Icom’s new IC-9700 can receive two bands at the same time. In DV mode, it can decode two digital signals at the same time, something even the IC-5100 cannot do. Since it has a stereo USB audio interface build in, it’s logical to expect the IC-9700 to output main and sub band audio at the same time over USB as well. Some sources on the Internet mention that only main band audio is output via USB. Given all the “at the same time” features of the IC-9700, I resisted to believe this to be true. So … let’s check the schematics first. Not only inRead More →

Some time ago, I read the statement that the sample rate of a DAC is set by the audio file that you play. It then occurred to me, that this is – sort of – wrong. Let me explain why, using a turntable for comparison. The turntable speed is set by you, after you looked at the label on the record (or the size..). You can put on a single, and play that “file” at LP speed. With digital audio, it’s the same. Set the DAC to 44.1 sample rate, and feed it a 96 kHz file. The DAC will process 44.100 samples per second,Read More →

After many years messing around with digital audio, I’m confident to have found the perfect setup. But it’s not an easy setup. The thing is, digital audio is not easy. In the analog world, you connect some equipment and then turn up the volume and put your ear next to the speaker. Hum, noise? Too much? Left and right the same? Depending on volume setting? All easy measurements we have made for decades. Let’s “Fourier Transform” these measurements and start listening for … jitter? harsh sounding music? I bought this beautiful piece of mechanical engineering from Technics some time ago. It’s called a turntable. AddedRead More →

The Apple Airport Express (AE) is a beautiful device. One of its functions is the ability to act as audio Airplay receiver. Airplay is a streaming protocol, based on a lossless 44.1KHz/16 bit stereo audio stream. It’s part of iTunes since a long time. It uses Bonjour for service advertisement and as such is zero conf. My AE is the 2nd gen model with 802.11n (update: The A1264 model). All models have a combined analog optical output. Many years ago I used it with an Apogee Minidac and the results were very good. One year ago I connected everything again and was disappointed with theRead More →