"Switching supplies are noisy."
"Linear power supplies are best for audio."
About 5 years ago, Benchmark stopped putting linear power supplies into our new products, and we replaced them with switching power supplies. We did this because linear supplies are too noisy. Yes, you read that correctly, linear supplies are noisy!
A well-designed switching power supply can be much quieter than a linear supply!
Find out why!
Benchmark has created a bi-directional 12 Volt trigger interface that is compatible with almost every trigger input and output. This interface can be used to connect Benchmark products together so that they will power up and down in a sequenced fashion. This same interface can be connected to the trigger inputs and outputs on other brands of audio products. This application note describes some typical configurations and it includes the full technical details of the Benchmark bi-directional trigger system.
A benchmark is a standard or point of measurement to which other things can be compared.
As our name implies, we are committed to excellence. Our products often define the current state-of-the-art in terms of audio performance.
Benchmark products are designed and built by audio enthusiasts. We are musicians, audiophiles and audio professionals who are passionate about audio quality. We also are passionate about the durability and build quality of our products. Most of our products are designed, assembled, tested, and shipped worldwide from our headquarters in Syracuse, NY, USA, where we have been for over 30 years.
Our goal is to build top-quality sonically-transparent products that you will enjoy for years to come.
Over 33 years ago (in 1983), Benchmark's founder, Allen H. Burdick, began building analog audio distribution amplifiers for television networks. This application demanded an audio amplifier with a very wide frequency response, very low noise, and very low distortion. The Benchmark DA101 distribution amplifier had a 160 kHz bandwidth, THD+N of 0.00044%, and a SNR of 130 dB, but the power output was only about 40 watts in bridged mono.
For many years, we used our distribution amplifiers to drive the speakers in our listening room. We couldn't buy an amplifier that came close to the performance of our distribution amplifiers, and Allen had often talked about building a bigger amplifier that could match the performance of the DA101.
In 2011 we began to talk about making Allen's dream for a power amp a reality. The goal was to meet or exceed the performance of Allen's DA101, while scaling up the power by a factor of 10.
The AHB2 power amplifier is named in honor of Benchmark's founder, Allen H. Burdick. Allen had a life-long passion for audio, and became one of the leading innovators in the pro-audio industry. Allen was a perfectionist and a prolific engineer. Most early Benchmark schematics bear the initials A.H.B.
Allen's DA101 distribution amplifier helped define the performance goals of the AHB2 power amplifier. The result is an amplifier that Allen would have been proud to call a "Benchmark".
In loving memory of Allen H. Burdick (June 29, 1942 - September 27, 2013).
Since 1983, Benchmark products have been designed, assembled, and tested in the USA. Our products are now shipped to every continent, but we are firmly committed to keeping our manufacturing in the USA.
Watch us transform a solid bar of aluminum into a finished Benchmark faceplate. Learn how sheets of metal are formed into finished enclosures. Watch as hundreds of tiny electronic components are accurately placed on circuit boards. See the chassis and electronic components converge at final assembly where each product is hand assembled. Watch our techniciansrun a comprehensivesequence of performance and safety tests.
This short 8-second video clip demonstrates some of the differences.
The following measurements and scope photos demonstrate the effectiveness of the feedforward system in the AHB2.
From the first Watt to the last Watt, the AHB2 shows no evidence of crossover distortion. In contrast, all conventional class-AB amplifiers have crossover-distortion artifacts.
Dick Olsher once said that "the first Watt is the most important Watt". We agree!
Most audio power amplifiers suffer from a defect known as "crossover distortion". This distortion is particularly troublesome at low output levels. At low power levels, the crossover distortion can rise to a high percentage of the output level and become the dominant source of distortion.
There are two distinct types of audio products. Some audio products are designed to be transparent while others are designed to provide a euphonic experience. These types are as different as a Porsche and a Cadillac.
There is not a right and wrong type of car. Likewise there is not a right and wrong type of audio product. The choice belongs to the user, but the user must be fully aware of the differences before they buy.
Benchmark has recorded a lab demonstration that shows what happens when a standard two-wire cable is exposed to common sources of magnetic interference.
You will be able to hear the interference, see it on an oscilloscope, and view its spectrum on an FFT. A star-quad cable is exposed to the same sources of magnetic interference and the results are compared. This demonstration shows the dramatic difference between the two cables. The star-quad cable provided a 20 to 50 dB reduction in magnetic interference, keeping the interference below audible levels.
Studios, live sound venues and homes all have magnetic fields that can cause interference. Magnetic fields are produced whenever current flows through a wire. AC power cables, transformers, power supplies, computers, portable chargers, motors and light dimmers are among the devices that can emit strong magnetic fields. A microphone cable can pick up magnetic interference if it happens to pass near one of these devices. Cables can also pick up magnetic fields when they run adjacent to AC power. Star-quad cables typically reduce this magnetic interference by at least 20 to 30 dB. This is almost always enough to reduce the interference to inaudible levels.
