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Home / Product Category / SPEAKERS / In Wall Speakers / In Wall Subwoofers / OSD Audio SMP500 DSP Mono-Channel Class D Subwoofer Amplifier 800W, Auto Sensing, 4 -8 Ohm ETL and CE Certified

OSD Audio SMP500 DSP Mono-Channel Class D Subwoofer Amplifier 800W, Auto Sensing, 4 -8 Ohm ETL and CE Certified

Product code: SMP-500DSP

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OSD Price: $399.99
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Features & Specifications

. Mono Class D Dedicated Subwoofer Amp
. 1000W Peak /400W RMS @ 4 ohm
. Variable High Cut Filter 30Hz-150Hz, front panel knob . Additional Front Panel Control: Phase Switch and Volume Control
. Choice of Signal Level Input or LEF (Low-Frequency Effects)
. Turn On Choice: Music Sensing, Manual On or 12V Trigger
. Adjustable Gain/Volume Control Limiter
. Signal (low level) and Speaker Level (high level) inputs
. 110/220V switchable ETL, CE

OSD Audio SMP500DSP Class D Subwoofer Amp is designed for use with higher wattage passive subwoofers such as in-wall subs that require external power. It is rack mountable and 1U chassis. This sturdy sub amplifier is not for the faint of heart. It serves up 1000 watts of power peak and 400W RMS @ 4 ohms, so to say that it is powerful is an understatement.

You'll experience deep, rich and crisp bass while watching your favorite movies, especially action and adventure flicks. A big bang for the buck, features include a front-mounted power meter, 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. Combining the best qualities of both class A and B amp technologies, distortion is low while efficiency is high, and the SMP500DSP Mono Amp also includes a variable high cut filter that routes higher frequencies to main speakers. This allows subs to concentrate on the low-frequency sound effects for which they are designed and keeps low bass away from your surround speakers for much cleaner highs and midrange.

This sub amp does more than just supply power. You'll notice an improvement in the overall sound quality of your entire home theater surround sound system.




  View Owner's Manual          


14 Questions & 14 Answers
from Austin, Texas asked:
October 11, 2019
HI,  I have two sets of Bowers and Wilkins AM1 outdoor speakers installed in my back yard both being pushed by one sonos 250 amp.  One set is on my deck area and the second set are in my fire pit area. I'm wanting to purchase two subwoofers and one amp.  One to go on the patio area and the other to go in the fire pit area. The fire pit area consist of  pea gravel  and i am not sure what sub would work best  Need help deciding on an amp and two subs.  Thanks.
1 Answer
Hi Doyle:

Good question on adding a couple of Subwoofers. You have two different applications. The first is to find a sub that would work on a deck. Our best choice would be out FORZA10 featuring a  10" Down-firing subwoofer. The FORZA10 is a 4-ohm sub, so it would need a dedicated Amplifier for like our SMP300. You could not connect two of these subs to a single amp in parallel, and you don't want to limit the output by wiring two subs in Series. For your second application out at the fire pit, you have a choice between out GLS8 in-Ground 500 Watt 8-inch subwoofer (8-ohm) and another FORZA 10. If you had two locations to bury two of the GLS8 (one near the deck and the second at the fire pit), I would recommend going with a single SMP500 Dedicated Subwoofer Amplifier to power two of the GLS8 8-ohm subs in parallel (a 4-ohm load). Note: if going with a single sub amp, you would connect to the subwoofer output on the SONOS 125 Watt amp. If you pick two subwoofer amplifiers, one will connect to the Subwoofer output of the SONOS (signal level) and a second Subwoofer would connect in-line with a pair of the Bower & Wilkins AM1, then to the speaker level input of the SMP300 and then out to the second pair of AM1. I am assuming you are connecting the two pairs of AM1 in parallel on the back of the SONOS Amp. One pair of conductors would go directly to a pair of the AM1(on the deck), and the second pair of conductors would go to the SMP300 then out to the AM1 at the firepit.

Submitted by: Tim Leahy on October 11, 2019

from North virginia asked:
September 1, 2019

I have a bose as5 sunning a pair of bose 151as speakers on my deck but feels like the set needs more bass. Wou!d your bass able to help of i also.get an outdoor sub? How would i.connect it as bose doesn't have a subwoofer output?



1 Answer
Hi Chris:

The SMP500 would be an excellent addition to your BOSE setup. We have a couple of choices for outdoor passive subs that would be a good match for your BOSE 151. Check out our FORZA 10 Passive 10" down-firing Deck/Patio Subwoofer (4 ohms). Or you can add one or two of our GLS8 8" in-ground subwoofer (8-ohm). The SMP500 will handle a 4-ohm load so one of the FORZA10 or one or two of the GLS8. The SMP500 features a Speaker (High) level input and Output so can be connected inline between the BOSE 5 and the Speaker 151. Or you can connect directly to Speaker B. And leave BOSE 151 connected directly to the Speaker A. I am pretty sure you could combine the SMP 500 in line with Speaker A and add a second pair of BOSE151 to Speaker B for even more coverage. 


