GLOW Audio Amp One Review

Speakers&Amps by KeithSuppe @ 2009-03-15

Glow Audio´s Amp One reflects what many industry professionals see as the future of home entertainment. The role of the Personal Computer as a multi-media center. Apple has been on top of this for sometime but even Apple doesn´t build sound systems per se. So what does the GLOW Amp One offer

Introduction to affordable High End sound

The Future of PC:

Madshrimps (c)


Glow Audio's Amp One is this company's first offering in the rapidly growing Computer Audiophile sector. Glow along with manufacturers such as Tecon Audio, AVI HiFi, Peachtree Audio and M-Audio are raising the bar on PC sound quality. Internet inspired like most things these days, the enormous number of music files available online eventually found its way to the ears of music lovers including Audiophiles. The Amp One is based on what is known as a SEP or Single Ended Pentode circuit and as an integrated amp with built in USB DAC, all that's needed is a USB (or RCA analog) source and a pair of efficient speakers. Amp One specifications taken from their website are listed below.

  • Removable tube cage included with all amplifiers
  • Simple plug-and-play USB connection for your laptop, PC or MAC (cable included)
  • 1 pair RCA inputs
  • Single ended (SE) Class A pentode design
  • EL84 power tubes
  • Ceramic Tube Sockets
  • All point-to-point wiring
  • Precision hand wound transformers
  • Minimum negative feedback
  • Tubes are self-biasing and never need adjusting
  • 1/4" Headphone jack
  • ALPS volume potentiometer
  • High quality binding posts
  • High Gloss Enamel paint with anti-corrosion undercoating
  • Steel chassis
  • Full one year warranty
  • 115-220 V switch able, fuse protected
  • CE certified in compliance with European Economic Area (EEA) requirements (09 version)


  • Until recently most PC Users connected their on-board sound or an add in sound-card to a pair of powered speakers or surround sound setup. For many years the term "PC-Audio" where music playback was concerned was practically a misnomer. Today companies such as AVI have given us some remarkable hardware. On the test bench at present is the AVI ADM9.1 system. Effectively these powered speakers each house powerful bi-amplifiers, with the main speaker incorporating a Wolfson Audio DAC via a S/PDIF Optical input, this fully remote controlled system sounds amazing (look for my review very soon). But that's another review. So what does the Amp One offer?

    Madshrimps (c)


    As far as incorporating Digital to Analog conversion the Glow Amp One employs the C-Media CM102S is a 2-channel 16-bit DAC with 48 KHz sampling frequency. A special USB cable is included for connection with your PC or any "music server" with USB connects (2.0). Looking at the rear of the amplifier we see decent five-way binding posts, RCA inputs for use with a pre-amp to circumvent the internal DAC, AC-input and USB (off to the right).

    Madshrimps (c)


    Onto build quality ->

    Build Quality

    Value in design and construction:

    Madshrimps (c)


    It is ironic how many elements of High End Audio gear utilize design topology and similar materials over 60 years old. Today some the best sounding and costly amplifiers are literally designed around tubes such as the Western Electric 300A/B. Originally intended for use in Radio its sonic characteristics are well documented as found in the article The 300B Tube Lives Again!. While there has been improvement in design execution, specific parts and materials play a larger role in Audio then perhaps any other area of consumer electronics. Prior to the advent of PCB's point to point wiring was the standard. While any digital audio based product must have their share of PCB mounted microchips, GLOW has chosen to eschew semi conductive materials wherever feasible, as seen below.

    Madshrimps (c)


    To the PC Enthusiast this may not seem pertinent, however; to the Audio Enthusiast any device, especially wiring because it denotes length through which the signal path flow's, is critical. PCB's often implement minute copper traces which are more susceptible to EMI and often just a fraction of the width of a single copper strand of internal shielded cable. We begin with the only PCB found in the GLOW Amp One supporting the C-Media DAC. In the thumbnail below, note the input wiring (brown) is passed through the DAC PCB, connecting the USB disables RCA analog input.

    Madshrimps (c)
    Click for Zoom


    From the photos above to those below we can follow the input path as it's divided to the transformers/capacitors and through the Alps potentiometer. This topology is indicative of the Single Ended design in which the vacuum tube is the final amplification device. Clicking on the thumbnail below provides a much closer look at the SE design defined in the intro.

