Lamhorn 1.8 Loudspeaker and Art Audio
PX-25 Specifications
Tom Horner's & Chuck
Bruce's program notes, 9/19/2000
The Lamhorn 1.8 auditioned at Sunday's program features
a single driver full range back-loaded horn loudspeaker.
The back side of the 1.8’s driver feeds into
the beginning or throat of the horn, hence back loaded.
Generally, full range drivers of very high efficiency
such as this one, are not capable of delivering adequate
bass to complement the mid and high frequency range.
For this reason, horns are used. Sensitivity of the
1.8 is about 104 dB in the cabinet. The driver alone
is 102.5 allowing use of low power, single-ended tupe
power amps.
This back-loaded horn is used to reinforce bass frequency
below 250 Hz. Frequencies above 250 Hz s are radiated
directly from the driver forward and do not pass through
the horn. This type of configuration permits most of
the audible spectrum to come from a single point source,
the voice coil. Even though the lower frequencies do
not come from the voice coil directly, this is not
a problem since they are mostly non-directional.
A point source yields very coherent sounding music
which is very difficult to obtain with a two or three
driver system. This coherence is further reinforced
since no cross-over is required. It is a known fact
that a cross-over will alter music and restrain its
full dynamic impact as well as induce audible phase
shifts. Full-range speakers free you of these constraints
while permitting the music to flow.
Another advantage of using high efficiency drivers
is that they permit the micro-dynamic nuances and detail
of the music to be heard with ease. Most conventional
speakers fail in this regard, robbing you from the
natural and realistic presentation of the recording.
The Lamhorn 1.8 uses the AER mark 1 fulll range driver.
It differs from the Lowther driver in sound and construction.
The AER cone material is of varing thickness to eliminate
cone resonances and coloration. This is quite evident
when swapping AER and Lowther drivers. The coloration
of Lowther cones become a little iritating and unatural
while masking the music. Another consequence of these
colorations is to predominately highlight the mid-range
area. The AER remains without resonance or coloration
to deliver a very natural and musical mid-range.
Another difference with the Lowthers is the necessity
of a phase plug. The AER has none. The design of the
AER has proven to be superior without any. In fact
the higher frequencies extend up to 20,000 Hz whereas
the Lowthers roll off at 18,000 Hz.
The Lamhorn 1.8 has been designed with the listerner
in mind. Over 3 years of reseach and development, study,
measurements and listening to most original and current
Lowther designs, has led to the development of the
Lamhorn 1.8 Loudspeaker. It has been recently optimized
for the AER driver. The horn measures 1.8 meters long
and enables bass response to 50 Hz at –3 dB.
Most other back loaded horn cabinets do not extend
as low in the bass while being even larger.
The cabinet is made of 1 inch Russian Birch with
oak or rosewood veneers. Reinforcing braces are also
used throughout the internal horn structure to eliminate
any unwanted panel vibration.
Dimensions are 48" tall by 12 ½" wide by 17" deep.
Each cabinet weighs 100 Lbs. and retails for around
$6k per pair
About the Art Audio PX-25
It's a 6 watt singleended amp using the KR PX-25 tube.
Operates in pure Class A with 1% distortion at full
power and possesses exceptional current delivery
cpapbility. Retail $5000-$5500 depending on
finish.
The companion VPL preamp, uses two 12AX7/CV4004. All amplification stages
are pure Class A with a cathode follower. The pre-amp also function in
two modes: passive which has zero feedback and active which uses feedback. the
pre-amp also uses the star system which uses a separate wire or pc track for
each ground connection, all terminating at one point.
Mike Masztal - SoundsRight Audio
The Notes & Listening Impressions
The September meeting of the Atlanta Audio Society
was again hosted by Mike Masztal, owner of SoundsRight
Audio in Roswell, GA. In this "Strictly Listening and
Single Ended Session", many members and guests brought
their own CD's to audition on the single ended amplifier
and full range driver speaker setup.
Sonically this was one of the most "open" and revealing
soundstage amplifier/loudspeaker ensembles heard is
quite awhile, especially after a good afternoon warmup.
Rembering that the loudspeakers were new out of the
box only a couple of days.
Since the whizzer cone tweeter element affixed to
the front center of the main driver -vs- a wide dispersion
dome unit found in muliti-driver designs, the Lamhorn
appeared more sweet spot critical than other designs.
Yet not requiring a "clamped head" position to hold
the best imaging. An appealing technical point about
this single-driver design is there is no crossover,
resluting a very coherent projected soundfield and
little if any coloration.
The prevailing sonic character that several listeners
concurred was exceptional detail and precise imaging.
And again, as the system warmed-up, a huge room filling
soundstage and the bass tightened.
The electronics consisted of Art Audio's PX25 amp,
which are a Single Ended Vacuum Tube amp, and the VPL
MkII pre-amp. The digital front end consisted of the
CEC TL2X Belt Drive CD transport and the Audiomat Maestro
DAC.
After Mike gave us an introduction to the equipment,
most of the afternoon was set aside for folks to spin
their favorite discs and enjoy the "single-ended" experience
in a relaxed home setting. Before listening to each
CD, the attendee introduced what we were about to hear
and why he/she enjoyed that particular piece. A wide
variety of music followed, ranging from classical symphony
to single vocalist to live recording of a big band
to mainstream CD's.
Thanks to Chuck's email asking for donations, we had
a very generous raffle with everyone a winner, including
the Audio Society's treasury. Thanks to everyone who
donated! We even have a lot of left over goodies ready
to be raffled in November. We even had several tickets
to the Variety Playhouse to enjoy "Leon Redbone" and "Little
Feet". The Society thanks Steve Harris of the Playhouse
for these and again to the many other members for their
generous donation of CD's and even DVD's.
During a very quick business meeting, Chuck reminded
the members of the upcoming election of 2001 officers
and the need for members to volunteer for the officer
positions.
Tom Horner/Chuck Bruce
Secretary, AAS
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