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Review: CH Precision L1 Dual Monaural Line Preamplifier, and M1 Reference Power Amplifier

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Reflecting on Swiss precision high fidelity.

Complaints. I had many complaints with this system.

Not from me, from my neighbours. You see, this was one of those systems that just begged to be played ridiculously loud. It was the sense of scale, it was the musicality, it was the tone, the timbre… the bass. The CH Precision L1 Dual Monaural Line Preamplifier, ($32,975 USD/$40,870 CAN) and M1 Reference Power Amplifier ( $51,000 USD/$63,960 CAN) being fed Redbook Tidal, and high-resolution local files (a mix of 24/192, and DSD) via a totaldac d-1 integral preamp/server/DAC paired with CH balanced interconnects, and speaker cables (Balanced-Link – $2,500 USD/$3,050 CAN – per meter pair, Speaker-Link – $2,500 USD/$3,050 CAN – per meter pair, additional length at $550 USD/$675 CAN per meter pair) running into a pair of Dynaudio Confidence C4 Signature loudspeakers ($22,000 USD/$27, 585 CAN) was a potent mix to have in a concrete high-rise apartment.  David Chan, and Lawrence Lock from DVL Audio had very kindly arranged through Edward Ku at Element Acoustics in Vancouver to have the Swiss gear hand-delivered to me. Ku also wisely supplied me with the C4 Signatures to take on the CH kit, which proved to be an excellent match.

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Perfect fit and finish.

CH Precision was not a company I was familiar with even a year ago, but when I had a chance to hear some demo gear at Element Acoustics, I was deeply impressed, and through Ku made contact with Chan, and Lock to see if review samples could be acquired. I was in luck, and soon after on a snowy spring afternoon Ku, and I made our way to my place with a couple pallets worth of gear. We took our time setting things up, and I let the gear warm up for a couple hours before I sat down to listen, and get the speaker positioning sorted out. The CH gear is very heavy, so we placed it on a pagode amplifier stand for the review, which worked perfectly.

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Well-engineered, and impeccably built: pagode.

The first thing you notice about the equipment upon close inspection – which was when we were setting it up – is the absolutely flawless fit, and finish of the components. I was aware that the components had a bespoke look, and feel about them during initial listening opportunities previously, but having the components in my home it became immediately apparent that CH Precision has spent a considerable amount of time, research, and development into engineering the chassis design, and exquisite metal finish. The way the chassis isolation posts fit together with other CH components for stacking is brilliant as well, and allows for a stunning presentation when placed upon one another as Ku, and I did for this review.

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Beauty, and the Beast together again off-off Broadway.

CH Precision uses a number of proprietary technologies in their designs. These range from advanced synchronization between the digital source, and their R2R (Ladder) DACs (Digital to Analog Converter) via a Phased-Locked Loop, and World Clock, their patent-pending ExactBias Circuit that monitors internal temperatures of power transistors, and adjusts (in real time) their amplifier’s bias, to the ability to adjust (in 10 per cent increments) local, and global feedback for controlling the amplifier’s damping factor to fine-tune it to any pair of speakers – got transducers with drivers (tweeter/mids/bass) that be driven independently? Perfect. The feedback ratio can be adjusted for each driver.

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A true monaural design: L1 Preamplifier.

The Preamplifer

The L1 is a modular design, and can be customized when ordered to include a number of options including an external X1 (identical chassis design) power supply. The volume attenuator is a chunky, but smooth affair that feels wonderful to the touch, and responds instantly to a click from the supplied matching remote control, which complimented the components perfectly in look, and had a weighty, tactile feel that made it enjoyable in use. The LED display was bright, and clear, and could be easily seen from across the room.

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L1 matching remote control.

