Furman SP-20A User manual

STEREO POWERAMPLIFIER
Furman Sound, Inc.
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1997 South McDowell Blvd.
●
Petaluma, CA 94954 USA
Phone: [phone]
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Fax: [phone]
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Web: http://www.furmansound.com
MODEL SP-20A
FEATURES
●20 watts per channel in stereo mode
●Toroidal transformer for ultra-quiet performance
●May be bridged for 40 watt mono operation
(requires load of 8 or more ohms)
●Front panel headphone jack with volume control
●Ideal for small speakers or headphone system
●Speaker on-off switch
●Overload and signal-present LED’s for each channel
●Power-on indicator
●Ground lift switch
●Provision for remotely located headphone volume controls
DESCRIPTION
The SP-20A Stereo Power Amplifier is a unique and
economical 20 watt per channel stereo amplifier. Its toroidal
transformer delivers ultra-quiet performance, making it ideal for
recording studio applications. The SP-20A may be operated in
any of three modes as selected by a rear-panel switch: normal
stereo, two channel mono, or single channel (bridged) mono.
The latter mode allows a power output of 40 watts provided the
load is 8 or more ohms.
The SP-20A is housed in a compact, half rack chassis,
allowing it to be mounted either alone or side by side with other
SP-20A’s in a 19" rack. Mounting kits are available from
Furman.
The SP-20A’s small size makes it ideal for modular use in
large commercial installations with multiple small speakers. Its
power capacity is also just right for driving the small “cube”
reference speakers used in most recording studios as a
comparison with the main control room monitors — it can
power them without overpowering them.
The SP-20A’s output is available through either of two
connectors: standard banana jack binding posts for speakers,
or through a male XLR connector. The latter allows the unit to
become a headphone driver, linking any number of Furman HR-2
Headphone Remote Stations together via standard microphone
cables. Each HR-2 station conveniently clips to a mic stand and
provides individual volume controls for two sets of headphones.
When used for overdubbing or rehearsal, this setup provides
plenty of loudness in any kind of headphones (even older low-
impedance models), and allows each musician to set his or her
own comfortable volume level. When the overdubbing is complete
and the musicians remove their headphones, the SP-20A can also
power the tape playback speakers through the banana jacks. The
output — headphone chain or speakers — is selected by pressing
a front panel pushbutton.An additional headset may be plugged
directly into the SP-20A’s front panel. A volume control is provided
for it.
The SP-20A has a convenient input level control on the left
side of the front panel. A pair of yellow LED’s — one for each
channel — light up whenever signal is present (threshold -28
dBu).Another pair of red LED’s show an overload condition in
either channel. The SP-20Ais fully protected against thermal
overload, and it can withstand a short circuit on any or all outputs
for an indefinite time without damage.
OPTIONS
●Model SP-20AB: Provides balanced inputs with XLR
connectors in place of 1/4" phone inputs.
●Rack Mounting Kits: Adaptor kits for mounting one SP-20A
centered in a 19" rack (HRKIT-1), or two SP-20A’s side by
side in a 19" rack (HRKIT-2).
●Accessory: Model HR-2 Headphone Remote Station: An
inexpensive, compact, unobtrusive box that attaches to a
mike stand or belt, providing two headphone jacks, each
with its own volume control. Any number of HR-2 stations
may be daisy-chained to an SP-20A using standard
microphone cables. Comes with snap-on, snap-off mike
stand clamp. (See picture on other side.)
®

SP-20AB RearView
ThreeYear Warranty
The Furman SP-20A is protected by a three year limited
warranty covering defects in materials and workmanship.
LEFT RIGHT
SPEAKERS
MONO
STEREO
BRIDGED
USE FOR BRIDGED
SATELLITE / REMOTE
LEFT / MONO INPUT
RIGHT INPUT
120 VAC
60 Hz
130 Watts
ON OFF LIFT
GND
Architects and Engineers Specifications
The Stereo Power Amplifier shall mount in a standard 19"
rack, and shall occupy no more than half of one rack unit (1 3/4")
of rack space. It shall conform to the HR specification, allowing it
to be mounted side by side with other HR units. It shall be of
stereo design but shall be capable of being bridged for mono
operation. There shall be LED indicators for Signal Present and
Overload conditions in each stereo channel. A headphone output
shall be provided and have its own volume control. Provision
shall be made for extending the number of headphones
accommodated by means of accessory Remote Stations, which
shall connect to the unit in daisy-chain fashion using standard
microphone cords.
Connections to speakers shall be via dual banana/binding
post terminals. An XLR connector shall be provided for
connection to Remote Stations. Power output shall be at least 20
watts per channel, into either 4 or 8 ohms, from 20 Hz to 20 KHz.
Distortion shall be .01% THD or less at full rated power at 1KHz,
and not more than .05% from 20 Hz to 20 KHz. The noise level
shall be at least 99 dB below full rated output. The unit shall be
protected against thermal overload, and shall be able to
withstand a short circuit on either or both outputs for an indefinite
time without damage. A switch shall be provided to select mono
(left input routed to both channels), normal stereo, or bridged
(left input drives a single load of 8 or more ohms to at least 40
watts) operation. The unit shall be internally fused, and shall
have a Ground Lift switch capable of isolating the signal ground
from the chassis. There shall also be an on/off switch with a
power-on indicator. Inputs shall be equipped with 1/4" phone
jacks, and XLR balanced inputs shall be optionally available.
Versions shall be available for 120 VAC, 60 Hz or 230 VAC, 50/60
Hz power.
The unit shall be the Furman SP-20A Stereo Power
Amplifier.
HR-2 Headphone Remote Box
AVAILABLE FROM:
SP-20A SPECIFICATIONS
OUTPUTS: Power: 20 watts per channel, stereo, into either 4 ohms or 8 ohms, or 40 watts mono into 8 ohms, 20 Hz to 20 KHz.
Connectors: Speakers: 5-way binding posts (accommodates dual banana plugs, spade lugs, bare wires, etc.) Remote
Headphone: XLR.
INPUTS: Input Impedance: 20K ohms.
Sensitivity: -1.9 dBu (625 mV) required for full output into 8 ohms.
Connectors: SP-20A, 1/4" phone, unbalanced; SP-20AB, XLR, balanced.
GENERAL: Distortion: .01% THD at full rated power at 1 KHz; .05% THD 20 Hz to 20 KHz.
Dynamic Range: Greater than 99 dB
Frequency Response: +0, -1 dB from 20 Hz to 20 KHz, 1 watt output.
Dynamic Headroom: 2 dB, stereo, measured with 10 ms toneburst at 1 KHz, 1% duty cycle.
Damping Factor: 120 at 1KHz.
Slew Rate: 20 V/µSec.
Power Requirement: 120 VAC, 60 Hz, 130 watts
Mechanical: Dimensions: 1.75" H x 8.45" W x 8.25" D. Weight: 6 lbs (2.7 kg).
NOTE: 0 dBu equals .775 Vrms.
The SP-20A is manufactured in the United States of America. 2-9733