Anyone try building dipole surrounds??

Do a search on the htguide forums. You'll find a few designs

I could never find a DIY dipole surround project that looked worthy of building. Some of them looked really weak or something was just missing from the design and I could never come to want to build any. All the other surround speaker projects were typical monopole and everyone was happy with that.

I found that for the price, a DIY dipole surround speaker just wasn't worth the money once I found Emotiva. Check out their site and look at the ERD-1. They are real affordable. About $300 a pair (on sale right now for $250 with free shipping) and they are build real well. They even have switches on the back to flip the polarity of the tweeters so if you want you can have it be dipole or bipole. I have a pair and plan on getting another pair soon to get my 7.1 capability back.

Vance Dickason's Loud Speaker Design Cookbook (6th addition) has a design with dipole tweeters + single mid-bass and how to get the levels right.

Good dipole surrounds actually have two separate low-frequency enclosures back to back with a low pass filter on one to avoid dipole cancellation at lower frequencies.

What if you took 2 identical bookshelf speakers, placed them back to back, and ran them out of phase? Would this not accomplish the same thing as a dipole?

I thought dipoles had fallen out of favor. If you have a 7.1 setup (multiple surrounds, IOW) does this not effectively thwart aurolocation of the surrounds (which is also supposedly the benefit of dipoles)?

Bass would roll off at 6dB/octave starting at .17 * 1130 * 12 / ( 2 * speaker depth in inches) Hz and you'd have a peak at .5 * 1130 * 12 / (2 * speaker depth in inches). Notch and shelving low-pass filters as on a pro-sound parametric equalizer could compensate for this although you risk running out of displacement with small mid-bass drivers - with 6" deep speakers you'll loose 6dB of headroom at 100Hz.


Nope. If you're trying to fit surround speakers into a modest (not 20' wide) room and have more than one listener they prevent a collapse of the sound field into the nearest speaker.


Multiple surrounds reproducing the same channel help but you still get sound movement into the nearest speaker. This also means using something like Lexicon Logic-7 which isn't just using the two rear speakers for the THX-EX/DTS-ES surround back channel.

I bailed out on the dipole surrounds about two years ago. You may want to look into small mono pole surrounds. Are you doing 5.1 or 7.1 ?

Just my two cents.

Kg

I've been working on a omni design surround, trying to figure a way to make it stealthy. As a test i placed some 6" coaxials in 36"x6" pvc tubes with the drivers upfiring and the results were pretty impressive on the imaging side considering the drivers are junk.

Drawing up a mission style torchier style lamp with the lamp dish as a sort of waveguide. Don't know if i'll ever build it but i did find the omni directional sound to be impressive...at 6ft high or so might be a real performer.

I've found that I prefer the presentation from high-mounted omni-ish surrounds as well. My current ones are upfiring 8" Tannoy Dual Concentrics. That is overkill. I don't think surrounds have to be particularly good. If I were starting from scratch I would probably use the cheap Pioneer 8" widebander designed for ceiling speakers. But I had the drivers, so why not?

I really like your general idea for integrating the surrounds into the room by building them into lamps, but I think you'd do better to just mount the driver on top. You don't really want to constrain power response here.

And maybe surround the driver with an LED ring so that your surrounds can function as an energy-efficient lamp, too.

I've actually been thinking about the SEAS coax with the clear cone and some clever use of LEDs to light upwards and down through the cone and use the cones rear wave as well....bass will be for sh%#t though but maybe i can figure a way around it. The seas cast frame would make a nice touch and have the magnet concealed in the base. OOOh i'm rambling again..sorry.

Thanks, Drew. I guess it means I would have to roll the bass off on one of the pair to prevent destructive interference at low freqs.

My understanding of 7.1 is that the rear surrounds have different content than the L/R surrounds. Is that not true and would that not then prevent the problem of aurolocation to the nearest speaker (especially if you time them to arrive concurrently)? I am interested in but a single "sweet spot" and would not have to compromise for multiple listeners.

I found that they took away from the directivity that you can sometimes get from monopoles. At the same time I have heard members say they miss the envelope effect they get from dipoles. The envelope effect can be created at the studio and be a part of your playback system with mono poles.

Also there are no studio's using diploes, it was a big part of Prologic back in the 80's which is pretty much a dinosuar at this point in our HT evolution.

I'm curious how an auto program like Audyssey would recognize diploes.

Kg

Hey DS-21,

I have DC's like you and have done some surround channel testing using my 8" DCs compared to the 6.5" ICTs (full-range crossover-less for those that don't know their Tannoy drivers ). I switched back and forth for about an hour between the two and really could not discern any appreciable difference when crossed over at 80 Hz.

Even though I have many other 6.5" and 8" DCs, I'm going to go ahead and run two pair of ICTs for the side surround and a pair for the back surround; all upfiring as my room is only 12' wide and this configuration should really help to make them less localizable. The ICT is a 4 ohm driver and there will be one to the side of each row of seats, with a series connection for an 8 ohm load.

I have to watch the impedance as I'm using an Emotiva DMR-1 receiver rated at 125x7 into 8 ohms with no rating into 4 ohms; I figure it will be fine for the two back surrounds since there is very little data coming from them. Front three are System 1000 and at 94/dB efficiency should yield plenty of output.

How high do you have your surrounds mounted?

I had the same result when I switched between the 8" DC's for KEF Q-Compacts, which have a 5.25" coincident driver. And that's with System 12 DMT II's up front.


I would think that a single 6.5ICT would be sufficient for the sides, as well. And I wouldn't really worry about the impedance issue. Frankly, if driving the surrounds at 4ohms causes any problems at all for the receiver, Emotiva should be ashamed of themselves.


They're at about 6' off the ground, plus or minus a bit. I only have side surrounds in my current room, and they're a little behind as well as to the sides of the main listening area.

I may run just one ICT, but I will have 2 rows of seating (and possibly a 3rd row counter with 3 barstools as well) and thought I might experiment with one speaker per row for the main two rows...I didn't want the side surrounds ending up in front of the people in the 2nd row.

You are correct...the Emotiva will be fine. I know of guys running 7 4-ohm speakers on their DMR-1's with no issues.