DaytonAudio SA25 User manual

25W SUBWOOFER
PLATE AMPLIFIER
Model: SA25 User Manual

(2)
Thank you for purchasing the SA25 Subwoofer Plate Amplifier. It has been designed and built to provide
years of high quality sound reproduction, and is ideal for use in compact subwoofers for home stereo, home
theater, and multimedia audio systems. Engineering features of this amplifier include a choice of high or
low level audio connections, selectable crossover frequency, and comprehensive internal protection against
shorted speaker loads, thermal faults, and overload conditions.
FEATURES:
• Line-level and speaker-level inputs for connection to any system
• Full complement of protection circuits for high reliability
• Variable frequency 4th order low-pass crossover for a clean transition to main speakers
• Robust LM1875 IC-based Class AB topology
• Continuous-on feature eliminates turn-on thumps and delays

(3)
INPUT/OUTPUT CONNECTIONS
1.) Low-Level Inputs (Left/Right)
RCA style jacks that will accept standard line level inputs from a pre-amp level source. They will accept a stereo signal
and internally combine it into mono. (Note: Both left and right input jacks must be connected to the source in order to
drive the amplifier to full output).
2.) High-Level Inputs
Speaker level inputs using spring clip type jacks to permit connection with bare wire. Allows the user to connect the
speaker level output of a full range amplifier to the input of the subwoofer amp using standard speaker wire. A mono
signal is derived from the stereo input, which then feeds the subwoofer amplifier crossover input.
3.) High-Level Outputs
Speaker level passthrough outputs using spring clip type jacks to permit connection with bare wire. Used to connect
from the subwoofer amp to pass signal from the full range amp on to the main L/R speakers. Signal is only present on
this output if the high level input is also used. The signal to the L/R speakers is not filtered. The impedance “seen” by
the full-range source amplifier will be that of the connected speakers only.
4.) Power input
This unit features a hardwired AC power cable and externally-accessible fuse. It is supplied with an 0.75 A, 250V fuse
and USA type polarized 2-pin plug. This unit is not suitable for 230V applications.
CONTROLS/INDICATORS
5.) Power/Gain Knob (“Gain”)
This control will match the amplifier’s input sensitivity to the output of the pre-amp source. If the source output has a
variable control, we recommend that the user spend a moment or two determining the best balance between the two
controls. When a balance is found between low noise, linear level control, and sufficient level to drive the amp to the
required output, the gain knob can be considered to be the “volume control” for the subwoofer system. To shut the
subwoofer amplifier off, turn the control all the way to the left until it ‘clicks’.
6.) Frequency Knob (“Freq”)
This control is used to establish the highest frequency that the subwoofer will reproduce and has a range between 60
to 180 Hz with a slope of 24 dB per octave. If you are using the system for music and your main speakers have good
bass capability, you could set the control to a fairly low value, often between 60 and 100 Hz. If the main speakers are
smaller or do not have much bass output, set the control higher. Experiment with the amount of “overlap” that you will
experience when all speakers are playing in the same range. This can be helpful when integrating the subwoofer with
the rest of the system and with the room. Note: When using the amp with a LFE (Low Frequency Effects) output on
a pre-amp or home theatre receiver the internal low pass filter circuitry should be bypassed by turning the frequency
control to maximum (180 Hz). The home theater receiver should be used to control the low pass crossover frequency.
7.) Power LED
When the power switch is moved to the “on” position, the LED will illuminate green, and the amp will be in “On” mode. If
the LED is not illuminated, check that the amplifier is plugged into a power source and that the “Gain” knob is not set to
the “Off” position.
8.) Output Lead for Subwoofer Driver:
This rear mounted output lead connects the amplifier to the subwoofer driver. The output lead is roughly 20" long and
is color coded. The red wire uses an insulated .250" quick disconnect and the black wire uses an insulated .205" quick
disconnect. These connectors can be easily removed if your driver requires another size or type of connector. Be sure
to observe proper polarity when connecting the amplifier to your subwoofer driver (red = positive, black = negative).

