Preamplifier
Percival Blanco
A preamplifier, also known as a preamp, is an electronic amplifier that converts a weak electrical signal into an output signal strong enough to be noise-tolerant and strong enough for further processing, or for sending to a power amplifier and a loudspeaker.[1] Without this, the final signal would be noisy or distorted. They are typically used to amplify signals from analog sensors such as microphones and pickups.[2] Because of this, the preamplifier is often placed close to the sensor to reduce the effects of noise and interference.
An ideal preamp will be linear (have a constant gain through its operating range), have high input impedance (requiring only a minimal amount of current to sense the input signal) and a low output impedance (when current is drawn from the output there is minimal change in the output voltage). It is used to boost the signal strength to drive the cable to the main instrument without significantly degrading the signal-to-noise ratio (SNR). The noise performance of a preamplifier is critical. According to Friis's formula, when the gain of the preamplifier is high, the SNR of the final signal is determined by the SNR of the input signal and the noise figure of the preamplifier.
In an audio system, they are typically used to amplify signals from analog sensors to line level. The second amplifier is typically a power amplifier (power amp). The preamplifier provides voltage gain (e.g., from 10 mV to 1 V) but no significant current gain. The power amplifier provides the higher current necessary to drive loudspeakers. For these systems, some common sensors are microphones, instrument pickups, and phonographs. Preamplifiers are often integrated into the audio inputs on mixing consoles, DJ mixers, and sound cards. They can also be stand-alone devices.
The revolutionary STR Preamplifier is a new type of audio component that gives you more control and more refinements, including more connection options and more advanced technology, in a single, easy-to-use component.
The STR Preamplifier includes the newest and most powerful generation of Anthem Room Correction (ARC), with 50% more processing power than any other version of ARC. This proprietary calibration tool, with its easy-to-use interface, automatically shapes the acoustic signature of your speakers for the best possible sound quality in your unique listening space.
Other innovations include a high- resolution preamplifier and digital section, which supports asynchronous USB up to 32-bit/384 kHz PCM and DSD 2.8/5.6 MHz sources, and uses signal processing that employs 64-bit accumulation and feedback to preserve the finest detail in the music and to avoid degradation. The digital to analog conversion section was designed to faithfully duplicate all the sounds in the original source.
Aside from its cutting-edge technology, one look tells you that the STR Preamplifier is a different animal altogether. The display on the front panel gives you surprisingly easy control through an easy to navigate setup menu, and the luxurious and elegant new contemporary design is available in two beautiful finishes, Black or Silver.
The STR Preamplifier gives you more options for subwoofer configuration. Use one subwoofer or two for both channels, or two independent right-and-left channel-specific subwoofers. The bass management in conjunction with ARC is uniquely engineered for seamless subwoofer blending, achieving incredibly accurate and lifelike performance.
Anthem has also taken into consideration the resurgent popularity of vinyl records, and has included separate inputs for moving magnet and moving coil cartridges, with the phono section completely shielded to maintain a clean signal. The transparency and refinement of the STR Preamplifier reveals the hidden magic of classic media.
Clarity is maintained using carefully selected components, many of them engineered exclusively in-house at Anthem. We believe that two-channel listening demands attention to detail, with flawless signal integrity being the benchmark of stereo performance. To that ultimate end, the Anthem STR Preamplifier is designed with the shortest possible signal paths, and differential analog to digital circuitry to cancel artifacts and keep noise to a minimum.
ARC is easy to use, and just a few simple steps can optimize your speakers for your unique listening space. ARC is sophisticated, one of the most accurate and detailed digital room correction technologies available today. ARC will work tomorrow, too; with constant advances and updates available for download on the Anthem website.
The Mirion Intelligent Preamplifier (iPA) for High-Purity Germanium (HPGe) Detectors is a low-noise, high-speed resistive feedback preamplifier designed for high resolution gamma spectroscopy and timing measurements.
