<s>
Thiele/Small	B-Device
parameters	I-Device
(	O
commonly	O
abbreviated	O
T/S	B-Device
parameters	I-Device
,	O
or	O
TSP	O
)	O
are	O
a	O
set	O
of	O
electromechanical	O
parameters	O
that	O
define	O
the	O
specified	O
low	O
frequency	O
performance	O
of	O
a	O
loudspeaker	O
driver	O
.	O
</s>
<s>
Using	O
these	O
parameters	O
,	O
a	O
loudspeaker	O
designer	O
may	O
simulate	O
the	O
position	O
,	O
velocity	O
and	O
acceleration	O
of	O
the	O
diaphragm	O
,	O
the	O
input	B-Architecture
impedance	I-Architecture
and	O
the	O
sound	O
output	O
of	O
a	O
system	O
comprising	O
a	O
loudspeaker	O
and	O
enclosure	B-Device
.	O
</s>
<s>
Thiele/Small	B-Device
parameters	I-Device
are	O
named	O
after	O
A	O
.	O
Neville	O
Thiele	O
of	O
the	O
Australian	O
Broadcasting	O
Commission	O
,	O
and	O
Richard	O
H	O
.	O
Small	O
of	O
the	O
University	O
of	O
Sydney	O
,	O
who	O
pioneered	O
this	O
line	O
of	O
analysis	O
for	O
loudspeakers	O
.	O
</s>
<s>
A	O
common	O
use	O
of	O
Thiele/Small	B-Device
parameters	I-Device
is	O
in	O
designing	O
PA	O
system	O
and	O
hi-fi	O
speaker	B-Device
enclosures	I-Device
;	O
the	O
TSP	O
calculations	O
indicate	O
to	O
the	O
speaker	O
design	O
professionals	O
how	O
large	O
a	O
speaker	B-Device
cabinet	I-Device
will	O
need	O
to	O
be	O
and	O
how	O
large	O
and	O
long	O
the	O
bass	O
reflex	O
port	O
(	O
if	O
it	O
is	O
used	O
)	O
should	O
be	O
.	O
</s>
<s>
1869178	O
)	O
his	O
"	O
Sound	O
Translating	O
Device	O
"	O
(	O
essentially	O
a	O
vented	O
box	O
)	O
which	O
was	O
evidence	O
of	O
the	O
interest	O
in	O
many	O
types	O
of	O
enclosure	B-Device
design	O
at	O
the	O
time	O
.	O
</s>
<s>
Progress	O
on	O
loudspeaker	B-Device
enclosure	I-Device
design	O
and	O
analysis	O
using	O
acoustic	O
analogous	O
circuits	O
by	O
academic	O
acousticians	O
like	O
Harry	O
F	O
.	O
Olson	O
continued	O
until	O
1954	O
when	O
Leo	O
L	O
.	O
Beranek	O
of	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
published	O
Acoustics	O
,	O
a	O
book	O
summarizing	O
and	O
extending	O
the	O
electroacoustics	O
of	O
the	O
era	O
.	O
</s>
<s>
In	O
1961	O
,	O
leaning	O
heavily	O
on	O
Novak	O
's	O
work	O
,	O
A	O
.	O
N	O
.	O
Thiele	O
described	O
a	O
series	O
of	O
sealed	O
and	O
vented	O
box	O
"	O
alignments	O
"	O
(	O
i.e.	O
,	O
enclosure	B-Device
designs	O
based	O
on	O
electrical	O
filter	O
theory	O
with	O
well-characterized	O
behavior	O
,	O
including	O
frequency	O
response	O
,	O
power	O
handling	O
,	O
cone	O
excursion	O
,	O
etc	O
.	O
)	O
</s>
<s>
It	O
is	O
important	O
to	O
note	O
that	O
Thiele	O
's	O
work	O
neglected	O
enclosure	B-Device
losses	O
and	O
,	O
although	O
the	O
application	O
of	O
filter	O
theory	O
is	O
still	O
important	O
,	O
his	O
alignment	O
tables	O
now	O
have	O
little	O
real-world	O
utility	O
due	O
to	O
neglecting	O
enclosure	B-Device
losses	O
.	O
</s>
<s>
Many	O
others	O
continued	O
to	O
develop	O
various	O
aspects	O
of	O
loudspeaker	B-Device
enclosure	I-Device
design	O
in	O
the	O
1960s	O
and	O
early	O
1970s	O
.	O
</s>
<s>
From	O
1968	O
to	O
1972	O
,	O
J	O
.	O
E	O
.	O
Benson	O
published	O
three	O
articles	O
in	O
an	O
Australian	O
journal	O
that	O
thoroughly	O
analyzed	O
sealed	O
,	O
vented	O
and	O
passive	B-Architecture
radiator	I-Architecture
designs	O
,	O
all	O
using	O
the	O
same	O
basic	O
model	O
,	O
which	O
included	O
the	O
effects	O
of	O
enclosure	B-Device
,	O
leakage	O
and	O
port	O
losses	O
.	O
</s>
<s>
Small	O
also	O
analyzed	O
the	O
systems	O
including	O
enclosure	B-Device
losses	O
.	O
</s>
<s>
These	O
values	O
