Bipolar speaker configuration ... need info! accoustical pros and cons ?

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JinMTVT said:
my guess is that a well treated rooom with really good quaity stereo setup + sub is really hard to beat for movies..
...
SPL takes an important place in HT setups!

My guess is that you could easily beat that setup if you add components and speakers of the same quality properly set up - same quality, more quantity. Now if you are talking about the same amount for stereo vs HT 5.1 ...

My approach is to set a benchmark with a stereo system, then add on the extra parts that are matching in quality and character. I think stereo has maximum bang for buck and you can get a quality system without spending large amounts. But to have 5 speakers with 5 channels of power plus a sep sub, as well as the processing and preamp .... that is going to cost a lot fo do it at the same quality as a stereo receiver with a pair of floorstanders. $1500 turns into $4000 quite easily!

SY ... is that you in the pic?
 
paul: your approach is absolutely correct, I have gone from a front & rear surround setup to back to plain old stereo, which is great for movies. I found with the surround setup I was forever changing eq & levels to try & get it to sound right. I think in the end the fact I was using different speakers all round really made it impossible to get something I was happy with. You must match all speakers.

JinMTVT: my idea of adding the second rearward driver, being a dome mid with its own sub enclosure the only impact it will have is reducing the volume for the front drivers. There is no wave interaction inside the box. All I am doing is adding some comb filtering to enhance (artificially) the depth effect.
I picked a driver which has a freq. range which is above the start of cancellation due to the baffle width ie. 500hz for a width of 220mm. As my target sensitivity is about 92db, the added benefit is I can add a couple of db to my 90db mid to match the tweeter level.

Dipoles have a type of soundstage were it sounds like the musicians are in the room.
Monopoles on the other hand are more like a window were you watch the musicians.
I am aiming for a bit of the former.
 
Ap said:
paul: your approach is absolutely correct, I have gone from a front & rear surround setup to back to plain old stereo, which is great for movies. I found with the surround setup I was forever changing eq & levels to try & get it to sound right.

every sound engineer has his / her own tastes. this is usually refelected in the recording. when tuning speakers i find that every speaker i have built favour some CDs over others.

Usually it is in the bass where this is most noticeable. This makes a good case for a biamped system with the subs being controlled by something like Audio Control's Richter scale or by other means that allow one to quickly adjust the Q and F3 of the bass roll off slope.

to cover most musical genres one needs a minimum of 32 (2x2x2x2x2) different Q-F3 combinaitons one must have on tap.

Now compund this with 5 channels and mix in WAF which gets even more sensitive in 5 channels and you can see where the problems can occur. Here this get crazy. One needs (I can only estimate at this point) 5x5x5x5x5x3 (front, rear, center) combinations to cover most movies.

Maybe my maths is wrong but I guess you guys get the jist. With 5 channels all issues compound exponentially.
 
to cover most musical genres one needs a minimum of 32 (2x2x2x2x2) different Q-F3 combinaitons one must have on tap

I've been very much wanting to bite the bullet and go surround, but you guys are doing a great job of scaring me off. When the format wars settle, perhaps...


SY ... is that you in the pic?

You mean the avatar? That's off by a Y chromosome, 25 years, and a gray beard. And her French is considerably better than mine. Moi, je suis un bucher de la langue sacrée.
 
navin said:


Yes, more than one enquiring minds want to know :)

Yes, when us guys get a hint of a female :bigeyes: on the forum, we get curios and wonder "could this be true?" ... even more so if it's a moderator. Which is not to say that women don't appreciate audio, it's more that they don't seem interested in building their own usually, or in discussing or talking about the technical side.

navin said:


every sound engineer has his / her own tastes. this is usually refelected in the recording
...
to cover most musical genres one needs a minimum of 32 (2x2x2x2x2) different Q-F3 combinaitons one must have on tap.

The thing that annoys me most with recordings is most often what happens with the treble, in particular with vocals having sounds coming through the tweeter that shouldn't be. Enya in particular - her CDs seem mixed with so much airiness that it can turn into noise almost. The natural purity of the vocals is lost.
...
I think it all depends on how you want to set up your system. If the bass is handled by one sub, then you don't have to worry about messing with the bass rolloff for 6 speakers. Or you might have two subs. Or your subs might only be for LFE use with the mains set to large, used alone for stereo music while centre and surrounds crossed at 100 Hz.