Specifications from the CH website are as follows:

Analog Signal Path

  • Each channel is physically mounted, and isolated on its own circuit board
  • Ultra low noise, high bandwidth, high slew-rate design
  • Pure Class A, fully-symmetrical design
  • Fully discrete transistor-based circuitry
  • Phase inversion, and Mono modes

Power Supply

  • Dedicated discrete regulated linear power supplies
  • Ultra-low noise, high-accuracy regulation
  • Oversized mains transformer
  • Shunt regulators for critical stages
  • Over-current protection

Analog Audio Inputs

  • Four balanced XLR connectors
  • Two single-ended RCA connectors
  • Two high-bandwidth coaxial BNC 50 Ohm connectors

Analog Audio Outputs

  • Powerful discrete output buffer
  • Two balanced XLR connectors
  • One single-ended RCA connector
  • One high-bandwidth coaxial BNC 50 Ohm connector
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M1 Power Amplifier chassis detail.

The Power Amplifier

The M1 is a beast with a patent-pending Class A/B circuit design, and cannot be moved by one person. Period. Weighing in at 165 lbs, it’s safe to say that over-engineering is built-in. Equipped with an absolutely massive 2,200 VA transformer which CH engineers have fully isolated from not only electrostatic, and magnetic interference, the transformer itself is also separately-mounted internally on “Silent Blocks” for full mechanical, and vibration isolation of all the internal circuitry. Discrete components are used throughout the amplifier, with no operational amplification in the analog stage, and no capacitors, or output relays in the signal path. CH says this ensures both the shortest signal path, and maximum transparency to source – both claims that after spending time with this gear I can say seem to be less hyperbole, and more merit as the M1, and L1 do an uncanny job of removing themselves from any colouration of the audio signal one might usually associate with amplification. One of the really cool things from an adjustability standpoint (or for those who like to tweak) is the ability to configure the M1’s output stage to include global feedback. I found this to affect the sound of the amp noticeably – always in a different way depending on the source material – and after a significant amount of listening at different settings (adjustable on-the-fly from zero per cent to 100 per cent in 10 per-cent increments) with different material, I settled on 10 per cent. The M1 also features unique circuit-monitoring design (measures both transistor, and heatsink temperature) that continuously assesses, and adjusts the output stage to maintain constant bias regardless of the analog waveform or room temperature.

The M1 can be run in multiple modes: stereo (single chassis, this is what I ran), monaural (two chassis, with one chassis/one channel powering one left/right transducer) bridged (two chassis, with one chassis/two channels  powering one left/right transducer) passive bi-amplification (two chassis, with one chassis/two channels powering one channel per transducer in parallel) active bi-amplification (two chassis, requires two analog input boards to be installed – one per chassis – each chassis channel drives a transducer a given frequency range), and daisy-chain mode (a chassis for every transducer, one chassis/one channel powering one left/right transducer).

Specifications from the CH website are as follows:

Analog inputs

  • Balanced (XLR), one connector per boardSingle-Ended (RCA & BNC), one connector per boardInput impedance Balanced: 94kΩSingle-Ended: 47kΩ or 300ΩInput stage JFET input stageUltra-low noise, discrete fully differential stage24dB range adjustable gain in 0.5dB steps

Amplification

  • Amplification Stage: Ultra-low noise full discrete class AB design – six pairs of complementary output transistors
  • Bias: Patent-pending bias circuitry for constant bias operation
  • Feedback User-adjustable local vs. global feedback ratio, from 0 per cent to 100 per cent in 10 per cent 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 per cent global feedback – Less than 0.01 per cent with 100 per cent global feedback

Analog outputs

  • Binding posts: Two pairs of Argento binding posts for loudspeakers connection
  • Monitoring:  Non-intrusive DSP-based protection of the amplifier and connected loudspeakers – Instantaneous voltage & current values are permanently monitored on each channel
  • Protections: Short-circuit protectedDisconnected loudspeaker detected – Over-temperature of the heatsink – Over-temperature of the output transistors

