University Sound MM2TC User manual
SPECIFICATIONS
Frequency Response:
800
-
5,000
HZ
f
5
dB
(see Figure
3)
Power Handling,
8
Hours, 6
-
dB Crest Factor:
25 watts
(500
-
5,000
Hz
pink noise)
Impedance:
16 ohms
Sound Pressure Level at
1
Meter,
1
Watt
Input Average, Pink Noise Band
-
Limited
from
800
-
5,000
Hz:
Horizontal Beamwidth:
104 dB
82O
@
2 kHz (see Figure
2)
Vertical Beamwidth:
82O
@
2 kHz (see Figure 2)
Directivity Factor
R,
(a):
10.25
@
2 kHz
Usable Low
-
Frequency Limit:
600 Hz
Construction:
Rugged die
-
cast aluminum case and
transformer housing. Diaphragm is
phenolic impregnated linen
-
base. All metal
speaker parts are of anodized aluminum
with baked
-
on acrylic paint.
A
cable
entrance is provided on the bottom side
Voice
-
Coil Diameter:
5.1 cm (2.0 in.)
Magnet Weight:
0.93
kg (2.1 Ib) with plates
Magnet Material:
Alnico
V
Dimensions,
Height:
Width:
Depth:
Net Weight:
4.0 kg
(8.8
Ib)
Shipping Weight:
4.5
kg
(10.0
Ib)
25.4 cm (10.0 in.)
16.4 cm (6.4 in.)
1
1.3
cm (4.4 in.)
DESCRIPTION
TheUniversitySound MM2TCis aconservatively rated25
-
watt
"
submergence
-
proof''speaker
designedfor wall, ceiling,or bulkheadmounting.
The driver employsadiaphragm with a phenolic impregnatedlinen
-
baseand 2.0
-
inchvoicecoil
with
"
W
"
shapedAlnico
V
magnetstructure.
Provisionsaremade inthe housingfor installation
of
a matchingtransformersuchasthe
UniversitySoundmodel
5030
(30
W).
Thevoice-coil/diaphragmassembly is protectedbyaspecialanit
-
fungicidetreatment and
is
easilyaccessiblefor cleaningby removalof the die
-
cast reflectoron the front of thespeaker.
The MM2TC
is
self
-
draininganddesigned
to
withstandfungus,dust,salt spray, livesteam,and
gases.
It
isbuilt
to
penetratehigh noiselevelsin boiler rooms,mines,railroads,etc.
_
-
I
DIRECTIONALPERFORMANCE
The directional characteristics of the MM2TC
were measured by running a set of polar
responses in University’s large anechoic
chamber. The test signal was %-octave-
band
-
limited pseudo
-
randompink noise
centered at the
IS0
standard frequencies
indicated in Figure 1
Additional typical data
is
provided in
Figure
2
which indicates 6-dB-down
beamwidth versus frequency for an MM2TC.
FREQUENCY RESPONSE
Figure 3 shows the axial frequency response
of the MM2TC.
It
was measured at a
distance of
1
meter, using a swept sine
wave.
INSTALLATION
Mountingof the MM2TC is by way of two
13/32’’
holes spaced 5.688” on centers.
A
cable entrance threaded for l/z”-14 I.P.S.
pipe or rigid conduit is provided in the bot
-
tom side of its cork
-
neoprenegasketed
transformer housing.
LOW-FREQUENCY DRIVER PROTECTION
When frequencies below the low
-
frequency
cutoff for the horn assembly are fed
to
the
driver, excessive current may be drawn the
by driver. For protection
of
driver, amplifier,
and transformer (if driver with built
-
in
transformer is used),capacitor(s) in series
with driver, or transformer primary are
recommended.
For drivers without transformers:
16-0hmdriver, 25
V
-
50
mf
150
V
dc or 150
V
non
-
polarizedelectrolytic,
or two 150
V
dc electrolytics of two times
requiredvalue in series, back
to
back, for
70
-
volt lines.
ARCHITECTS’ AND ENGINEERS’
SPECIFICATIONS
The loudspeaker shall be integral driver and
submergence
-
proof speaker with a phenolic
impregnatedlinen
-
base diaphragm and
rugged two
-
inch voice coil.
The axial frequency response will extend
from 800
to
5,000
Hz
and the horn shall
exhibit
a
low
-
frequencycutoff of
600
Hz.
Sound pressure level will be 104 dB
(1
Wl1 M) with an 800
to
5,000
Hz
pink
noise signal applied. Dispersion shall be 82O
at 2 kHz.
