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Channel Islands Audio C-100S Power Amplifier

Channel Islands Audio C-100S Power Amplifier

One of the more egalitarian aspects of highperformance audio is that not all manufacturers are multi-national corporations. Some are smaller, more focused operations such as Channel Islands Audio, which opened its doors in 1997, 22 years ago. Founded by designer Dusty Vawter—who began his audio career as the head of the technical service department at Audio Alchemy—Channel Islands Audio (CIA) specializes in well-built, high-performance audio components manufactured to last for more than one product cycle. What’s more, the components are not outrageously priced; those in CIA’s “Classic” line all retail for under $600. CIA also makes six different accessory power supplies, five preamplifiers, and four power amplifiers.

Here, we will be looking at the C-100S stereo power amplifier ($1500), which is CIA’s lowest-power amplifier, though it still produces 180 watts into 4 ohms and 100 watts into 8 ohms. Its footprint is only 8.5″ wide by 2.75″ high by 10″ deep and it weighs a scant six pounds. One of the reasons the C-100S weighs so little and takes up so little space is because its entire aluminum chassis gets used as its heatsink so it doesn’t require big cooling fins.

Tech Tour
The C-100S stereo power amplifier utilizes a Hypex Class D power module. And while many amps use those amplifier modules, most are “complete” amp circuits that require little more than a power supply and input and output connections to be fully functional. The C-100S is different because it uses an abbreviated Hypex amplifier section without input or power-supply sections. The C-100S amplifier uses a proprietary and completely separate power supply that is incased in its own separate and shielded partition at the front of the amp. The amplifier employs its own front-end circuit that is also separate from the Hypex board. If you look at the photo of the C-100S amplifier’s inner workings, you can see that the two Hypex boards are connected directly to the output connectors and can be easily replaced after four connectors and two screws are removed. This not only gives CIA an option for Hypex circuit board updates in the future, but also makes repairs to the C-100S stereo power amplifier simple and easy for customers anywhere in the world.

Channel Islands Audio C-100S Power Amplifier

The Hypex module was chosen primarily because it employs a patented control loop and output filter that provides flat frequency response regardless of the load impedance. Most other Class D output stages are optimized for a 6-ohm load, and exhibit a rising response into 8 ohms and a roll-off into 4 ohms. 

Few power amplifiers have a variable gain option, although this is not a unique feature. But the C-100S can be set for either 26dB, which is the usual standard, or a higher sensitivity of 32dB. This 6dB increase makes it easier to use the C-100S power amp with a passive, no-gain preamplifier. However, changing the setting switches on the amplifier’s backside does require a toothpick and a steady hand.

Ergonomics and Setup
Installing the C-100S stereo power amplifier within a system is simple—just connect the speaker cables to the amp’s five-way binding posts, and join an input to the amp’s single-ended RCA input jacks, plug it in to a power source, turn it on, and you’re ready to go. This is a good place to mention that the C-100S amp only has single-ended RCA jacks for inputs. If you have a long cable run and prefer balanced XLR connections this could require adapters (which will negate the advantages of the balanced line).

During a majority of the review period I used the C-100S stereo power amplifier in my nearfield desktop system where it was attached to the CIA PC-4 Mk II passive preamplifier/attenuator either being fed by the Chord Qutest DAC or connected directly to the single-ended outputs of the PS Audio DSD Jr. I used a variety of loudspeakers including the Audience 1+1 Mk III, Role Audio Kayak, ATC SCM7 Mk II, Silverline Minuet Plus, and Mark Volti Crespi. When I installed the C-100S in my primary room-based system, where it was connected to the single-ended outputs of the Mytek Manhattan II DAC while driving a pair of Spatial Audio X2 loudspeakers, I did notice a bit of hiss coming from the tweeter/midrange ribbon drivers when I was closer than four feet away. This hiss was not present when the Spatial X2s were connected to the Pass Labs X150.8 power amplifier, which was attached via a balanced cable connection.

In some systems the ability to use the 32dB gain instead of 26dB can deliver better signal-to-noise, but in both of my systems I discovered that 26dB was a better match since it allowed me to use a more compatible setting on my preamplifiers and gain controls. Since CIA has a 30-day trial period for all its products you will have ample time to try both settings to determine which works best in your system.

