Dipoles ?

[Gary P]

This is interesting stuff. I've just started playing around with dipole bass and the linked page answers some stuff I was seeing but did not understand where it was comming from. My room has a peak at 22Hz and drops off pretty fast after that.

My room is 6.7M x 4.1M x 2.43M and has a hallway that extends the room on one end and an open door into the kitchen on the other end.

I really like the way the dipole bass charges the room. Nice full clean sound without overhang. The main transverse standing wave that was causing a major suckout at 70Hz using monopole speakers is missing in action with the dipole subs. Much nicer!

I'm using 4 Dayton IB15 drivers in pairs in W frames. Plenty of displacement for my setup. With the high Q of the IB15's and the room peak I'm finding that the slow rolloff of a Bessel 12dB/octive at 40Hz matches up with the rest of the system nicely.

Gotta get back to work, the bass-mid speakers are waiting for me to make some changes...

Gary

[mac]

In my room, and in the other rooms that I've heard the Orion, the bass response has been superlative. Not only do Orions have puhch, they also have articulation. Dipoles excite fewer room modes and depending on the room the difference can be rather dramatic.

[AJinFLA]

My dipole to 35hz, monopole below system has as much "punch" as there is in a recording. No more. No less. It absolutely trounces any type of box boom bass. My 2nd job is audio/video setup for corporate events.
A friend who I work with at these events is a drummer. Tours with some (relatively) well known rock bands as a drum set tuner.
He said the bass in my room is the most realistic rendition of a "live" drum set he has ever heard. I agree. After 20+yrs of owning many,many a high end box (like the B&W 801 for example), I'm never going back. Unless you live in a castle, go sealed below 35-45hz, dipole above. End of story.

Cheers,

AJ

[exipnos]

With all this positive remarks about dipoles I just have to try it soon. Okay low point for dipole bass 35-45hz upwards. But how high up in freq would the 2 bass woofers play?

All the OB dipole threads seem to focus for music and only 2 main speakers. Whats your take on dipoles for home theatre use? Could/should dipoles be used not only for the mains but also surrounds?

[ScottG]

Originally posted by LennyK


Scott - do you say, that dipole designs, like Orion for example, lack bass punch ?

I like punches [in terms of bass of corse ].

L.

As Rudolf has suggested, yes dipoles in general lack "punch" when compared to the monopoles - BUT I would go further (contrary to what others have suggested) and state that a dipole (in the repsective passband) is not just less accurate than the "event", but perhaps CONSIDERABLY less accurate. (..I remember quite clearly when SL was struggling with this same subjective "qualifier" on the MAD board (..and unfortunetly little if any help was forthcoming at that time).

At the same time though dipoles seem more accurate to the source/recording (as Scott and AJ have remarked). Certainly imaging is F A R more accurate for the respective bandwidth, whereas your typical bass reflex or acoustic suspension in the same bandwith is subjectivly pushed forward in the soundstage.

Of course I mentioned a solution, but what is really happening here?

As Scott, Mac, and AJ have remarked - the general concensus is that this is a LISTENING room generated distortion. I however, do not think this at all.

OK - why not?

1. I hear/feel more "punch" at an event (depending on proximity to the source - AND nature of that source) than I do from recorded ("music") reproduction via traditional monopoles (..let alone dipoles). This even includes event's in a nearly free-field enviorment (like an outdoor concert).

2. I've heard room modes generate something similar to "punch" on occasion, HOWEVER such an effect is always acompanied by a "booming"/"droning" decay. This is clearly NOT what "punch" sounds like at an event where room modes are a non-issue.

3. A NON free-air dipole can reproduce more "punch", (considerably more all else equal), than a free-air dipole. (..i.e. free-air would be 2 drivers without enclosures with the same directional behaviour running in phase, NON free-air would be drivers in an acoustic suspension within their own sealed and seperated enclosures with the forward driver in-phase and the rearward driver in reverse phase. Both of course eq.ed flat.)