Submitted by: Tim Leahy on September 2, 2019

from Omaha asked:
August 29, 2019
I purchased the GLS8 sub and the SMP500 amp. What are the optimal settings for the amp to get the most out of the sub? 
1 Answer
Hi Spencer:

I need to know more about your application in order to answer your question better. What makes up the rest of your system? How many speakers will the subwoofer be working with (Brand and model numbers)? Do you have room for two Subs; the SMP500 will drive two of these subs. What other amplification are you using, what sources are you using?


Submitted by: Tim Leahy on August 31, 2019

from Utica, NY asked:
July 12, 2019
I am currently running a 6 speaker audio system from an old but very good Akai amu06 integrated amplifier. The 3 sets of speakers are controlled through your 4 channel speaker controller.  I'm very happy with the clean power and the sound quality but I'm thinking about adding an in-wall subwoofer. If I were to purchase this amplifier would it be advisable to run the Akai pre out line to the amplifier and run all 6 full range outdoor speakers and the subwoofer directly from the new amplifier or alternatively, should I continue to run the 6 outdoor speakers from the Power Amp section of the Akai and use the B speaker channel from the Akai to run into the input of this amplifier and then run only the sub directly from the new amplifier? Thanks
1 Answer
Hi Mike:

I would suggest connecting to Speaker B to the SMP500 while leaving your current setup with the Speaker B connecting to the Source A input of the Speaker Selector. The in-wall sub would wire directly to the speaker outputs of the SMP500 using 14 or even 12 gauge wire. You want to make sure the output is variable, so the master volume control from your AKAI affects both the high and low frequencies equally. Sometimes the Preamp level is fixed so you might need to adjust the volume from the SMP500. I would try it both ways.

Another thing to consider is are you using Impedance Matching Volume Controls for your protection (either the SSVC4 with internal IMVC or the DSM4/ISS4 with external IMVC). The AKAI should see an 8-ohn load on Speaker A from the Speaker Selector. The Impedance is not as much of a factor if you utilize the Preamp output from the AKAI to RCA signal level inputs. It would help to know more about your overall system. What Speaker Selector are you using, and what Brand and model number of the six speakers (3 pair) and In-Wall sub.

Thank you in advance;


Submitted by: Tim Leahy on July 14, 2019

from Alpharetta, GA asked:
June 28, 2019

I have 4 outdoor Def Tech AW6500 speakers.
I am considering the following set up, please let me know if feasible:

Zone 2 line out from my Receiver to OSD SMP500 line in

    I would like to connect two OSD GLS8 subs to the SMP500

      How would I do this?

      Would the SMP500 see a 4ohm load?

Next - line out from SMP500 to OSD XMP300 line in

    How would I make this connection?

    How would I connect the 4 Def Tech speakers to the XMP300?

    Would the XMP300 see a 4ohm load?

Would the OSD AMP300 be better for this set up, or does the XMP300 work just fine?

What is the difference between these two amplifiers?

Which is better?

Thank you

1 Answer
Hi Nana:

Great setup. The SMP500 would be ideal for driving the 2 GLS8 in-ground subwoofers. You have two choices for connecting the 2 GLS8's. I would recommend using our CL3 12/2 gauge speaker wire for the subs. You could run a single two-conductor to the first speaker and tie the inputs to a second two conductor pair to output to the second pair. The other choice would be to home run both wires from each GLS8  to the SMP500. In both cases, you have a parallel connection creating a 4-ohm load. Ideal for max power from the SMP500. Then you connect an RCA Stereo Cable from the signal level output to the Main RCA Inputs of the XMP300. Note: The XMP300 is a newer Digital design versus the Class AB AMP300. Typically the Class D Digital design features a 93% efficient Power Supply so no need for a heavy-duty power supply like the AMP300. You also have a higher power output from the XMP300 for a lower price as well. The XMP500 is also a Class D design with a similar physical size as the XMP300. You can not go wrong with either the AMP300 or XMP300.

You have made good choices, along with your Def Tech speakers.


Submitted by: Tim Leahy on June 29, 2019

from Morris, IL asked:
June 14, 2019
Is there a factory reset?  
1 Answer
HI Eric:

According to our engineers, there is no factory reset; you would need to go through and make changes manually for each feature you might want to change. 


Submitted by: Tim Leahy on June 23, 2019

from Omaha, NE asked:
April 21, 2019
What is the 8 ohm peak output? I saw you said it was rated 240W RMS continuous for 8 ohm, but what is the 8 ohm peak output?
1 Answer
Hi Chet: I would say the 8-ohm peak is a minimum of 500 watts. TL/5512
Submitted by: Tim Leahy on April 22, 2019

