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February 2015
Enjoy the Music.com Review Magazine
World Premiere Review!
Atma-Sphere Music Systems Ultraviolet Preamplifier
Let the music escape the bondage of your listening room.
Review By Ron Nagle


Atma-Sphere Music Systems Ultraviolet Preamplifier

 To follow a different drummer is to fall in line behind the likes of Ralph Karsten. It is he who provides a stepping stone to the present. The Atma-Sphere Ultraviolet preamplifier as reviewed here is a great example of Ralph's design genius. Yet first we need to fire up Mr. Peabody's Wayback Machine to take a look at the device that ties this narrative together. Zap! We find ourselves back in the year 1950. We are sitting at a desk in a  patent office shuffling through a large stack of new patent applications. Buried in amongst them is a connecting thread, it's the Circlotron Amplifier application. This patent application is for an innovative circuit design for a triode push pull type of electronic amplifier. As you may see from the diagram below, in its simplest form this amplifier stage can function without any type of feedback or an output transformer and without coupling capacitors.

Simple Circlotron Output Stage
Today some people refer to this design as simply an OTL amplifier. The OTL designation refers to the, Output Transformer Less circuit. The beauty of this Circlotron arrangement is in its simple straight forward topology. Over the years there have been many companies and many men making adaptations of this circuit. Previously a Mister Futterman and Mister Rosenberg did independently produce and influence the OTL (Tube) design that caught the attention of the high-end audio community. But today we attribute the driving force behind the OTL amplifier innovations to the 38 years of Atma-Sphere Music Systems research. And it is here that Mister Karsten steps to the front of the lineage. As an aside in July of 1998 I reviewed the Atma-Sphere M60 MKII OTL Mono-Block Amplifiers. At the time I was very impressed and now I look forward to listening to a new Atma-Sphere Preamplifier.

From the man to his machine, the Ultraviolet Preamplifier: As suggested by the designer Ralph Karsten, let us now refer to the preamplifier as the UV-1. The back story is that the UV-1 circuit design was something that had been kicked around and refined over a period of forty years. My attempt to pry some specific circuit details out of the guys that build the UV-1 got me absolutely nowhere.  However I do have a strong impression that the design is just as innovative as the OTL amplifier. But as I recall specifications were not all that emphasized even back in July of 1998. The UV-1 preamplifier under evaluation is one of three configurations available. The UV-1 is available as a basic $1,900 line stage without a Phono Cartridge amplifier. Or you could   purchase a full function preamp for $2400 with the addition of a high output moving magnet (MM) cartridge amplifier. My review sample is the most expensive at $2800. It has all of the line functions and with the inclusion of a pair of Jensen step up transformers it then becomes a full function Moving Coil cartridge preamplifier. At this time most of the production will be the line stage version.


Atma-Sphere’s Ultraviolet Preamplifier
You can bet whatever Atma-Sphere builds and Karsten designs it will be handmade and the circuit rendered in its purest form utilizing an all triode tube design similar to the OTL amplifier circuit. The UV-1 certainly looks vintage; it has a very retro Wayback thing going on. Most of that effect comes from the chassis which is painted with what looks like a blue crinkle finished enamel. The appearance reminds me of something removed from an old Edison power plant. But in truth it doesn’t look that bad at all. You could opine that the appearance is a very masculine and macho no nonsense machine. The crinkly blue paint covers an aluminum chassis 15.318" wide x 7.5" deep x 5" high. What saves the preamplifier from being just a blue rectangular box is the slanted front face that serves as the control panel. The front panels control functions and the source names including the Atma-Sphere logo are all printed with black ink on a blue background. I think the black printing is a bit too hard to see.  Mounted on the panel is an array of no nonsense industrial style controls. On the left side is a four position rotary source selection switch. The positions are labeled, AUX. 1, 2, 3 and PHONO. Moving from left to right we can see the printed Atma-Sphere logo followed by the volume control knob and next a balance control knob then a very retro jewel style lamp and lastly a heavy duty power switch.

