ACME sound Low B-1 User Manual

Owners Notes Low B
-
2 and Low B
-
4 Systems
8
on their sides, with the midranges and tweeters oriented on a common vertical axis. Acoustically, this
orientation offers a bett
er “line source” than stacking the two boxes upright or side
-
by
-
side.
Experiment.
Placement: Low B
-
1
At first glance, the Low B
-
1 looks a little strange. As was mentioned above, the speaker uses a Fender
-
type strap handle. The port is apparently located o
n the top, next to the handle. Unusual.
In fact, however, the port and the handle are located on the
side
of the speaker. They
are placed on a
common surface to discourage the user from stacking another speaker (or anything else) over the port,
thereby ru
ining the operation of the port, and placing the woofer at great risk. As was mentioned in the
section on placement of the B
-
2,
blocking the port(s) greatly reduces system power
-
handling, and is to be
avoided at all costs.
As a consequence, the disadvant
age of this type of handle for use on the Low B
-
2, limiting stacking
options, is a necessity on this smaller speaker, and allows
the use of this excellent handle on the B
-
1.
Place the speaker with the midrange and the tweeter toward the top.
The port and
handle will be on the side, correctly, and the top of the box will provide an open surface for
placement of your amplifier, or f
or stacking a second Low B
-
1.
Cables
As a design goal, internal system
resistance has been kept to a
minimum. To maintain the s
ame
level of electrical integrity, short,
heavy gauge cables are best. Don't
run out and spend a fortune
however, unless you're
certain that
what you have is inadequate. I
recommend a cable of under .3
Ohms, and the larger the cable the
better.
Stands
Som
e customers have successfully
used the Low B
-
2 systems as PA
speakers. This has led to the idea of
using the units elevated on s
peaker
stands. Be warned: There are only
two small places on the cabinet
where a recessed receptacle can be
mounted, and you don
’t know
where they are. To cut holes
anywhere else in the box will do
irreparable harm to the enclosure.
This is because of the
orientation of
the special bracing that is used to
stress the enclosure. DO NOT CUT
HOLES IN THE ENCLOSURES FOR THE
PURPOSE OF I
NSERTING SPEAKER
STANDS WITHOUT CONSULTING
WITH US FIRST! If you need to do
this, please call before you destroy
Port Placement: Front, Rear, or Side?
Bass players seem to enjoy discussing the merits of front or rear placement of ports.
Based on their experiences, many players and manufacturers alike are convinced that
front placement has distinct advantages over
rear placement, or vice
-
versa.
When asked to justify their opinions, these partisans will invariably refer to vague
impressions
and gut feelings. They will never talk about wave propagation or
Helmholtz resonation. In fact, a bass
-
reflex enclosure, at the
frequencies where the
port contributes to the system’s output, is a pressure device, as opposed to a wave
device. So the intera
ction of the enclosure and the port, and the port's position with
respect to the woofer, itself, are unaffected by any direction
al activity. Direction is
utterly unimportant. By way of illustration, examine another pressure
-
related model,
a balloon. As you
inflate a balloon, does it expand on one direction only, or in all
directions at once?
Only after a port’s output leaves the c
abinet, and enters the environment, does it
assume the characteristics of a wave, one of which is direction of propagation.
Direction does assume importance when speaking of waves. Only, however, at
frequencies where the size of the source is large com
pared to the wavelength under
consideration. The highest frequencies at which the port in our Low
-
B systems
contribute to system
output have wavelengths of 14 feet or so. The speakers are
obviously quite small compared to these wavelengths, and the port ou
tput is
omnidirectional. Again, port placement is irrelevant to system performance.
Why does the B
-
2 have ports in the back? Be
cause that’s where they fit. Why does the
B
-
4 have its third port in the front? Same reason.
The B
-
1 system could have been cor
rectly tuned with a shorter, smaller diameter port
located in either the front or the back, if location mattered. But it doesn’t
. The
drawback would have been that at higher power levels, excessive port friction would
have resulted in diminished power hand
ling capability. This larger diameter, longer
port fits when installed on the side of the box. Plain and simple.
Tell your frie
nds that the reason your B
-
1 system sounds so good is that the
tremendous innovation of a side
-
mounted port results in some type
of magical
quantum
-
leap in performance. In fact, the truth is much less exciting: a high
-
quality
woofer in a solid and correctl
y
-
tuned enclosure. Feel free to let other people lose sleep
over where their ports are located. Now you know the truth.

ACME sound Low B-1 Specifications

General

Brand	ACME sound
Model	Low B-1
Category	Speakers
Language	English