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Definitive Technology BP-8040ST

Bipolar floor-standing speaker with built-in powered subwoofer

Item # 735BP8040

Tired of sub-par speakers that just fire sound at you, rather than all around you? Then check out Definitive's...

Tired of sub-par speakers that just fire sound at you, rather than all around you? Then check out Definitive's...

8 questions - 23 answers

Item # 735BP8040

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About the Definitive Technology BP-8040ST

Kristen Schaub

Big sound from a slim powered tower

Tired of sub-par speakers that just fire sound at you, rather than all around you? Then check out Definitive's high-performance BP-8040ST Bipolar SuperTower™. It uses a unique driver design with both front- and rear-firing speaker arrays to surround you with rich, lifelike sound. This tower also adds a built-in powered subwoofer to the bottom of the cabinet for intense bass. Even in large rooms, every listener will experience a huge, three-dimensional soundstage with both music and movies. Plus, this speaker has attractive high-gloss black top and bottom caps with a cloth grille-wrapped enclosure for a sleek look.

Big sound from a slim powered tower

Tired of sub-par speakers that just fire sound at you, rather than all around you? Then check out Definitive's high-performance BP-8040ST Bipolar SuperTower™. It uses a unique driver design with both front- and rear-firing speaker arrays to surround you with rich, lifelike sound. This tower also adds a built-in powered subwoofer to the bottom of the cabinet for intense bass. Even in large rooms, every listener will experience a huge, three-dimensional soundstage with both music and movies. Plus, this speaker has attractive high-gloss black top and bottom caps with a cloth grille-wrapped enclosure for a sleek look.

Bipolar speaker technology immerses you in detailed sound

sound waves

Front and rear speaker arrays work together to create enveloping sound.

Here's how it works: direct sound from the front midrange drivers and tweeter arrives at your ears first, to provide clear, focused imaging. That's followed by sound from the rear mid and tweeter, which is slightly delayed, to enhance spaciousness. The combination creates a lush, seamless soundstage that's more like the way we hear sounds in real life. And thanks to Definitive's Balanced Double Surround System (BDSS) drivers, your music and surround effects will sound incredibly clear, allowing you to pinpoint the soloist in a band or the direction of a jaguar's call in the jungle.

Cutaway view

Cutaway view of the BP-8040ST's drivers

Powerful bass built right into the cabinet

At the base of the speaker is an 8" side-firing subwoofer coupled to two bass radiators. This trio creates a total surface area that nearly matches that of a traditional 15" woofer, but has better bass control, speed, and detail than a single huge woofer could achieve. A built-in 300-watt amplifier powers the subwoofer, delivering hard-hitting bass that eliminates the need for an external sub. And because a subwoofer is built into the cabinet, bass output is already perfectly blended with the mids and the highs. All you have to do is set the bass volume to match your room and taste, then sit back and enjoy your music and movie soundtracks.

Build a complete Definitive Bipolar home theater system using perfectly matched centers (see the CS-8040HD, CS-8060HD, and CS-8080HD) and bipolar surrounds (see the SR-8040BP and SR-8080BP).

Got wire?

Most speakers don't include any. Learn about choosing and installing speaker wire at the Crutchfield Learning Center.
Shop our selection of speaker wire.

Did you know?
Your new speakers will probably sound better after several weeks of use than they do right out of the box. That's because the material surrounding the woofers will loosen up, allowing the drivers to move more fully. Definitive Technology estimates a break-in period of 24 to 48 hours of playback before the speakers will deliver optimum sound quality. For more information and helpful tips, check out this article from Definitive's website about conditioning your speakers.


Product highlights:

  • Forward Focused Bipolar Array™ technology for lifelike imaging and pinpoint localization
  • Balanced Dual Surround System (BDSS) driver technology places rubber surrounds on both the outer and inner edges of each speaker cone for improved clarity
  • frequency response 25-30,000 Hz (±3 dB)
  • sensitivity 92 dB
  • 8-ohm impedance
  • handles up to 300 watts
  • front array: dual 3-1/2" mids and 1" pure aluminum dome tweeter
  • rear array: 3-1/2" mid and 1" pure aluminum dome tweeter
  • 8" woofer with dual 8" passive radiators
  • built-in 300-watt subwoofer amp
  • one set of 5-way binding posts
  • high-gloss black finish on top and bottom caps with cloth grille-wrapped enclosure
  • 10-9/16"W x 39-1/16"H x 12-1/4"D (with included stabilizer feet)
  • warranty: 5 years woofers, 3 years subwoofer amp
  • MFR # IDCA

What's in the box:

  • One tower loudspeaker (with black cloth covering and glossy black top cap installed)
  • 7' AC power cord (IEC 2-prong type)
  • 4 Black stabilizer feet
  • 8 Self-tapping screws (length=1.375")
  • 8 Threaded carpet spikes
  • 8 Threaded rubber floor glides
  • Owner's Manual
  • Feature booklet
  • Registration card

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More details on the Definitive Technology BP-8040ST

Stacey B.

