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Home / Product Category / AMP / Subwoofer Amplifiers / OSD Audio SMP250 Mono High Current Class A/B Subwoofer Amplifier with 250 Watts of Power

OSD Audio SMP250 Mono High Current Class A/B Subwoofer Amplifier with 250 Watts of Power

Product code: OSD-SMP250

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Features & Specifications

If you're looking for a subwoofer amplifier, Outdoor Speaker Depot has you covered. The SMP250 Mono Subwoofer Amp features variable low-pass crossover, easily accessible volume control and a low-frequency effect input. It's designed for use with higher wattage passive subwoofers so you can tighten the level of the bass signal. You can even use the high-pass ins and outs to send the signal back into your sound system.

OSD Audio’s SMP250 Mono Subwoofer Amp gives passive subwoofers up to 250 watts of power so you can experience all the crashes, crunches and car chases with spine-tingling exhilaration. Designed for use with higher wattage passive subwoofers such as in-wall subs that require external power, the SMP250 Mono Subwoofer provides stable power and enhances the low frequency sound effects. Moderately priced with high-end features, this sub amp includes a variable high cut filter that routes higher frequencies to main speakers so subs can concentrate on the low frequency sound effects they are designed to handle. The result is bass that does not sound muddy or overly thumpy but rather crisp and detailed. You’ll immediately feel and hear the difference. Other features include a back panel adjustable gain and volume control limiter to protect the woofers as well as low-level and high-level pass-through input/outputs to cover newer and old school sound systems.

Why Do You Need Subwoofer Amp?

If you have a powered subwoofer, you don’t. A powered subwoofer has its own internal amplifier which is why they are extremely heavy to lift. A passive subwoofer is simply a woofer or woofers in an enclosure that is designed to handle low frequencies but does not have an internal amplifier, which is why they are not heavy to lift. In-wall subs are most commonly passive. After all, it’s not so easy to install a 100-pound sub inside a wall. That’s where an amp like the SMP250 Mono Subwoofer Amp comes into play. This amp not only adds necessary power but the high-cut filter keeps low bass away from your surround speakers, which in turn gives you much cleaner highs and midrange. This subwoofer amp does much more than supply power. It also improves the overall sound quality of your entire surround sound system.

What Is A Class A/B Amplifier?

In home theater, Class A/B are the most common because they combine the efficiency of Class B with the sound quality of Class A amps. A Class A amplifier uses the input signal 100% of the time, which means that the output signal to your sub matches the input signal from your receiver. The result is virtually no clipping or distortion. Sounds perfect, right? The downside is that Class A amplifiers run very hot because the transistors are working all the time. Class B amplifiers only amplify half of the input signal which creates some distortion but these amps are far more efficient than Class A amplifiers and run a lot cooler. A Class A/B amp combines the best of A and B, so distortion is lower yet efficiency is high so sound quality is truly maximized.



  View Owner's Manual          


By steve from toronto on January 29, 2013
I have 2 10" cerwin vega subwoofers in a box that I used in my car years ago. Can I use this amp and hook those subwoofers up to use for an inhome subwoofer setup? If so what would I have to do? Thanks, Steve
By Customer Service - Q&A on January 30, 2013

Hi Steve,

First you need to determine if these subwoofers are 8, 4 or even 2-ohm impedance. Check to see if they are labeled on the drivers themselves. If you have a model number you can go to the Cerwin Vega web site to look them up. If they are 8 ohm,you can wire them in parallel. If they are 4-ohm you need to go in series (same with 2 ohm.) For parallel, you wire the two positives of the drivers together and terminate to positive output of SMP250. Connect the negatives to negative output of the SMP250. The amplifier will see a 4-ohm load and should have plenty of output and run a little hot. If they are 4 ohm (most likely) or 2 ohm, you will need to connect in series which means connecting the positive output of the SMP250 to the positive input of driver #1 then connect a wire from the negative of the speaker #1 and connect to the positive of speaker #2. Final connection would be between the Negative of Speaker #2 to the Negative output from the SMP250 amplifier. If you can not determine the true impedance of the drivers, go with in series to be on the safe side.

