Reviewer: Srajan Ebaen
Source: Custom PC (Windows XP), Stello CDT100 / DAC100 Signature
Preamp/Integrated: Peachtree Audio Nova, Glow Audio 2008 Amp One [on review]
Speakers: Beyerdynamic DT880 and B&O 19-ohm earphones, Era Design 5 Sat, Glow Audio Sub One [on review]
Cables: Entreq Crossword Discover USB [on review], Zu Audio Pivot, Zu Audio Varial, AntiCables
Desktop: Ikea glass table
Powerline conditioning: Furutech e-TP80
Desktop size: Diagonal corner placement in 4m x 3m room open to main ground floor.
Review Component Retail: $150
It was Christine Han from April Music of Korea. I'd recently tested her Stello CDT 100 and DA100 Signature. Would I be interested to do the tiny Korean Calyx Kong USB headphone amp? That's what she listens to on her office PC. And, she likes it better than her HeadRoom. If I wanted, she'd make the arrangements. What the heck was the world coming to? Fraternizing with the enemy? A big thumbs up to Christine for promoting a competitor. That's exactly the spirit of cooperation the world needs today!
For background, I asked Seungmok Yi, CEO & President of Digital & Analog Co., Ltd. to paint the picture behind the tiny kong. "Digital & Analog Co., Ltd, started in 1999 as a fab-less* digital amplifier company. We have a few class D patents and proprietary technologies and focused on making single-chip digital amplifiers. To date, we have developed 4 different chips and provide those to various OEM audio makers like Samsung and Daewoo who develop audio products for big brands whose names I must protect. We have shipped more than 10 million chips to these companies.
_________________
* Fab-less means a semi-conductor or IC maker without fabrication facilities. Most IC companies operate that way. Samsung Electronics manufactures D&A's chips in their semiconductor manufacturing facility (FAB) for example, Magna Chips of Korea makes the popular Wolfson Semiconductor integrated circuits
"Last year, I decided to make high-end products under my own brand. High-end audio has always been my goal since I listened to and was moved by Beethoven's 5th Symphony in 1974. Last year we launched our first product, the Calyx 500. That is a 500-watt mono amplifier running the ASP500 module from ICEPower. Alas, ours is very different from other amplifiers using this module. We add more input and power supply circuitry to improve what we regard as the weak points of the ASP500. As you know, other companies just buy the stock modules and put them in their chassis. Our Calyx 500 hit the Korean market with rave reviews.
"This year we debuted CTI Calyx The Integrated at T.H.E. Show in Las Vegas with Usher BE-718 speakers. During the second day, Magnepan president Mark Winey visited our room, spent some time listening and asked me to visit his room with our CTI. Closing my exhibit at 2:00PM well early, I brought my CTI to Magnepan's demo room. There were several people from Magnepan and some dealers. We all listened to the CTI with their new mini Maggie system. All were amazed by the sound. It was much better than their former big system with Bryston electronics. Mr. Winey ordered a CTI for himself on the spot. In turn, we used their mini Maggies during this year's Eyear show 2009 in Korea for which Magnepan had generously sent us a set. We had great success together [above].
"For the Calyx Kong, we use TI's PCM2704* USB DAC and some special custom-made Nichicon capacitors. We were very careful to design the circuit board so computer-generated noise would not enter the Calyx Kong. As a chip provider to various audio companies, we have engineered many audio circuits for them without a single claim from our customers. This shows how we are true experts in class D amplifiers. We use both measurements and subjective auditions during the development of our products. As a concert goer, I have been to a lot of famous concert halls. I always try for the best equivalent performance in our products.
"We have some sales contacts for certain countries already but not Europe yet so we take direct orders at the official US retail of $150. We provide a 1-year warranty but be assured that our company has never yet received a single repair call for products which used our D&A chips."
_______________
*Texas Instruments specifies this as a 16-bit Delta-Sigma 28-pin stereo DAC requiring no dedicated device driver and running an on-chip clock generator from a single 12MHz clock source.