Features & specs

Enclosure Passive Radiator
Finish Cloth-covered MDF
Color Black
Tweeter Dome
Tweeter Size (inches) 1
Midrange Size (inches) 3.5
Woofer Size (inches) 8
Woofer Composition Polymer composite
Woofer Surround Rubber
Built-in Powered Sub Yes
Dolby Atmos Drivers
Connector Type 5-way post
Bi-amp Inputs No
Parts Warranty 5 Years
Labor Warranty 5 Years
Power Range 20-300
Frequency Response 25-30k Hz
Sensitivity 92 dB
Impedance (Ohms) 8
Subwoofer Amp Power 300
Height (inches) 39-1/16
Width (inches) 10-9/16
Depth (inches) 12-1/4
Weight 40 lbs
The Definitive Technology BP-8040ST replaces these items:

Product Research

Speaker Features

Speaker Features

Bipolar Design: The Definitive Technology BP-8040ST is a 3rd generation "SuperTower." This bipolar speaker contains drivers on the front and rear of the cabinet. The BP-8040ST uses a new patent-pending design called Forward Focused Bipolar Array. By radiating sound both forward and rearward, the speaker produces sound as it is in real life, with improved pinpoint localization of soloists, greater placement flexibility, and superior intelligibility.

Non-Resonant Tapered Cabinet: The BP-8040ST features a highly-engineered inert and resonance-free heavy MDF (medium-density fiberboard) cabinet to prevent coloring the sound. The front of the enclosure is tapered to make it appear slimmer. Wherever a driver is attached to the cabinet, a second layer of MDF is attached to prevent the drivers from causing vibration to the rest of the enclosure. The sealed midrange enclosures serve as braces for the side walls, while MDF cross braces near the woofer further stiffen the cabinet. The entire enclosure is wrapped in a cloth "grille sock", while the high-gloss polymer composite end-cap and bottom panel add a touch of elegance.

High-Definition Drivers: The BP-8040ST utilizes two cast-basket 3-1/2" high-definition polymer composite midrange drivers surrounding a 1" annealed Pure Aluminum dome tweeter in a D'Appolito front array. On the rear, there is a single identical 3-1/2" driver and the same 1" aluminum dome tweeter as used in the front array. The front and rear arrays are housed in separately sealed MDF enclosures to isolate the midranges from the influence of the subwoofer. The drivers feature Definitive Technology's patented 2nd-generation Balanced Double Surround System (BDSS) that supports the speaker cone at both the inner and outer edges, allowing longer, more linear excursion over a wider area. A new patent-pending Linear Response Waveguide smoothes off-axis frequency response and disperses sound over a wider area.

Built-in Powered Subwoofer: The BP-8040ST is equipped with a long-excursion, side-firing 8" subwoofer, driven by a 300-watt Class D amplifier with an integrated Digital Signal Processor. The subwoofer is pressure-coupled with two 8" Low Bass Radiators. The combination of the active subwoofer and two bass radiators gives you 30% more surface area than a single 12" woofer, but with better control, speed, and detail. The benefits of a built-in subwoofer include:

  • Eliminates the need for a separate subwoofer that takes up additional floor space.
  • More bass output from two subwoofers, compared to one.
  • Two subwoofers reduce standing wave room resonances and dead zones for more evenly distributed bass.
  • The subwoofers are perfectly integrated and blended with the mids and highs, eliminating the crossover and phase controls of a separate subwoofer.

Subwoofer Volume: The level of the subwoofer (relative to the other drivers) can be adjusted using the rotary dial on the back panel of the speaker. Once the bass level is set, the overall volume of the speaker system can be controlled by the receiver/amplifier.

Auto Power: The BP-8040ST has a special circuit that automatically turns on the amplifier when a signal is fed to the speaker. The LED on the back panel will glow when a signal is sensed and the amplifier turns on. After the signal ceases, it may take up to an hour for the amplifier to turn off. When first powering up after being unplugged, the LED will flash for about 30 seconds while the firmware is loading.

