*** There will be a 6% price increase effective June 15. Buy now and save. Free shipping within the USA for all orders over $700. Our offices will be closed on Memorial Day (Monday May 29).

0

Your Cart is Empty

UltraLockDDS™ Clock System

by John Siau November 01, 2010 2 min read

UltraLockDDS™ Clock System

By John Siau

November 2010

New Clock Technology from Benchmark

When Benchmark unveiled UltraLock™, it caused quite a stir. Benchmark claimed that this proprietary clock-syncing system made their converters immune to jitter. UltraLock™ keeps jitter-induced distortion at or below -135 dB FS (well below audibility). Of course, the audio community was skeptical; they set out to prove (or disprove) Benchmark’s claims. Since then, several journalists, end-users, and manufacturers of audio test-equipment have verified Benchmark’s claim of jitter-immunity.

However, there was still room for improvement. There is an asynchronous sample rate conversion (ASRC) process in UltraLock™ that adds about 1 millisecond of latency. This latency is usually only of concern when musicians are monitoring themselves real-time, post-converter. Even in this case, 1 millisecond of latency is hardly noticeable; it is roughly equivalent to having the instrument 1 foot further away. Nevertheless, it can contribute to a system-wide latency problem.

When designing the ADC16, Benchmark decided to revisit its clock-management solution, to reduce latency. The technology that Benchmark developed during this quest is called UltraLockDDS™.

Benchmark’s new UltraLockDDS™ clock system utilizes the latest low-jitter clock technology developed for high-frequency RF communications systems. The master oscillator is a low phase-noise, temperature-compensated, fixed-frequency crystal oscillator with a +/- 2 PPM frequency accuracy. This oscillator drives a 500 MHz Direct Digital Synthesis (DDS) system that generates a 3072 x WC system clock. This high-frequency clock is divided and distributed directly to the A/D converters using a high-speed PECL clock distribution chip. Each of the 8 converters is driven directly through a dedicated, matched-impedance transmission line.

Jitter attenuation is achieved with digital filters in a custom FPGA that controls the DDS system. All jitter-induced distortion artifacts are well below audibility under all operating conditions. Jitter-induced distortion is always at least 135 dB below the level of the music. The jitter-performance of UltraLockDDS™ meets or exceeds the performance of Benchmark’s UltraLock™ system, but does not use an ASRC DSP process. The elimination of the ASRC processing significantly reduces system lateancy and provides the most direct path from the A/D to the digital interface.



Also in Audio Application Notes

System Performance Calculations
System Performance Calculations

by John Siau March 02, 2023 13 min read

If an audio system is composed of multiple components, we may have detailed specifications for each component, but we will not know the performance of the combined system without doing some calculations. You may have questions such as these:

  • Will my audio system produce audible noise?
  • Will my audio system produce audible distortion?
  • How will my audio components work together as a system?
  • How loud will my audio system play?

Use Benchmark's online audio calculators to find answers!

For example, if we know the output power of an amplifier, as well as the sensitivity and impedance of our loudspeakers, we can calculate the maximum sound pressure level that our system can produce.

PEAK SPL CALCULATOR
Speaker Sensitivity: dB SPL (2.83 V, 1 M)
Amplifier Power Per Channel into 8 Ohms: Watts
RESULTS
Peak Output Level (at typical listening position): dB SPL

 

This application note provides interactive examples that help to answer the questions listed above.

Read More
Audio Calculators
Audio Calculators

by John Siau November 29, 2022 1 min read

We have added an "Audio Calculators" section to our webpage. Click "Calculators" on the top menu to see more like these:

 

THD % to dB Converter
% THD
RESULTS
dB THD
THD dB to % Converter
dB THD
RESULTS
% THD
Read More
SECRETS Q&A WITH JOHN SIAU OF BENCHMARK MEDIA SYSTEMS
SECRETS Q&A WITH JOHN SIAU OF BENCHMARK MEDIA SYSTEMS

by Benchmark Media Systems January 07, 2022 1 min read

Secrets contributor Sumit Chawla recently caught up with Benchmark’s VP and Chief Designer, John Siau to get a little more in-depth on several subjects.

John Siau, VP Engineering, Benchmark Media Systems, Inc.

Q: "Benchmark is one of the few companies that publishes an extensive set of measurements, but you also balance that with subjective testing. Can you talk about the equipment, the listening room, and the process for subjective testing?"

Q: "Was there ever a time where you learned something from a subjective test that was not captured by measurements?"

Q: "You conducted some listening tests to determine whether distortion in the “First Watt” was audible. What test material did you use for this, and what did you find?"

Q: "The AHB2 amplifier incorporates THX Audio Achromatic Amplifier technology. When and how did the partnership with THX come about?"

Q: "Linear power supplies have been and remain quite popular in high-end devices. You favor switch-mode power supplies. When and why did you make this switch?"

... and more!

Read the full interview here 

Read More