Yamaha NS-615B User manual

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The NS-615B has been designed in accordance
with Yamaha Audio’s policy of accurately and
naturally reproducing not just “sound,” but
"music." Its directivity characteristics are especial-
ly superior, and at 96 dB/1 m output the distor-
tion rate is very low — less than 1% over 100 Hz.
A woofer with a large diameter voice coil, a
tweeter with unique tangential edge support and
an enclosure benefitting from Yamaha's genera-
tions of woodworking experience all add up to
a compact, high performance, high power handling
capacity unit.
Enjoy the natural sound of all types of music
to your heart's content with the stylishly com-
pact NS-615B.
m j FA Û Ht
The NS-6158 grille is removable.
To remove the grille, first grasp it at the bottom
on both sides and gently pull it away from the
cabinet. Once it is loose, continue by removing
the upper part.
During removal, be careful not to damage the
attachment parts.
The output terminals on your amplifier can take
several different shapes. Be sure to check the
amplifier owner's manual for proper connection
procedures.
The higher the amplifier's maximum output power
capacity, the. more it is capable of providing
low-distortion music response. However, if your
amplifier is capable of producing power in excess
of the NS-615B maximum input capacity it is
important that this maximum capacity should not
be exceeded. In general, when an amplifier vol-
ume control is set at its mid-point the amplifier
is producing approximately 70% of its maximum
output capacity.
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Connect the speaker output terminals on the
amplifier to the terminals on the rear of the NS-
615B using the connector cords provided. At this
time be sure the amplifier power is switched off.
The connection terminals on the rear of the NS-
615B are push-spring types, as shown in the
illustration.
Connect the left speaker to the amplifier left-
channel output terminals, the right to the right.
In each case be sure to observe the proper plus-
minus polarity. If the polarity is different for
the speakers, stereo response and tonal clarity
will be affected. The side of the cord with the
silver line is plus (+), the other side minus (—).
* The NS-615B impedance is 8 ohms. When con-
necting to a transistor amplifier, it is not neces-
sary to worry about terminal impedance; simply
connect to the output terminals on the amplifier.
If you are using a tube-type amplifier, however,
be sure that only 8 ohm terminals are used.
Connect the red terminal to plus terminal of the am-
plifier, also the black terminal to minus terminal.
Push the lever on the bottom of the terminal, and
insert the stripped end of the wire into the hole
while holding the lever down. Then release the lever
to fix the wire.
To Plus Terminal
Û
To
Minus
Terminal
SFEARER LOCATII
Your speaker performance depends to a great
extent upon the conditions of your listening
room. To derive maximum listening pleasure from
your NS-615B system, be sure to follow the points
below.
4
By placing the speaker so that the tweeter is at
the height at which you normally listen (for
example, on a solid shelf or bookcase), you can
obtain a natural concert hall feeling.
Placing the speakers directly on the floor or on
the carpet will impair the bass response, there-
fore they should be placed on heavy, solid stands.
Ideally, left and right speakers should be separated
by a distance of 1.5 — 2 meters. If they are
placed too close together there will be a reduc-
tion in the stereo effect. Conversely, if placed
too far apart, the so-called “middle omission”
effect will occur and the sound will become
skimpy.
The wall behind the speakers should have a live
(reflecting) surface (a polished surface is best),
while the wall behind the listener should have
a sound-absorbing surface. This is the optimum
condition for best sound reproduction.
If the wall behind the listener is made of con-
crete or has a glass window, thick curtains should
be hung to absorb the sound. This will allow
you to listen to natural sound without reverbera-
tion or other unnecessary distortion. |
Experiment with different locations to make sure
that the balance of walls, carpet, etc. provides
optimum bass, midrange and treble response while
listening.

Be careful where you place your turntable. If it
is on the same support as the speakers, or directly
in front of them, howling can occur.
Avoid locations where the speaker cabinet is
exposed to direct sunlight or high temperatures.
5
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w
€
The NS-615BEB rated input is 25W, maximum input
capacity is 50W. The following precautions should
be observed with regard to input power.
1. Rated Input
This value is the maximum average input pos-
sible for long listening with optimum, fatigue-
free music response. - |
2. Maximum Input Capacity
The input can rise to this value for short
periods. in any program source there are peak
values which can rise to dynamic levels as
high as ten times that of the average level of
the source material. However, these peaks
should not exceed a level of two times the
rated input. Dynamic passages should be regu-
lated using level meters to be sure this maxi-
mum is not exceeded.
3. Operation Precautions
Be very careful not to exceed the RATED
input in any of the following cases:
When the tone controls on your preamp or
pre/main amplifier are set to maximum (bass
or treble). When a special signal (created by
fast winding or rewinding magnetic tape, by
the shock noise when the turntable needle is
bumped, or when the power is switched on,
or by signals or sine waves from a signal
generator) is fed through the speakers.
# E
Frequency Response and Harmonic Distortion Charac-
teristics (Imput 6V, Measured at 1m)
10 20 Hz 50 100 200 500 1k 2k 5k 10k 20k 40k
DET.
too boi qu
10k 20k 40k
Type 2-way acoustic suspension
Woofer JA-1801 180mmó cone
type
Tweeter JA-0518 38mmó soft
dome type
2 kHz (12 dB/Oct)
Crossover frequency
Fundamental reso-
nance frequency
Impedance
Directional characteristics
(Horizontal Plane)
p
Output sound
pressure level
Rated input capacity
Maximum input capacity
Frequency response
96 dB at 1m 4 Watt Input
25W E
50W
60 Hz — 20,000 Hz
(+4 — — 8dB)
Dimensions (HxWxD)
Weight
382 x 215 x 199 mm
(15" x 8-1/2" x 7-13/16")
6.0 kg (13 Ibs 4 oz)
Specifications subject to change without notice,

SINCE 1887
YAMAHA
NIPPON GAKKI „ HAMAMATSU, JAPAN
Printed in Japan 77Y@