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CH Precision A1 Power Amplifier

Quick Overview

CH Precision A1 Amplifier ( available in Stereo or Mono version).

As the driving force behind recreating the full musical experience, the task of the power amplifier may seam desperately simple but is indeed highly complex. Achieving our simple goal of ”add nothing, remove nothing” to preserve the full musical emotion has resulted in a ground breaking new amplifier topology. Housed in a chassis similar to the C1 and D1, the A1 sets new standards in terms of performance, flexibility of adjustments, industrial design and pure enjoyment.

The A1 is based on a novel proprietary amplifier architecture which optimizes the critical matching of the amplifier with the speaker. It can be operated either as a stereo amplifier (2x 100WRMS under 8Ω), as a monaural bi-amping amplifier (2x 100WRMS under 8Ω) or as a bridged amplifier (1x 350WRMS under 8Ω). Monaural analog input boards - one or two need to be installed depending of the chosen operating mode - provide single-ended RCA, single-ended BNC and balanced XLR input buffering. Each channel gain can be individually adjusted by steps of 0.5 dB in a range of +/- 6 dB.

The analog input stage is a class A full discrete, zero global feedback design, optimized for ultra-low noise and transient response. The analog output stage contains the key innovation of the A1. It is built around a class A full discrete ultra-low noise driver and a power stage operated as a pure follower in class AB. The feedback topology of the output stage allows for programmable global or local feedback or a mix thereof. Modifying the feedback ratio between global and local allows for adjustment of the A1's output to match a given loudspeaker, or even each specific driver when used in bi-amp or bridge modes. The amplifier includes a sophisticated monitoring system for each channel to report operating conditions (temperature, peak power into loudspeakers) and to ensure the security and stability of the system. There is no capacitor in the signal path. Premium grade components are used throughout such as 4-poles Mundorf capacitors, Argento loudspeaker binding posts and internal wiring, as well as many tight tolerances passive parts. A sophisticated mechanical chassis design and full USB based firmware update support contribute to make the A1 a real long term enjoyment.

Manufacturer's website CH Precision

Details

Please find reviews below

 

" MUSIC EMOTION " Magazine review, 2016

http://www.ch-precision.com/images/reviews/Review_WB_CHP_English_ME7-8_16.pdf

Positive Feedback " Online Magazine Review , Ultimate Digital Source

http://www.positive-feedback.com/Issue74/ch_precision.htm

The Absolute Sound " Magazine Review , TAS Editor's Choice and Golden Ear Award Winner.

CH Precision C1 Linestage/ DAC and A1 Power Amplifier

Image result for 2016 editors choice award the absolute sound

"These highly modular components from new-but-pedigreed CH Precision represent the latest Swiss thinking on high-bandwidth, low-noise amplification and digital circuitry. Technology aside, the CH gestalt is linearity (in the frequency, time, and dynamic domains) and musicality in equal parts. The result is accuracy in the service of music rather than for its own sake. The C1/ A1 combo creates magnificent colors (but never euphony), dynamic fireworks (without overshoot), startling transients (minus any edginess), and jump-up-and-dance rhythms (with zero slop). Nor are spatiality and resolution slighted. These electronics reproduce every dynamic, timbral, and rhythmic flux. And although you can hear every little thing going on in the mix, it all comes together organically—as it does in real life. Order the C1 with the network card. Once you hear high-res streaming from a NAS drive to the C1, you will never go back to USB. As for the A1, the stereo version gets you about 95% of the performance of the monoblocks. But if you have an extra thirty-seven grand lying around, the monoblocks are unparalleled." - TAS (239)

 


Hi-Fi+ Issue 120 February 2015

" HI FI + " Magazine Review , February 2015

" This must rank as one of the most expensive one-make audio systems we’ve ever explored. CH Precision is based in Switzerland and it’s designed and built by people who used to design and build Goldmund audio equipment. Each component is built like a brick outhouse, without even an implication of a suggestion of compromise. It’s hyper-flexible, engineer’s engineering. And the whole package costs well north of £60,000. Cor!