The
bell,
reflector, and weatherproof
transformer housing shall be die
-
cast
aluminum and designed
so
that reflector can
be
removedfor easy accessibility and clean
-
ing of diaphragm. Voice-coilldiaphragm
assembly shall be protected by special anti
-
fungicide treatment.
Transformer housing shall be provided for
installationof line
-
matchingtransformer not
to
exceed
5.8
cm (2.25 in.), by 5.8 cm (2.25
in.),by 7.0 cm (2.75 in.). Two 13/32-inch
diameter holes shall be provided for moun
-
ting purposes.
Dimensions shall be 25.4 cm (10.0 in.) high,
by 16.4 cm (6.4 in.) wide, by 11.3cm (4.4
in.) deep. Net weight shall not exceed
4.0
kg
(8.8 Ib).The loudspeaker shall be the
University Sound MM2TC.
WARRANTY
(Limited)
-
University Sound
Speakers and Speaker Systems (excluding
active electronics) are guaranteed for five
years from date of original purchase against
malfunction due
to
defects in workmanship
and materials.
If
such malfunction occurs,
unit will be repairedor replaced (at our
option) without charge for materials or labor
if delivered prepaid to University Sound. Unit
will be returned prepaid.Warranty does not
extend
to
finish, appearance items, burned
coils, or malfunction due
to
abuse or opera
-
tion under other than specified conditions,
includingcone andlor coil damage resulting
from improperly designed enclosures, nor
does it extend
to
incidental or consequential
damages. Some states do not allow the
exclusion or limitation of incidental or
consequential damages,
so
the above exclu
-
sion may not apply
to
you. Repair by other
than University Sound will void this
guarantee. This warranty gives you specific
legal rights, and you may also have other
rights which vary from state
to
state.
Service and repair information for this
product: University Sound, Inc.,
Phone 818l362-9516.FAX 8181367-5292
Applications and technical informationfor
University Sound products:
University Sound, Inc.,Technical
Coordinator,Phone 8181362-9516,
FAX 81
813673292,
Specifications subject
to
change
without notice.
BASICGUIDELINES
FOR
THE USE
OF
HORNSAND DRIVERSWITHINASOUNDSYSTEM.
DESIGNING
FOR
INTELLIGIBILITY AND ADEQUATE SPL
The Basic Idea
Manysoundsystemswould havebetter performance
if
thefollowing basic
principlesarekeptinmind Speakerswiththeappropriatecoveragepatterns
shouldbechosen,aimedandpowered
to
achieveauniformdirectfieldinthe
highlyabsorbtiveaudience,with nosoundaimedatthereflectivewallandceil
-
ing surfaces Where multiple speakers are required in order
to
achieve a
uniformdirectfield,theircoveragepatternsshouldbeonlyslightlyoverlapped,
so
thateachsectionof the audienceiscovered bya singlespeaker To the
extentthis ideal is achieved reverberationis minimizedandintelligibilityis
maximized
Thefollowingmaterialexplainstheseconceptsinmoredetailandillustrates
two designapproaches
What isReverberation?
Reverberationisthepersistenceof soundwithinanenclosure,suchasaroom,
afterthe originalsoundhasceased Reverberationmayalsobeconsidered
asaseriesof multipleechoes
so
closelyspacedintime thatthey mergeinto
asinglecontinuoussound Theseechoesdecreaseinlevelwith successive
reflections,andeventuallyarecompletelyabsorbed by the room
Non
-
Reverberant Environments
Anopen,outdoor space isconsidered
to
beanon
-
reverberantenvironment,
as virtually allsound escapestheareawithoutreflection.
Variations inLevelDueto Distancefor Non
-
Reverberant Environments
Innon
-
reverberantenvironments,suchasoutdoors,soundpressurelevelwill
bereducedbyhalf
(6
dB)everytimethedistanceformthespeakerisdoubled
(thisis calledthe inverse
-
squarelaw).Figure
A
shows thedB losses
to
be
expected as distance from the speaker is increased from the one
-
meter
(3 28
-
foot)measuringdistancetypicallyusedinSPL specifications.
