female voices still sounded colored. My pulse tests indicated that it was the arm tube itself that was taking off and resonating. It, too, needed to be damped.
I use a thin-walled stainless-steel tube for the arm. I tried filling the arm with various things, including Dacron yarn. I tried expanding foams and liquids. Liquid made it much worse. One morning while I was having breakfast, I noticed the salt shaker and thought, "Hey, salt! How about salt?" And man, I zoomed out to the garage and took one of the arms apart and filled that thing with salt, and when I listened to it, I knew I was on to something.
I also knew I couldn't use salt, because it's highly corrosive and in a humid climate it would absorb water and turn to liquid. That was when I thought of sand.
I bought some of the "play" variety that's processed for use in kiddie sand boxes. It's very clean, sterile, beautiful stuff, dust-free and all that. It really deadened the arm, and that's what I now use to fill the arm. And when we applied for the patent on the arm, we threw that in too, and sure enough, I got the patent on sand-filled tonearms.
Holt: Is the sand loose in there or is it held by some kind of binder?
Firebaugh: No, it's in there loose, but it's packed pretty tight. It's kept in with a cotton plug.
Holt: You haven't mentioned those incredible cartridge-connector clips that you use. I don't believe any other tonearm manufacturer has ever thought to look around for a connecting clip that would adapt to different-sized cartridge pins.
Firebaugh: I had a heck of a time with that. All the available cartridge clips seemed to be too darned stiff, and they had to be adjusted to fit different cartridges. I thought they would be uniform, but they varied all over the place. And adjusting those conventional clips to fit is a terrible job!
Holt: So tell me about it! I've been complaining about this in Stereophile for years.
Firebaugh: I started looking through all the surplus stores within a wide radius of my house, in their Pins and Connectors departments. I came across some things made by Amp. They're nifty little gold-plated things, designed to accept pins from integrated circuits, or to attach to wire-wrap pins on a circuit board. I tried some of these, and they were perfect. This particular clip fits snugly on a wide range of pin sizes without any adjustment.
Those things cost 20 cents each, though! I ordered 1000 of them, and when I went to pick them up, those guys at the store were laughing. Two hundred bucks these cost me, and I get a little plastic bag with maybe a tablespoon of them in there!
Holt: Bill, what's your background in all this? Were you schooled as a mechanical engineer?
Firebaugh: Well, I'm an engineer for Ford Aerospace, and have been for about 25 years. I have a degree in physics, and I work as an engineer in optics and electronics. I'm a laboratory-type engineer; I'm not the type that wants to be in administration. I like interesting engineering work.
Holt: And you do all of this audio designing in your spare time?
Firebaugh: Yes. I'm hanging on, but barely. My life will soon be undergoing a tremendous upheaval though, because I have to turn out 1000 turntables PDQ. And that's going to eat up a lot of my time.
Holt: Somewhere along the line you're going to have to make a momentous decision: to curtail your audio activities or quit your job with Ford Aerospace.
Firebaugh: I am. When I turn 55 in just a few years, I'll probably retire from Ford Aerospace. But right now, I'm going to have to hire some helpers, and believe me I'm not exactly looking forward to that, because production is nothing but a headache. However, there may be a rather nice financial payoff, which can tend to diminish one's reluctance.
But the thing is, right now the quality of my life has taken a step backward. I don't have much chance to go scuba diving or to listen to music any more, and I enjoy both.
When I'm 55, I will have 15 years before I'm 70. I figure that's the amount of time left during which I'll have some degree of steam. And during that time there are a lot of things I want to do. Basically I want to enjoy myself.
Yes, you're right; I've got some fundamental decisions to make. How am I going to spend those 15 years? You know, the object of being down here is to enjoy yourself. If you're not enjoying yourself there's definitely something wrong.