Benchmark DAC1 and DAC2 converters are equipped with Benchmark’s HPA2™ headphone power amplifier. This is a high-current design with very low output impedance (less than 0.1 Ohms). It is capable of driving a wide variety of headphones while achieving extraordinarily low distortion. The full rated performance of the DAC is achieved at the headphone jack while driving two sets of headphones. THD+N is less than 0.0003% under full load. The HPA2™ may be the quietest and cleanest headphone amplifier available.
The HPA2™ has jumpers that allow it to be matched to the sensitivity of your headphones. These jumpers can be used to optimize the system performance.
"DSD provides a simple and direct digital path between the A/D and D/A."
"DSD is simpler than PCM."
"DSD is not PCM."
While DSD can provide spectacular audio performance, all of the statements above are false.
There are many wonderful DSD recordings, but the quality is not due to any virtues of the DSD format.
Direct Stream Digital (DSD) seems like a simple and attractive system, but it absolutely fails to deliver a "direct" path between the A/D and the D/A.
There was a 10-year time span between the introduction of the Benchmark DAC1 and DAC2 audio D/A converters. The DAC1 defined the state of the art when it was introduced in 2002. Thirteen years later, Enjoy the Music.com selected the DAC1 as one of the 20 most significant digital audio products from the past 20 years. Today the DAC2 defines the state of the art in audio D/A conversion. John Atkinson said that the "DAC2 offered one of the highest resolutions I have measured". Both products set performance benchmarks when they were introduced. In a sense, they provide snapshots of technological progress.
This paper shows high-precision side-by-side measurements of the DAC1 and DAC2 converters. These measurements show how technology has improved, and they show that there may be two or three audible differences between these two products.
Travel through 10 years of audio technology, learn the significance of audio measurements, and see what has improved in our quest for transparent audio reproduction.
Benchmark introduced the DAC1 in 2002 and it quickly became the best-selling 2-channel professional D/A converter. To this day, the DAC1 is a standard fixture in many recording studios, and it is also a central component in many high-end hi-fi systems. In August of 2015, Enjoy the Music.com selected the DAC1 as one of the20 most significant digital audio products from the past 20 years.
It is easy to show that the DAC2 measures better than the DAC1 in almost every way. From a marketing perspective it would be tempting to claim that all of these measured differences make audible improvements, but this just isn't the case.
One reviewer, Gary Galo, recently had the opportunity to hear a DAC1 and DAC2 side-by-side. He noted some audible differences and we agree with his conclusions. We have had a great deal of experience listening to these converters side-by-side in our own listening room and we are familiar with some subtle differences.
This paper examines the subtle audible differences between the DAC1 and the DAC2. It also includes measurements that may help to explain these differences.
Many Benchmark products include our HPA2™ headphone power amplifier. Unlike most headphone amplifiers, the HPA2™ is designed to behave like a small but very clean power amplifier. What makes the HPA2™ different, and what do we mean when we say that the HPA2™ is a "power amplifier"?
Consumer products are usually packed with features but they often fall short when it comes to audio quality. These products deliver a level of performance that is acceptable to most consumers, and they do so at very affordable prices. Nevertheless there is often a large performance difference between consumer and professional audio products.
One of our customers, Jeff Switzer, owns a Marantz AV8801 pre-pro and he took a look inside to see how it was built. His detailed analysis shows how consumer product cost constraints limit audio performance.
Jeff's teardown analysis is a bit technical, but I know that some of our readers will appreciate the detail. For the rest of our readers, let me summarize by saying that there are real differences between consumer products and high-end professional audio products.
- John Siau, Benchmark Media Systems, Inc.
Blu-ray disks often contain high-resolution audio formats. Dolby TrueHD and DTS-HD are two Blu-ray audio encoding formats that support lossless high-resolution audio. These systems support up to 8 channels of 24-bit, 96kHz audio, or up to 6 channels of 24-bit 192 kHz audio.
Blu-ray disks may seem like an ideal solution for the distribution of high-resolution audio, but there are problems. It is not easy to gain access to the high-resolution audio stored on these disks.
Our solution was to set up a PC-based music (and video) server. We used a Blu-ray equipped PC running Windows 7 and the JRiver MediaCenter software.
This application note provides a guide for setting up a music server that can play the lossless high-resolution audio tracks found on DVD and Blu-ray disks.
Digital recordings are now available in a variety of sample rates. The CD uses a 44.1 kHz sample rate, but high-resolution audio recordings are now available in sample rates of 96 kHz and 192 kHz. What are the advantages of higher sample rates? How high a sample rate do we really need?
Digital audio systems take instantaneous snapshots or "samples" of an analog audio signal and then store each of these samples as numeric values. The digital samples can be stored and transmitted without any loss of quality, but these samples must be used to reconstruct an analog signal before we can listen to the audio. The sample rate places very specific limitations ...