can	O
be	O
determined	O
by	O
measuring	O
the	O
input	B-Architecture
impedance	I-Architecture
of	O
the	O
driver	O
,	O
near	O
the	O
resonance	O
frequency	O
,	O
at	O
small	O
input	O
levels	O
for	O
which	O
the	O
mechanical	O
behavior	O
of	O
the	O
driver	O
is	O
effectively	O
linear	O
(	O
i.e.	O
,	O
proportional	O
to	O
its	O
input	O
)	O
.	O
</s>
<s>
In	O
addition	O
,	O
power	B-Architecture
compression	I-Architecture
,	O
thermal	O
,	O
and	O
mechanical	O
effects	O
due	O
to	O
high	O
signal	O
levels	O
(	O
e.g.	O
,	O
high	O
electric	O
current	O
and	O
voltage	O
,	O
extended	O
mechanical	O
motion	O
,	O
and	O
so	O
on	O
)	O
all	O
change	O
driver	O
behavior	O
,	O
often	O
increasing	O
distortion	O
of	O
several	O
kinds	O
.	O
</s>
<s>
A	O
common	O
rule	O
of	O
thumb	O
indicates	O
that	O
for	O
,	O
a	O
driver	O
is	O
perhaps	O
best	O
used	O
in	O
a	O
vented	O
enclosure	B-Device
,	O
while	O
indicates	O
a	O
sealed	O
enclosure	B-Device
.	O
</s>
<s>
For	O
,	O
either	O
enclosure	B-Device
may	O
be	O
used	O
effectively	O
.	O
</s>
<s>
Actual	O
mechanical	O
power	O
handling	O
depends	O
greatly	O
on	O
the	O
enclosure	B-Device
in	O
which	O
the	O
driver	O
is	O
installed	O
.	O
</s>
<s>
Some	O
caution	O
is	O
required	O
when	O
using	O
and	O
interpreting	O
T/S	B-Device
parameters	I-Device
.	O
</s>
<s>
It	O
is	O
also	O
important	O
to	O
understand	O
that	O
most	O
T/S	B-Device
parameters	I-Device
are	O
linearized	O
small	O
signal	O
values	O
.	O
</s>
<s>
From	O
this	O
example	O
,	O
it	O
is	O
seen	O
that	O
the	O
measurements	O
to	O
be	O
preferred	O
while	O
designing	O
an	O
enclosure	B-Device
or	O
system	O
are	O
those	O
likely	O
to	O
represent	O
typical	O
operating	O
conditions	O
.	O
</s>
<s>
Level	O
shifts	O
caused	O
by	O
resistive	O
heating	O
of	O
the	O
voice	O
coil	O
are	O
termed	O
power	B-Architecture
compression	I-Architecture
.	O
</s>
<s>
Design	O
techniques	O
which	O
reduce	O
nonlinearities	O
may	O
also	O
reduce	O
power	B-Architecture
compression	I-Architecture
,	O
and	O
possibly	O
distortions	O
not	O
caused	O
by	O
power	B-Architecture
compression	I-Architecture
.	O
</s>
<s>
There	O
have	O
been	O
several	O
commercial	O
designs	O
that	O
have	O
included	O
cooling	O
arrangements	O
for	O
driver	O
magnetic	O
structures	O
,	O
which	O
are	O
intended	O
to	O
mitigate	O
voice	O
coil	O
temperature	O
rise	O
,	O
and	O
the	O
attendant	O
rise	O
in	O
resistance	O
that	O
is	O
the	O
cause	O
of	O
the	O
power	B-Architecture
compression	I-Architecture
.	O
</s>
<s>
Several	O
studies	O
have	O
been	O
published	O
documenting	O
substantial	O
changes	O
in	O
the	O
T/S	B-Device
parameters	I-Device
over	O
the	O
first	O
few	O
hours	O
of	O
use	O
,	O
some	O
parameters	O
changing	O
by	O
as	O
much	O
as	O
15%	O
or	O
more	O
over	O
these	O
initial	O
periods	O
.	O
</s>
<s>
If	O
the	O
performance	O
of	O
speaker	O
system	O
is	O
critical	O
,	O
as	O
with	O
high	O
order	O
(	O
complex	O
)	O
or	O
heavily	O
equalized	O
systems	O
,	O
it	O
is	O
sensible	O
to	O
measure	O
T/S	B-Device
parameters	I-Device
after	O
a	O
period	O
of	O
run-in	O
(	O
some	O
hours	O
,	O
typically	O
,	O
using	O
program	O
material	O
)	O
,	O
and	O
to	O
model	O
the	O
effects	O
of	O
normal	O
parameter	O
changes	O
on	O
driver	O
performance	O
.	O
</s>
<s>
There	O
are	O
numerous	O
methods	O
to	O
measure	O
Thiele-Small	B-Device
parameters	I-Device
,	O
but	O
the	O
simplest	O
use	O
the	O
input	B-Architecture
impedance	I-Architecture
of	O
the	O
driver	O
,	O
measured	O
near	O
resonance	O
.	O
</s>