SPECIFICATIONS:
NOTES ABOUT HUM:
While the SA25 has been designed to minimize the possibility of hum in the subwoofer system, it is still possible that
a hum will occur in rare circumstances. Its safety grounding can create a path for small amounts of 60 Hz energy to
travel through the line-level audio system. While not dangerous, this energy can cause difficulty with the subwoofer auto
signal sensing circuit, and at the very least will interfere with the quiet enjoyment of your system. The first course of ac-
tion should be trying to make sure that all of the audio components are connected to either the same electrical outlet, or
at least into the same circuit branch. Next, cable TV systems are notoriously the culprit, so be sure to try disconnecting
all coaxial feeds that are connected to the system. If this solves the problem, install a coaxial line isolator and recon-
nect the system. In the very worst case, a line-level audio isolator/transformer connected to the line-in of the subwoofer
amplifier will usually solve the problem.
Rated Power Output: 15 watts RMS into 8 ohms @ 0.1% THD
25 watts RMS into 4 ohms @ 0.2% THD
Signal to Noise Ratio: 90 dB A-weighted
Input Impedance: 10.4K ohms
Low Pass Adjustment: 60 Hz – 180 Hz
Dimensions: 6-5/16" W x 6-5/16" H x 2-9/16” D
Enclosure Cutout: 5-1/4” x 5-1/4”
Power Requirements: 120 VAC, 60 Hz, 48W
Stand-By Power Rating: N/A
Weight: 2.50 lbs.
(4)
IMPORTANT SAFETY INSTRUCTIONS
Read these instructions – All the safety and operating instructions should be read before this product is operated.
Keep these instructions – The safety and operating instructions should be retained for future reference.
To reduce the risk of electric shock, do not remove cover. No user serviceable parts inside. The unit should be connected to an earth grounded AC electri-
cal socket. Do not defeat the safety purpose of the polarized or grounding plug. If the provided plug does not fit into your outlet, consult an electrician for
replacement of the obsolete outlet. Refer servicing to qualified personnel. To reduce the risk of fire and shock do not expose unit to rain or moisture. Clean
only with dry cloth. Unplug the unit during lightning storms or when unused for long periods of time.
The unit should be operated in a well ventilated area. Minimum clearance is 2 inches from the ventilation openings. Do not install near any heat sources such
as radiators, heat registers, stoves, or other apparatus (including amplifiers) that produce heat. Protect the power cord from being walked on or pinched,
particularly at the plugs, convenience receptacles, and at the point where they exit the unit. Only use attachments/accessories specified by the manufacturer.
© Dayton Audio®Last Revised: 3/20/2015
Note: Unit is set at the factory for 115V operation. Unit may not be adjusted or modified for 230V operation.
daytonaudio.com
tel + 937.743.8248
[e-mail]
705 Pleasant Valley Dr.
Springboro, OH 45066
USA
Warranty Information
Dayton Audio products are warranted free from defects in material and workmanship for 5 years from date of purchase. 1 year warranty applies to the
following products: powered subwoofers and electronic devices (e.g. subwoofer amplifiers, and plate amplifiers, as well as the Omnimic V2 and DATS
loudspeaker testing devices). In the rare case of a product failure, please contact your place of purchase or call our Customer Support Department at
[phone].
Warranty Limitations
There are no other warranties, either expressed or implied, that extend the foregoing, and there are no warranties of merchantability or fitness for any
particular purpose. Dayton Audio is not responsible for any consequential or inconsequential damage to any other unit or component or the cost for
installation or extraction of any component of the audio system, or for the improper use of products. This includes but is not limited to burnt voice coils,
overheating, bent frames, holes in the cone, or broken lead wires.
This warranty gives you specific legal rights and you may also have other rights that vary from state to state.
Non-Warranty Service: If non-warranty service is required, the product may be sent to the Company for repair/replacement, transportation prepaid, by
calling [phone] for details, complete instructions, and service fee charges.