The system tested here is comprised of a D1 SACD/CD player, which becomes a transport to the C1 digital to analogue controller that in turn drives an A1 power amplifier. This last is perhaps the easiest way to define the ‘hyperflexible’ nature of the system, because it’s designed to be used as a lone 2x 100W amplifier, or with another A1 amp as a dual-mono, a passive or active bi-amplified system, or as a bridged design, delivering up to 350W per channel. All are equally good and valid ways to make sound, and all depend on what best suits your system. There is also an X1 power supply, designed to feed the D1 or C1, and this can be factory configured to feed one or two units. There is also an M1 reference two-channel amplifier. This has all the flexibility options of the A1, but doubles the power throughout. At twice the height and 75kg per chassis, it makes the 43kg A1 seem almost sylph-like. Like the X1, the M1 was not available at the time of review, in part because I wouldn’t be able to get this into my room without having to resort to structural changes to the property. There’s a common theme to all CH Precision components in terms of design and overall look. They are share the same wave like front panel with centre display panel and all use the same chassis: large, heavy, and allowing the designs to be built on a common modular motherboard/card layout akin to a desktop PC. This not only means shared chassis components, but extends the working life of the design, by allowing up-coming changes to the design to be implemented by card additions and substitutions. The common chassis also allows a clever stacking arrangement, where decoupled screw-in bars fit in the place of the four feet, meaning the system becomes its own rack. Of course, this means whatever the three or four components rest on needs to be structurally sound, because it’s taking a load that tips the scales at an impressive 99kg (142kg if you use two A1 amps) – that’s almost 220lb in the developed world. The ‘no-quarter’ build quality extends throughout. Take the D1 for example; it is a SACD/CD player based around a modified Esoteric VMK-5 VRDS transport mechanism. CH Precision uses that big, weighty chassis to its advantage by mounting the VMK-5 on a 15kg steel plate and heavy steel rails, thereby conferring even more vibration immunity to the disc replay mechanism. You could do this on a smaller, lighter player, but run the risk of the steel plate buckling the chassis. If you take the top off the player (no mean feat in and of itself) you are met with a series of custom-made circuit boards, each one isolated from the others (which helps explain why all the CH Precision products come with a transit screws to lock things in place). Then, the modular layout underpins the flexibility of the system. There are five slots for daughter cards at the back of the player, allowing the D1 to be configured as a stereo player, a stereo transport, a dualmono player (one dedicated output card per channel), a multichannel player, a multichannel transport (for a multichannel DAC), or a multichannel transport for multiple DACs. There’s also a clock board for connection to an external clock, or synching to the D1. You can also control the D1 through Ethernet and update its firmware through USB. It’s a potentially bewildering array of options, made no simpler by reading the manual, but is explicable by someone who understands the CH configuration options. The C1 is no less flexible, and no less daunting in configuration. There are options for digital and analogue inputs, USB and Ethernet connections, and clock connections, as well as the aforementioned X1 power supply upgrade block. It’s ultimately best to pick and choose what you need instead of just stacking the C1 up with extra features. There are fewer options on the A1 (as befits a Class AB power amplifier), although there is a USB input for software updates, Ethernet for remote control, and the mono buffer boards for dual mono use. Card options aside, the CH Precision components can be neatly summed up as products made the way they should be made, to deliver their best. Where possible, discrete components abound. CH Precision developed its own ‘CH Link’ allowing PCM up to 32bit, 768kHz, and one bit DSD to 5.6448MHz, as well as asynchronous USB to 24/192 PCM and 2.8224MHz DSD and asynchronous Ethernet to 24/192 PCM and 5.6448MHz DSD. There are superbly clever aspects to the design (small remote controls with magnetic bases that attach to one side of the cabinet), but with these come some frustrations. Until recently, the player and DAC controller were controlled by a series of menus on the AMOLED screen, driven by a dual concentric knob with a central push button. Functions change relative to what ‘state’ the device is in at the time you access these menus, and whether you tap the push button, or press it for two seconds (the former puts it into shortcut mode, the latter puts it into standby). The manuals describe the processes needed to access these menus accurately, but they are BIG manuals. The A1 has a more conventional array of five buttons, but these also allow you to adjust global feedback levels in 20% steps and precise adjustable gain control to match your loudspeakers in room. Fortunately, at CES this year, CH Precision showed a handy app that took over these functions, as well as acting as the control point for a streaming solution. This means you no longer need to be a safecracker with an eidetic memory just to know how to fast forward. The CH Precision system is pretty damn outstanding in its default settings, but if you don’t delve through the manual, you may never know there are five PCM filter settings and four DSD settings, or that it allows you to synchronise the clock in the D1 to the C1, the clock in the C1 to the D1, synchronise both to an external clock, or simply ignore the clock options altogether, depending on your tastes and the rest of the system. Although I received two A1s, my system (culminating in Wilson Duette Series 2) needed just one. The second used in bridged mode didn’t justify its inclusion. Your speakers and room may make different demands. CH Precision’s ‘thing’ is one of gradually winning over the listener. It’s impressive by not being impressive, although there’s some of the typically Goldmund ‘writ large’ presentation about the overall sound. But more importantly, it’s one of those systems that defies description, because the flexibility allows it to adapt to the demands of the loudspeaker so well, it becomes something of a shape-shifter. It does the big, bold Wilson loudspeaker signature sound, but when you move from Wilson to Wilson-Benesch, it delivers the kind of tight, controlled, and authoritative sound you expect from Wilson-Benesch. And when you plug in a pair of loudspeakers that don’t have the word ‘Wilson’ in their name, CH Precision adapts to them too.

