as appeared in Bound
For Sound
May 1998
by Martin DeWulfHow good can this amp sound?
I've been associated with audio in one form or
another for the last thirty years. During that
time I've heard and played with at least several
hundred power amplifiers. None, not one, that
I've auditioned with transistors inside has had
the potential to sound as good or as bad as this
one depending on the loudspeakers used.
And it's not a matter of power. The CA35 at 25
wpc is something less than a powerhouse, and it
might be expected that an amp with specs like
this one, would be limited in the loudspeapkers
it could be used with. In this case, I have found
the amplifier to be more limited than most with
similar output ratings. For example, I have on
hand a 25 wpc channel, class A, stereo amplifier
from Monarchy. It retails for about $700. It will
easily drive, and sound good doing it,
loudspeakers that drove the CA35 nuts. The CA35
sounded terrible trying o drive the Gallo
Reference II's. No highs, rubber bass, a bad
match period. On the other hand, the Monarchy
sounded fine with it. I needed a speaker that the
amp liked.
Why not the Genesis APM-1? An easy to drive,
extremely efficient loudspeaker capable of
revealing warts and all, the Genesis seemed a
likely companion for the little CA35; and seldom
have I heard better. In its own way, as good as
the Sunfire Signature/Gallo combo that lit a fire
under my skiddle just a few weeks before.
Recordings of live events were especially
riveting and thrilling at the same time. Stadiums
appeared at the other end of the room; fans
cheered, spectators applauded, and the live
sounds of a large venue came to life. Putting the
APM-1 and CA35 together resulted in a sound truly
hard to fault as long as the speakers weren't
driven to overload the room (something the
APM-1's can definitely do).
With a few weeks of audio heaven under my belt
with the Genesis, I decided to try the CA35 with
another easy loudspeaker to drive - the Echelon
II. This speaker at 12 ohms has made many an
amplifier a happy lad; it should have been good
with the CA35. The results were mixed. The highs
with the Echelon II were a little softer than I
liked, and the bass wasn't exactly pancreas
shaking. The mids were luscious though, not ultra
real and accurate as they were with the APM-1,
but very good nonetheless, an easy listen.
Why a sound so unpredictable? The damping factor
of 80 (output impedance=0.1 ohm) isn't very high,
but is high enough to control most loudspeakers.
This really shouldn't be a problem. As far as I
could tell, in the high-bias operational mode
this amp runs almost all class A. Nothing wrong
with that. So I peaked inside. Beautiful layout,
a real classy job of putting things together,
even nicer than the Electrocompaniet construction
wise. A single-ended design to be sure from a
small company, but it couldn't be nicer, even if
it is a little unusual internally. One problem
that I saw-couldn't we have more power supply? I
lost my notes taken while looking inside, and I
don't have the amp as I write this, but my memory
says "little transformer, small filter
section." I understand that with a design
this well thought out, that Alternate probably
has a reason for keeping things on the modest
side, but I can't help but think that a bit more
macho in the supply might tighten things up
sufficiently to let the amp work with a few more
loudspeakers. The amp would certainly work better
into low impedance speakers if the supply
contained more heft.
Two more things regarding compatibility and other
components. The input impedance is a very low
18kOhms, I don't suggest the use of a tube preamp
with it. Low output impedance preamps such as the
BCAP from Alternate, the Diffet 5 from Audire and
the Placete should be good choices. This amp
worked its considerable best with power cords
that I usually associate as working well with
tube amplifiers, but one worked better than all
the rest - the RWA. It's from Real World Audio,
and it retails for $200. While the CA35 was
absolutely singing in ways I can only describe as
breathtaking with eyes open with the Genesis
APM-1, it was fired up with the RWA power cord
and nothing else. The "lightness of
being" that seems to follow the RWA cord
around fits absoperfectly the character of the
Alternate Audio amplifier. These two worked so
well together that I kept them together through
almost all of my auditioning.
All other compatibility concerns aside, under
optimum conditions the amp has an extremely
expressive character, a character that lets the
compositional heart of a creation be heard.
Without a doubt, the amp tends toward the
romantic and the warm. But it doesn't obliterate
or mask the detail of a sound, and the highs of
the amp can cut through the warmth with a
sparkle. With the right speaker it has a midrange
that threatens the state-o-the art, but don't ask
it to do bass. As a result, it may in some
systems, be the perfect amp for a person
utilizing a powered subwoofer. The Genesis APM-1
has a 15" powered woofer driver on each
side, and as a result, the CA35 was never called
upon to supply the current and drive necessary to
move a room full of air at 30 Hz. I must assume
that the extreme success experienced with the
APM-1 was in large part due to those powered bass
drivers. To support that, I had the brief
opportunity to use the amp to drive a set of
satellites on top while using an M&K powered
sub on the bottom. Again, superior results,
though not up the level of the Genesis. I am
therefore of the opinion that the CA35 is not the
amp for a full range system unless its rather
demanding requirements of high efficiency and
benign impedance are met precisely. It is not
unlike a single-ended triode in this respect. I
would also match it with two-way pedestal
speakers that are to be used in smallish rooms
and the demand for true bass is low.
Somewhere, sometime, someone is going to put this
amp with just the right speakers (Quads perhaps)
and a set of powered subwoofers, and the person
doing it is going to proclaim the Alternate a
"perfect" power amplifier. It's good
enough to do that, you just have to put it with
the right company. As for me, if this amp came
with more power supply, and something around
100-200 wpc with some current capabilities, it
might be enough to get me to forget other amps
for a while, a real long while.
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