Music Preamplifier 3 (MP-3)
Getting back to basics pays
off big time.
Review By Wayne Donnelly
here to e-mail reviewer.
Atma-Sphere Music Systems
certainly has one of the more distinctive (and, to me, endearingly goofy)
marques in high-end audio. Sometimes I think this St. Paul,
Minnesota-based outfit might adopt a more directly descriptive moniker —
something like "Different Drummer Audio" or "Plain is Beautiful
Electronics." Atma-Sphere honcho Ralph Karsten has very clear convictions
on the right way to make audio gear, and year after year he adheres
unwaveringly to his approach, unswayed by technical and market trends —
you know, far out stuff like remote volume control. For this writer, the
company's inner-directed philosophy is by turns inspiring and slightly
frustrating. How so? Read on.
Balance, Balance, Balance
The foundation of the Atma-Sphere way lies in the phrase "Balanced
Differential Design®." I was surprised a couple of years back to discover
that the company had registered that familiar phrase as a trademark. I
(and many other audio writers) have long flung it about as a generic
descriptive term — like people casually say Coke or Kleenex for any
similar product. At Atma-Sphere they mean it; every component the company
builds is a fully balanced differential design.
A couple of other key factors separate the MP-3 from the general
run of tube preamplifiers. The company cites the patented direct-coupled
Circlotronic® output, derived from their line of OTL amplifiers. In
addition, the MP-3 employs zero feedback throughout. Taken together, those
attributes are unique among tube preamplifiers in today's market,
according to Atma-Sphere.
Other notable technical features include balanced passive phono
equalization, which contributes materially to the fine performance of the
internal phono stage. Volume control does not use a conventional
potentiometer, but a precision 23-position stepped control built with 96
resistors on a custom-built switch. A front-panel toggle switch enables
180-degree phase flip (a good feature, but much more useful to this writer
when remote–controllable). "Star" grounding is used
throughout, a scheme that has yielded superior quietness in other units I
have reviewed previously.
The depth of the company's allegiance to balanced operation is evident
when examining the MP-3's rear panel. There are pairs of XLR jacks (only)
for the phono and auxiliary 1 and 2 inputs, as well as the output to the
amplifier. Only the two sets of tape out/monitor in circuits use RCA
jacks. The tape monitor in jacks can of course be used to connect
single-ended source components, but otherwise the MP–3 sticks strictly
to its balanced guns.
The front panel is also unconventional. Rather than a source selection
knob, we get a row of toggle switches. This scheme is unintuitive, but not
hard to figure out. In lieu of a balance control knob, small knobs for
level setting of the left and right channels flank the large main volume
control. (I like that arrangement.)
Several extra–cost options are available to enhance the performance
of the MP-3. Here is the list, with retail prices for each:
• Power supply regulation ($600)
• Teflon® custom coupling caps ($600)
• Damping package ($500)
• Caddock resistor package ($1,500)
• Low-output MC phono step-up transformers ($750);
recommended only if cartridge output is less than 0.3mV
Ralph Karsten tells me that the review unit is upgraded with power
supply regulation; that brings the price of the unit as reviewed to
$4,800. I suspect that the regulation contributes substantially to the
MP-3's impressive dynamic control across the full frequency spectrum. My trusty adding machine tells me that a "fully loaded" MP-3 would
price out at $8,150. Can't help wondering what that would sound
The MP-3 replaced my reference VTL 7.5 line stage during the review
period. The analog source was my Basis 2800 TT/Graham 2.2
arm/Transfiguration Temper cartridge. The digital source was the
ModWright/Denon 3910 all-format player I reviewed in July. Loudspeakers
were the planar-ribbon Analysis Amphitryons, larger siblings of the Omegas
I reviewed in March. Cabling included excellent power cords and cable
enhancement accessories from Jack Bybee, with A Capella interconnects and
speaker cables (review coming). The MP-3 drove the Spectron Musician III
Class D stereo (reviewed in March) and VTL Siegfried Reference monoblock
(review in progress) amplifiers. Both are true fully balanced (dare I say,
differential) amplifiers, excellent partners for the balanced MP-3.
Because the MP-3's phono jacks are XLR, and my Graham phono cables are
RCA — like, I would guess, probably 99 percent of the phono cables in
use today — I briefly used a pair of RCA-to-XLR adapters to do some "ballpark"
comparisons among the MP-3's phono section, my reference Thor TA-3000 Mk.