As to WHY this occurs? Well its likely that it is a number of factors, BUT I'd say that acoustic compression is high on the list.

[Scottmoose]

Some interesting points above, and I don't disagree that compression is quite possibly (probably?) a factor. That said, we need to keep in mind that at real live events, especially if it's a rock concert, a heck of a lot more air is being shifted than you'd ever achieve in your living room, so I'm not surprised you can feel more physical SPLs, even at an outdoor event. It's all down to taste really, and what you want to achieve, and what you enjoy. Generally, I'd rather try to get as close to the recording as I can, which is what dipoles achieve, rather than second-guess the artist, but that in itself is subjective, and opens up another big can of worms!

Personally, I found these (I think there's a link to it on SL's site, but don't hold me to that!) most instructive when looking at the behaviour of different enclosures at room boundaries. The Orion BTW, is, as I understand it, illustrated by the last diagram, at least in the bass-regions.

http://www.kettering.edu/~drussell/Demos/rad2/mdq.html

Oh -a surround setup with dipoles? Why not. If you've got a big enough room (they aren't small enclosures...) then this would be a superb way forward. That said, remember that human hearing behind the head isn't so hot. We can't locallise sound as accurately, so they won't make as dramatic a difference as those at the front.


Best
Scott

[AJinFLA]

You also must understand that for some, "accurate" bass is the bloated "boom" that you hear driving down the road in car stereos. You know the sound I'm referring to. Boom thump boom. If you were to stop and ask one of these types whether their boom/bloat bass system "hit hard" (their words for "punch" or "slam",etc) they would tell you absolutely yes! If one of those types were to listen to the bass produced by a dipole like my Orion clones, they would tell you that it sounded CONSIDERABLY inaccurate,etc., because it doesn't have that bloated boom that they crave and consider accurate. They want room mode excitation and they want the power response to have a huge tilted imbalance towards the bass region because it represents "CONSIDERABLE accuracy" to them . So it really all depends on what you're looking for. Obviously, myself and the others who have (hopefully ) competently built dipoles for our normal sized rooms are not looking for that type of (bass)sound. (We also don't suffer from a serious case of SL envy - quite common on these internet forums - hence no SL). We would rather it sound like an actual drum set playing in room than the rendition you hear at a stoplight.

Cheers,

AJ

[Rudolf]

Originally posted by AJinFLA
You also must understand that for some, "accurate" bass is the bloated "boom" that you hear driving down the road in car stereos. You know the sound I'm referring to. Boom thump boom.

That was exactly what I had in mind when saying that my dipoles don´t deliver punch.
With linear response in anechoic environment being a dominant sales argument today most commercial speakers MUST sound boomy in real rooms.

Regarding ScottGs argumentation:
Many times I hear a band perform their records on stage the bass is obviously exaggerated compared to the record. The same "relative" amount of bass boost on the CD would immediately have woofers clip in the average ghetto blaster. So I don´t see the argument that dipoles per se must be less accurate than the "event".
Obviously must of us don´t have the space and collected amount of loudspeakers to do "real" bass levels at home.

[reins]

in an open air concert, acoustic instruments sound different (at least I hear them different) as the original unamplified instrument. I made this expierence at B&W demo sessions as well.
What I want to achieve with my system is, that a guitar sounds like a guitar, that I have the feeling it as as small as one and not some huge airy monster instrument. And the same is true for drums.
A bit of a problem I get with electronic instruments. Should they sound as in an open air concert?

Stephan

[opp]

A suggestion for those who want to play around with dipole without offering a fortune on Peerless XLS. - or similar.

I am currently designing a dipole system using 4 Tang Band W8-740E, those 4 cost less than one Peerless XLS! They are even reasonably small and can thus be designed to an acceptable WAF value. The system is up and running as a prototype, so far – and based on these low-priced drivers – dipole is superior.