Atma-Sphere Music Systems Ultraviolet Preamplifier

The things that do the amplifying are on the top of the chassis and in plain sight. Fixed to the top of the chassis are two power supply capacitors and their individual clamps. Next and side by side are two 12AT7 Phono Stage mini twin triode tubes. In the center there are two JAN 6SN7GT Line amplification dual triodes and at the far right a power supply transformer. At the rear panel there are six pairs of hi quality RCA line input jacks. When I say hi quality that means the RCA connectors are fixed and wired to the rear panel and are not just poking through holes in the sheet metal.

Again moving from left to right there is an IEC power cord socket followed by a 1 Ampere fuse holder. Near the rear middle are two pairs of RCA jacks, the first is the main preamplifier output, next a secondary preamplifier out. At the right side we see the line level input connections AUX, 1, 2, and 3 plus the last pair is the Phono amplifier input and finally a chassis grounding lug.


Fire In The Whole
Unpacked the UV-1 and placed the vacuum tubes into their sockets, then slotted sample UV-1 preamplifier into my reference system. The virgin UV-1 preamplifier with no break and from a cold start sounds strange. It was all like midrange and with an added dog whistle top end. What that means Audiopals is without much bass or even upper bass the sound was midrange dominant capped by a hard sounding treble. All in all it takes about four or five hours before the UV-1 frequency response locks on and there are no noticeable changes in the sound. What is evident at this point is the volume and the large amount of gain available in my system. And of course this will vary from system to system. The very first critical recording I played was a demonstration CD, this was a hand out from the speaker manufacturer German Physics. As is my penchant I chose as my reference the sound of the human voice. The first Demo track was written and performed by Sting. It is titled (An) Englishman In New York. This track was excerpted from the Sting album Symphonicities [Deutsche Grammophon]. A truly great album, recorded with London’s Royal Philharmonic Orchestra. The music’s tempo is provided by a plucked acoustic bass. With a slight delay there follows an accompanying warm resonant echo that tells us the size of the venue.. At this point you cannot mistake the preamplifiers voice for anything but the signature sound of hollow state sound.

Lucky me, for a gift of music from the Ms. It is Carole King and James Taylor, Live At The Troubadour [Syzygy CD-88072 32053]. Listening to this CD we enter a night club surrounded by adoring fans. The sound of this performance is remarkably clear and articulate. The Ultra Violet conveys not just the music but the atmosphere surrounding the performance. It is intimate and layered through the audience with a very real ability to draw you upfront and into the audience. On track 13 You've Got A Friend, both James Taylor and Carole King sing an emotional duet imbued with the warmth of an enduring mutual friendship.  After long hours conditioning the UV-1 using my Sangean HDT-1 digital tuner and many CD's. Transitioning to vinyl is like waking up with a strong cup of coffee. Your senses are more alive and now full of small details buried in the soundscape. At this time the most notable characteristic of the UV-1 is the ability to easily amplify the volume of my low output 0.20 Uv (Micro Volt) Denon 103 moving coil cartridge. There is gain to spare and running the Denon cartridge is no challenge. I doubt very much that there is any very low output moving coil cartridge that the UV-1 could not amplify with ease.

First up, a black disk Flea Market find: Huey Lewis and the News [Chrysalis Records CHS 12 2798]. This record had a nasty gouge through the first track on the A side. But this was a four dollar 45 RPM album that I could not pass up. Although this better buy it when you see it album is a little more compressed than I would like. Still it does what tubes do best, it has three dimensional. Width, Height and most important on my list, Depth. It does expand the space in my room by pushing back the rear wall and It allows me to join the space they perform in. The dynamic tempo and the in your lap presentation can not fail to get your emotions involved. I must mention one other go to black disk, another flea market acquisition. It is Sting, The Dream of the Blue Turtles [A&M SP-3750]. This album is by far the least compressed slab of vinyl I own and so it has become one of my references. The very first cut, If you love someone set them free.