Reverberant Environments
Wheresoundisreflectedfromwallsandothersurfaces,thereisapoint beyond
which the
"
reverberantfield
"
dominatesand the sound pressurelevel is
higherand more constantthan predicted by usingthe inverse
-
squarelaw
alone
Variations inLevelDue
to
Distancefor Reverberant Environments
The reverberantfieldwillbegin
todominatetypicallyatdistancesof
10to30
feet Thisdistanceisgreatestfor the least reverberantroomsandspeakers
withnarrowbeamwidthangles Thefrequencyandbeamwidthspeckations
providedbythe datasheetarestillrequired
to
obtainsatisfactorydistribution
of
thedirectsound(ordirectfield)fromthe loudspeaker(s) whichstillfollows
the inversesquare law
It
is the direct signal that contributes
to
speech
intelligibility This iswhy the sound systemdesignershouldseeka uniform
directfield, withaslittlereverberantfieldas possible Forexample,consider
asinglespeakerwithawidebeamwidthangleused
to
coveralong,narrow
reverberantroom The directfieldwill be
so
far belowthe reverberantfieldat
the backofthe roomthat speechwill probably beunintelligible
Calculating Variations inLevelDue
to
ChangesinElectricalPower
Eachtimethe powerdelivered
to
the speakerisreducedbyone
-
half,alevel
dropof3dBoccurs Thenomographof
FigureBshowsthethechangein
dB
to
beexpectedas the powervariesfromtheone
-
wattinputtypicallyusedin
SPL specifications
Power Handling
Thepowerratingof aspeakermustbeknown
to
determinewhetheradesign
iscapable of meetingthe soundpressurelevelrequirementsof the system
Thepowerratingcombinedwiththesensitivitywill enableasystemdesigner
tocalculatethemaximumsoundpressurelevelattainableatagivendistance
DISTANCE
FROM
CHANGE
IN
SPEAKE:IH;
4
(dB)
M
f25
lmm
::$a
M
M
3+m
FIGURE
A
FIGUREB
LevelVariation LevelVariation
WithDistance WithPower
PoweringtoAchieve BothAverage andPeakSPL
Theaveragepower that must bedelivered
to
the speaker@)
to
achievethe
desired average SPL can be determined from the previously presented
materialonspeaker sensitivity, levelvariationwithdistanceand levelvaria
-
tion with power. Enoughadditionalpower must beavailable
to
reproduce
withoutdistortiontheshort
-
termpeaksthatexist invoiceandmusic program.
Thisdifferencebetweenthepeakandaveragecapabilityof asoundsystem,
whenexpressedindB,isoftencalled
"
peak
-
to
-
averageratio,
""
crestfactor
"
or
"
headroom.
"
The peakscanbelarge,as notedearlier:at least
10
times
theaverage
(1
0
dB).
Thebettersoundsystemsare designedfor peaksthat are
10
dBabovethe
average,although
6
dBof headroomissufficientfor most general
-
purpose
voicepagingsystems The
1
0-dBpeaksrequireamplifier powertentimesthat
requiredfortheaveragesound levels The6
-
dBpeaksrequirefourtimesthe
power.
Utilizing Speaker BeamwidthInformationfor Maximum Intelligibility
Knowingthebeamwidthangle
of
aloudspeakercanaidinprovidingaunlorm
directfieldinthe listeningarea After selectingadesiredspeaker location,the
beamwidthangle needed
to
adequatelycover the listenerswithoutspilling
over
to
the walls or ceilings must be determined Once these angles are
known thecorrect speaker can befound by usingcatalogspecifications
UsingEasy
-
VAMP
TM
andFloor
-
PlanIsobars
Insomecircumstances
d
isdesirable
to
useanapproachthat ismoredetailed
thanusingthe basichorizontalandvertical beamwidthangles Environments
which have excessive reverberationor high ambient noise levels make
it
especially difficult
to
achievethe desired
SPL
and intelligibility
In recent years a number of computer based techniques have been
developed
to
help sound system designers Some of the more complex
systems use personal computers with relatively sophisticatedgraphics
Simplersystems,suchas ElectroVoice
s
VAMP
TM
(VeryAccurateMapping
Program) utilize clear overlays and require programmable scientific
calculators However,the hardwareisoftwareandtraininginvestmentrequired
to
utilizeeventhesimpler systemsarenotattractivetosomesoundsystems
designers Because of this University Sound has developed a special
adaptationof VAMP,calledEasy VAMP
TM
whichprovidesasimilardesign
aidwithout the complexityandcostof the VAMP programs
More information
on
boththe Easy VAMP
TM
and floor planisobarscan be
found inthe UniversitySoundGuide
Part Number
531291
-
923
Litho
in
U.S.A
US
42
-
02
-
0261
17
Other University Sound Speakers manuals