I like small-footprint, lightweight power amplifiers that generate little heat. You can put them anywhere, leave them on all the time, and move them without risking a hernia. The only disadvantage of an amplifier as small and lightweight as the C-100S stereo amp is that some of the larger, heavier, and stiffer interconnects and speaker and power cables may be harder to use with the C-100S unless you add some weight to the top of its small chassis to keep it in place. I used a VPI brick combined with a weighted doorstop.

 

Sound
In my world a “good” power amplifier is one that can drive a wide variety of loudspeakers successfully without drawing undue attention to itself. The C-100S stereo power amplifier accomplished this goal easily. No matter which of my loudspeakers I tethered to the C-100S, they sounded like they should have sounded. I never had any sense that there was anything different happening to their harmonic balance as a result of the amplifier/speaker interface.

In spatial rendition and imaging the C-100S matched the dimensionality of my reference amplifier, the Pass X150.8. Whether it was my own two-channel live concert recordings or streaming sources from Tidal or Qobuz, the image placement, depth, and space between the instruments were preserved. The C-100S was also exceedingly quiet in terms of background noise within my desktop system. Regardless of which loudspeaker I employed, I couldn’t hear any hiss or hum even when my ears were only inches away from the drivers. At normal nearfield listening distances—approximately two feet from drivers to my ears—the system with the C-100S stereo power amp in place was dead quiet. As I indicated earlier, in my room-based system there was some hiss, but it was due to the long single-ended run, rather than the amplifier itself.

When it comes to power capabilities, although it delivers “only” 100 watts into 8 ohms, the C-100S had no issues driving the 91dB-sensitive Spatial X2 loudspeakers to more than adequate volume levels with plenty of additional travel left on my preamplifier’s volume knob. In my desktop setup, I found no need to boost the C-100S amp’s gain to 32dB because even 26dB of gain was more than sufficient. If you have inefficient loudspeakers with less than 84dB sensitivity you may want to investigate one of CIA’s more powerful amplifiers, but for anything above 90dB, the C-100S stereo power amplifier should do the job with ease.

Speaking of ease, the C-100S delivered all the music in a relaxed, natural way. I never got any sense of solid-state upper-frequency grain or grit. Also, I never heard any upper-midrange or lower-treble glare when the power amp was pushed by challenging material. In that way the C-100S amplifier reminded me of my favorite reference microphone preamplifier, the Grace Lunatec 3, which always retains its clean, clear, and controlled sound even when hammered by hard, fast transients. Like the Lunatec, the C-100S remained unruffled by even my most dynamic live recordings. 


Channel Islands Audio C-100S Power Amplifier

Summary
For some audiophiles the highest praise that can be heaped upon a discrete solid-state or Class D amplifier is that is sounds “tube-like.” My position is different. I prefer a power amplifier that attempts to sound as invisible as possible—a straight wire with gain, to repeat that old audio cliché. The C-100S stereo amp provided more than enough power to drive all the loudspeakers I threw at it and did so in a way that allowed each loudspeaker’s unique personality to come to the fore. I suppose if you want an amplifier that has “personality” you should look elsewhere. But if you need a harmonically neutral power amplifier that you can attach to a wide variety of loudspeakers, the C-100S would be an excellent choice. And priced at $1500, the C-100S stereo power amplifier ranks as a “best buy” in my world.

Specs & Pricing

Power output: 180Wpc into 4 ohms, both channels driven; 100Wpc into 8 ohms
THD + Noise: <.006% (1 watt/1kHz)
Input impedance: 100k ohms (Teflon-insulated RCA jacks)
Output impedance: 0.015 ohms (5-way binding posts)
Voltage gain: 26dB/32dB (user-selectable via external DIP switches)
Input sensitivity: 1.4V/26dB, 0.7V/32dB
Maximum output current: 14A (per channel)
Power consumption: <15w (idle)/90% efficient @ rated power
Dimensions: 8.5″ x 2.75″ x 10″ (including binding posts, etc.)
Weight: 6 lbs. (9 lbs. shipping weight)
Price: $1500

CHANNEL ISLANDS AUDIO
567 W. Channel Islands Blvd.
PMB #300
Port Hueneme, CA 93041
(805) 984-8282
ciaudio.com

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