For specifications, the Calyx Kong is a USB-powered integrated amplifier with a USB input on one end, a stereo mini port on the other and three small push-button controls marked + and - for volume, o for mute. A blue/white LED confirms PC power lock. Output impedance is 32Ω. Measured on their Audio Precision bench, Calyx specifies THD+N 0.01 [%] @ 1kHz, S/N -98dB @ 1kHz, channel separation better than 70dB, dynamic range of 98dB and an upper bandwidth -3dB point of 140kHz. The volume control operates from 0 to 64dB and power output is 12mW into 32 ohms with a swing voltage of 600mV. Dimensions are a petite 52 x 86 x 22mm and weight is 167g. The entire affair is ensconced in a machined aluminum body whose bottom plate is covered by a protective non-slip foam pad. Various anodizing colors are available, with the review loaner lime green.
The review context was my desk top with its custom Windows XP PC or a big MacBook running XP Parallels. Stello's DA100 Signature DAC with USB input, Peachtree Audio's Nova or Glow Audio Amp One 2009 integrateds and the Era Design Sat 5 speakers plus Glow Audio Sub One represented the hifi hardware. Direct comparators for D/A conversion thus were the April Music and Peachtree Audio Nova units on the upper end and the USB DAC built into the Glow Audio EL84 amplifier on the lower. To assess headphone drive, I used B&O's stylish 19-ohm clip-on earspeakers and a full-size pair of Beyerdynamic DT880 with convertible mini plug.
Unlike the Style Audio competitor also from Korea I'd reviewed earlier, the Calyx Kong had sufficient output to get even the big Beyerdynamic phones to useful levels. The DT880s of course will not be what most potential owners would ever use. They simply were the only 'serious' cans in my arsenal that integrate the necessary big-to-mini plug adaptor to run off the Calyx. Standing in for the far more typical in/on-ear 'phones one expects for the Kong user, I used Bang & Olufsen's cool clip-on units. But first...
... nit alert. By opting for sleek, the Calyx push-button volume -- rather than protruding rotary knob or recessed wheel -- gives zero indication where within its range one might be. Worse, the mute function has no visual feedback either. If you get no sound at first, you'll have to call up your PC's volume setting window. Ascertain whether there's a check mark in the mute all square (clicking/unclicking the mute on the Kong immediately puts the check mark there). If you still have no sound, go into the Sound Devices menu to insure that your PC has recognized and set itself to the USB DAC [below].
The big Beyers ran at the very top of the range, i.e. in attenuation bypass or full throttle mode with zero headroom left. On most recordings, I personally wasn't left wanting for more power. I did however stay away from classical recordings. Due to their usually far higher recorded dynamic range, those tend to have a rather lower median level. A mellow adagio at max volume with the DT880s might fall below the threshold of what you find fully satisfying.
Using the above window, I tracked how switching to the B&Os affected the speaker volume setting for levels equal to the Beyers. I clicked the Kong volume minus 6 times and the software slider ended up just below the second mark from the top [right].
Translated, for my tastes the Calyx Kong could get uncomfortably loud on the minis to have sufficient headroom. Of course the tonal balance of the Danish 'phones vs. the bigger drive units of the Beyers upshifted noticeably. Bass fullness evaporated and even voices leaned out. That was simple Physics of course, not the Kong's doing. More relevant, the Korean box nicely avoided the subtle scratchiness or treble dirt I expect from inferior USB converters.
For meaningful listening sessions however, I had to return to the Beyers (which themselves are outclassed by my audiotechnica ATH-W1000s). From the lower midrange on down, the B&Os simply leave too much under the table to make the cut.
In Beyer/Kong mode, I was struck by how very listenable things were - slightly soft, mellow and decidedly not sharp, aggressive, forward or with hyped transients. On my big Woo Audio headphone amp with EAT 300Bs and twin 5U4G Emission Labs rectifiers, the Beyers are leaner, thinner and less communicative than the warmer Cherry-wood clad Japanese cans. They're somewhat flat and staid where the W1000s are spacy and nubile.
Over the Calyx, the Beyers mysteriously acquired a modicum of W1000 traits. Was this because lack of ultimate drive incurred an overall mellifluousness? I couldn't say. Frankly, I didn't really care either. The combination was pleasing and even bass-buster tracks surprised to suggest that whatever op amp drives the output is fully capable of the low stuff.
How about a bigger (real speaker) desk top system?
