DACport development blog

The Internet is still down, and so is Internet radio, such as Shoutcast, Pandora and Last.fm… This is uncomfortable. A modern man needs to be connected.

Today was devoted to cleaning up the crystal oscillator. DACport uses a mil-spec, precision crystal oscillator that supplies the clock for all the digital chips inside.

We now have several units under extensive burn-in test. The purpose of a burn-in is to make sure that nothing in the circuit is affected by a prolonged exposure to higher temperatures. This test usually reveals the weak links in the circuit – those components that are “on the edge” and may fail sometime down the road in the field. Of course, we want the DACport to provide uninterrupted listening experience for our customers, so we are testing hard… And guess what we found – the precision crystall oscilator that features 10 ppm (parts per million stability, or .000001% frequency deviation) became unstable under a demanding temperature test. It’s actually very hard to trip it up, but our vigilant testers figured out a complicated sequence of powering/unpowering that left the crystal in the proverbial “state of shock”. It comes back to life, but you have to cycle the power again.

Well, this was definitely not good and so we immediately went for the scope and logic analyser to debug the pesky circuit looking for the culprit of instability. Turns out it was a faulty part. The part was replaced, supplier noted and a new battery of tests started… So far so good. We will be adding a new, more reliable supplier to the list.

This is a short post. Our Internet line went down yesterday and while we are waiting for it to be restored I am blogging from the iPhone. It’s amazing how dependent we are on this modern lifeline.

Meantime, we have finalized the text for the unit’s chassis. The original plan was to use silk-screened labels, but we experimented and decided against that. DACport will have laser engraved labels instead. It’s more expensive, but looks solid and professional compared to paint. We are going for color contrast with the white tube and black end caps. It will look super-sharp when we finally get those chassis finished!

Our Internet connection should be restored shortly. Until then, I’ll be taking a break and reading a book… Turns out those things are made out of wood – how entirely analog!

DACport is ideal for travel as a portable, audiophile-quality sound card. Pack your favorite headphones and relax – watch blue ray movies on your laptop in an airplane, listen to hi-res music at a hotel room, or in a coffee shop. DACport has been called “the ideal coffee shop rig” because it transforms your portable listening experience, upgrading it to High Resolution Audio.

But Hi-Fi on-the-go is not the only way to use it. DACport is equally comfortable at home, as part of a permanent audio setup.

We designed DACport’s headphone amp in such a way so you can easily connect it to an external power amplifier and a set of speakers. To do that you would need a cable with a 1/4″stereo plug on one side (same plug as on pro headphones) and a pair of RCA or XLR connectors on the other side, to connect to the amplifier. Plug in the cable and DACport becomes a high-quality USB DAC, making it possible to use it as part of a home computer audio setup.

If using as a USB DAC, CEntrance recommends turning DACport’s volume knob to the max and using external amplifier’s volume control to adjust the volume (this is the best way to manage gain.) There is no danger in setting DACport’s volume level to maximum – the internal amplifier has plenty of headroom and is guaranteed to never overload, even during the loudest musical passages!

DACport’s headphone amplifier deserves a special mention.

CEntrance recently developed a brand new, direct Class A amplifier design, which is characterized by ultra-low noise floor and lowest THD. We minimized distortion by getting rid of all capacitors in the audio signal path. Capacitors can exhibit non-linear characteristics and increase distortion. Rather than experimenting with different capacitor materials to find a compromise and hoping that the selected capacitors will not deteriorate over time, we got rid of them altogether. There are zero capacitors in DACport’s signal path and the sound is cleaner for it!

DACport’s output noise is so low that we need to provide a warning. You have to be careful with your ears. With most audio products you can hear some residual noise when you turn up the volume knob. But not so on DACport – the output is equally quiet if the volume knob is at min or max settings. If you max out the volume knob while no music is playing you will not know it – the headphones will be completely quiet. So be careful to avoid accidentally blasting your ears with loud music!

This level of low-noise performance was not possible 10 years ago, but today’s circuits improved dramatically. DACport’s output amplifier features 120 dB of dynamic range, making such unbelievable performance a reality.

DACport has an internal microprocessor, which is responsible for moving digital audio over USB but also for making sure that all internal circuitry blocks, including the precision Digital to Analog converter are functioning smoothly. This week (as we wait for the correct chassis to arrive), we spent time to tune up the microprocessor code for smoother overall operation.  Such mundane operations as Start and Stop of playback, changing tracks, switching sampling frequencies and bit depths sound simple, but they take a lot of work behind the scenes. All of these functions need to happen smoothly and quietly, so that the machinery is completely transparent to the listener. All you want to hear is your music in its full 24-bit resolution glory.