II (tubed) and the superb solid-state Ray Samuels Emmeline XR-10B phono
preamplifiers. As I expected, both of the far more expensive separate
phono stages (costing as much or more than the entire MP-3) clearly
outpointed the MP-3 — although less decisively than I expected. But I knew
that using those adapters to connect to the MP-3 put the latter at a
disadvantage. So, for the serious review listening sessions I replaced my
Graham phono cables with a set of DIN-to-XLR cables supplied by Atma-Sphere.
The improvement from that change was easily audible. The descriptions of
phono performance below are based only on listening through the Atma-Sphere
XLR phono cable.
As near as I can recall (can't find the literature), my particular
version of the Transfiguration Temper cartridge outputs around .3 to .4mV.
That's on the low side, but within the range specified by Atma-Sphere for
use with the MP-3's phono section.
Considering the cartridge's lowish output, the MP-3 was surprisingly
quiet on phono, especially since the section uses seven 12AT7 tubes and no
step-up transformer. Tube noise was discernible, but not very
obtrusive--really noticeable only on quiet, intimate recordings. (Bill
Evans' Waltz for Debby comes to mind.) Records with big dynamics
— orchestral blockbusters (such as the Classic Records reissue of the
great Dorati/LSO Firebird on single-sided 200-gram pressing), or
large jazz ensembles (such as Gil Evans' Out of the Cool), were
consistently exciting to hear. And great rock LPs — especially live ones
such as the Stones' Get Yer Ya-Yas Out or The Band's The Last
Waltz — seemed to leap out of the speakers and take over the room.
Fun fun fun!
This excellent-sounding phono section adds just $550 to the price of a
line-stage-only MP-3. I suspect it would be hard to find a separate phono
stage near that price that would deliver the impressive combination of
glorious dynamics, timbral fidelity, imaging precision and voluminous
soundscaping that I heard from the MP-3 with record after record.
Line Stage Performance
My CD player does not provide for balanced output, so I connected it to
the MP-3 through tape monitor RCA jacks. Despite that "handicap," the
sound of various types of silver discs through the MP-3 seemed more like
than unlike the qualities I so admired in the phono presentation.
Especially impressive was the unit's control over dynamic scaling. The
microdynamic elements in particular benefited from the MP-3's very quiet
line section and excellent detail retrieval. The Michael Tilson Thomas/San
Francisco Mahler Second Symphony SACD has become one of my favorite review
discs, partly because its dynamic range is as wide as any CD I can think
of. On one hand, it contains barely audible moments of ethereal delicacy.
On the other, this is the only disc with which I have managed to blow the
circuit breakers powering the 800-watt VTL Siegfrieds. (Gotta get those
dedicated 20-Ampre outlets installed in my listening room!)
From Mahler to Gershwin to Verdi to Miles, to Aimee Mann to Roseanne
Cash to Dylan to Horowitz to… well, you get the picture. The MP-3
consistently dug into the heart of the music and brought me into intense
emotional involvement with virtually every recording. No, I didn't like
having to cross my darkened room to adjust the volume or verify polarity
at the preamplifier, but the musical presentation left little to complain
about. Some audio components are just instruments; the MP-3 is a true
I suggested at the beginning, even if the MP-3 is not my personal cup of
tea, I truly admire the integrity of concept and execution evident in this
and other Atma-Sphere products. There are still a lot of purist,
minimalist music lovers out there, and this preamplifier was made for
them. It's easy to understand why brand loyalty among Atma-Sphere owners
is among the highest in the audio industry.
I love my VTL 7.5 preamp. It sounds great, looks great, and offers
degrees of flexible functionality and ergonomic ease that can be matched
by very few competitors. In the couple of years I have owned it, the 7.5
has proven itself an ideal reviewer's tool. But after a recent price
increase, it now retails for a cool $15,000. The MP-3 comes very close to the sonic performance of the VTL, at
one-third the price. No bells, whistles, or remote controls, not much
flexibility, and it is hardly an example of audio jewelry. Back to basics
with a vengeance.
Type: Tubed preamplifier with moving coil and moving magnet
(MC / MM) phonostage
Tube Complement: seven 12AT7 (phono section)
two 6SN7GT (output section)
two 12AU7 (line stage)
Frequency Response: 0.2Hz to 200KHz (+0dB, -2dB)
Gain: ~15dB linestage, ~50dB for phonostage
Phono Section Frequency Response: 0.5Hz to 90KHz
RIAA Accuracy: 0.1dB
RIAA Phono Sensitivity: for 0.5V @ 1KHz = 0.2mV
Minimum Recommended Phono Input: 0.3mV
Phono Input Overload: 500mv
Warranty: 3 years
Price as reviewed: $4,800
Atma-Sphere Music Systems, Inc.
160 South Wheeler
St. Paul, MN 55105