TL/MA - 1592

By Joe from Canada on November 21, 2012
Can this amp run both subwoofers rated at 150W each?
By Customer Service - Q&A on November 23, 2012

Hi Joe,
The bigger concern when trying to match a pair of woofers to a sub amplifier is the Impedance Rating of the subs not the power handling. I am assuming you are using two 8-ohm drivers for home (car audio uses mostly 4 ohm drivers). When you connect both 8-ohm subs in parallel, you will increase the output of the SMP250 so you will have plenty of current to drive both subs. The SMP250 is a High Current Amplifier that will work in a 4-ohm load, which is what the impedance drops to when connecting two eight ohm drivers in parallel. Connect both the Positives to the Positive Output and both of the Negatives to the Negative Output. In Series, connect the Positive from the amplifier to the first Subwoofer's Positive connection then connect the Negative from the First sub to the Positive of the second sub. The Negative from Second Sub is then wired back to the Negative Output from the SMP250 amplifier. This creates a 16-ohm load and drops the output of the amplifier in half. Let us know if this helps.

TL/MA - 1398

By nimish from chicago on December 23, 2012
I have a IWS-88 connected to the SMP-250. I have the SMP-250 connected to a Pioneer Elite SC-65 receiver. I'm getting very faint sound coming from the sub (and only at max volume setting). I have speaker wires from IWS-88 sub connected to SMP-250 "subwoofer speaker output" port. I have one end of the mono cable connected to the SMP-250 "LFE IN" port and other end connected to SC-65 "subwoofer out" port. Do I need to set the phase correctly? How about the Low Pass Filter? Can you help?
By Customer Service - Q&A on December 24, 2012

Hi Nimish,
Regarding the SMP250, here are a couple of things to consider. You have the Pioneer Elite Audio Video Receiver connected to the LFE input of the SMP250. Make sure your LFE setting on the Pioneer is set to 0 db (the highest setting). Then on the front of the SMP250 set the controls as follows: Polarity to zero all way to the left, the crossover setting should be at 12:00 o'clock (the LFE overrides the high-cut filter) and the Volume Control at 12:00 as well. On the back panel of the SMP250 there is a level (gain) control right next to the LFE input. You want to turn this adjustment at least half way or more depending how much output you want. If you have not touched this, you will notice a huge difference as you turn it clockwise. Once you have set it to acceptable levels, the volume level will be directly affected by the volume levels of the Pioneer. It will increase or decrease along with the other 5, 7 or 9 channels when you adjust the master volume levels. We hope this helps!

TL/MA - 1487

Product Reviews

OSD Audio SMP250 Mono High Current Class A/B Subwoofer Amplifier with 250 Watts of Power
4 Stars based on 3 Review(s)
Florence, KY
4 Stars
I would recommend this item to a friend.

Does the job
August 13, 2016
I have a pair of Cambridge Soundworks sub woofers. Recently purchased a new 5.1 receiver. Could drop them and purchase a powered sub woofer, but hated to give up a good pair of woofers, so I looked around for a amp that would power them off the sub woofer jack on the receiver. Since low frequency singles are less directional, I wasn't worried about a mono output. Wired the speakers in series and the bass and perfect.

Kinnelon, NJ
4 Stars
I would recommend this item to a friend.

Great amplifier!
May 21, 2013
Works great, good solid bass! Only thing I would like is for it to turn off after 30 seconds of inactivity. Would buy it again.
Nice looking, solid construction
Should have auto power down sensing

Boynton Beach, FL
4 Stars
I would recommend this item to a friend.

Great Amp !!!!
December 15, 2012
I have 2 of these Amps with 2 - 18" subs ( Behringer VP1800'S) on each Amp , Their performance is nothing short of fantastic
Easy to Mount, Good Power Output, Easy To Set Up, Great Sound Quality, Attractive Design
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