    Madshrimps (c)
    Click for Zoom


    Finally we take a close look at the internal wiring from the front of the amplifier, certainly a labor intensive project considering how many amplifiers must be sold for any company to remain financially viable.

    Madshrimps (c)
    Click for Zoom


    It seems GLOW has done everything in their power to create a great sounding amplifier. Of course this is where Audio and High End Audio in general cannot simply be judged by the parts, or the sum thereof to succeed. This is where listening is a pre-requisite.

    Onto Listening Tests ->

    The Glow

    The "glow."

    Madshrimps (c)


    Vaccum tubes have been a mainstay in "HiFi" since the term was coined. Perhaps no other area of consumer electronics derives its materials and designs from such esoteric and exotic sources. As far as single ended tube amps many are based on tubes made in the early 1900's. As an example the Western Electric 300B vacuum tube, originally manufactured for telephone transmission in 1938, was found to be an exceptional device for audio. The 300B is widely considered to be one of the most quiet, natural sounding vacuum tubes with recent demand's so great Western Electric re-issued their 300B, you can learn more in this Antique Radio Classified article; The 300B Lives Again! As audio components become more detailed and accurate in their presentation, the underlying theme is neutrality. At some point cohesiveness between audio devices becomes critical and the slightest change replacing one device for another can have a major impact on sound. This includes cables and for testing I chose the Oyadie Tunami Nigo speaker cables which will be included in my upcoming cable round-up. Below the Tunami Nigo cables terminated with their SRBN banana plugs.

    Madshrimps (c)


    Musicality is a term tossed around like a direct heated triode. Yet this is what separates "listening" to music from an involving musical experience which most people have only heard at a live event, rarely is ever in their homes. What the Audiophile craves is a musical presentation so convincing you swear the performers are in the room. Many Audiophiles have spent enough on the hardware to actually hire the performers to perform in their homes. What has prevented the rest of us music lovers is either a wall of midfi mass-market, lack of knowledge such products exist, or lack of funds. GLOW Audio has spent considerable R&D in an attempt to bring musical realism to those once unable to afford the hardware. One method they've employed to keep costs down is direct marketing and I've chosen the often difficult task of describing how a specific product "might sound" in your home. My motivation is simply to share the auditory amazement and pleasure of my "first time." Whence in a small High End shop I sat, as 3-dimensional images infused with life and tonal accuracy convinced me I was there in the Studio. Some claim the ability of a product to re-produce recorded music can be "measured" objectively utilizing even more (costly) electronic instruments. The majority of the Audio Enthusiast community would disagree. While there are a plethora of SEP designed vacuum tube amps out there with the same specifications each has its own sonic characteristics. However, the Laws of physic's take no prisoners and when it comes to single ended Pentode and Triode amplifiers speakers make or break the sonic deal. With a power rating of 5W the Amp One requires a highly efficient (92B ~ 100+dB @ around 8 Ohm) pair of speakers. After many, many hours of research I chose Lovecraft Designs Cain & Cain Abby speakers and consider myself fortunate they were sent. They are an amazing product, emulating the source signal via the preceding electronics. Seen below in my hodge-podge system photo, their near-field drivers (white) were matched to my room dimensions.

    Madshrimps (c)


    Test System
    CPU Intel Quad-Core Q6600 Kentfield (SLACR) Socket-775
    Mainboard Foxconn Black Ops (X48/ICH9R chipset) BIOS P05)
    Memory Patriot Viper DDR3-1600 2x1GB (CL7-7-7-20)
    Graphics XFX 260GTX PCIe
    Power Supply PCPower&Cooling TurboCool 1200W
    Cooling D-Tek Fusion S-775 cpu cooler, Danger Den Black Ice Xtreme III triple radiator, 3x12cm Sunon fans (98CFM), LAING D5-38 Vario (setting #5) 1/2ID Tygon
    Audio
  • Decco 50W hybrid integrated amp (USB-DAC Phillips TDA1541)
  • Tecon Model 55 single ended integrated amp (USB-DAC Burr Brown PCM2707)
  • GLOW Amp One Single Ended Pentode integrated with internal USB-DAC (C Media-102S)
  • Cain & Cain Abby single driver loudspeaker
  • Era Design 4 satellite loudspeakers
  • Zu Audio Julian speaker cable
  • Unity Audio Basic Link speaker cable
  • Unity Audio Solid Link speaker cable
  • Oyaide Tunami Nigo speaker cable
  • Unity Audio Basic power cable
  • Oyaide Tunami power cable
  • Operating System Windows XP SP3

    Listing Test Continued & Conclusive Thoughts

    Digital Sound:

    I began testing with the Black Ops mainboard without its native audio card. Without the soundcard the Block Ops has no sound system at all. The card doesn’t use the typical PCI or PCIe slot, seen below the board uses a connector substituting for a hard wired ad-on chip.