Here the Calyx connected to an input of the Peachtree Audio Nova to compare to the latter's inbuilt Sabre DAC. Another comparison involved the Stello DA100 Signature DAC's USB input. Yet another comparison inserted Glow Audio's 2009 version Amp One over Miu Audio's 805 speakers.
Obviously the Calyx got murdered two ways (Nova and Stello). Yet it also did some killing of its own (Glow).
Here is the comparison setup, with Glow Audio's Sub One hiding dead center on the floor beneath the desk. The Glow Audio sub is great also for headphone listening. Running it through the Nova's pre-out (which does not mute when the headphones are inserted) feeds back sufficiently into the ears even when full-size headphones cover them. It makes for stupendous low-end can jamming. It's not friendly to cohabitators of course who will just hear the subwoofer.
The converters built into the Peachtree and Stello units had plainly more drive, presence and focus. They also expanded the soundstage particularly in the depth domain. Ambiance like hall sound surrounding a singer's voice improved significantly, exactly what higher resolution should buy. Everything got bigger, more substantial and meaningful. Outclassing a $150 unit without dedicated power supply (i.e. running exclusively off the 5V power line inside the USB cable) with two that benefit from dedicated supplies and class A output stages admittedly was a cheap and dirty trick. It simply demonstrated the limits of the Calyx within a bigger, far more expensive picture.
A rather more meaningful comparison was by way of setup N°2 where my MacBook in Windows Media Player mode fed the Glow Audio Amp One and Miu Audio 805 speakers via USB either directly into the Glow or through the Calyx. Because Glow Audio strangely opted for an A-type USB input, I had to run an A-to-A cable for it and a standard A-to-B cable into the Calyx. And because the Glow stupidly defaults its non-switchable inputs to USB automatically, I had to disconnect that input each time I wanted to hear the Calyx. I likewise had to rematch levels.
Long story short, the Calyx outperformed the USB converter inside the Glow but the former 'kill' slang suggests far too massive a performance delta. The Calyx was more precise and better timed on the leading edge where the Glow played it fuzzier. Music over the Calyx also had a straighter stiffer back in general. It was grippier. Over the Glow the musical posture became more slumped back into the chair. It didn't lean forward to feel more alert. In audio lingo, the Glow was more diffuse, less sorted and separated. More amorphous. The Calyx had better definition and articulation. It was an upgrade over the internal Glow converter but reduced achievable max levels in turn.
If its primary application had been regular rather than PC/mobile audio, the Calyx Kong should pack more gain. However, its solitary mini-jack output reminds one that it really is a miniature headphone amplifier for portable use. All other described uses are possible but more fringe benefits than core focus.
There are 25 click stops of volume including full attenuation. Continuous press traverses them all in a little more than one second. In certain applications, these individual steps could be just a bit coarser than ideal. A future Gen 2 wish list would include higher gain and a recessed continuous volume wheel with an engraved marker and perhaps 'push' for mute where mute also extinguishes the indicator LED for visual feedback.
These paid-to-find-fault issues are of little consequence however. The Calyx Kong operates beautifully as is and neither my PC or laptop had any recognition or handshake issues. It was plug 'n' play all the way including endless unplugs and reseats of the USB cable during A/B comparisons.
To recap, the Calyx Kong is a very solid step up from the headphone jacks of computer sound cards and mobile audio devices like the iPod and its derivatives. Its monolithic metal casing is luxuriously finished to have that pride of ownership cool factor down pat. Its performance is surprisingly refined and well articulated.
I was most impressed by its showing over the Beyerdynamic DT880s. Those aren't famous for being the easiest of cans to drive. While for such headphones, maximally attainable output voltage would ideally be higher to accommodate weaker recordings, sound quality was persuasive - robust yet gentle, articulate yet not overly PRaTty to support longer listening sessions.
Priced exactly right for what it delivers, Seungmok Yi's Calyx Kong is an ideal bridge product. It was sized, profiled and designed specifically for USB audio which presupposes PC or mobile sources. If one industry insider I spoke to at the Munich show this year had it right, the only items currently enjoying an upswing are USB converters and headphones; the two bits which hifi-centric companies can easily improve upon in that arena. The Calyx Kong then is perfectly timely. It's a fine seed that implants future hifi lust in mobile and computer audio users by quietly preaching the gospel of higher performance.