The Mirion Intelligent Preamplifier (iPA) for High-Purity Germanium (HPGe) Detectors is a low-noise, high-speed resistive feedback preamplifier designed for high resolution gamma spectroscopy and timing measurements. When energy is deposited in the detector, the iPA detector converts the charge to a step-function output pulse of which the amplitude is proportional to the total charge accumulated in the event.
The preamplifier includes a low-noise FET input circuit optimized for the ultra-high source impedance of germanium detectors. A protection network prevents damage to the preamplifier input from high voltage transients. The charge amplifier and buffer stages have been designed for both the low noise and high speed performance needed for precise energy and timing spectroscopy. In addition, special circuits monitor both the temperature and activity of the detector, and warn when improper operating conditions exist.
The iPA detector is equipped with a high-speed USB 2.0 serial data interface. This interface facilitates extensive control and monitoring of many critical preamplifier and detector functions. The included iPA Control Panel software application provides the user with realtime monitoring of the detector current and temperature, along with pertinent internal preamplifier operating voltages. The integrated data logging feature continuously records several of these key operating parameters on a periodic basis, and stores them within the iPA mass storage memory. The stored data log files can be readily downloaded and viewed. This allows the user to take preventative measures if a key parameter starts to shift and ultimately improves equipment availability and productivity. A standard test input and internal test pulser are provided to assist system setup and as a diagnostic aid. The internal test pulser is digitally-controlled through the iPA Control Panel software.
The iPA detector also includes an integrated LN2 level monitoring circuit, for use with an optional Mirion capacitive LN2 level-sensing probe. The iPA and probe work together to continuously measure the LN2 level within the Dewar. The measurement is displayed on the iPA Control Panel status screen, and warns the user when the LN2 level becomes low and the Dewar requires refilling.
I'm disappointed that McIntosh seems to be insisting on the purchase of their DAC module with just about any of their preamps--as you point out, it's not quite as good as current separates. A few years ago it was easy to choose--the C22 was essentially a C2600 without a DAC for about $2,000 less.
Kirk, agreed and for the most part that is in fact true. That said, in more than three decades of futzing with this hobby, I learned that there is generally a massive difference between reality and theory, or theorems that supposedly prove one thing or another. Take for example the hoopla that exists in the analog domain with vinyl playback: "you must adjust VTA for each and every record!" Sure, in theory that's true: each record has different thickness, etc. That said, in practice, I have found this to be irrelevant to the extent that whatever minute differences there may be in going from a 140 to 150 or 180 gram record (and the resulting difference in thickness, thus different VTA), it simply makes little to no difference in the actual playback. There are so many other factors involved that even if you took properly setting exact VTA for each and every record, you'd also have to check the specs for 5 or 9 other parameters, not least of which those influenced by the raising and lowering of your VTA. To boot, you then haven't even taken into account the cartridge manufacturers own - usually horrendous - specs, since all of these cartridges - well, most if not all of those retailing for say more than $1000, are all hand built and there are variations within even the same model, etc. Or take any other alternative ideological must be true for its online and opined by expert XYZ or some such demagoguery and you'll find the same reality check. Another great example are air bearing linear tracking arms and which sort of disposition you take regarding the arm's nature of the air bearing. Do you use a high pressure sleeve air bearing or do you use the rail air bearing approach where the entire rail consists of multiple tiny holes which through a low pressure air pump push the arm up. Each have their pros and cons; each are supposed to definitely produce some result or another until they don't. Virtually every review of the Bergman Galder / Odin table and arm combo has been absolutely bonkers positive despite the fact that Bergman chose the low pressure rail bearing approach instead of the sleeved high pressure approach. Go figure. What's it all mean Basil?
We auditioned a Mac (MA 352) this morning (we are looking for a new amp). The tone controles were quite useful in a few cases (to my own surprise, we haven't owned an amp with tone controles for decades).