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    With the Sonar installed (Realtek ALC885 (jpg)) all connections are analog and of the 1/8" mini-jack type. The Sonar audio card is mandatory for any sound. Under the WinXP operating system the device is described under volume or audio as "USB Speakers /Audio."

    Madshrimps (c)


    I began with streaming audio, for this feed I chose the website Deezer.com. Very few sites offer this level of sound quality. Among their streaming offerings/stations they I chose the French station Chanson Françoise the song in particular Pierrot - Loic Lantoine simply sounded amazing. While there are countless words, terms and expressions which have no counterpart translation in English (especially in German philosophy,) fortunately the beauty, the mathematical prose in music transcends this obstacle. Listening through the GLOW Amp One, Tunami Nigo cables and Cain & Cain Abby single driver speakers, every guitar string, every instrument and nuance was clear, these products drew me in

    Compared to the Tecon Model 55 (integrated single ended tube Pentode featuring Burr Brown DAC) reviewed here recently. The Glow had a more stable frequency range although the Tecon did image more precisely. The tune by Corlalie Clement Ça valait la peine has some close mike vocals which vacuum tubes simply love. Saliva, lips and the entire repertoire of guttural intonations are all present in palpable 3D. The gift of tubes and single ended just wrap it in a tighter package with air between each inflection.

    Analog Sound:
    Using the Foxconn Black Ops ad-on card (Sonar) and a 1/8" mini-jack to RCA splitter I was able to bypasses the Amp One's C-Media 102S USB DAC. Oddly enough many details absent in the on-board DAC jumped out using the Realtek ACL885 DAC through the 1/8" to RCA connector. It’s debatable, but the Realtek ACL885 DAC is considered superior in sound to the C-Media 102S. Of course a DAC in-and-of-itself means little in the world of Audio. Though their advertised because of sampling rate or bit rate, Digital to Analog Conversion as well as Analog to Digital Conversion play a smaller role then you may think.

    Playing the exact same tunes I found a marked improvement in everything except imaging, while there were subtle improvements here, none of these were as extreme as the bass tightening up or sweeping frequency control. Highs were smoother and midrange had a somewhat analog flavor to it. Not turntable analog, but an improvement.

    Conclusive Thoughts

    The Glow Audio Amp One is still a great value at its current reduced list price of $488, although that may be difficult to find. The current improved 2009 model sells direct for 648USD free shipping in the Continental US. Glow ships Internationally return policy, information and warranty info can be found here. With money back 30-day satisfaction guarantee policy you would have to toss the amp down a flight of stairs to go wrong. Entering the tube amp level of Audio sophistication (especially Single Ended) would be difficult if one were investing 2,000USD. To find an integrated, hard-wired, valve amp with an Alps potentiometer, internal USB DAC for PC and RCA connections for analog at 648USD (shipped in USA) is very rare indeed. Of course the best part is the sound, it has its limitations but so do 5,000USD integrated tube amps single ended or ultra linear.

    As far as shortcomings there is the DAC itself which honestly falls short. Then there's the power, of course there are of any SE amp requires careful speaker matching. It's a vacuum tube amp and won't shake the foundation it’s better for small rooms and PC-Users usually keep their PC in a private area. Mated to a pair of bookshelf or high efficiency floor standing transducers like the Abby’s, the Glow will involve you. You’ll be amazed at what you may have been missing and most likely frustrated you’ve been missing out. Well designed audio is supposed to be about experiencing music, not just listening or listening loudly. For 2009 the Amp One replaces the DAC, improves shielding and headphone circuitry. For $648 shipped within the USA you have 30-days to give it a listen. I can tell you when I first heard tubes I was immediately convinced of their attributes compared to transistors or Mosfetts. You'll know in the first few days, so long as you’ve made the correct speaker choice.

    I would like to thank Patrick Cherry for his excellent photography and Amery Martinet for all their help in this article.
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