Speakerlab S3 User manual

35+
spfiqfgilpp"ratin$ Manual

One of lhe more sublime ioys of the technological age we
live in comes when you hook up a new speaker system for
the first time. But you have to do it ri8ht. Stereo
equipment is by no means foolproof. Fools are advised to
take up some other hobby, like going into politics. A high
quality stereo system is a delicate precision instrument
that requires some knowledge and care to obtain
maximum performance.
CONTENTS
How to connect up your speakers
Howto place your speakers in the room
How to adiust the crossover controls
How to use your amplif ier
Troubleshooting your speaker system
Principles of operation
Speakerlab speaker kits
@SPEAKERLAB, INC,, 1978. All rights reserved. Printed in U.S.A. This publication contains proprietary. information which is the
property of Speakerlab, Inc., and is furnished only for the purpose of heiping ownersmake proper use of Speakerlab producls. No
baris ofinis pubtication may be reproduced in any form without written permission ol Speakerlab, Inc'
Both the word ,,Speakerlab" and the distinctiv€ Speakerlab design-mark are registered trademarks of Speakerlab, lnc., a Washington
State corporation- They are registered Federally, in thirty individual states, and in Canada'
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How to connect uP Youf sPeakers.
How to connect your speakers to your amplifier with the
proper phasing.
Most soeaker svstems have their terminals Iocated on
the back. Cenerally one terminal is the ground, or
common, terminal and another is the positive, or hot,
terminal. Connect the terminals for each speaker
throuqh 2-conductor wire to corresponding terminals
on thd back of Your amPIi{ier.
lf vou have d stereo pair of speakers, it is importanl for
odtimurn sound that you connect up both cabinets in
phase with one another. To do this, {ollow the rule.
Use the marked conductor to connect the amplifer
common (black, minus) terminal to the speaker common
(black, minus) terminal. Do this for both woofers and
they will then move in-phase. What this means is that
they will move outward together in response to a
positive signal, augmenting each olher. lmproperly
phased, or- ou t-of-phase, speakers will oppose each
other----one will be moving outward as the other is
movinq inward-and will have a diminishing effect on
the overall sound levet.
In zip-cord one conductor is marked by printing or a
ridge on the insulation, by tinning (silver color) on the
conductor itself, or by a colored thread along the
'' conductor. Make it a ru le to use the marked conductor
' Ior ground (common) and you will always get your
speakers phased correctlY.
lf your speakers have screw-type terminals and you
use stranded wire, twist the strands before placing the
wire underneath the screwhead so that the strands
won't frav. Be careful to make sure that there are no
strands g,oing from one lerminal to another which
could sh"ort olu t the amplifier. A short here can make
your amp start popping fuses like flashbulbs at a
wedding.
On some speakers you may not be able to tell which
terminal goes to positive and which goes to ground; it
doesn't riake any difference so long as both speakers
are con nected the same way. lf one is connected in the '
opposite way from the olher, the speakers will be out
oi phase. Out-of-phase operation may cause weak
bass and a poorly defined slereo image, but is not
harmful to the equipment.
What kind of wire to use.
We recommend that you use two-conductor stranded
copper wire (zipcord) No. '16 gauge or No. 18 8auge.
Oori't Ue fooled the larger the Sauge number, lhe
smaller the wire- Ordinary lamp cord is No.18zipcord.
We do nol recommend No. 22 Sauge wire, which is
commonly sold as speaker wire by mail order outfits
and stereo stores that shou ld know bette r. lt can n ot be
used for very long runs without interposing excessive
resistdnce between the amplifier and speaker.
The table belorv shorts the allowable run lengths for
difierent g,auges of wire- The lengths shorvn are the
distance rieaiured one'rvay from amplifier to speaker-
You mav use different wire sizes for each speaker, so
long as each speaker has large enough wire for itself'
MAXIMUM TENGTH
OFWIRE
FROM AMPLIFIER
TO SPEAKER
up to 18 teet
up to 30 feet
Up to 48 feet
*We recommend the-larger diameter wire (the smaller
gauge number) of the two.