Reviewer: Srajan Ebaen
Source: Custom PC (Windows XP), Stello CDT100 / DAC100 Signature
Preamp/Integrated: Peachtree Audio Nova, Glow Audio 2008 Amp One [on review]
Speakers: Beyerdynamic DT880 and B&O 19-ohm earphones, Era Design 5 Sat, Glow Audio Sub One [on review]
Cables: Entreq Crossword Discover USB [on review], Zu Audio Pivot, Zu Audio Varial, AntiCables
Desktop: Ikea glass table
Powerline conditioning: Furutech e-TP80
Desktop size: Diagonal corner placement in 4m x 3m room open to main ground floor.
Review Component Retail: $150
It was Christine Han from April Music of Korea. I'd recently tested her Stello CDT 100 and DA100 Signature. Would I be interested to do the tiny Korean Calyx Kong USB headphone amp? That's what she listens to on her office PC. And, she likes it better than her HeadRoom. If I wanted, she'd make the arrangements. What the heck was the world coming to? Fraternizing with the enemy? A big thumbs up to Christine for promoting a competitor. That's exactly the spirit of cooperation the world needs today!
For background, I asked Seungmok Yi, CEO & President of Digital & Analog Co., Ltd. to paint the picture behind the tiny kong. "Digital & Analog Co., Ltd, started in 1999 as a fab-less* digital amplifier company. We have a few class D patents and proprietary technologies and focused on making single-chip digital amplifiers. To date, we have developed 4 different chips and provide those to various OEM audio makers like Samsung and Daewoo who develop audio products for big brands whose names I must protect. We have shipped more than 10 million chips to these companies.
_________________
* Fab-less means a semi-conductor or IC maker without fabrication facilities. Most IC companies operate that way. Samsung Electronics manufactures D&A's chips in their semiconductor manufacturing facility (FAB) for example, Magna Chips of Korea makes the popular Wolfson Semiconductor integrated circuits
"Last year, I decided to make high-end products under my own brand. High-end audio has always been my goal since I listened to and was moved by Beethoven's 5th Symphony in 1974. Last year we launched our first product, the Calyx 500. That is a 500-watt mono amplifier running the ASP500 module from ICEPower. Alas, ours is very different from other amplifiers using this module. We add more input and power supply circuitry to improve what we regard as the weak points of the ASP500. As you know, other companies just buy the stock modules and put them in their chassis. Our Calyx 500 hit the Korean market with rave reviews.
"This year we debuted CTI Calyx The Integrated at T.H.E. Show in Las Vegas with Usher BE-718 speakers. During the second day, Magnepan president Mark Winey visited our room, spent some time listening and asked me to visit his room with our CTI. Closing my exhibit at 2:00PM well early, I brought my CTI to Magnepan's demo room. There were several people from Magnepan and some dealers. We all listened to the CTI with their new mini Maggie system. All were amazed by the sound. It was much better than their former big system with Bryston electronics. Mr. Winey ordered a CTI for himself on the spot. In turn, we used their mini Maggies during this year's Eyear show 2009 in Korea for which Magnepan had generously sent us a set. We had great success together [above].
"For the Calyx Kong, we use TI's PCM2704* USB DAC and some special custom-made Nichicon capacitors. We were very careful to design the circuit board so computer-generated noise would not enter the Calyx Kong. As a chip provider to various audio companies, we have engineered many audio circuits for them without a single claim from our customers. This shows how we are true experts in class D amplifiers. We use both measurements and subjective auditions during the development of our products. As a concert goer, I have been to a lot of famous concert halls. I always try for the best equivalent performance in our products.
"We have some sales contacts for certain countries already but not Europe yet so we take direct orders at the official US retail of $150. We provide a 1-year warranty but be assured that our company has never yet received a single repair call for products which used our D&A chips."
_______________
*Texas Instruments specifies this as a 16-bit Delta-Sigma 28-pin stereo DAC requiring no dedicated device driver and running an on-chip clock generator from a single 12MHz clock source.