Stabilizer Feet: The speaker comes with four stabilizer feet which attach to the bottom of the cabinet, two per side, with the supplied self-tapping screws. Each foot has a threaded insert to allow you to screw in the supplied carpet spikes or smooth floor glides, depending upon the type of floor they're being placed upon. Four additional threaded inserts are provided on the bottom panel (along with 4 additional carpet spikes and floor glides) in case you decide not to use the stabilizer feet. The spikes and glides add approximately 1" to the overall height of the speaker.

Placement: The BP-8040ST Bipolar speakers have a lot of flexibility when it comes to placement and positioning. It is recommended that the speakers be placed at least 4" from a back wall, and at least 6" from a side wall. When used as left and right main speakers, you should set up the speakers and the listening position in an equilateral triangle, with the speaker cabinets turned slightly inward.


Binding Posts: The BP-8040ST is equipped with a pair of gold-plated, 5-way binding posts on the back of the cabinet to attach your receiver's speaker wire. The terminals will accept bare wire, pin connectors, spade lugs, single and dual banana plugs. Recommended amplifier power: 20 to 300 watts RMS.

LFE Input: For the powered subwoofer, the BP-8040ST has a single RCA LFE (low-frequency effects) input. Since you'll be using two speakers, you will need a Y-adapter to split the LFE output from your receiver to each subwoofer.

Wiring Options/Speaker Setup: You can connect the BP-8040ST in one of two ways, with or without the LFE connection. If you use only speaker wire, you should set the speaker setup on the receiver to "Large" and Sub to "No." If you connect the speaker with speaker wire and the LFE, the speaker setup should be "Large" and "Yes."

Note: It is recommended that you do not use the receiver's auto setup function, as it is often ineffective in setting up and adjusting speakers with built-in subwoofers.

AC Power: The speaker has an AC power input (IEC 2-prong type) on the back panel for plugging in the powered subwoofer. A 7' AC power cord is included.


  • Width:
    • 5.6" enclosure only
    • 10.5625" with stabilizer feet
  • Height:
    • 39.0625" enclosure only
    • 40.0625" with carpet spikes or floor glides
  • Depth: 12.25" including binding posts
  • Weight: 40 pounds