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GAUGE OF COPPER WIRE:
FOR4OHM FORsOHM
SPEAKER SPEAKER
*No. 18 or 20 No.20
*No. 16 or 18 tNo. 18or20
*No. 14 or 16 *No. -16 or 18
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Speakerlab speakers have push-button lerminals on
tie back. Push in the bunon and insert the bare end o[
Vour connecting wire into lhe hole which opens in the
ironL of the terminal. Release the button and the
terminal will grip the wire. The red terminal connects
to the red, plus, positive, or 4 or 8 ohm terminal on
vour amplifier or receiver. The black terminal
connects to the black, minus, negative' Sround or
common amplifier terminal. A pair of speakers
connected in this manner will be in-phase.

How to place your speakers in the room.
Speaker placement affects both the stereo imaging of
your system and the frequency response.
Best stereo is obtained when the two soeakers and
Iistener form a trianele with the distance between the
speakers approximalely equal to their distance from
the listener. Best four channel operation is obtained
when the soeakers are placed al the corners of an
imaginary square with the listener in the center.
Q,
TOO NEAR
Not many homes, however, allow an ideal setup.
Architects who design with acoustics in mind are rarer
than psychoanalysts with common sense. You end up
having to experiment. In a reasonable compromise
both stereo speakers will be within earshot and not so
close toqether that the stereo channels are
indistinguishable. Four-channel speakers will be
placed somewhere to your left and right, before and
behind you.
ln a properly arranged system you need not be able to
say "that sound is coming out of that speaker." The
idea of stereo is not to make the Seattle Symphony
seem like the musicians got in a fight and chose up
sides along opposite wallJof the ro6m. The idea is tb
reproduce a sense of depth and spaciousness in the
m usic which makes it m uch more realistic and pleasant
to listen to.
The frequency response of the speakers will be
affected by how close they are placed to the walls and
floor, and also by the materials which cover the walls
and floor. Mostwriters treat these effects as some kind
of mystery with the magical name "room acoustics,"
but they are more properly called "wall acoustics" and
are quite predictable.
Nearby surfaces reflect low frequencies, so placing a
speaker in a corner which gives three adiacent
surfaces will boost the bass. You can make a little
speaker sound like a big one if you place it right. Soft
surfaces such as rugs, drapes, upholstery and people
absorb high frequencies and cut the treble, while hard
surfaces such as closed windows, painted walls, and
wood or tile floors reflect high frequencies and boost
the treble-
Speakerlab speakers (except the corner horns) are
designed.for placement against a wall, either on the
floor or on a shelf, because these are the most
common locations used. Out in the middle of the
room, especially if raised off the floor, they will have
Iess bass. Placine them in a corner on the floor will
exaggerate the 6ass. Some kinds of speakers (and
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some listeners) need the bass boost furnished by
corner placement, so try it if necessary.
Frequency response measurements of the Speakerlab 1
with the speaker in different locations,
UPPER-speaker up off floor away from walls. The 51's
free-space response is about :t3 dB from 90 Hz-17
kHz.
MIDDLE-speaker on floor away from walls.
LOWER-speaker on floor in a corner. Corner
placement extends the bass to about 50 Hz. The
pronounced dip at 800 Hz in the third picture
indicates that the bass-strengthening corner
. reflections are delayed about 2.5 milliseconds lrom
the direct radiation. The delay makes no difference
below 150 Hz, but disrupts the measurement about
'150 Hz due to interference effects between the direct
and reflected sound. These interference effects do
not seem to iniure the audible performance of a
speaker in a corner; probably because the ear
disregards the delayed sound-a psychoacoustic
phenomenon little studied or understood.