For specifications, the Calyx Kong is a USB-powered integrated amplifier with a USB input on one end, a stereo mini port on the other and three small push-button controls marked + and - for volume, o for mute. A blue/white LED confirms PC power lock. Output impedance is 32Ω. Measured on their Audio Precision bench, Calyx specifies THD+N 0.01 [%] @ 1kHz, S/N -98dB @ 1kHz, channel separation better than 70dB, dynamic range of 98dB and an upper bandwidth -3dB point of 140kHz. The volume control operates from 0 to 64dB and power output is 12mW into 32 ohms with a swing voltage of 600mV. Dimensions are a petite 52 x 86 x 22mm and weight is 167g. The entire affair is ensconced in a machined aluminum body whose bottom plate is covered by a protective non-slip foam pad. Various anodizing colors are available, with the review loaner lime green.
The review context was my desk top with its custom Windows XP PC or a big MacBook running XP Parallels. Stello's DA100 Signature DAC with USB input, Peachtree Audio's Nova or Glow Audio Amp One 2009 integrateds and the Era Design Sat 5 speakers plus Glow Audio Sub One represented the hifi hardware. Direct comparators for D/A conversion thus were the April Music and Peachtree Audio Nova units on the upper end and the USB DAC built into the Glow Audio EL84 amplifier on the lower. To assess headphone drive, I used B&O's stylish 19-ohm clip-on earspeakers and a full-size pair of Beyerdynamic DT880 with convertible mini plug.
Unlike the Style Audio competitor also from Korea I'd reviewed earlier, the Calyx Kong had sufficient output to get even the big Beyerdynamic phones to useful levels. The DT880s of course will not be what most potential owners would ever use. They simply were the only 'serious' cans in my arsenal that integrate the necessary big-to-mini plug adaptor to run off the Calyx. Standing in for the far more typical in/on-ear 'phones one expects for the Kong user, I used Bang & Olufsen's cool clip-on units. But first...
... nit alert. By opting for sleek, the Calyx push-button volume -- rather than protruding rotary knob or recessed wheel -- gives zero indication where within its range one might be. Worse, the mute function has no visual feedback either. If you get no sound at first, you'll have to call up your PC's volume setting window. Ascertain whether there's a check mark in the mute all square (clicking/unclicking the mute on the Kong immediately puts the check mark there). If you still have no sound, go into the Sound Devices menu to insure that your PC has recognized and set itself to the USB DAC [below].
The big Beyers ran at the very top of the range, i.e. in attenuation bypass or full throttle mode with zero headroom left. On most recordings, I personally wasn't left wanting for more power. I did however stay away from classical recordings. Due to their usually far higher recorded dynamic range, those tend to have a rather lower median level. A mellow adagio at max volume with the DT880s might fall below the threshold of what you find fully satisfying.
Using the above window, I tracked how switching to the B&Os affected the speaker volume setting for levels equal to the Beyers. I clicked the Kong volume minus 6 times and the software slider ended up just below the second mark from the top [right].
Translated, for my tastes the Calyx Kong could get uncomfortably loud on the minis to have sufficient headroom. Of course the tonal balance of the Danish 'phones vs. the bigger drive units of the Beyers upshifted noticeably. Bass fullness evaporated and even voices leaned out. That was simple Physics of course, not the Kong's doing. More relevant, the Korean box nicely avoided the subtle scratchiness or treble dirt I expect from inferior USB converters.
For meaningful listening sessions however, I had to return to the Beyers (which themselves are outclassed by my audiotechnica ATH-W1000s). From the lower midrange on down, the B&Os simply leave too much under the table to make the cut.
In Beyer/Kong mode, I was struck by how very listenable things were - slightly soft, mellow and decidedly not sharp, aggressive, forward or with hyped transients. On my big Woo Audio headphone amp with EAT 300Bs and twin 5U4G Emission Labs rectifiers, the Beyers are leaner, thinner and less communicative than the warmer Cherry-wood clad Japanese cans. They're somewhat flat and staid where the W1000s are spacy and nubile.
Over the Calyx, the Beyers mysteriously acquired a modicum of W1000 traits. Was this because lack of ultimate drive incurred an overall mellifluousness? I couldn't say. Frankly, I didn't really care either. The combination was pleasing and even bass-buster tracks surprised to suggest that whatever op amp drives the output is fully capable of the low stuff.
How about a bigger (real speaker) desk top system?