Power supply

  • Transformer: 2’200VA toroidal transformer for output stages, oversized for low-noise operation100VA separate toroidal transformer for input stages
  • Power capacitors: 2x 100’000uF/100V 4-poles capacitors
  • Regulators: Non-regulated symmetrical power supply for the power stages
  • Eight local regulation stages for input/driver stages – Seven local regulation stages for the logic/display

General

  • Display: 480×272 pixels, 24bits color, AMOLED
  • Mains operation: Selectable 100V, 115, 230V AC, 47-63Hz
  • Power supply consumption <1W (standby), 2200W max in operation
  • Dimensions/Weight 440 x 440 x 266mm (W x D x H), 75kg
  • Remote control: Ethernet-based system control via the Android CH Control App
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The totaldac d1 integral source, L1 Monaural Preamplifier, and M1 Stereo Power Amplifier.

Now, those who read my reviews know that I’m not huge judging a component on its tech specs, or measurements other than from a standpoint of don’t mate a two-watt triode with Wilson Alexx speakers if you want to hear the best from both. Measurements are a great starting point when it comes to building a system from disparate manufacturers as you need to curate the signal path for the most musical listening experience. That said, when Edward Ku suggested the Dynaudio Confidence C4 Signature to go with the CH gear, I didn’t bat an eyelid because Ku knows his stuff, and doesn’t sell anything he hasn’t thoroughly vetted. The C4 is an intimidating loudspeaker for the non-audiophile in its profile: it’s big. Turning over my shared living room space to this system required some balancing of needs, but in the end a deal was struck, and the “butlers” as they became known (because of their tuxedo-like appearance) were OK to stay for a few weeks to facilitate the review.

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The butlers await their next command.

Listening

These were not the easiest speakers to position, and it took me several days of listening to dial them in, I’ve had fussier, I’ve had easier – I guess I’d say these were somewhere in the middle, but worth it in spades once I was able to find the sweet spot for my particular room. The C4s are rated at 88dB with a four-Ohm impedance, 400 watts of power handling, and 27Hz ~ 25kHz (± 3dB) of measured frequency range according to Dynaudio. I have no reason to doubt this – as my neighbours can attest to – because they were able to evenly pressurize my concrete-walled, and floored condo, and at times produce what I would describe as window-flexing SPLs. The three-way bass-reflex design with it’s D’Appolito transducer array has a listed crossover of 730Hz ~2,200Hz, and delivered clean, non-fatiguing highs, fast, uncoloured midrange, and deep, resolving bass that punched a clear 3D image from anywhere between 10 to 15 feet behind the speakers focal plane, to roughly five feet in front of it depending on source material. The imaging was life-sized, and instrumentation, vocals, and placement was clearly delineated in every spatial plane. The C4s exhibited uncannily excellent timbral reproduction – particularly on drum skins – of trumpet blaat, piano note decay, and wood-bodied instruments appeared in the aural stage as fully-formed, with grainy texture to resined bows: so what I’m saying is they delivered the goods on all the sharp, fine pointy bits that make music, music to me.

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D’Appolito array C4.

In my experience it took the CH gear about an hour to come fully-on song, and I found they definitely like to be kept on all day for listening sessions. If I went out for a couple hours, and shut down the gear, and then came back for some listening, it would take close to another hour for them to really open up again. I didn’t mind this at all, and to be honest I’d say the same for pretty much all gear I’ve got coming through. Achieving optimal thermal conditions for all the internal circuitry, resistors, transistors, tubes, chassis, etc. seems to require about an hour of playing before no more changes were noticeable to the sound. I’ve covered my source for this review – the totaldac d1 integraltwice previously so check out the highlighted text for links to coverage.

Again, I chose disparate albums for the critical listening sessions of this review,  but I played everything from folk, to drum ‘n bass through this system with excellent results. These files were 16/44 Tidal streamed via Roon.

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Pressurizing the living space with ease.