Surfaces near your head have the same effect as do
surfaces close to the speakers. The receiving
transducers you were born with are subiect to the
same acoustic laws as the transmitting transducers you
built (or bought).
lf you have a choice of _several places to put your
speakers, experiment. " i-
The effects of hard or soft surfaces will be
compensated for to some extent when you set the
midrange and tweeter level controls.
,a>
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TOO FAR /\
IUST RIGHT

How to adjust the cfossover controls.
Midrange and tweeter level controls on the crossover.
After you get the speakers in place, it is time to adjust
the tweeter and midrange level controls that
Speakerlab speakers (and most others) have on the
back. Many people (including some equipment
reviewers for the slick audio magazines) mistakenly
assume that the center settinqs of the controls
corresoond to " flal. " Variations in wallacoustics make
the "flat" setting vary with speaker locations. Settings
the controls correctlv comDensates for this.
0dB
rwEErER LEVEL coNrRor e) _, ou
MIDRANGE LEVEL CONTROL
-4 dB
0dB
-2 dB
-4 dB
o
INPUT TERMINALS
When adjusting srvitches or L-pads as suggested here,
you are adjusting the speaker in place and
automatically compensate for reflections from nearby
surfaces. Surprisingly enough, setting the controls by
trial also compensates for defects in the frequency
response of your ears-it will make the frequency
response o{ the total system, including you r ears, flat. lf
you have poor hearing, your speakers will end up
sounding great to you, but terrible to everybody else.
We use two kinds of level controls-three position
switches and L-pads. Switched settings are more pre-
cise and repeatable while L-pads have awider range of
variation.
How to set crossovers with L-pads.
We recommend that you use a crossover with L-pads
for systems of your own design because the L-pads'
greater range of variability will accommodate a wide
range of driver sensitivities- To set L-pads u'e susgest
that you put on your turntable a recori o. .c::e =;.r:
that you are familiar with r iolin r-cu::t . 3:;no rr-::c.
or music with natural voices in it are all good. \1oog
music, made on an electronic sYnthesizer, is no good
for adjusting level controls on speakers because
nobody knows what they really sound like. lt has never
been heard except over speakers or headphones.
Set the tone controls on your amplifier to nominally
"flat" and rotate the balance control so that only one
speaker is playing. Turn all the controls on the back of
the speaker down to minimum. The sound coming
from the speaker will now be very muffled because
you are only hearing the woofer. Cet close to the
speaker and slowly turn up the midrange control until
you can hear the sound from the midrange also. The
midranse sound and the woofer sound will be
separate; it is easy for you to tell which speaker the
sound is coming from. As you turn up the midrange
control, you will find the point where the sounds
blend and that sou nd seems to be coming from a point
haliraray between the midrange speaker and the
woofer. You will not be able to distinquish which part
of the sound is coming {rom which speaker. At this
point, the midrange control is correctly set. Now turn
up the tvveeter level control in the same way untilthe
tweeter sound blends in with the midrange and
woofer sound, and does not seem separate.
Reoeat the orocess for the other channel.
How to set crossovers with switches.
On the switched crossover, the maximum position
(0 dB) corresponds to measured flat frequency
resDonse. The other two positions reduce the tweeter
(or midrange) output by 2 dB or -4 dB. \,Ve
recommend the 0 dB setting ior normal operation.
This setting ma1, sound rather "bright" at first in
com parison to other speakers because of the high-end
rollon still used by man-v manufacturers. However,
ivith rvideband, Iorv-distortion electronics the 0 dB
settings will give music an "openness" and
"spaciousness" normally associated only with live
music. Use the 2 dB or -4 dB setting in an unusually
reflective environment one with hard walls, hard
ceilines and little or no soft furniture or curtains. The
reduced settings may also be used to compensate for a
"peaky" or "shrill" cartridge.
The 0 dB (maximum) switch settings are designed for
use with speakers on the floor. Floor placement tends
to help the bass because of reflections of the low
frequencies off the {loor. Mounting the speakers on a
wall or shelf will reduce the bass slightly because of
Ioss of this effect, and it may be desirable to reduce the
m id range and tweeter settings to match. Try it and see.
