Audio Precision to the rescue, of Jim Williams no less

Chris Gill, the Audio Precision sales engineer serving Silicon Valley was nice enough to bring their latest and greatest over to Linear Technology where he took some measurements of a Jim Williams’ low-noise/ low distortion oscillator. Chris was really cool, no sales pitch or pressure to buy one, just pure customer service goodness. It was great since he really knew the SYS-2722 and was able to get good data in a few minutes, using his own laptop.

• Here is Chris and Linear Technology’s Jim Williams, setting up the SYS-2722 to measure a 1.8kHz oscillator Jim designed.

• Here they are pouring over the data like any two great engineers would.

• This is the setup; Jim Williams’ oscillator board is at bottom left.

• The SYS-2722 comes with this handy USB adapter, I am pretty sure Chris told me it was included in the price.

Jim Williams had to design this ultra-pure low-distortion oscillator to use in a circuit feeding a Linear Technology high-performance ADC. After all, how do you know how good your ADC is working if you feed it a crappy sine wave full of distortion and artifacts? So Jim did his first crack at the circuit a few months ago. He sent it to Portland, to Bruce E. Hofer, the former Tektronix engineer and founder of Audio Precision. Bruce measured the oscillator and sent it back along with the test data. You gotta love a guy whose title is “Chairman, co-founder, and head analog engineer”.

Well, Jim Williams is the kind of engineer that seeks to improve things. So he did some tweaks and redesign on his oscillator circuit. Jim didn’t want to bother Bruce again; he is the chairman of AP, after all. So Jim asked me if I could scrounge up an AP box we could use to measure the SNR and distortion. My buddy Joe Curcio, an apps engineer at National Semiconductor owns the classic Audio Precision System-1 (S1), but wondered if we couldn’t get our hands on some brand-new calibrated hardware.

That’s when AP vice president of marketing Tom Williams put me in touch with Chris Gill. Shortly thereafter Chris met me over at Linear Tech and we saw the several dB improvement Jim had made in his oscillator board. It proves my point that the key to being a good design engineer is knowing how to test, and having the equipment to test your designs.

I don’t want to steal Jim’s thunder, we are going to publish his whole design and the test results in our August issue. Still here is a little crop, just the corner of one of the beautiful plots Chris made with the SYS-2722. Even Jim was impressed. The SYS-2722 has a quieter, lower-noise oscillator built in, and that one sweeps across the audio band, rather than a fixed 1.8kHz like Jim’s.

• I don’t want to spoil Jim Williams’ article by giving away the data a few months early, but lets just say the axis I cropped off on this Audio Precision SYS-2722 measurement goes down to -160dB.

Audio Precision has really built up a great brand. I have dozens of inputs that tell me this. When I was at National Semi, all the engineers in the audio group used to talk about how great AP stuff was, and this was 10 years ago. My electronic flea market buddies would be talking about how great the AP stuff was and eventually Joe Curcio bought a used unit to have at his house. Then, when I visited Tektronix up in Portland and mentioned my next stop was Audio Precision, one of the engineers sighed and said, “We never should have let Bruce leave Tektronix!” Finally, I met with the Audio Precision folks in person. When marketing VP Tom Williams took me over to Bruce Hofer’s cubicle, there was an Audio Precision product half disassembled on his desk surrounded by a scopes and meters. That’s the kind of chairman I want to work for.

• Here is the Audio Precision team, that’s Bruce in the middle holding up the sign. He always wants to pitch in and help, just like any great boss.