Current Unedited Reviews
AudioMusings
This may come back to haunt me, but I tend to follow the same regimen
every day after work. After wending my way up the winding driveway that
leads to our palatial estate, I (1) check the mail, (2) turn on my audio
equipment, (3) use the privy, (4) go on line and respond to the masses
of audioMUSINGS e-mail, and then (5) sit down on the couch and, with a
CD spinning some favorite music, drift off for awhile. Now, being the
astute audio reviewer (or as Art Dudley might say, the audio weenie)
that I am, I have found that all audio components fall into one of two
distinct categories. The first is populated by components that keep me
from drifting off, and the second by those that do. Let me clarify
things here—by "drifting off" I am not suggesting that I am sleeping!
Rather, I am still aware of my surroundings, but I am not fully awake.
I do this for about a CD or so of music, say 30 to 40 minutes a day.
Upon stirring, I find myself refreshed and much more willing to face the
responsibilities of being a father, husband, and all around idiot
savant.
I believe we are all looking for both of these attributes in our systems
the ability to excite us and the ability to allow us to drift away. One
friend is attempting to have two systems—one for each purpose which is
the obvious ideal, but heck, we can barely afford one system, let alone
two.
Most of us settle for something in between, but unfortunately, reaching
a compromise is not easy. Some systems lack life and excitement, others
never let up. Neither extreme is what we want for the long term. On an
emotional scale with a range of 1-10, with 1 being the most sedate and
10 the most thrilling, I would give the Clayton M70s a 5.5. With these
svelte, "tubey"-sounding amps in the system, I always drift away in a
wash of warm, rich music. However, when I want to make a fool of myself
by dancing around the room, it falls more on me than on the Claytons to
make it happen. The Naked Truth Calla OTL amplifiers, on the other
hand, are a solid 7.5 (no, make that a 7.563245-my token poke at rating
components numerically) fast, clean, transparent, and not the least bit
"tube-like" in their sonic account of what's on a disc. Mind you, these
differences are more subtle in nature-though clearly discernable-and are
not to be taken to any extreme. With the Calla, there is no watching
from the sidelines. They bring the game to you. So go figure—tube
sound from solid state and solid state sound from tubes! In the case of
the Callas, this may be a result of their being OTL. The designer
suggests that using their optional output transformers (provided for use
with low impedance speakers) will reduce their transparency and speed.
In other words, less of the "naked truth" will be revealed.
Now, on to the audio-geek stuff. The Callas are 60 wpc OTL monoblock
amplifiers based on the Svetlana 6AS7 output tube. I am somewhat in the
dark about amplifier design, so let me quote from the Naked Truth
literature:
The Naked Truth amplifier combines two old and time-tested ideas, the
Williamson front end and a circlotron. The Williamson is one of the
simplest ways to combine a voltage amplifier with a phase inverter.
Being simple it uses very few components in the signal path and is
therefore quieter and has less deleterious effect on the signal. The
circlotron is a circuit originally developed in the '50s by Mr. Alpha
Wiggins and the Electro-Voice Co. It is a novel design that has all the
advantages of a single ended amplifier and is push pull and in this case
class A. The problem with this is you have current constantly flowing
in one direction. If you hook this up to a speaker the current (dc)
will pull the speaker to one side of its throw; this is not good. By
combining two single ended amplifiers together you can balance them so
that the current no longer flows through the speaker or the matching
transformer. This is very advantageous. It gives you the ability to
run class A triode push pull transformerless.
What this all means sonically is that the Callas kept me on the edge of
my seat, with the most exciting and dynamic music I have ever
experienced in our system. As visceral as all get out, they never
appeared to run out of steam or headroom. They just kept the music
racing along at breakneck speed. Very coherent and clean, the Callas
offered no grain, grit, glare, etch, or euphonic coloration to get in
the way. This may make you think that they are cold, sterile, and
ruthlessly revealing. They are very revealing, in a way that will
accentuate blemishes and recording traits that you may prefer to remain
hidden—some of your music may no longer sound as good as it did before.
