Jitter

• 2.6 ps RMS phase jitter integrated from 10 Hz to 100 kHz. This is measured using a TSC 5120A phase noise analyzer.

• 8 ps RMS phase jitter integrated from 1 Hz to 100 kHz. This is measured using a TSC 5120A phase noise analyzer.

• < 5 ps RMS period jitter (< 15 ps peak-peak) This is measured using a WaveCrest DTS with a sample size of 8000.

 

Many S/PDIF test and measurement devices are designed for earlier generations of digital gear. Their noise "floors" are too high to allow accurate measurement of the Audiophilleo designs, which required us to develop new test methodologies.

 

The Symmetricom TSC 5120A phase noise analyzer, normally used to characterize clocks in the communications industry, is one of the few commercially-available devices suitable for the task. It's designed primarily to measure the accuracy of clocks, and can generate phase noise plots from 1 Hz to 100 kHz. These plots essentially show at what frequency, and by how much, a given clock deviates from the ideal.

 

S/PDIF digital audio signals are a combination of clocks and data, but the TSC 5120A just measures clocks. So, in order to use the 5102A, we added a firmware feature to the Audiophilleo1 that allows it to route the clocks normally used to create S/PDIF, directly to the BNC output connector. This approach uses the exact same hardware path and clocks that generate the SPDIF audio during normal operation.

 

If you have the right equipment, you can try this yourself by going to SPDIF->Advanced->Test Wave.

 

Using the 5120A, we gathered data for several common "carrier" frequencies used in digital audio, and calculated phase jitter measurements for offset frequencies ranging from 1 and 10 Hz to 100 kHz away from the nominal carrier frequency. Leading audio recording engineers have come to believe that in addition to the obvious effect of jitter at higher frequency offsets from the carrier, reducing even very low frequency jitter, in the 1 to 10 Hz range, is important for conveying a sense of presence and vitality. Here's a typical phase noise plot for the Audiophilleo1/2. It shows just 3.8 ps RMS phase noise integrated from 1 Hz to 100 kHz taken with a Symmetricom 5120A from a standard production (serial 0029) Audiophilleo1.

 

This testing paradigm includes any noise from power supplies, output stage drivers, and the crystal clocks, but because it looks only at the underlying clocking information, it doesn't measure any data-correlated jitter that might be present in the complete S/PDIF (clock plus data) signal. However, initial testing shows that the RMS phase jitter increases less than 1ps with various data patterns.

 

To get an idea how various levels of jitter influence sound quality, simply enable the JitterSimulator feature on the Audiophilleo1. When set to Level 1, the firmware adds roughly 250 ps RMS period jitter, and around 1300 ps RMS phase jitter integrated from 1 Hz to 100 kHz. These levels are typical for mid-range USB- S/PDIF interfaces, and on a higher-end system, it should be easy to hear their effects.

 

Compatibility

• Windows Vista/7/8/8.1/10

• Windows XP

• Apple OSX 10.5+

• Linux Ubuntu 9+. Although there are several popular Linux distributions, their USB audio drivers similar. Most are compatible.

• iPad iOS 4.2+. The iPad supports 16 bit 44/48 kHz audio, through the iPad camera connection kit and an external powered USB hub. Using 3rd party apps like flac player, the iPad/iPhone can support up to 192/24 audio.

• Logitech Squeezebox Touch. The Touch supports 24 bit 192 kHz audio after installing this plug-in.

• Android. All newer versions of Android (5+) and many older versions (4.2+) have USB Audio built in.

• Any USB Audio capable media server. Many NAS servers and other transports support USB Audio and are compatible with the Audiophilleo.

 

No driver is required for the OS X, Linux and Windows XP operating systems for 192 kHz, 24 bit performance. Windows Vista and 7 require our custom driver for 176/192 kHz operation; a signed 32 and 64 bit versions are available.

 

Note that the Audiophilleo1 Special Edition support up to 384Khz under Windows Vista/7/8/8.1/10, OSX, and Linux.

 

Under Windows, both the standard and custom drivers are compatible with WASAPI and ASIO4ALL as well as DS. When using ASIO4ALL, the kernel buffers should be set to 4. Note that under XP, for maximum reliability, we recommend using ASIO4ALL instead of kernel streaming.

 

Physical

Display:1.7 inch (43 mm) diagonal, 262K Colors, 160x128 pixel resolution (Audiophilleo1)

Dimensions:3 x 2 x 0.75 in (76 x 51 x 19 mm)

Weight:~ 4 oz (113 g)

Space required:15cm of space is required behind the DAC BNC/RCA tip. Right angle adapters can be used to reduce this space.

 

Sample rates

24 bits at 44.1, 48, 88.2, 96, 176.4, and 192 kHz. 16 bits at 44 and 48 kHz is also supported for iPad compatibility. Note that to the DAC, 24 and 16 bit S/PDIF data look the same, so it does not matter whether you play a 16 bit audio file in 24 or 16 bit mode. All devices support DSD64 over DoP. The Audiophilleo1 Special Edition additionally supports 352.8 and 384 Khz sample rates and DSD128.

 

Electrical

SPDIF output:    75 Ohm female BNC, +/- 300 mV amplitude, minimal overshoot, galvanically isolated

Edge transitions:    < 700 ps (Audiophilleo1 has programmable rise-times up to 15 ns)

USB bus power:    < 400 mA, 6V max

USB cable length:    Up to 15 ft/5 m. Active USB extenders may be to 50 ft/15 m

 

In the box

• USB S/PDIF converter

• USB A-B Cable (generic cable for Audiophilleo2, Wireworld Ultraviolet cable for Audiophilleo1).

• PurePower equipped models come with additional 12 inch power cable and 12 inch USB cable

• S/PDIF BNC adapters: BNC 75 Ohm, for connection to BNC female on DAC; RCA male, for connection to RCA female on DAC; RCA female, for use with RCA SPDIF cable

• 12V Trigger international power supply (Audiophilleo1 only)