Magico - Wide vs. Narrow

@tomic601: To your list of RIP geniuses I would ad Siegfried Linkwitz. By the way, Linkwitz himself "believed" in narrow front baffles, and in his open baffle models used electronic means of compensating for the dipole cancellation that is inherent in open baffle loudspeakers.

Danny Richie of GR Research is also a proponent of both open baffle loudspeakers and narrow front baffles, but uses a different method to deal with dipole cancellation: He makes his front baffles just wide enough to house the driver(s) being used, but then uses side wings to manipulate the frequency at which dipole cancellation begins. The greater the distance between the front and rear of the driver(s) in an open baffle design, the lower the frequency at which dipole cancellation occurs. Danny’s use of side wings provides the front-to-back separation dipoles require (in the GR Research OB models), while at the same time allowing him to use a narrow front baffle.

And by the way, in the Infinity IRS and RS models, Arnie Nudell used curved wings on either side of the EMIT and EMIM drivers those models used for the same reason Danny Richie does: 1- To prevent front baffle diffraction, and 2- To lower the frequency at which dipole cancellation begins to effect the frequency response of the loudspeaker.

In his Eminent Technology LFT-4 planar-magnetic dipole loudspeaker (out of production for many years), Bruce Thigpen did as Danny Richie does: he incorporated a sloped wing on either side of the panel the LFT drivers are mounted on, the two wings facing each other. The wing is only 2" wide at it’s top (and 41" off the floor), gradually increasing to 12" at it’s bottom. I assume the shape of the wings was chosen to create the desired frequency response.

There are several GR Research YouTube videos in which Danny Richie discusses and explains this topic in great detail, showing in measurements the effects different wing sizes and shapes have on the response of different drivers. Well worth searching for.

@erik_squires wrote: "That’s an interesting POV. I would have thought that the slot [the area between back of a speaker with a rear-firing tweeter and the well immediately behind it] would act like a severe low pass filter."

Sorry I over looked responding to this earlier.

I manufacture a bass guitar speaker cabinet which uses a 3" cone unit for the top end. It’s gently highpassed around 1.5 kHz or so. Behind the cone is a wide, shallow isolation chamber which extends laterally the full width of the cabinet, with generous openings on the top and sides. So, it’s a slot of sorts. The openings allow enough of the 3" cone’s backwave energy to escape out the top and sides that the bass player can clearly hear his overtones even if he is virtually atop the cab, and I’ve gotten feedback that the other musicians can better hear what the bass player is doing as well.

I’m sure there are some losses in the slot behind the 3" cone, but it’s still making a worthwhile contribution, so I don’t think the net effect is a particularly severe lowpass filter.

Duke

@audiokinesis Thanks for that input. See I keep thinking about Snell’s downward firing cone and the behavior that the 3-4" high slot would have. Not that I can replicate it in my current listening environment, but still find very few speakers with that sense of the speaker dominating the air pressure in a room like that.

I had thought that the slot loading was a kind of low pass filter, and when you mentioned the tweeter and close wall placement I had to rethink what I knew.

I’ve been away in wine country for a week..looking for reverberation trails in casks and later on in the right glass…

I think a quick look at any of my rooms on virtual systems or of hundreds i’ve setup over 45 years of doing this will reveal zero, ZERO in the live end dead end school… in my reference room which as ive said includes if desired a rear tweeter, you will find a great affinity for diffusion. When in Seattle, stop by for a listen. 

@bdp24  i sold a lot of Infinity gear back in the golden age of that brand, we stocked everything but the IRS.  Regrets we never had the ET which ive heard in many excellent systems. We carried ADS, Apogee, Infinity, KEF, Vandersteen, Quad, Gale, Soundlab, Acoustat, Beveridge….probably a few i’ve forgot.. oh and kits …I think we had one of the first FFT for speaker design in the usa… a retail store … fun…

one learning is people love certain distortions….that is ok

left out Wilson… The WATT Puppy…. heard a significantly modified pair of mk7 two days ago…. in a perfectly balanced room…. you are there…with no rear tweeter… Essentially a fantastic balance of a modified quadratic residue and some very high tech diffuser / absorbers…

Core Audio … Novato

@bdp24 Eric - i’ve heard Apogee and the big Quad in same room… stunning…..

Best in music…..