from Avon, IN asked:
April 6, 2019
The signal for this SMP500 originates at the receiver inside my house. The receiver has an RCA output for Sub 1 & Sub 2. The GLS8 only gets a signal when I use a RCA cable in both sub 1 & 2 connecting those to R & L on the SMP500. Sounds awesome what a great combination!! How can I send a signal to the GLS8 without having to use both outputs? I need one output for my interior sub. If I try to use a RCA splitter (Y) output from Sub 1 or 2 doesn't matter to both inputs on the SMP500 I do not get signal. I am also using a XMP300 for my exterior speakers. Any thoughts / help would be great thank you.
1 Answer
Hi James: I am assuming you are connecting the XMP300 to the Zone 2 output of the Audio Video Receiver. What you might consider is connecting the XMP500 directly to the signal level inputs of the SMP500 and the XMP300 from the XMP500 signal level outputs. The Sub output on the AVR is dedicated to the Surround Sound processed System. Connect that to your internal subwoofer. The external sub wants to see information destined for the External Zone 2. You could also try connecting Zone 2 to your Main Line input of the XMP300 and the SMP500 from the Mainline output of the XMP300. Try both options and see if either one shows a loss in signal strength. I am thinking the best connection is going to the SMP500 first. TL/5496
Submitted by: Tim Leahy on April 14, 2019

from Omaha, NE asked:
February 5, 2019
What is the power output specifications for this amplifier at 8 Ohm?
1 Answer
Hi Chet: 8-ohm rating: 240 watts Continous RMS 4-ohm rating: 400 watts Continous RMS 1000 watts peak You can connect two 8-ohm subs to get the 4-ohm power. TL/5399
Submitted by: Tim Leahy on February 6, 2019

from Front Royal, Va asked:
January 7, 2019
If you were to run 2x SL800D, could this amplifier handle that load or would you you need 2 SMP500 amplifiers?
1 Answer
Hi Alan: The SMP500 has plenty of power for a four-ohm load which is what the Amplifier would see when wiring two 8-ohm SL-800D subs in parallel. A perfect match. TL/5359
Submitted by: Tim Leahy on January 10, 2019

Kent Johnson
from Oklahoma asked:
January 1, 2019
Does this amp have a built in crossover?
1 Answer
Hi Kent: Yes, the SMP500 has a built-in Low Pass Crossover network with additional adjustments for Gain level, Phase and High Cut filter. It also has a remote control and DSP circuit that allows you to save up to three different EQ settings. Good choice TL/5351
Submitted by: Tim Leahy on January 6, 2019

Thomas Turk
from Vienna Audstria asked:
November 20, 2018
Is there any/much difference for sub-woofers, crossed over below 150Hz using a stereo amp or using this mono amp.. with same signal from both channels?, How many Watts for each channel would that give me into 8 Ohms
1 Answer
Hi Thomas: It depends on what Sub or Subwoofers you are connecting to, and if they have a crossover built in so, you can feed a direct full range signal. But this dedicated subwoofer amplifier provides a whole lot more control on the crossovers frequency range and slope that are selec=table. There are also 3 DSP presets available controlled at the front panel or by remote control. You can easily connect two 8 ohm subs for a 4-ohm load rated at 400 watts. Note low pass is typically mono from an AVR. The speaker level output is a single two-conductor which should be 12 gauge or higher. There is no comparison, no need to look any further. The amp is both multi-voltage and CE rated for European distribution. We do have an online dealer located in Norway; That has been adding our amplifiers to their mix. Good luck TL/5292
Submitted by: Tim Leahy on November 24, 2018

from Largo Florida asked:
October 25, 2018
Can this unit be used in full range mode? Considering 2 of these and your preamp one.
1 Answer
Hi Patrick: The SMP500 is a dedicated Subwoofer Amplifier that can power two 8 ohm Subwoofers in Parallel like our GLS-8; 8.0" in-ground sub. The new XMP300 would make a nice combo along with the Pre-One. The XMP300 can also power a couple of Pair of 8-ohm speakers. I would connect the Pre-1 to the SMP500 and then to the XMP300. That would give you 400 watts for your Subs at 4 ohms and 225 watts for the XMP300 at 4 ohms as well. Let me know if can help with your system? TL/5260
Submitted by: Tim Leahy on October 25, 2018

from Poland, OH asked:
June 11, 2018
What does the remote do for the amp? I am assuming on/off, volume. Anything else? Thank you
1 Answer
HI John: You can see an image of the IR Remote Control in the Owner's manual; It works in conjunction with the Digital display on the front. It features the usual suspects: Power On/Power Off, Volume Up/ Volume Down, Menu-Enter, Scroll Right/Scroll Left, Mute, Exit, There a number of settings in the menu that you can configure High pass filter, Low pass Filter, Change the slope from 0 to 48dB plus adjust the Phase Mode. You can save up to three different settings in the store 1, store 2, or store 3 buttons. Then you have a recall button for each corresponding store button. So you would store the settings/memory on store 1 button and you would need to push recall 1 button to listen to the amp with those settings. The last three buttons are Flat (no equalization) and then Night Mode On/Night Mode off. Night Mode: Limits the dynamic range of the amplifier so the louder context of the source signal is reduced. This feature allows the user to select night mode. Choose either enable or disable. I will post infographics with more info on the remote including the hex codes in case you want to control it with a universal remote. TL/5047
Submitted by: Tim Leahy on June 17, 2018

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