From the very first uttered phrase there are loads of dynamic energy, some reviewers call this the "jump factor". From somewhere deep in the center stage the back up voices chant, "Free, Free set them free" this chant reverberates off the rear wall. The air is charged with dynamic bass energy. once again the UV-1unravels the performance separates and expands the venue into my room. The overall performance has a subtle and yet familiar quality that you think you might have heard somewhere before. But then you realize the recording is amazingly clean and clear with a quality very much like listening to a reel to reel tape.

Atma-Sphere Music Systems Ultraviolet Preamplifier

A marriage made in heaven? Perhaps, but you need to be of a certain tubular frame of mind. (That means you should have a preference for audio valves.) As for myself I have long followed the inner light and trod the path to the mysterious inner circle of the filamentary elements. I suggest that the UV-1 preamplifier is best mated to a system with a modern tube power amplifier. (OTL?) At the bottom of all I hear is my fervent desire to escape the bondage of my small room and step into another reality filled with music. The natural organic way the UV-1 triode tubes can recall a voice performance lifts it far above the common place. None of that can exist if it were not for the UV-1 incredible vanishingly low noise floor and the panorama it can paint between my speakers. Is the Ultra Violet a time machine, a friend to turn to, or a way to escape from a hard day, the answer is yes. The Ultra Violet takes me where I can reside quite contented, you can to.

Semper Hi-Fi.


Review System Components
Source components: Sangean Digital tuner and Marantz 8400 Universal CD/SACD/DVD player.

Amplification: Sanders ESL power amplifier.

Speakers: Rocket Strata Mini 3.5-way and Aurum Cantus Leisure 2 SE two way monitors on 24" stands.

Speaker Cables: Kimber Kable 12tc 9’ length

Interconnect Cables: Monster Reference Four pairs 2.5 meter, 1 meter and 1.5 meters, and Nordost Red Dawn 1 meter. Chord Silver Siren 1 meter, Homemade Teflon 1 meter, Autobahn 0.5 meter digital

AC Power: Wire World 10 gauge IEC line cord, Homemade 3 pairs, 12 gauge IEC

Islatrol Industrial 20 Ampere AC line conditioner, Richard Gray 20 Ampere Sub Station

Alpha Core Balanced Transformer Power Supply and Audio Power PE-1 power enhancer.

Triad 2-Ampere isolation transformer

And a comfortable chair.



Sub-bass (10Hz - 60Hz)

Mid-bass (80Hz - 200Hz)

Midrange (200Hz - 3,000Hz)

High Frequencies (3,000Hz On Up)



Inner Resolution

Soundscape Width Front

Soundscape Width Rear
Soundscape Depth Behind Speakers

Soundscape Extension Into Room


Fit And Finish

Self Noise

Value For The Money


Type: Stereo vacuum tube OTL preamplifier with phonostage
Tube Complement: Two 12AT7 phono and two 6SN7GT line section 
Linestage Frequency Response: 2 Hz to 200 kHz 
Linestage Gain: 15 dB 
Linestage Input Impedance: 100 kOhm single-ended 
Linestage Output: 12V 
Output Impedance: 400 Ohms from 2Hz to 100 kHz

Phono Bandwidth: 5 Hz to 90 kHz within 0.5 dB 
RIAA Accuracy: Within 0.1 dB
RIAA Phono Sensitivity: 0.2 mV (0.5 V @ 1 kHz) 
Phonostage Input Impedance: 47 kOhm 
Phonostage Input Overload: 500 mV 
Phonostage Gain: 55 dB

Dimensions: 15.318" x 7.5" x 5" (WxDxH) 
Weight: 7 lbs. 
Warranty: Three years transferable and one year for tubes 
Price: $2800


Company Information
Atma-Sphere Music Systems, Inc. 
1742 Selby Avenue 
St. Paul, MN 55104

Voice: (651) 690-2246
Website: www.Atma-Sphere.com













































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