However, cold and sterile they are not. As a matter of fact, the Callas
are very musical and involving, but on their own terms. They will not
provide blooming, "tube-like," palpable images, though they do image
very well and do so with a fair amount of air and dimension. The Callas
will go very deep, with all of the speed, dynamics, and impact one would
expect from a brutish solid state amp, but the bass is not rich and
full. They are amazingly transparent and startlingly pure—they're like
lie detectors, in that what's on the disc will come ruthlessly through
your speakers. The truth, the whole truth, nothing but the truth, I
solemnly swear.
Could I live with the truth 24 hours a day? Well, it is nice to have a
system that keeps one awake and rocks the house, but as I get older I
want to sit back and relax, too. Also, the Callas are not what I'd call
inexpensive, though they are like works of art, and the price is
justified by the time spent on construction and the quality of the
parts. Finally, in many ways the Callas are somewhat tweaky. I found
myself needing to check the bias and balance every time they were
powered up. While these two parameters never changed drastically, I did
find the need to make frequent small adjustments. But, I love the sound
of the tubes crackling and snapping as they heat up, and what a
wonderful blue and orange glow in the dark!
Ultimately, the Callas offered me too much of a good thing—too much
truthfulness. This is not to suggest the Claytons don't tell the
truth. They just do so differently. Much like studying History, there
is always more than one side to every event. And then again, sometimes
we don't want to know everything. We want a little less truth.
Ignorance can sometimes be bliss. But when the day comes that I can
have two systems, one to excite and the other to sedate, the Callas will
be at the top of the excitement list. 'Til then, I will have to
stimulate myself the old-fashioned way.
Dave Clark
The Calla amplifiers from Naked Truth Audio arrived in several boxes,
along with a warning from Frank that I might need to call Victor for
set-up help and a request to let him know what I thought of the sound.
I looked up the Naked Truth Audio web site and read about the design, a
"Circlotron." These flat amps, which resemble nicely-painted black
pizza boxes with tubes on top—6SN7s in the middle, surrounded by a
circle of eight 6AS7s—reminded me a bit of Stonehenge.
These are the first OTL amps I've tried. I looked at the pile of tubes
and the limited instructions and set to work, donning a pair of cotton
gloves to handle all those tubes. Each box was marked with the position
in which the tube should go. Once the tubes were plugged in, I read
about balancing the amps and adjusting the bias current. The binding
posts didn't thrill me, but they were adequate to the task. I hooked
the amps to my Tannoy Saturn 8s with Luminous ladder-type speaker
cable. The preamp was the Kora Triode and source an old Pioneer 701
laser disc player in CD mode. One of the amps hummed loudly. I
adjusted the balance and bias as instructed—no better. I started
swapping tubes from the spares until I noticed in the dimming evening
light that one of the tubes was glowing blue and oscillating. I changed
the tube with a spare 6AS7 and the hum went away. Rebiasing and
balancing with the ten-turn pot took only a few more minutes. At this
point, I realized that nearly two hours had passed and I had yet to
listen to music. First recommendation to the manufacturer: Rewrite the
manual with clearer instructions. The ones that came with the amp were
barely adequate.
I haven't gotten to the sound of these 60-watt OTL amps. (To be
precise, they're OTL only if one wants, since they can be hooked up
through their internal output transformers.) I warmed them up with some
marches from the Reference Recording CD of Frederick Fennell conducting
the Dallas Wind Symphony (RR 58-CD). I heard detail without harshness,
layers of sound, excellent dynamics, full top-to-bottom frequency
response. The instruments sounded real. If you like detail, you'll
love this amp. It is amazingly transparent. Disc after disc had this
consistency of revelation. On the Beethoven Cello Sonatas on Arabesque,
bow on string and the accompanying p ano had equal subtlety. On Joshua
Bell's Gershwin Fantasy CD, the violin's every nuance came through with
no edginess or brittleness. Even with a pop recording like the Eagles'
Hell Freezes Over, the music seemed to flow unhindered from the
speakers. The amps sounded great! The only sonic flaw I could discern
was a slightly recessed midrange that was more apparent with the Saturns
on male vocals. When I engaged the transformer by using the enclosed
plugs, some of the transparency was lost, and great sound became merely
very good. The midrange was more fleshed out, but the "see into the
music" quality faded. I can't imagine anyone buying a pair of Callas to
listen with the transformer in the circuit.
