bipolar speakers

[dnnone]

Hi,

I have a question. For front stereo towers. if bipolar speakers produce excellent sound, why there are only few companies produce bipolar speakers like definitive technology ? I don't know who-else make them, but I know a great number of companies make non-bipolar speakers.

Thanks

 

[j_garcia]

The obvious answer to me is, because there's nothing wrong with monopole speakers. While bipolars do give spaciousness, I personally don't find the sound to be an improvement over monopoles.

 

[GlocksRock]

Most bi/di polar speakers are used for surrounds, not much advantage to using them for main stereo speakers, and many prefer the direct sound that monopole speakers produce.

 

[TLS Guy]

Hi,

I have a question. For front stereo towers. if bipolar speakers produce excellent sound, why there are only few companies produce bipolar speakers like definitive technology ? I don't know who-else make them, but I know a great number of companies make non-bipolar speakers.

Thanks

First of all the speakers you mention is only bi-polar to a very limited extent.

In the low mid and bass all monopole speakers become spherical, or that is to say full space radiators at a point 380/baffle width in feet. Above that they are half space radiators.

So if you put a rear facing tweeter on a speaker enclosure, then you have half space radiation front and back separated in time by the depth of the speaker at frequencies above the pass band of the tweeters.

There is absolutely nothing to recommend this, and everything against it.

It is not the same as a membrane speaker like a Quad electrostatic or Maganpalanar ribbon, where a single membrane radiates a figure of 8 polar response time aligned with the rear out of phase with the front. The two situations are no way comparable. The latter makes sense the former does not.

 

[lsiberian]

Generally speaking the bipolar designs require a significant distance from the wall for optimal results. It also adds unnecessary cost to the project.

Another problem is the size of the woofers voice coil can make bracing difficult in bi-polar designs. Woofer clearance is one of my primary reasons for electing monopolar design. Given the desired box tuning and parameters making a box long enough to give me the bracing I wanted with opposed firing woofers was not doable. These are practical reasons I went away from the bipolar design. Despite the widened sweet spot per Dr. Toole's research.

 

[Nuance AH]

The obvious answer to me is, because there's nothing wrong with monopole speakers. While bipolars do give spaciousness, I personally don't find the sound to be an improvement over monopoles.

^ What he said. I'm sure it's based on overall sales of monopole vs. bipolar as well. If they don't sell as well...

 

[zieglj01]

Mirage use to make Bipolar speakers - Not enough sales.
They were not easy to position, and did not sound balanced.
And, they were distracting due to the lack of a precise central
image, in stereo mode.

 

[j_garcia]

Mirage use to make Bipolar speakers - Not enough sales.
They were not easy to position, and did not sound balanced.
And, they were distracting due to the lack of a precise central
image, in stereo mode.

Mirage still make Omni-polar speakers though. It is easy to understand wanting the sound to seem like it comes from everywhere. For critical listening, whether bi/di/omni, you've got the exact answer though: you give up precision. For surrounds, I am sure it probably works well too, but I wouldn't do it for mains personally.

 

[GranteedEV]

There is absolutely nothing to recommend this, and everything against it.

Mirage has shown that the mere presence of delayed, reflected rear wave radiation is a positive coloration that adds to perceived realism. In a lot of situations though it's not sufficiently delayed. Linkwitz with his pluto suggested very unusual placement to balance out the direct to reflected ratio.

The real issue with bipolars is that the dispersion is wide enough that the signals can become decorrelated if they meet at the sides, leading to unpredictable and uncontrolled lobing. The other issue is that they can be placement sensitive because you want to delay the rear wave information by about 15ms

It is not the same as a membrane speaker like a Quad electrostatic or Maganpalanar ribbon, where a single membrane radiates a figure of 8 polar response time aligned with the rear out of phase with the front. The two situations are no way comparable. The latter makes sense the former does not.

As far as figure 8 radiation, those large dipole panels beam so much of their response that the radiation pattern is only "8" in the lower mids and bass. And even then it's a myth/exaggeration that dipoles have true figure 8 radiation. JohnK discusses it here:

Dipoles and Open Baffles

Anyways i'm not sure time alignment would matter enough. I think you want the rear wave information to be coherent as a reflection and reduced in amplitude, and delayed in time.

For what it's worth, to the OP, in my opinion the def tech stuff seems questionable at best. I think these are the smartest bipole design:

AudioKinesis - sound that moves you

Because the oblate spheroid waveguide prevents decorelated side energy from phasey interaction at higher frequencies, overall provides a constant 90deg directivity without getting 'beamy', so the sweet spot is wide if crossfired as recommended. Crossfiring also maximizes late arriving lateral /opposite side wall information while minimizing earliest arriving vertical and horizontal reflections.

At lower frequencies the front and rear wave information add up in phase for omni behavior, though. So you won't get the lower mids and bass of a dipole with the figure 8 ish pattern. The bipolar def tech speakers won't give this either, nor will any monopole speaker.

 

[zieglj01]

Mirage still make Omni-polar speakers though. It is easy to understand wanting the sound to seem like it comes from everywhere. For critical listening, whether bi/di/omni, you've got the exact answer though: you give up precision. For surrounds, I am sure it probably works well too, but I wouldn't do it for mains personally.

Still around on Ebay
mirage bipolar speakers | eBay

I had some bookshelf Omni-polar, I got tired of trying to find
that central image - and the bass and mids did not blend well.
They left the house.