Now that the controls ard set.,-
Don'l use the level (onirols io acifusi::::=:.- =---=
in program material. The bass and trebie coniro:s o::
your receiver or preamp are for that.

How to use your amplifien
How to use your bass and treble controls.
A popu lar su perstition holds that setting you r bass and
treble controls "straight up" will give flat frequency
response. It would be so nice if thatweretrue.
Unfortunately small frequency response errors in the
cartridge, preamp, recording equalization circuit, and
other places add up so that rarely is a system perfectly
flat. There are also the effects of reflections from far
walls mentioned previously. ln addition nearly all
records are equalized with a built-in gradual treble
boost on the assumption that they will be played back
on systems with a gradual rolloff in the high end,
which most systems (constrained by the laws of
economics-a good high end is too expensive for most
speakers) do indeed have. lf you have a careful ear,
and if you have speakers with a flat, low-distortion
high end such as horn speakers-all these effects will
be oainfu llv evident.
The ooint here is this: vou shouldn't be afraid to use
your tone controls. Bais and treble controls enable
you to make slight adlustments to correct for all these
errors. Usually the high frequency end of the
spectrum will require most attention. A small
adiustment. no more than .10 o'clock cut or 2 o'clock
bobst, will usually su{fice. Cut the treble to
compensate for over-bright recordings and reduce
noise on FM. Cut the bass if vou must use vour
speakers in a corner and they sound boomy. Boost
bass if they sound thin because you have a large room
or lots of open doors and windows that drain off low
frequency energy, or have hard-surface walls that
reinforce midrange and highs.
On most preamplifiers and receivers, the tone
controls mav be set anlrarhere from 10 o'clock to 2
o'clock without makins the music sound unnatural.
Do not let the exiesses oracticed bv some
extremists such as turning the loudness, bass, and
volume full up to rattle neighbor's china-discou rage
you from making reasonable use of the tone controls.
A word of warning Speakerlab speakers usually
require very little bass boost. They have very good
low-end response, achieved by using Ioose-
susDension woofers, and too much bass boost can
cause excessive cone motion. This can result in
suspension "thumping," distortion, and possible
damage.
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420
ITJ
"How much power do I need?"
The answer to this question is shown below.
YOUR AGE (Years)
Seriously, the power you need really depends on how
loud you like to listen to music. The actual power
being put out by your amplifier depends on the setting
of the volume control; amplifier power ratings
correspond to maximum power before distortion
begins. You can safely play a 50 watt speaker with a 100
wattamplifier if you don'tturn up the volume too high.
We rate Speakerlab speakers for both minimum and
maximum power. For example, the Speakerlab 3 is
rated at 15-25 watts RMS minimum, 100 watts RMS
maximum. The ratings correspond to the watts RMS
per channel of amplifier power. The lower minimum
rating (15 watts) is for moderate listening level; the
other minimum rating (25 watts) is for high level rock
music. Rock music is typically played at high volume
levels and has more low freouencv content than
classical music, requiring more power.
The maximum rating refers to the largest amplifier
which it is guaranteed sa{e to use for home music
reproduction. Speakerlab's guarantee covers burnout
so long as you use the speakers as recommended. You
can use a larger-than-recommended amplifier at your
own risk. The risk is minimal if you're careful. The
times speakers get burned out is when you put them
outside for a party and somebody decides to serenade
the people on the other side of the lake.
\
We design Speakerlab speakers to cover as wide a
power range as possible, and especially to handle the
high power amps and receivers that are becoming
more popular. Cetting a new speaker system and
finding out that you r amp either won't drive it or bu rns
it out can ruin vour whole dav.

Amplifier overload.
A common mistake speaker "test" shoppers and new
speaker owners make is to turn up lhe amplifier
volume u ntil the syslem distorts audibly. They call this
distortion "cone break-up." What you hear in such a
case is amplifier clipping, not speaker distortion. The
amplifier is ru nning out of power on the music peaks.
