The Making of KSE1500 & SHA900: An Interview

Allison Wolcott | January 13, 2016 The Making of KSE1500 & SHA900: An Interview







What were your roles in the development of these products?


ROGER GRINNIP: It started on my bench. I had this feeling of, Hey, let's not talk about it officially, but I've got this idea for something cool we could do, and I don't know if it's really practical. We had the ability to prototype some things on a pretty crude level and get some people to weigh in on the possibilities. So, my role has been to overcome the technical challenges to get it to the finish line. (I'm the engineer. I'm supposed to solve all those problems, right?)

Yeah, Roger was the lead in this project from the beginning. No question. My role has been to steer direction for the details. My team would determine the market requirements, and Roger would figure out a way to fulfill them. Roger's one of those engineers who can translate back and forth between engineering and marketing, which is an amazing quality. We'd try something, then make a change that would have an unexpected impact on another aspect of the product, and then we'd have to figure that out. It was a blast working on it, like an engineering mystery. And as many setbacks as we experienced, there were just as many moments where we'd figure something out, and the project would take a giant leap forward.

Right? The moments when you've solved the problem and you've made something that makes you think, I wouldn't mind listening to this for a while...those times were pretty incredible. The fact that nowhere else in the world was anyone able to listen to what we were hearing was an incredible feeling.




It's not like we discovered some magical property or material that allowed electrostatic transduction to be used in a portable form factor. It's really that we have an engineering team that specializes in making transducers, plus the fact that we're very familiar with working in miniature. We've been making earphones for about 20 years, after all. I can't think of another company with the expertise that would allow them to pull this off.

To make a lot of sound, you need to move a lot of air using a very large surface, so there are some tradeoffs in terms of surface area and size with electrostatic drivers. Typically, electrostatic speakers and headphones are really big, and they're typically dipole. They radiate front and back. That has some disadvantages when reproducing low frequencies because you're creating compression and rarefaction, so the low frequencies end up cancelling. In the KSE1500 earphones, we don't allow that cancellation. The radiation off the back of the diaphragm is actually enclosed and isolated from the front. Then, when you design in all the little bits and pieces that allow electrostatic transduction to work on a miniature scale, you end up eliminating a lot of the original disadvantages.

The earphone portion of the KSE1500 isn't the only major innovation here. The cable is too. What's the story there?

The electrical requirements for an electrostatic earphone cable are much different than for a moving coil or balanced armature driver earphone cable. The capacitance almost doesn't matter for those. The impedance of the driver is low enough that any kind of stray capacitance doesn't matter. In this case, the earphone driver capacitance is Pico-Farads, so very, very low. The way an electrostatic driver operates is by injecting charge across the different plates. The amount of charge you inject is a function of the capacitance. So, a very small capacitance means you don't inject much charge. The earphone driver capacitance is about 20 to 30 times less than the capacitance of the cable.

The challenge was to drive the cable capacitance down to the point where we could drive it with our amplifier. That required some fairly significant changes to the way the cable's designed compared to our other earphone cable designs. The minute you take out the things that make our usual design work, you move from having an electrical problem (reducing capacitance) to a mechanical problem because you've greatly reduced the strength of your cable. Add to that the fact that Sean wanted a round cable for comfort in portability even though electrostatic cables are typically flat ribbon cables because their capacitance is low, and you've got a fairly big engineering problem.




Which came first: the KSE1500 or the SHA900?


The portable DAC amplifier market has grown in the past few years. Had we started out just to make the SHA900 eight years ago, it's likely that nobody would have signed off on it because there wasn't really much of a market for it at that time. Because we were already making the KSE1500 with all the features needed for a standalone portable DAC amplifier, we saw the opportunity to jump in. A lot of what made the portable DAC market grow is the increase in device capacity. Plus, people realized that instead of spending money on a home sound system they never use because they're always on the go, they could invest instead in a portable high-fidelity system.

You can use the SHA900 with any earphone or headphone with a 3.5 mm jack, but are there particular Shure models that you would or wouldn't recommend using with it?

There's no particular earphone or headphone that's better suited for use with the SHA900 than another; however, there are aspects of some of our earphones and headphones that the SHA900 will enhance more than another portable DAC might. So, it's more that the SHA900 is better suited than another portable DAC to whichever Shure listening product you favor.


There are a lot of settings that users can control. How did you make the need for that align with portability's demand for quick adjustments?





You're absolutely right. It matters quite a bit. In the moment, working on it, you're thinking, Ugh! Enough! but when you go to use the product, it makes all the difference.


Oh, absolutely.




We met with the Japan Audio Society. They're a not-for-profit organization, and their goal is to improve the listening experience by improving recording and printing quality for digital audio. What they're trying to do is a good idea and also very difficult. Their principles aligned with ours, so we agreed for our product to feature their logo.



It's similar. The KSE1500 gets seven to 10 hours of battery life.

What's the benefit of having both DAC and ADC functionality?



How did people react at the October 2015 Tokyo launch?

Tokyo is a big market for high-end portable audio. Almost everyone commutes to work via train and listens to music. The launch event there was everything we hoped it would be. People were even more impressed than I could have imagined. I was so proud to be able to show the products after so many years of development. I don't speak Japanese, but a smile is international. You don't need to speak any particular language to know what it means when somebody's face lights up. They loved it.

So far, the U.S. equivalent was during prototype testing. When you listen to Sound Isolating earphones, you don't know how loud you're speaking. So, I'd hear some colorful language screamed loudly across the project team area, and I'd be thinking, Aha! Somebody just listened to the KSE1500 for the first time.


Allison Wolcott

Allison Wolcott
