Guest Peter the Greek Posted February 12, 2014 Posted February 12, 2014 (edited) Note: I don't want to get into a dipole v monopole discussion. Has anyone ever made a dipole rear speaker or can point me in the direction on where to get info on their design? I can't seem to find much info on them. Crossover? driver characteristics? Any help or advice would be most appreciated Cheers, Peter P.S. I am away at the moment and reception is average (so if I go MIA that's why) Edited February 12, 2014 by Peter the Greek
svenr Posted February 12, 2014 Posted February 12, 2014 Disregarding your note - dipoles are not suited for surround applications. Refer to Floyd Toole's "Sound Reproduction" for a detailed discussion.
Guest Peter the Greek Posted February 13, 2014 Posted February 13, 2014 Hi Sven - my room is ~3.6m wide......in these instances they can be better
betty boop Posted February 13, 2014 Posted February 13, 2014 Please be carefull re definition of dipoles/bi-poles, which are you looking for ?Di- poles in surround use, utilise drivers firing either side out of phase. Idea is they work with other speaker out of phase to create a null zone.Bi-poles have same phase sound fired either side.Can utilise a simple switch as some speakers have to change bi-pole to Di-pole. Ie just switches phase on one set of drivers.Di-poles out of phase in my opinion are little old hack / old school from pro logic days and cause havoc when trying to run audyssey and thd like to measure, calibrate, setup and eq. Their directionality is also not upto bi-poles and mono poles.My previous pair of side surrounds were bi-poles I had back in pro logic days switched to Di-poles that I had switched back to bi- poles to Better handle surround mixes of today.Current side surrounds are bi- poles and work better with better directionality to suit the discrete surround mixes of today.For rear surrounds I use mono poles and would not use anything else.
svenr Posted February 13, 2014 Posted February 13, 2014 Hi Sven - my room is ~3.6m wide......in these instances they can be better Could you make a sketch showing the room, the listening position, the location and orientation of the dipole surround speaker and the arrival direction of the direct sound and 1st reflection from that dipole? Would be interested to see how that comes together in your room. 1
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 (edited) Disregarding your note - dipoles are not suited for surround applications. Refer to Floyd Toole's "Sound Reproduction" for a detailed discussion. Indeed people should read what Toole says, before taking this as a generalisation. He identifies a number of issues which may be present with dipole loudspeakers.... which are very real issues and should be avoided.... in the end you can understand why he says "dipoles are unsuitable" .... however. Essentially it boils down to two big things... which are criticisms which should not be limited to just surround applications Dipole can behave worse close to boundaries (than other speakers) Dipoles with too much distance between the front and back radiation will not have uniform directivity What this means is the 'traditional' surround dipole is a bad idea. This is the one which uses two separate drivers to create the dipole.... often they are very small drivers (with a relatively large distance between) ... and often they are designed to mount on walls. If one were to place a dipole away from boundaries (ie. free standing, with the wall behind them a very long way behind) ... and the dipole had small enough distance between its radiators .... then there isn't any remaining issues. Very few people would be lucky enough to have room for this setup. My new room later this year, is going to have 4m+ behind the listening position. This allows the surround speakers to be placed where the side nulls correspond to the reflection points, and the rear radiations reflection is outside the early reflection time window. When the problems are avoided (that is often difficult).... dipoles can be "state of the art" surrounds due to their tighter and more more uniform directivity (tighter directivity being a desirable as the room decreases in size) Di- poles in surround use, utilise drivers firing either side out of phase. Yes. Dipoles like this (with too much distance between the two drivers for their size) are ridiculed by Toole for good reason. Edited February 13, 2014 by davewantsmoore 1
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 Hi Sven - my room is ~3.6m wide......in these instances they can be better Could you make a sketch showing.... Yes. It will require quite a lot of distance behind the listening position. FWIW - The speakers I am talking about are the "Note II RS" ... which are very similar to Linkwitz' successor to the Orion (the LX521)
Guest Peter the Greek Posted February 13, 2014 Posted February 13, 2014 (edited) Yawn.......I knew the discussion would go this way Ok, so given my room nuances (read annoying size) I have engaged The Erskine Group to assist with plans and layout. They have suggested that given the size (3.6m'ish x 5m) that they have a preference for dipoles to assist with localisation issues, which in their opinion is a more serious issue for rear effect speakers. Here is an old, old, version I had drawn. Ignore all the speakers, but the seats are about right: Edited February 13, 2014 by Peter the Greek
svenr Posted February 13, 2014 Posted February 13, 2014 The discussion is indeed going in that one annoying direction. Superimpose the directivity chart on the wall-mounted dipoles and work out the direction of direct sound arrival amd 1st reflection. Then compare that to Toole's comments.