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Customer Q&A

8 questions already asked

With the rear facing speakers, what is the recommended distance for the wall behind them? What is the minimum clearance required?
weldon g  Mar 05, 2016
1 answer
2-3' recommended. The closer you get, the more influence the wall will have on the overall sound quality. That said, mime are spaced 10" from the wall, 8' apart, and towed in about 15 degrees. They still sound better than anything else I've had in the past.
john  Mar 05, 2016
Could you explain the Y adapter to get the low frequency effect? What is the Y adapter and what does it connect?
big b  Feb 18, 2016
8 answers
These speakers have built in powered subwoofers and you have two options for sending a signal to the subwoofers. The first being an LFE signal. Your receiver/amplifier should have a "subwoofer out" connector, some have two if you are using a newer 7.2 surround receiver. Your other option would be to leave the LFE plug on the back of the speaker unconnected. The speaker's built in circuitry will pull an audio signal from the attached speaker wire to send a signal to the powered subwoofers. If connecting the speaker's subwoofers via the LFE route, here is where the use of a "y-connector" comes in. Say you have these speakers and an additional separate, stand alone powered subwoofer. In this case, you would either have zero (if receiver is 5.1), or one (is receiver is 7.2) subwoofer connections open on the back the your receiver. The y connector essentially splits your subwoofer connector on the back of the receiver. There is a lot of information on the internet about properly setting up these speakers. I ended up not using the LFE connector on the back of the speakers because I wanted my dedicated subwoofer signal from my receiver to go my standalone powered subwoofer at a certain lower frequency. This allows the speakers built subs to achieve different bass frequency rounding out the overall sound in a better way. If you don't have an additional stand alone powered sub in your setup, then I would just connect them via the LFE connector.
william  Feb 19, 2016
A "Y" adapter takes to RCA inputs and combines them into one connection. Subwoofers use a single RCA input since it focuses on bass instead of left and right channel audio. "Y" = a single male cable RCA to two females RCA inputs. If your amplifier has a single sub output you would need an adapter to connect the sub's that are built into the cabinets.
gabriel  Feb 18, 2016
Big B, I'm sorry, but I don't know what the Y adapter is. I can tell you that I love these speakers. I've had them now for about two years. They fill a huge room with great sound in our house. The "tech guys" at Crutchfield are great. Call them, tell them you're interested in the Def. Tech speakers and ask them about the Y adapter. I still call them about an amp I bought and other audio equip. I've purchased from them. The free tech help is good for life of ownership of the product. Good Luck. Sorry I couldn't help more specifically. You won't go wrong with these speakers. I also got the center speaker... home theater...
tedd  Feb 18, 2016
If you have a receiver that has an LFE (low frequency effect) output, it will typically be a single RCA connector, since you would normally have just one subwoofer. In this case, you've got two subwoofers (one in each tower), so you would use a Y connector to take that single output from your receiver and feed it to both towers. For just music listening, this is all irrelevant - you can just connect the regular speaker connections (L and R) to the towers. The LFE output from a home theater receiver comes into play only with some videos, where you might want to control the deepest bass separately at the receiver (think "explosions").
jeffrey  Feb 18, 2016
The Y Adapter goes from your receiver's Sub-Out to connect each of the powered subwoofers built into the speakers. Typically a receiver will have one powered sub out. If, however, your receiver has 2 sub-out's, you do not need it. I.e. If your receiver is 5.2, 7.2, etc., channel rather than 5.1 or 7.1.
sharat  Feb 18, 2016
The speakers have a separate amplifier built in for the woofers. If nothing is connected to the LFE input, the amplifier will get its signal from the built In crossover network. Otherwise you can connect the LFE to the sub woofer output on your amplifier. If your amplifier has only one sub woofer output then you would use a Y connector but most amps that have left and right channel sub outputs are common anyway. This is a better way to input the base because low-frequency sounds are not necessary in stereo and probably more powerful when in phase. Personally on mine I never used these connections because as is they can restart a heart and knock pictures off the wall.
basilis  Feb 18, 2016
Not sure if this is what you are asking, but... My receiver has only one sub-woofer output. I used a "y" adapter to split the signal into two wires. Each "super tower" has its own sub-woofer input. FYI. I love these speakers. They were more than enough to fill a very large room with sound.
j  Feb 18, 2016
These speakers have a powered sub woofer in each of the towers. The normal receiver/amplifier only has a single output for a sub woofer. You plug the Y adapter single end into the receiver then run a wire to each of the sub woofer inputs (one on each speaker).
michael  Feb 18, 2016
I'm looking for a slim, but semi-tall floor standing with decent bass output. The BP-8020ST and BP-8040ST appear to fit the bill and are in my price range. The specs for both speakers list the width including the stabilizer feet. Can you please tell me the width of only the speaker cabinet without the feet?
richard  Jan 02, 2016
1 answer
To answer your question without feet the width is 5.6". Here are the full dimensions: Width: ?5.6" enclosure only ?10.5625" with stabilizer feet Height: ?39.0625" enclosure only ?40.0625" with carpet spikes or floor glides Depth: 12.25" including binding posts
kenneth  Jan 02, 2016 (Staff)
Looking at getting quality home sound system. Would like to get Definitive speakers. Which model would you recommend?
chad  Dec 27, 2015
4 answers
I got the 3000 speakers Thay are great
jody  Dec 29, 2015
How large is the room, and what do you like to listen to? My listening room is roughly 25'x13', with a 13' cathedral ceiling, and the BP-8040ST's produce plenty of room-filling sound, including good, solid bass down to about 25-30Hz. I'm listening to classical music, however. If you want window-breaking bass, enough to recreate the experience of standing next to a Saturn V rocket during launch, then you'd want one of the larger models.