So we kept working to improve the code, making sure all switching is completely silent. Today we finally arrived at a totally invisible solution. And it is truly amazing. Your humble reporter decided to listen to some of his favorite CDs - Donald Fagen, Karrin Allyson, Patricia Barber, Diana Krall and others. The results are astounding. I thought I knew these records inside out… When I listened to them over DACport I’ve discovered a lot of new material – new sounds, new instruments, even new recording imperfections.

DACport is very revealing of the tiny little details and once you try it, your music will never sound the same again. We are building the first production run off 100 units in late November. The price will be announced soon. Please submit your name here if you would like to be informed of pricing unit availability.

DACport is housed in a rugged, roadworthy aircraft aluminum cylinder. The same cylinder houses our award-winning MicPort and AxePort products, used by Hollywood producers and musicians all over the world. Our aluminum chassis was designed in Holland and features easy access to two circuit boards, maintains small package size and acts as a heatsink. A lot of innovations.

Production has its ups and downs and that’s what this blog is all about. Today we received the sample DACport cylinders from our supplier.

Good news and bad news. The color is correct – a beautiful white, anodized, brushed aluminum that looks super-sharp. That’s great. But the supplier did not remove the second hole at the top of the cylinder. Scroll down and you will see a post on this issue.

Develop enough products and you know what to expect. You cannot overcommunicate. Something always gets lost in translation. If that wasn’t the case products would be developed in weeks, rather than months… But I have to honestly say, we are getting faster with each new product. Faster and more experienced. We are learning to anticipate the challenges and avoid them early on.

Apparently not in this case however, so we have to wait… Fortunately, our supplier is fast. We are expecting new cylinders in a week or two.

The reason DACport works with Windows, Mac and Linux without needing to install any custom drivers is because it supports the USB class-compliant audio standard. All major operating systems ship with built-in standard audio drivers, which is the reason that most USB headsets are plug-and-play. Typically, however, these built-in drivers only support 16-bit/44kHz soundcards.  Most 24/96 products ship with custom drivers and require the user to go through a cumbersome installation procedure.

But not DACport, a true CEntrance innovation. We spent years of intense R&D effort learning how to make a 24-bit/96kHz USB DAC compatible with the existing OS drivers. The good news is that now you can reap the benefit of that effort. DACport is true 24/96 and plug-and-play. It works works right out of the box, with any computer. How’s that for convenience.

You will ask – Really? How does weather affect electronic assembly? Well, unfortunately, it does. We just learned that several semiconductor companies including TI shut down their factories in the Philippines because of the recent typhoon activity. This means that some electronic parts won’t be available for an extra month or in some cases two. The semiconductor industry is coping with a generally slow economy, pockets of extreme activity (iPhone) and now weather delays…  It’s amazing they can predict anything anymore!

We are keeping our fingers crossed that our initial run of 100 units will not be affected, since we have most of the parts already in house. Will keep you posted.

The goal of this blog is to keep you, our loyal reader duly informed about product availability. We can design great electronics all day long, but it all becomes worth it when our customers get to experience for themselves the audio quality we keep talking about.

The good news is that we are pretty much done with circuitry and so it is time to “shoot the engineer”! (what? me?)

The entire month of October since the product premiered at RMAF was devoted to optimizing power consumption, lowering distortion, raising the gain a little to compensate for less sensitive headphones and making sure that DACport can be built. This meant making sure that all necessary parts were in stock at our suppliers.

Let’s cut to the chase. We are planning to build 100 pcs in November and make them available for Christmas. Those of you, who have already submitted your emails will get an early bird discount – 10% off the regular price, as we promised. The final price will be announced soon. We will be building these in USA.

If you want to get the unit by Christmas, please submit your email on this page.

With DACport CEntrance set out to create the smallest portable audiophile USB DAC. Not a simple USB sound card with a compromised set of parameters, but the best, yet portable headphone amp with USB input. You can’t always be near your expensive home audio setup. With DACPort, you could use it on a plane, in a coffee shop or in a hotel room to relax and listen to high quality music away from home.

A high quality DAC needs to have descrete parts for everything. It can’t use an all-in-one chip, which is typically consumer quality, but has to have separate power supply, DAC and amplifier circuits. Normally this level of miniaturization would be impossible because of physical constraints. But CEntrance also designed the MicPort and AxePort, the recording interfaces used by musicians and broadcasters all over the world. So we had some minaturization experience. We also developed dozens of pro audio products for the largest brands in the industry, such as Mackie, Alesis, Harman Pro, and Gibson. CEntrance started out as a design firm back in 2000 and since then built up our “chops” in designing miniature electronics.

Here is a picture of the two circuit boards inside the chasis, actual size (depending on your monitor, of course). We are stil counting the total number of parts, but it’s a couple of hundred, mounted on the top and bottom of both circuit boards. There is no space left – it’s a tight squeese. The first prototypes are built manually, so a steady hand, good light and magnifciation are key. You can’t assemble these if you were partying the night before…