Since the distorted sound is coming out of the
speakers, you can easily attribute it lolhe speakers
themselves. This is a simple mistake no matter what
goes wrong with a system, the result will be heard in
the speakers since everything comes out of the
SDCAKETS.
The remedy to this problem is easy tu rn down the
volume or get a more powerful amplifier.
Clipping will occur at lower settings of the volume
control if the loudness switch is on or if the bass is
turned up. Both these controls work by boosting the
bass signal, which uses more amplifier power.
How do you avoid acoustic feedback?
A. common problem with stereo systems where the
sp-eakers are located close to the turntable is acoustic
{eedback. lt usually shows up as a Iarge-amplitude
"flutter" in the woofer cones (if they are visible) or as
distorted sound. The problem is aggravated by high
settings of the volume or bass control, or by having the
loudness switch on. The listener typically reports that
he can turn up the volume control (orthebasscohtrol)
only so far, then the oscillation starts.
The problem is most likely to occurwith speakers with
u n usually good bass response. What occu rs is this: the
soeakers vibrate the floor, the floor vibrates the
turntable, and the turntable vibrates the record. The
cartridge stylus cannot distinguish vibrations in the
record sroove from vibration of the record itself so
the stylus moves and injects the signal into the system,
where the signal is amplified and moves the woofer
cone, contin uing the cycle.
The cure is to prevent speaker vibrations from shaking
the turntable. Place the turntable and speakers as far
apart as possible. lf you have an unusually shaky floor,
mount the turntable on a shelf on a wall, or place a
heavy (30 lbs. ) stone slab on foam rubber, ju st benealh
the turntable. Putting a soft pad under the speakers to
isolate them from the floor often helps. Turntables are
spring mounted to reduce acoustic feedback; in
newer turntables the isolation is more effective.
What is the difference between 4 ohm sneakers and B
ohm speakers?
"Ohms" is the measure of a speaker's impedance-the
amount that it impedes, or resists, the amplifier's
current. The smaller the "ohms," the greater the
current and power drawn by the speaker. Where the
impedance becomes important is when you use more
than one set of soeakers. Most stereo receivers have
terminals for two sets of speakers, A and B, and a
switch to select A, or B, or A+ B. However, most
amplifiers will not drive more than one pair of 4 ohm
speakers at a time without overheating. That means
both pairs of speakers must be 8 ohms to play A+8. So
if you want to play two sets of speakers at the same
time, I ohm speakers are best.
On the other hand, most amplifiers develop maximum
power into 4 ohms. So if you are going to use a single
set of speakers, and are pushing for maximum power,
4 ohm speakers are best.
Two side effects of impedance differences take place
when comparing speaker systems.4 ohm speakerswill
draw more power at a given volume control setting
than 8 ohm speakers, sotheywill play louderand seem
more efficient. On the other hand, the volume control
setting can be turned higher be{ore the amplifier
begins to distort with B ohm speakers, again because
thev draw less oower.
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Troubleshoolin$ your speaker system.
Problems with our kits are infrequent mosl go right
together and work perfectly the first time you hook
them up. Speakers are inherently quite reliable when
operated within their ratings, and unlike electronic
kits, our speaker kits are nearly foolproof to wire. The
crossover is completely prewired. The color-coded
leads to the drivers minimize the chance of incorrect
driver hookup. The aircraft-type push-on tefminals
eliminate the possibility of bad solder joints since no
soldering is involved.
Nevertheless, problems occasionally occur. A
warning-do not assume that the problem is in the
speaker if your system misbehaves the first time you
hook on a new speaker. A defect anywhere in the
system shows up first in the speakers because that's
where the sound comes from, and a change of
connections will often provoke breakdown of a weak
link somewhere else in the system that was about to
failanvlvav.