Here the Calyx connected to an input of the Peachtree Audio Nova to compare to the latter's inbuilt Sabre DAC. Another comparison involved the Stello DA100 Signature DAC's USB input. Yet another comparison inserted Glow Audio's 2009 version Amp One over Miu Audio's 805 speakers.
Obviously the Calyx got murdered two ways (Nova and Stello). Yet it also did some killing of its own (Glow).
Here is the comparison setup, with Glow Audio's Sub One hiding dead center on the floor beneath the desk. The Glow Audio sub is great also for headphone listening. Running it through the Nova's pre-out (which does not mute when the headphones are inserted) feeds back sufficiently into the ears even when full-size headphones cover them. It makes for stupendous low-end can jamming. It's not friendly to cohabitators of course who will just hear the subwoofer.
The converters built into the Peachtree and Stello units had plainly more drive, presence and focus. They also expanded the soundstage particularly in the depth domain. Ambiance like hall sound surrounding a singer's voice improved significantly, exactly what higher resolution should buy. Everything got bigger, more substantial and meaningful. Outclassing a $150 unit without dedicated power supply (i.e. running exclusively off the 5V power line inside the USB cable) with two that benefit from dedicated supplies and class A output stages admittedly was a cheap and dirty trick. It simply demonstrated the limits of the Calyx within a bigger, far more expensive picture.
A rather more meaningful comparison was by way of setup N°2 where my MacBook in Windows Media Player mode fed the Glow Audio Amp One and Miu Audio 805 speakers via USB either directly into the Glow or through the Calyx. Because Glow Audio strangely opted for an A-type USB input, I had to run an A-to-A cable for it and a standard A-to-B cable into the Calyx. And because the Glow stupidly defaults its non-switchable inputs to USB automatically, I had to disconnect that input each time I wanted to hear the Calyx. I likewise had to rematch levels.
Long story short, the Calyx outperformed the USB converter inside the Glow but the former 'kill' slang suggests far too massive a performance delta. The Calyx was more precise and better timed on the leading edge where the Glow played it fuzzier. Music over the Calyx also had a straighter stiffer back in general. It was grippier. Over the Glow the musical posture became more slumped back into the chair. It didn't lean forward to feel more alert. In audio lingo, the Glow was more diffuse, less sorted and separated. More amorphous. The Calyx had better definition and articulation. It was an upgrade over the internal Glow converter but reduced achievable max levels in turn.
If its primary application had been regular rather than PC/mobile audio, the Calyx Kong should pack more gain. However, its solitary mini-jack output reminds one that it really is a miniature headphone amplifier for portable use. All other described uses are possible but more fringe benefits than core focus.
There are 25 click stops of volume including full attenuation. Continuous press traverses them all in a little more than one second. In certain applications, these individual steps could be just a bit coarser than ideal. A future Gen 2 wish list would include higher gain and a recessed continuous volume wheel with an engraved marker and perhaps 'push' for mute where mute also extinguishes the indicator LED for visual feedback.
These paid-to-find-fault issues are of little consequence however. The Calyx Kong operates beautifully as is and neither my PC or laptop had any recognition or handshake issues. It was plug 'n' play all the way including endless unplugs and reseats of the USB cable during A/B comparisons.
To recap, the Calyx Kong is a very solid step up from the headphone jacks of computer sound cards and mobile audio devices like the iPod and its derivatives. Its monolithic metal casing is luxuriously finished to have that pride of ownership cool factor down pat. Its performance is surprisingly refined and well articulated.
I was most impressed by its showing over the Beyerdynamic DT880s. Those aren't famous for being the easiest of cans to drive. While for such headphones, maximally attainable output voltage would ideally be higher to accommodate weaker recordings, sound quality was persuasive - robust yet gentle, articulate yet not overly PRaTty to support longer listening sessions.
Priced exactly right for what it delivers, Seungmok Yi's Calyx Kong is an ideal bridge product. It was sized, profiled and designed specifically for USB audio which presupposes PC or mobile sources. If one industry insider I spoke to at the Munich show this year had it right, the only items currently enjoying an upswing are USB converters and headphones; the two bits which hifi-centric companies can easily improve upon in that arena. The Calyx Kong then is perfectly timely. It's a fine seed that implants future hifi lust in mobile and computer audio users by quietly preaching the gospel of higher performance.