ST15 ST15
■
■
1.
2.
3.
4.
5.
■
●
■
1.
2.
1 2
■
■
■
Audio Products Sales and Marketing Division, Yamaha Corporation
Nakazawa-cho 10-1, Naka-ku, Hamamatsu, Japan 430-8650
Yamaha Pro Audio global web site: Yamaha Manual Library:
http://www.yamahaproaudio.com/ http://www.yamaha.co.jp/manual/
ST15
BLU
BLK100VPri. WHT
670Ω
YELORNBRWWHT
Sec. COM. 2Ω 4Ω 6Ω 8Ω
Thank you for purchasing the Yamaha ST15 Speaker Transformer.
This device is a matching transformer that is used for the parallel
connection of low impedance speakers to a high impedance type
distribution power amplifier.
Please read this manual carefully to get the most out of the ST15 and use
in a safe manner.
■ Outline
This device has a capacity of 15 W, the line output of the power
amplifier connected to the primary pole is assumed to be 100 V
(using a 70 V line is also possible).
The blue, yellow, orange and brown secondary cords each
correspond to speakers whose nominal impedance is 8, 6, 4 and 2Ω,
while the input impedance of the connected power amplifier is 670.
■ Connection
1. Turn the power switch OFF on the power amplifier you are
going to connect the ST15 to.
2. Use two 4 mm (1/8") tapping screws, securely attach the unit to
a speaker or some other convenient location.
3. Connect the ST15’s white primary cord to the power amplifier’s
100 V or 70 V negative (–) pole, connect the black cord to the
power amplifier’s 100 V or 70 V positive (+) pole.
4.
Connect the white secondary cord to the speaker’s negative (–)
pole. From the blue (8), yellow (6), orange (4) and brown
(2) cords, choose a cord that matches the speaker’s impedance
and connect the selected cord to speaker’s positive (+) pole.
5. Bundle together the unused secondary cords to prevent shot
circuits, etc.
■ Advanced Applications
Connecting Speakers of Different Impedance
An 8 speaker can be connected to the lower impenitence yellow
(6), orange (4) cords however, low impedance speakers
cannot be connected to higher impedance cords. The capacity will
be exceeded creating a hazard.
When connecting speakers of different impedance, refer to the
following chart. Please use caution when in such applications
since speaker input dB and the input impedance will change.
● 100 V Line Connections
● 70 V Line Connections
■ Limitations for Parallel Use
Depending upon the manner in which this device is used, the
connection of multiple speakers is possible however; the number
of speakers will be limited according to the power amplifier’s
specifications.
1. The total input for the speakers that are being used should not
exceed the power amplifier’s maximum output.
When the line output transformer is used, its capacity should
not be exceeded.
2. The total input impedance for the speakers that are being used
should not be less than the minimum load impedance of the
power amplifier, including the line output transformer.
The ST15 can be used in this manner as long as both conditions
1 and 2 are met.
■ Specifications
The contents of this manual apply to the latest specifications as of the
printing date. Since Yamaha makes continuous improvements to the product,
this manual may not apply to the specifications of your particular product.
To obtain the latest manual, access the Yamaha website then download the
manual file. Since specifications, equipment or separately sold accessories
may not be the same in every locale, please check with your Yamaha dealer.
* Color Chart
■ Wiring Diagram
■ Dimensions
8Ω Speaker Input
Impedance
6Ω Speaker Input
Impedance
4Ω Speaker Input
Impedance
Blue 15 W 670 × ×
Yellow 11.3 W 890 15 W 670 ×
Orange 7.5 W 1330 10 W 1000 15 W 670
Brown 3.8 W 2670 5 W 2000 7.5 W 1330
8Ω Speaker Input
Impedance
6Ω Speaker Input
Impedance
4Ω Speaker Input
Impedance
Blue 7.5W 670 × ×
Yellow 5.65W 890 7.5W 670 ×
Orange 3.75W 1330 5W 1000 7.5W 670
Brown 1.9W 2670 2.5W 2000 3.75W 1330
Capacity 15 W Continuous
Frequency Response 50 Hz–20 kHz
Total Harmonic Distortion ≤ 1% (1 kHz, 15 W)
Insertion Loss ≤1.5dB
Dimensions (W × H × D)
80 × 48 × 46 mm
(3-1/8" × 1-7/8" × 1-13/16")
Weight 450 g (15.8 oz)
Coil Ratio Primary: Secondary Secondary Voltage Ratio
*BLU 1:0.110 0 dB
*YEL 1:0.095 –1.25 dB
*ORN 1:0.077 –3.0 dB
*BRW 1:0.055 –6.0 dB
BLU: Blue YEL: Yellow ORN: Orange
BRW: Brown WHT: White BLK: Black
Primary
Secondary
100 V Line
or
70 V Line
BLK
WHT
BLU
YEL
ORN
BRW
7.5 W
7.5 W
7.5 W
7.5 W
Speaker (Common)
WHT
100 V Line
or
70 V Line
ST15
Primary
Secondary
Power Amplifier
Speaker
(70 V Line)(100 V Line)
15 W
15 W
15 W
15 W
8
6
4
2
Power Amplifier’s
[SPEAKERS]
+ terminal
Power Amplifier’s
[SPEAKERS]
– terminal
BLU
BLK100VPri. WHT
670Ω
YELORNBRWWHT
Sec. COM. 2Ω 4Ω 6Ω 8Ω
48 mm (1-7/8")
2 - ø4.5×6.5 mm
46 mm (1-13/16")
BLK
WHT
BLU
YEL
ORN
BRW
WHT
80 mm(3-1/8")
69 mm (2-11/16")
56.5 mm (2-1/4")
(2 - ø3/16"×1/4")
SPEAKER
TRANSFORMER
OWNER’S MANUAL
SPEAKER
TRANSFORMER
Manual Development Department
© 1992 Yamaha Corporation
Published 12/2014 IP-C0
Printed in Japan
ENJA
/