First, try to isolate the problem. Determine whether it
is in the speakers, and if so which speaker.
ls the problem even in the speakers?
lf both speakers sou nd bad or don't play at all, the fault
is probably somewhere else in the system it is
unlikely that both speakers would simultaneously
contract the same disease. Working backwards, check
out the wires from speakers to amp; check the amp
{uses or circuit breakers; the cables from amp to
turntable or tape deck; the wires from turntable to
cartridge; the Iine cord from amp to wall socket; and
the wall socket (blown house fuse?). Always suspect
connections first they are the weakest link in any
electronics system.
Which speaker cabinet is the problem in?
lf onlv one speaker sounds bad or is silent, make the
two speakers change places. Don't jusl switch wires at
the amp- the problem could be in the wires. Physically
move the speakers (hard work but positive test).
l{ the problem stays on the same side after you moved
the speakers, it must not be the speaker. Check the
amp, turnable, line cord, etc, and their connections,
as recommended above.
lf, on the other hand, one speaker misbehaves no
matter where it's placed, while the other works fine,
then the speaker itself must be at fault. Run the level
control-L-pads or switches up and down to check
for intermittent action. Remove the erille cloth and
check for physical damage lo lhe speaker cones. Tears
will ruin their oerformance but small dents have little
effect.
Which driver (woofer, midrange or tweeter) is at fault?
In multiway systems you can isolate the problem to
woofer, midrange, or tlveeter by listening with your
head close. Pluck out the offending radiator and
examine its wires perhaps a terminalwas not pushed
on all the way.
How do you get back inside a Speakerlab kit after it's
assembled?
Stick a screwdriver under the edge of the woofer
frame and pry it up the silicone rubber glue
stretches and will pull loose. Cut the glue with a razor
it necessary.
To seal it back up again, peel or cut off the old rubber.
Then put down another layer of silicone rubber glue
and install the woofer as you did originally.

A dead driver usually indicates either a broken wire in
the driver or in the corresponding crossover section.
Test the driver afteryou remove it by applying 1.5 volts
to its terminals with a flashlight battery-i{ it's good
vou'll hear a healthv click. tf it's bad send it to us and
we'll send vou another one. with or without a bill
depending on whether you're covered under the "kit
assembly" (no bill) or "5 year" part of the guarantee,
and if the latter, whether insoection shows it was due
to a manufacturing defect or misuse.
Check out the crossover.
lf the driver tests OK, trace the wires back to the
crossover and check for a pulled-loose wire or part.
Remove and examine the crossover if necessarv.
working through the woofer hole. lf your crossover
has L-pads, check them out: L-pads thdt have a very
rough "feel" as you rotate lhem, or that stink when
you smell them closely, are burned out. Do not be
alarmed if the L-pads generate noise when
rotated they are wirewound and noise as the wiper
jumps from turn to turn on the resistance winding is
normal. Once set, though, they should introduce no
n orse.
There may be a mechanical problem.
A "rattling" or "ttuzzing" sound in the woofer
indicates a rubbingvoice coil-due to a shifted magnet
perhaps, or a warped voice coil caused by
overheating. "Raspiness" in the midrange or tweeter
indicates the same thing. (Though our tweeters have a
very extended, flat high end that will reproduce any
distortion generated elsewhere in the system.)
"Whispery" noises, especially during music passages
with lots of low bass and little else, may be caused bv
air leaks. Lislen around the speaker to locate them.
Driver mountinq holes and the crossover mount are
Iikely suspects. lf you locate a leak, caulk it over with
additional silicone rubberglue. The glue can be pur on
from the outside to eood efJect.
Buzzes and rattles are often traced to nearbv windows.
lamps, and so on, that may never have caused trouble
previously because they were not subjected to the low
frequency output of which Speakerlab speakers are
capable. Most of ou r systems have response extending
down into the subsonic range. (The ear itself actually
responds down to only 50 hertz-sound perception
below that is tactile, not aural.)
Cats have an irresistable urge to sharpen their claws on
woofer cones, so don't leave the grille cloth off even if
you like to listen to the speakers that way.