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 (edited) Use all monopoles with high and controlled directivity localisation issues Localisation is essential for discrete channel surround formats. Yes, you will be sitting too close to the rear speakers in the rear seats .... but using a bipole or dipole in that way (to destroy localisation) is not the solution. Edited February 13, 2014 by davewantsmoore
betty boop Posted February 13, 2014 Posted February 13, 2014 ok looking at that plan for speakers you would need to ensure phase was something like below for driver sets, ie so they cancel and create a null zone between cancellations also as mentioned before though this sort of arrangement is pure havoc for likes of audyssey for setup, config, eq and calibration. also I think people need to be aware we are talking about di-poles in this case as suited for ht surround duties, not dipoles in the sense of linkwitz orions or panel speakers and such.
Guest Peter the Greek Posted February 13, 2014 Posted February 13, 2014 Right, so I assume no one has actually built a pair of di-pole rears? No audyssey in this house BTW, every channel will have its own parametric eq/dsp, with the mains/subs being fully active. ......I'll take the advice of the foremost expert in the field globally (from a practical implementation perspective)....I know this flies in the face of Toole, but that's the way it is
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 (edited) also as mentioned before though this sort of arrangement is pure havoc for likes of audyssey for setup, config, eq and calibration It also doesn't work well for discrete channels of surround (which is what everyone uses) ... stereo or mono surround channels where the speaker which are supposed so cancel have the same signal, then it can work. Edited February 13, 2014 by davewantsmoore
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 Just to be clear.... (Al, you seem confused) di-poles in this case as suited for ht surround duties These dipoles are completely unsuitable for ht surround duties (when using discrete channel surround) not dipoles in the sense of linkwitz orions or panel speakers and such. Which are very well suited for surround speakers if they do not have boundaries too close
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 Right, so I assume no one has actually built a pair of di-pole rears? Me?! (did you read my posts?)
betty boop Posted February 13, 2014 Posted February 13, 2014 Right, so I assume no one has actually built a pair of di-pole rears? No audyssey in this house BTW, every channel will have its own parametric eq/dsp, with the mains/subs being fully active. ......I'll take the advice of the foremost expert in the field globally (from a practical implementation perspective)....I know this flies in the face of Toole, but that's the way it is as I think have tried to explain there isnt anything fancy about a di-pole surround. its same as a bi-pole surround just one side wired out of phase to other. typically the phase inversion is done via switch on the tweeter on one side. if have a full driver set either side, would be matter of phase inverting one whole side. ps with regard audyssey whether use it or not, the issues of phase given nature of di-poles dont go away just because use a different system of eq/dsp. with regards some "foremost expert" in the field, have they made the suggestion speaker/driver arrangement above as well, as would have some questions as to why !
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 ......I'll take the advice of the foremost expert in the field globally (from a practical implementation perspective)....I know this flies in the face of Toole, but that's the way it is Surely if you read the justification Toole gives you will see it is obvious that he is correct. The dipole speakers like in your picture will not work for discrete channel surround .... Who recommended them is irrelevant. If they are trying to remove 'localisation' by using dipoles in that config (with the polarity suggest by Al) .... then they have assumed mono surround (same in all four speaker) ... or stereo surround (same signal in LS and LB). Is that what you will be using? 1
davewantsmoore Posted February 13, 2014 Posted February 13, 2014 Note: I don't want to get into a dipole v monopole discussion Oh. Without the word of a lie, I only just read that. All I can say is that I hope you change your mind.
Guest Peter the Greek Posted February 13, 2014 Posted February 13, 2014 I guess we'll see what they come back with....worst case I end up with some more mids and tweeters sitting around that I might need to flog, not the end of the earth. Here is some of the reason for their use: The null field is created as a result of the cancellation that occurs with dipoles being out of phase. Your ear should be in that field to create the desired diffuse effect. Also given multiple seats and rows and being so close to the walls you have issues with SPL differences as the closest seat is very close "relatively speaking" and the end seat is 2-3 times that distance. In a larger room, these variances are smaller, in a relative sense
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