If there is a ‘house’ sound for CH Precision, it’s one of dry precision and infinite dynamic range. By ‘dry’ I’m talking more ‘Martini’ than ‘Gobi desert’, because the whole package is sophisticated, refined, elegant, and mature. I’m making this sound a little cool and distant, and that’s not the way the CH Precision system sounds. Instead, it’s so fundamentally correct that it makes other amplifiers and digital sources sound like they have some kind of overhang and bloat, and there’s often no way back once you hear that. Talking musical examples is invalid here. Everything is a musical example. If you find yourself thinking how good the backing vocals are on Funkadelic albums, you know that you are in the presence of audiophile royalty, and yet CH Precision wears the crown well. While it gives you insight into the music, it doesn’t do so at the expense of the music. Of the three components tested, the D1 is the breakout star of the show. That’s not an easy statement to make, because that show has one hell of a cast. But if the rest are Oscar winners, the D1 is Brando in The Godfather.

The CH Precision D1, C1, and A1 are in our Formula One; precision products, custom made for uncompromising users to deliver the ultimate performance. This top elite remain an ultimate, a goal towards which we should all strive, even if not all of us can reach it. And that’s the thing; CH Precision is one of that select list of products we as audiophiles should try at least once in our lives. And for a lucky few (who not only have the financial clout, but are prepared to take time to learn how to learn how to really use the system), they get to live with one of the best systems ever." - Alan Sircom , Hi Fi Plus , February 2015


CH Presicion A1 Features & Specifications

Analog inputs

Inputs type Balanced (XLR), one connector per board
Single-Ended (RCA & BNC), one connector per board
Input impedance Balanced: 94kΩ
Single-Ended: 47kΩ or 300Ω
Input stage JFET input stage
Ultra-low noise, discrete fully differential stage
24dB range adjustable gain in 0.5dB steps

 

Amplification

Amplification stage Ultra-low noise full discrete class AB design
5 pairs of complementary output transistors
Bias Patent-pending bias circuitry for constant bias operation
Feedback User-adjustable local vs. global feedback ratio, from 0% to 100% with 20% steps 
Bandwidth DC to 450kHz (-3dB) at 1W into an 8Ω resistive load
Signal to Noise Ratio Better than 115dB in stereo and bi-amp modes
Better than 118dB in bridge mode
Total Harmonic Distortion + Noise Less than 0.1% with 0% global feedback
Less than 0.01% with 100% global feedback

 

Analog outputs

Binding posts Two pairs of Argento binding posts for loudspeakers connection
Monitoring Non-intrusive DSP-based protection of the amplifier
Instantaneous voltage & current values are permanently monitored for each channel
Protections Short-circuit protected
Disconnected loudspeaker detected
Over-temperature of the heatsink, f