Dipole/Bipole Surrounds?

[Hdale85]

Making this thread for a friend to get answers on some stuff. Basically I'm looking for answers as to why they are not used in DIY much if ever? Are they not good? Why do so many MFG's use them but noone in the DIY world does?

[kgveteran]

I found that once I got use to monopole surrounds, I found them more accurate to the soundtrack. I'm not sure if studio's use dipoles or bipoles.

KG

[ThomasW]

We don't have any DIY dipole/bipole surrounds.

I know it's not fashionable by THX standards, but personally I prefer monopole effects speakers.

[---k---]

I've been waiting to see what type of reponses you would get. -Nothing- Sort of what I expected.

If you plan to do any 5-channel music, like SACD of DVD-A, you will want all monopoles.

I've always done Monoples and been happy. I don't understand the whole 'monopoles are bad' thinking. A good, properly placed monopoles should be able to create whatever sound you want. The soundstage of a good monopole, say ModulaMT, extends furth enough to the sides that it should be able to create a big rear stage. You can always point them outward a little. If the sound needs to sound 'diffused', I don't understand why the guy mixing it can't do that - speakers out of phase sound pretty diffused.

Dipoles have big nulls that you're supposed to sit in, and then relies upon reflecting sound off of the walls. Huh? Not a good way to be repeatable and accurate.

Dipoles became fashionable with Dobly Prologic II, prior to Dolby Digital. I think they've fallen out of fashon as Digital allows for better placement of the sound image. Considering that most of the cheap HTIB and Bose all are 5 monopoles, I think the industry is swinging back to monopoles.

Dipoles are also a lot more expensive with 2x the drivers.

[cjd]

Dipoles and bipoles are recommended because they create a diffuse sound field, NOT an accurate one. Particularly in a home environment where distance to the surround speaker can be SO different - if I sit on the end of my couch, one speaker is 2 feet above my head, the other is that high and 8 feet over... HOW do you balance SPL? The other side of the couch, it's the same problem with opposite levels...

C

[littlesaint]

Remember though that modern surround sound is not mono in the side channels, so if you're sitting more to one side, the information should be louder because you'd be more to that side of the visual information. Also, adding rear channels (6.1/7.1) would help if the two sides are far apart. The rears are usually mono, so they would help anchor the information more to the center. That said, if the speakers are too close to the listening position, there could be too much directionality. There's a formula somewhere (Dolby?) that takes into account distance and angle from the side surrounds that determines whether dipoles would be beneficial over monopole speakers.

[dlneubec]

Dipoles and bipoles are recommended because they create a diffuse sound field, NOT an accurate one. Particularly in a home environment where distance to the surround speaker can be SO different - if I sit on the end of my couch, one speaker is 2 feet above my head, the other is that high and 8 feet over... HOW do you balance SPL? The other side of the couch, it's the same problem with opposite levels...

C

Exactly! I think a diffuse sound field will work better in most home environments for the reasons you mention.

I hope to do a surround design that combines both direct and diffuse qualities. If you can come up with a design that has greatly enhanced off axis performance from the traditional design, that would be one approach. For example, a semi-omnidirectional design that covers a 180º sphere from the wall might provide both qualities. Something like the BeoLab5 concept might work.

Another approach might be drivers that are oriented in more than one plane, taking care that the nulls are not aimed at seating positions. I had the idea of trying a vertical MTMT design, covering 3 sides of a box something like this, but it would take a lot of testing to see if it is even remotely feasible.


Allison had a speaker line back in the early 80's (I owned both the 8 and 9) and I recall them having a great sound, both on and off axis. They were designed to be placed right agains the wall. Here is s sheet I still had from them. I've often thought about trying this approach, not only for surrounds, but for a CC, where the speaker could set up against the front of a large flat screen TV instead of a wall. It has the potential to have excellent off and on axis performance.

[dlneubec]

Remember though that modern surround sound is not mono in the side channels, so if you're sitting more to one side, the information should be louder because you'd be more to that side of the visual information. Also, adding rear channels (6.1/7.1) would help if the two sides are far apart. The rears are usually mono, so they would help anchor the information more to the center. That said, if the speakers are too close to the listening position, there could be too much directionality. There's a formula somewhere (Dolby?) that takes into account distance and angle from the side surrounds that determines whether dipoles would be beneficial over monopole speakers.

What I have observed is that if I'm setting significantly closer to one side with my current monopole surround setup (RJB's Microbe/Seas), I find it quite distracting that one speaker is louder, or if even closer, the sound goes over my head on that side and is nearly lost. While they may not be mono signals, I bet they carry a lot of the same information at times as well. It certainly sounds that way to my ear.

[MuaDibb]

Hey, where can I get "computer grade caps"? :P

[dlneubec]

:yesnod:

I have to ask. Is MauDibb from Dune or something else?