When you get to the stage of extreme complexity in your speaker controls that you have to mess with, you reach a point where you may be better off going with more quality, less quantity.

Nevertheless, I certainly agree that 5 channels adds compexity. But then, it's all a lot of fun and gives you an excuse to do a lot of extra things. Perhaps another advantage is that your spouse is likely to enjoy and appreciate it more than a music only system. When it comes to music, many people will turn on the ghetto blaster as its easier, rather than having to press a few more on switches to get the hifi system going. But for movies, if you have a dedicated room, big screen and a 5.1 surround setup done well, anyone can appreciate that.

SY said:
I've been very much wanting to bite the bullet and go surround, but you guys are doing a great job of scaring me off. When the format wars settle, perhaps...

The main reason I can see to put off going to surround is budget! I think the best way to transition for the most impact for your dollar is .......

1. start with your stereo audio system which probably has a music bias

1b. add room treatment if you dont' have it already

2. add a diy projector

3. add a diy subwoofer if you don't have one

4. purchase HT receiver

5. add diy matching centre and surrounds

A diy projector is cheaper than most of the other diy items like subs, amps and speakers, yet its impact in a movie experience is probably more (at least with your average person, us audio nuts are very biased usually.)
 
I've been very much wanting to bite the bullet and go surround.........

Then do so! From my own experiments I've found that in almost every install I've seen in pics or auditioned, they were so highly compromised regardless of who designed them or how lavish/expensive they were that they didn't do the better multi-channel mixes justice.

That said, HIFI and surround sound are at this point in time mutually exclusive WRT the speaker system unless you have a very large room and deep pockets, so I recommend building a separate inexpensive system to experiment with, designed by scaling down a cinema system to get the proper diffuse soundfield as low as your room Vb allows. Here's a start: http://www.jblpro.com/pub/cinema/specifying_cinema_loudspeakers.pdf
http://www.jblpro.com/pub/cinema/cinedsgn.pdf
http://www.dolby.com/tech/L.mn.0002.5.1Guide.s.pdf

If you plan to play back both older Dolby formats and the newer DD/DTS, then both dipole and monopole surrounds will be required, and a way to switch between the two. Also, I found that it's better to have too many speakers in the surround and LFE channels than 'making do' with too few when the room size dictates an either/or quantity. Not surprising when you consider how an 'infinite' line source fools our hearing by having so much comb filtering we process it as a discrete set of frequencies.

GM
 
GM: I agree with your conclusion. At the end of my surround experience I decided that a dedicated surround & a dedicated music setup is the way to go. As I don't have the funds or space, I ended up with my high-quality 2 channel (plus subs) setup for both music & movies, works great.
 
planet10 said:


Any sub is omni-polar anyway... having a pair of push-pish drivers has huge advantages with few disadvantages (except for having to buy 2 drivers instead of 1).

dave


ok sure thing DAVE!

but THEN LIST PLEASE! :p
hahaha

i need to understand at least a little
what is happening with bipolar?

and about softwares when desinging the box,
no one offers bipolar option, what should i take in consideration?

and also, if i put 4 drivers in the same box
2 pairs in bipolar kinda config .. wonder what it would do!
 
frugal-phile™
Joined 2001
Paid Member
Well, i sort of implied you can't build a bipolar sub, because even a single woofer is omni-polar. The advantage of using a bipolar cinfiguration to build a push-push sub that gives you active force/vibration cancellation improving downward dynamic range, reduced transmitted vibration to the box, and no problems with seeing your sub dance.

dave
 
planet10 said:
Well, i sort of implied you can't build a bipolar sub, because even a single woofer is omni-polar. The advantage of using a bipolar cinfiguration to build a push-push sub that gives you active force/vibration cancellation improving downward dynamic range, reduced transmitted vibration to the box, and no problems with seeing your sub dance.

dave


well that's the kind of good information i'm looking for ..

so is it worth it to use bipolar config on sub?
what are the cons?

i am expecting largrer volume enclosure required ..but not 100% on that one..
 
>please guys! back to the BIPOLAR subject!

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Multi-channel playback is relevant to bi- and di-polar speaker designs.

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>NEED MORE INFO ON BIPOLAR CONFIGURATION

the + and -

implications .. drivers requierement

is it good in use for sub?

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Already answered.

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>for mid?
frequency related problems?

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No, though can work well if a more diffuse soundfield is desired.

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>enclosure design considerations ( volume? )

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For a given alignment, Vb doubles.

GM
 
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