Dents in domes can be pulled out with a pin. Small
tears can be patched with rubber cement or contact
cement and a patch made of a nylon stocking or other
lightweight nylon mesh material. We have found that
some awful-looking damage can be repaired to leave a
driver's sound performance unharmed, particularly
with woofers.
If a corner of your enclosure gets mashed from
dropping, beat it back into shape with a hammer (no
kidding) and re-oil it. Sanding and re-oilingwill make a
cabinet that has laken most kinds oI abuse -scratches,
small dents, scuffing, water look acceptable, if not
perfect. One exception: milk rings. Sour milk contains
an acid that bleaches walnut and makes an
ineradicable mar. Don't set baby's bottle on you
speaker. (Baby's diaper is even worse but we assume
you don't need to be warned about that.)

Principles of operation.
Most o{ ou r Speakerlab speakers are tvvo-way or th ree-
way systems employing acoustic suspension woofer
sections and dome or horn midrange and tweeter
sections. We prefer three-way designs where
economically practical because a separate midrange
gives lower distortion. In two-way systems the
midrange frequencies are reproduced by the woofer,
and the woofer's cone motion in response to low
frequencies introduces some distortion into the
midrange.
Woofer
ln making our woofers we use large diameter, long
throw voice coils to give high power handling cap-
ability and low distortion. The voice coils are wound
on aluminum formers to conduct away heat. The turns
are baked on at 325"with thermosetting cements so
they will withstand momentary overloads which cause
high temperatures.
Midrange and Tweeter
Horn midranges and tweeters provide the most
accurate u pper-freq uency-range reproduction, man-
ifested as an uncanny sharpness and aliveness to ihe
sound. (Horn woofer sections are also superb but are
impractical in most applications due to their large
size you need a 7.5 ft. diameter mouth for response
down to 30 Hz.)
Horns are necessarily costly due to the precision
machine work required. In fact, few consumer
systems usethem at all, in spite of their acknowledged
superiority and near-universal usuage in recording
studio monitor and other professional applications,
because of the cost factor only by building her own
can the average listener a{ford horns.
The second choice after horns is dome radiators.
Some Speakerlab dome drivers are combination
dome/cone units, with the cone radiating the lower
part of the range and the dome the upper. At 10 kHz a
wavelength in paper cone material is on ly about 1 inch,
so a dome or cap 1 inch or less in diameter is required
to obtain in-phase motion all across its surtace.
Crossover
Speaker systems use coil-and-capacitor crossovers to
send the right frequencies to the;ight drivers. We use
air core and open iron core coils to avoid the distortion
introduced by closed iron cores, which are
magnetically nonlinear. The coils are large, wound
with hea\ry gauge magnet wire, to keep the series
resistance low. This reduces losses in the crossover
and maintains high damping factor in the woofer
section. The capacitors used are close-tolerance
nonpola r-electrolytic or solid dielectric types.
For each model we first design a crossover along
theoretical principles (see our "Crossover Design
Cuide") based on frequency response measurements
on the drivers with which it will be used. Then we
modify it to provide optimum response when
connected with the drivers in the system. Crossover
frequencies, 6 dB/octave or 12 dB/octave crossover
slopes, and controlled overlap or underlap are all
manipulated so that the crossover serves to equalize
any slight frequency response deficiencies remaining
in the driver themselves.
We use a Real Time Analyzer, which provides a
continuous, instantaneous display of the system
irequenc'- iesponse, to f ind our \r'a1'lr h ile rr, e make all
these modifications and adjustments.
Finally the speaker systems are provided with
midrange and tweeter level controls so you can
"adjust out" slight production variations in the
efficiencies of the drivers in each system and also
correct for the acoustics of you r listening environment
to some extent to get uniform frequency response in
your home.
We can't test each system, of course, because the kits
aren't assembled yet. But any kit builder can bring in
his completed speakers and we'll individually test each
one and give him a frequency response graph for it.