I couldn't resist trying the Callas with the much more difficult to
drive Soundlab A-1s. These speakers have a reputation of sounding their
best with OTL amps. Feeding these huge, power-hungry speakers with
sixty watts should not have been a wise move, but why not? The Callas
surprised me. On less demanding material (NOT power piano) played at
low to moderate volume, they worked. All the things I heard with the
easier to drive Tannoys I heard to a greater degree with the big
Soundlabs. Bela Fleck's banjo twanged along in "Star of the County
Down" on the humorous and overly-played Flight of the Cosmic Hippo
disc. Berla Roja's guitar came through with tremendous clarity, power,
and emotion in Dorian's release of Latin American classical guitar
music, Intimate Barrios. The Fairfield Four's Standing in the Safety
Zone acapella gospel CD is well-recorded (for a mass-market CD) and has
some nice performances. Both the acoustic space and tonal balance
worked. The Coffee Cantata from Dorian's J.S. Bach Secular Cantatas is
a longstanding favorite for its music and the beautifully-recorded
voices plus accompanying harpsichord and flute solos. Kathryn Stott
plays Debussy and Ravel Piano works on the Conifer label. Piano on the
Images was delicate, with good impact and resonance. The combination of
the A-1s and the Calla amps had marvelous detail, but some thinness in
the lower mids compared to what I was used to.
When I tried the Pope CD of Naum Starkmann playing Chopin, the illusion
that these amps could handle the big A-1s was gone. The more dynamic
portions sounded compressed or actively distorted. Earl Wild Plays his
Transcriptions of Gershwin piano CD on Chesky had noticeable dynamic
compression at moderate volumes. If you want to try to see if your amp
is within its limits with a speaker, play some acoustic classical piano
at moderate volume. In fairness, these same piano CDs on the Tannoys
sounded effortless.
I view the Calla amps as a work in progress. They may ultimately be
superb products, but certain things need refinement. When I moved them
from place to place, the little rubber inserts in their feet tended to
fall off. The binding posts seem only so-so for a $7500 amp. The
instruction manual needs to be rewritten. Finally, when we transported
them to Art Shapiro's house to try them with his speakers, the LCD
meters stopped working on both amps and we couldn't dial out the hum.
Per the manufacturer, the batteries supplying the meters simply ran out
of juice from being continually on. Since there is nothing in the
manual about batteries, or about leaving the meters on, I had no way of
knowing this was a potential problem. It shouldn't be an issue, and I
was told that the manufacturer is addressing it. These points aside,
these amps let one hear into the music, with detail and layering of
information that is truly remarkable. On more efficient electrostats, I
suspect it the sound would be amazing. I hope the manufacturer corrects
the weaknesses, so more people can appreciate what these amps can do.
Mark Katz
Being part of the audioMUSINGS partnership is a great privilege—around
once a month I get to play with a new component in my system, and with a
little luck, my assignment is something interesting and unusual. Naked
Truth Audio's Calla 60 amplifiers are both. Naked Truth is a new
manufacturer out of Ojai, California. The Calla (as in the lily) 60s
are sixty-watt triode monoblocks. A description of their Circlotron
circuit design is elsewhere in this issue. Although each amp contains
four toroidal transformers, they are intended to be used
transformerless. The amps accept both RCA and balanced inputs. The
amps feature ceramic tube sockets and point-to-point wiring. Their
build quality is good, but not as refined as other products in their
price category. Even before listening, the Calla 60s make a strong
impression by their appearance. With their circular crown of glowing
glass tubes and square black bases, the Callas are artfully retro, in a
mad-scientist kind of way.
The Calla 60s are not amps that you just bring home, plug in, and
play—some careful calibration is required before enjoying. First, each
tube must be inserted into its color-coded socket. Next, the amps have
to be warmed up in standby mode. This is followed by some twiddling of
knobs for bias and balance while laying on the floor and peering into
the amps' digital meters. Once the correct values are dialed in, have a
cup of tea, because the ritual isn't quite over. After tea, return to
the amps and fine tune the settings. Finally, it's time for listening.