Billie Holiday: Stay With Me

I Wished on the Moon/Ain’t Misbehavin’/Everything Happens to Me/Say It Isn’t So/I’ve Got my Love to Keep me Warm

Stay-with-me-HolidayPalpable sense of scale/lifelike presentation, with organic textures to every instrument, and Billie’s voice in particular. Musicians had clearly defined locations in the sound stage, with deep 3D-imaging that punched through the speaker focal plane. The drummer on these tracks was well outside my apartment windows (back about 15 feet behind the speakers). Absolutely convincing tonality, and timbre to horns, strings, piano, and percussion. A human touch to the voice which I usually only associate with tubes. Tight, life-sized bass, and horn reproduction with plenty of micro-detail on guitar strings/fret. Beautifully-bodied, decay off cymbals, and high hat. Every inflection, and breath of Holiday’s voice reproduced with wet-lipped enunciation, and believability.

Effortless scaling to the sound with relative weight, and body size of instruments, and Holiday’s voice, which was perfectly in sync as the volume went up. Piano reproduction carried rock-solid pitch.

Kevin Morby: Singing Saw

Cut Me Down/I Have Been To The Mountain/Singing Saw/Drunk On A Star

kevinmorby-singingsaw

These tracks had deep, guttural, and perfectly-bodied bass, and guitar that seemed to bleed, thick organic notes over everything. Plenty of air, and space around the vocals of Morby, which seemed to mist the room like the whiff of negative ions pushed ahead of a thunderstorm. The organ’s voicing is haunting, and resonated in what felt like sympathetic frequency with my spine. Weighty percussion presented in such a live-venue sounding way… as if you’re standing next to the stage at a bar. Separation of vocals from the instrumentation was eerie in its clarity. Deep sub-bass was present that spread with a room-distorting flex. Real speed, and transparency to notes, but each carried rich tonal colours. There was no time smearing that I sometimes associate with  computer audio, and while there was a crispness, and sharp delineation between instruments, songs still carried themselves with musicality, and true timbre throughout.

The Japanese House: Pools To Bathe In

Pools To bathe In/Teeth/Still/Sister

Japanese-House-PoolsA jewel of a little EP from 2015 with sweet, paper-thin vocals, and real chest-rattling bass that seemed to create a simultaneous up/down feeling in my stomach. The thick, jammy midrange reproduction on the track Teeth had wonderful tonal texture. There is no Peter robbing Paul to give to Jack here in the CH sound. Everyone is getting paid, and the sense you’re left with is one of balance to the musical experience: It’s sort of like pushing your head into a calfskin-lined motorcycle helmet – if that makes any sense.

Conclusions

CH Precision is a company that seems focused on perfecting the audio signal-path, and delivering every atom of information that’s available from a source file through it. It’s a transparent musical experience to my ears, and I felt like the old adage of “a straight wire with gain” was the missive for the company’s engineers to adhere to when composing the circuit schematics. While this isn’t gear for everyone’s pocketbook, it’s gear for music lovers. Just the way a Rolex Submariner is the destination of a lifetime for some, so too could the L1, and M1 be for those inclined to such precise measurement of fidelity to source. Highly recommended.

–Rafe Arnott

Get your Occasional now
About Rafe Arnott (306 Articles)
Editor and Creative Director for Part-Time Audiophile & The Occasional Magazine.

4 Comments on Review: CH Precision L1 Dual Monaural Line Preamplifier, and M1 Reference Power Amplifier

  1. patrick Moreau // September 5, 2017 at 6:25 AM //

    only a Rolex, not a Patek Philippe ?

  2. peter jasz // September 3, 2017 at 7:08 AM //

    Yes. I do. But remain speechless … other than to say this verbose is without peer.

    pj

  3. Does it have a UL listed sticker for that kind of cash? CE is NOT ETL or UL, different stuff

  4. What a system. Great stuff. The butlers. Hilarious. Great to read all these reviews. More, more… Thanks.

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