 

[AcuDefTechGuy]

So if you put a rear facing tweeter on a speaker enclosure, then you have half space radiation front and back separated in time by the depth of the speaker at frequencies above the pass band of the tweeters.

There is absolutely nothing to recommend this, and everything against it.

The Linkwitz Orion has a rear facing tweeter.

The Salon1, regarded as one of the best speakers in the world, also had a rear facing tweeter.

The DefTech BP7000SC & BP7001SC have one rear facing tweeter and TWO rear facing midrange drivers.

 

[AcuDefTechGuy]

Hi,

I have a question. For front stereo towers. if bipolar speakers produce excellent sound, why there are only few companies produce bipolar speakers like definitive technology ? I don't know who-else make them, but I know a great number of companies make non-bipolar speakers.

Thanks

Every speaker design has a compromise.

There are pros and cons to each speaker type.

Monopole may be easier to place especially when you have a small room. They are easier to design. They may also measure a lot flatter or linear than bipole, dipole, & omnipole (which are the hardest to get a flat/linear frequency response).

A lot of people want to buy speakers with a flat frequency response. I won't name any names.

It is almost as if the frequency response measurements were designed specifically for monopole.

Bipole, dipole, omnipole may not measure as flat, but they may sound just as good or even better than some monopole.

What you will hear from people who like BP, DP, OP is that these speakers give you a bigger and more 3D lifelike soundstage than monopole.

I know people who have auditioned monopole speakers that have great flat frequency responses with many rave reviews. Yet they were not satisfied until they listened to some BP, DP, & OP speakers. And they end up buying the BP, DP, & OP even though they don't measure as flat on the FR as the monopoles.

 

[HexOmega]

My current mains are a set of Mirage OM-9 towers that I picked up a few weeks ago for a decent price. They are a bi-polar design, or "omni-polar" as Mirage prefers to state in their literature. Each tower contains a 1" tweeter and 6" woofer on both the front and rear faces. Previous to these, I ran a set of front-firing monopole Mirage towers with fairly similar drivers. Some very casual A/B testing had my wife and I in agreement that the OM-9s were much more pleasing to the ear.

Multi-pole speakers are certainly not for every listener or application. For those who seek a larger, more natural soundstage that changes less with listening position, a well-executed multi-polar speaker can be very appealing. They are an excellent example of a "desired coloration" in a loudspeaker.

 

[cpp]

As long as it sounds good in my listening room, I really don't care if it's monopole vs. bipolar.

 

[lsiberian]

And they end up buying the BP, DP, & OP even though they don't measure as flat on the FR as the monopoles.

FR in a chamber won't include the benefits of bipolar speakers. You really need several FR measurements from the listening area. BP speakers excel in widening the sweet spot for a better group experience. I don't see the benefit in home theater though.

 

[AcuDefTechGuy]

As long as it sounds good in my listening room, I really don't care if it's monopole vs. bipolar.

That's right. The important thing is that they sound great. Doesn't matter the technology. As long as they sound great to us.

FR in a chamber won't include the benefits of bipolar speakers. You really need several FR measurements from the listening area. BP speakers excel in widening the sweet spot for a better group experience. I don't see the benefit in home theater though.

I agree.

If they sound great, that is all the benefit you need. Whether you are listening to music, watching TV or movies, great sounding speakers will enhance the experience.

Some people prefer BP, DP, OP over MP. But everyone is different and every room is different.

 

[Nuance AH]

As long as it sounds good in my listening room, I really don't care if it's monopole vs. bipolar.

And that's really the only thing that matters in the end.

 

[zieglj01]

As long as it sounds good in my listening room, I really don't care if it's monopole vs. bipolar.

There is something for everyone out there - and that is good.

 

[dnnone]

bipolar vs mono-polar speakers

Hi all,

First English is my second language, so pardon me if I confuse some one here.
Thank for all your replies. The reason, I ask my question, because I like to make sure my decision is right for me.

My brother has a $1200 pair of Def-tech. He likes his def-tech a lot. He convinced me that with a same price range or even more expensive mono-polar speakers. Bipolar def-tech will give better mid-range, better upper mid-range, and better high-frequency range than mono-polar speakers even for music listeners. At that time he compares his bipolar def-tech with the mono-polar B&W CM9 $3000 a pair.

In contrast with my brother's experience, Majority, people around the net point out the bipolar speakers is only good for movies. I am not a movie guy, and my type of music like Jazz (like Diana Krall, Herbie Hancock), instrument music (like armik, yiruma), pop/rock (Adele, Sting), classical (Andrea Bocelli). Personally, with this type of music I prefer detail, accurate sound than 3D spacious feeling sound. I believe with tweeters, and mid-range drives in the back of the bipolar speaker reflect sound from the back wall, and then few other objects around the room then to my ears, with the same sound difference phase from the front drivers. With this nature of sound behavior, I believe bipolar speakers give more spacious feeling sound, but not accurate, and detail sound.

I end up bough a pair of Wharfedale Evo2-50. I have not have a chance to listen to higher-end speakers, but so far I like my Wharfedale Evo2-50 a lot with my so-so AVR equipment in stereo mode.

Again I would like to say thank to all of your own opinion replies.

 

[zieglj01]

^^^^
Thanks, have fun and enjoy.