jeffrey  Dec 28, 2015
Purchased the 8040st on black friday and could not be happier with my decision. Use them to listen to music more often than home theater and love the clean full sound they produce. Still recommend a true sub with them, but overall amazing speakers for the price
mark  Dec 28, 2015
The 8040 towers have never let me down or left me wishing I went bigger.
ryan  Dec 28, 2015
Using the LFE connection with main speakers set to "Large": Will I still get deep bass from the built-in sub on 2 channel stereo?
matthew  May 28, 2015
1 answer
I forwarded your question to an Advisor and they responded with the following: On most receivers if you set the front speakers to "large" it will automatically turn the LFE output on the amp off. If this is the case you will get no output from the sub at all. If you have a receiver that will allow for an LFE to be used in conjunction with a "large" speaker, it would work, but the receiver would be sending frequencies to the mid range drivers that would be filtered out by the speakers internal cross over. I personally see no advantage in attempting to run it this way. Your two options is to run it as a full range speaker using a full range, speaker level input, and setting your front speakers as "large", or us the LFE output and run them as "small". In a Music listening application, I would run them as a large full range loudspeaker, and forget about the LFE. If you would like to discuss further you can contact an Advisor directly by phone (1-800-324-9695) or online chat.
kristina  Jun 02, 2015 (Staff)
I am close to purchasing these speakers. I guess I am a bit paranoid about the installation of the stabilizer feet since I am retired and far from handy. Would if be all right if I (with help from my wife) very carefully turned the speaker upside down to install the feet and then just as carefully turn them back to their upright position?
matthew  May 25, 2015
2 answers
Late reply, but maybe it will help someone else. The trick is to lay the speaker down on its side, and screw on two of the feet. Then flip it over and attach the other two. The screws are tight, and it takes a bit of muscle to get them fully attached.
jeffrey  Nov 10, 2015
We have not received any answers from other customers on your question. I would recommend reaching out to an Advisor by phone (1-800-324-9695) or online chat. They should be able to help answer your question.
kristina  May 25, 2015 (Staff)
Since bass is not directional, how can one know exactly how to adjust the sub level on one speaker vs. the other? Someone somewhere stated that he had the level for one speaker at 12 o'clock but the other one at 3 o'clock. How could he have made such a determination? I would think that the level should be adjusted the same on both speakers. Please enlighten me on this. Thank you.
matthew  May 24, 2015
5 answers
Hi Matthew. These speakers have base level controls which allow you to adjust the output level of the powered subwoofers to match your room and personal listening preference. The manufacturer suggest you begin with the level control set at 12:00 which is where I have mine set. I have a Yamaha Adventage Series Receiver which I can automatically set speaker adjustments to the room or I can make manual adjustments for each individual speaker from the receiver for my own personal listening preference. I hope this helps.
david  May 25, 2015
If your room is symmetrical and the placement of your towers are symmetrical then having the level adjusted equally should be fine. In my case, one tower is near the corner of my room so the perceived loudness of bass from this tower is much greater than the other tower where the tower's sub fires directly into an open space, which happens to be my dining room. So the tower with the sub facing the dining room is turned up quite a bit higher.
joshua  May 25, 2015
Hey Matthew, I bought a new Yamaha RXV 577 amp with my Def Tech speakers. The amp came with a monitoring device that measures the acoustic feedback from the speakers and automatically balances it to your room... I didn't use it and instead chose to just adjust my speakers to sound good to my untrained ears. My amp came with a 130 pg manual and I read it all as I want to get the best sound quality/performance I can out of my system. Sit back, put on a few songs you really like and adjust the speakers until you like what you hear. You can always change it again to suit your particular listening mood... If you're going to have a wild party maybe you change the settings! I went through the same types of questions myself. We all want to get it "right." Trust your ears more than the numbers on the dials... You'll be a happy camper. Cheers.
tedd  May 25, 2015
update, there is actually a pre amp input to the sub woofer so it can be controlled via a separate channel if desired.
basilis  May 25, 2015
Directional or not you can clearly hear the bass volume level coming from one speaker vs the other,unless your not in the room. as far as having one speaker at 12 and the other at 3 may be a matter of preference since every song,every recording is different. Room configuration,walls object etc. all are contributing factors. Your ears will tell you what sounds best. While most recordings don't require you to make adjustments to these volume controls,there's no standard that says bass drums or low frequency's must be distributed equally between the 2 stereo channels and is sometime varying throughout the track. I keep mine about mid way and balanced from left to right. (there is a significant difference between 3 and 12 ) There's times I find myself upping the bass volume on the speakers for a particular track only to be lowering it later on. Sometimes I wish these were front panel mounted. I've thought of dissecting the speaker and separating the input to the bass amp and control it with separate channels. But for now they sound great as is and the adjustments give me something to tweak every now and then when I feel the need to.
basilis  May 25, 2015
Best receiver in the $800.00 range to drive my 8040 5.1 set-up. I have a Pioneer VSX1020 currently in use but feel the sound this produces is sub par especially on the high end. Suggestions please?
thomas  Nov 27, 2013
1 answer
Thanks for question Thomas. For product recommendation please reach out to an Advisor by phone or chat. They'll be able to look at current inventory and deals, and help find a receiver that will work great in your system.
jeff  Nov 29, 2013 (Staff)

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