Viewing the glorious glow of those halos of tubes, one anticipates a
warm and harmonious sound, but the Calla 60s do not impart a burnished
tone. Their sound is absolutely uncolored, and clear as daylight. The
Callas cast light on every aspect of the recording, in a manner that was
thoroughly captivating. I was feeling a sense of accomplishment for
having recently organized my CD collection: classical and soundtracks,
Cuban, latin jazz, small combo jazz, guitar, Latin American folk, and
pop. However, by the end of my first listening session with the Callas,
a pile of CDs had accumulated in the middle of the carpet. One of the
first discs I listened to was the Beatles' newly-remastered songtrack to
Yellow Submarine. The music of the Beatles is deeply engrained in my
memory, but I don't recall ever hearing their music with such clarity
and detail. I was completely enthralled by the studio wizardry and
performance aspects of this disc. The title track's submarine sound
effects and dialogue were quite convincing. The last verse of the song
is echoed by a vague voice far in the background. The Calla 60s brought
this voice into the light and gave it a clear image, as if the performer
were in the back of the room. This sensation of discovery continued
through another studio disc: Kiko, by Los Lobos. The ability of the
Callas to portray each part of a vocal harmony was outstanding. My
Anthem does a good job with the first voice in a harmony—it has body and
character. Nevertheless, second and third voices tend to blend.
Listening to the Callas, one is aware of each voice. Each is projected
with a distinct character.
Two live discs proved the Callas' way with dynamics: Bob Marley's
Greatest Hits and Mana's Unplugged. In both these cases, audience
applause was uncanny. I do not listen to hi fi to judge how well a
component reproduces a meaningless detail like applause, but the Calla
60s let nothing go unnoticed. With many amps, applause sounds like
white noise, but with the Callas, the applause started with just a few
hands towards the front and then extended exponentially to the rear of
the performance space. Voices, hoots and whistles came from every
direction. Kick drum had large proportions and quick, tight response.
Woodwinds were incredibly vivid. I practically wiped the wetness from
my face after listening to the flutist on Frank Emilio's Rico Melao.
His mouthpiece sounded like it was inches from my face. The clarinet on
Don Byron's Bug Music not only sounded reedy and woody, but the clatter
of its mechanism was also present. The low keys of the piano sounded
twangy, while the high keys shimmered with bell-like overtones.
After listening and enjoying the Callas in OTL mode, I proceeded to
listen with the transformers in line. To do this, one must loosen the
speaker cables and reattach them to a different set of binding posts.
In this mode, the Callas produced a more familiar tube sound. I noticed
a softening of transient edges, in contrast to the razor-sharp images in
the OTL mode. I also detected a slight warmth and distance to the
music, and a light veiling in the vocal range that I probably would not
have perceived if I hadn't experienced the amps in OTL mode first. I
soon returned to the OTL mode for the remainder of my time with the
Callas. I love warmth and harmonic richness, but the Callas' clarity of
vision had me hooked. I usually don't have time to enjoy music at the
end of a work day. At best, I have a few moments to myself late at
night to practice some guitar in the dark while the wife and kids are
asleep. With the Callas in the house, I found time to enjoy a CD, even
if only for a few minutes.
Even though I found the Callas beguiling, they are not for everyone. To
begin with, the Callas are rather tweaky, with all their tubes and
knobs. The Callas also aren't the amps for bass heads, nor are they
romantic amps. Alas, they may be too revealing for some of your
favorite discs. However, if you value clarity and precision above all
else, the Calla 60s are a "must audition." I hope that at some point
in the future, technology from the Calla 60s will trickle down to a more
affordable model. They certainly whet my appetite for an affordable OTL
design.
Victor Chavira
--
audioMUSINGS featuring multiple reviews of individual components
Upcoming Reviews
Soundstage is scheduled to have John Potis review a pair of Calla amps in April.
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805. 646.8383
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Last updated December 26 2000