Just thinking out loud here, but aren't multicells a lobbing nightmare if you run them too high? Each cell is like a tweeter at high frequency and they need to satisfy the 1/2 wavelength c2c spacing rule once the individual cells start to beam?
The rule is 1/2 wavelength center to center. My cells are about 8.5" apart c2c. So 1/2 of that is 4.25" which means there is potential for lobbing starts at 800hz.
However this is all mute since I'm sure the cells are not narrowing on axis at 800hz.
I guess the burning question is, at what frequency do the individual cells start to beam to the point they cause lobbing?
And for that matter, do we really improve things by handing off to a HF horn (assuming we could get the 288's to play that high)? Obviously, due to the size of the multi cells, combined with very short wavelengths at 7Khz there will be serious lobbing at the crossover point. But I guess that's better than lobbing from 10-15+ beaming horns all the way up to 15+ khz.
I had a pair of Polk SDA 2A's for a while and they they could place sounds behind you. IIRC they worked by simulating ambiophonics by reversing the phase of the right speaker's output and sending it to a dedicated driver on the left speaker, and vice versa.
I though recording engineers could do ambiophonics in a recording with a bit of reverse phase in the opposite channel trickery.
Please understand I'm not saying you or djn are wrong, I'm just having trouble getting my head around this. Listening to cone and dome speakers in the near field, with their wide dispersion, doesn't give that ambiophonics effect, so why do the 1505s? Is it the difference between 180 deg dispersion (cones and domes) and the 100x60? of the 1505s?
Can you elaborate on this? Why cross them at 3Khz, and what do you mean by colorful? What is it about a large room that negates this? Does lobbing become less of an issue at greater listening distances?
Sorry for the barrage of question, I'm just very curious about all this.
I'm loath to mention this since I can't remember where I read it.... maybe I just dreamt it.
But I thought a very knowledgeable person once said, that comb filtering, once sufficiently complex, act just like the peaks and dips present in room modes and as such our brains ignore it.
I'd image that multi cells could well fit into that category as there would be interference between each individual cell and the HF horn.
I don't know why I thought they were 1804's. I was going on the mistaken thought that you said they were awhile back.Don't know were I got that though. Sorry Cal !!
All the literature I have seen says they are all dual throat the (1803-1804's). GM that link appears to be broken.
Well I have to disagree with this. I have both 511B's and 3 pair of 511E's.
And the E's sound much,much,better IMHO. I also have the 21216 attachment with a set of 802G's on a pair they sound fabulous.
On my project Pano and I have measured the 511E w/288 and they extend out to 16 KHz before rolling off steeply !! And they sound great.My EV T350 tweets don't extend much past that.
Last edited:
Westrex had the WE drivers available to them whereas Altec are JBL and enough different to keep from having patent problems. Somewhere I read something though about JBL having some patent problems initially WRT phase plugs?, so maybe Steve S. and/or Todd W. can elaborate.
GM
I don't think the "centre to centre" is the same as you would expect on a direct radiator.I think there's a kind of smearing that happens.
Perhaps, or maybe it's not really there?
I Don't know were I got that though. Sorry Cal !!
No problem my friend.
That's interesting. Are you running the E's with an adaptor and a 1" driver? Like GM, I would have thought the B would sound better in that case.
same as Altec was All Technical division
( I hate everything Altec , WE and Westrex )
Question for Mr. ZM. OK - I know U luv all things Papa for electron things - but what do you like for da speaker stuff???? Any ZM speaker porn photo's???
splattered around da wakoo board
and I mumble too often about them
ask me in our official pub and I'll not resist ......
edit :
sand is for little kids
real man use toobz for amplification ( toobz - when you forget what boobz are good for )
editedit : Papa obviously still knows for what boobz are good
and I mumble too often about them
ask me in our official pub and I'll not resist ......
edit :
sand is for little kids
real man use toobz for amplification ( toobz - when you forget what boobz are good for )
editedit : Papa obviously still knows for what boobz are good
Last edited:
I guess it all comes down to whether or not the individual cells beam and if so, at what frequency.
Does anyone know what the cell's flairs are? Exponential? There should be a formula to determine if/when on axis narrowing starts. We just need the right numbers to plug in. Or is there more to it then just the horn flair?
I'm quite interested in the answer, because it makes the most sense to crossover to a HF horn below this frequency. However it might not become a problem till well above it's useful bandwidth...
Of course they are, just visualize a small 'full-range' driver at the entrance of each cell. It's a cheap way to make a shallow multi-cell.
Bozak used it to good effect to make (8) cell tweeter 'horns' for the original B310 Concert Grands.This is an oversimplification of course since the individual cell's design, ergo wall angle affects it, but it's close enough to make a point once beaming begins in earnest.
Cells, like drivers begin beaming when they're ~ 1 WL across, so an 8.5" square cell is at ~160 deg around 1595 Hz, so I'm thinking this 1/2 WL rule pertains to something else.
Again, folks like what they like. Me, I either want to XO up really high where none of us have any hearing acuity (just adds top end 'air') or down where the driver (horn) has collapsed to whatever polar response I want. This makes the tweeter horn large enough to mate well with the larger horn before beaming becomes an audible issue.
GM
Trumpets in the Bouganvillea
Funny. This reminds me of once when I was running Altec 811 horns on top of open baffle woofers. Seems I had gotten the polarity reversed on the horns without knowing. Wow! What an effect.
Since the windows in house were always open the soundstage went right outside, there was a trumpet player hiding in the bougainvillea out the window on the right, a snare drum in the hall, guitars in the kitchen. But my neighbors in the house behind would not shut up. Kept mumbling, grumbling about something. Until I realized it was not the neighbors but the piano player! Probably Keith Jarrett. Really sounding like he was out the window 30' behind me at the neighbor's house.
As fun as that all was, it sure killed normal vocals recorded right in the center. So the wiring got put back "right".
Funny. This reminds me of once when I was running Altec 811 horns on top of open baffle woofers. Seems I had gotten the polarity reversed on the horns without knowing. Wow! What an effect.
Since the windows in house were always open the soundstage went right outside, there was a trumpet player hiding in the bougainvillea out the window on the right, a snare drum in the hall, guitars in the kitchen. But my neighbors in the house behind would not shut up. Kept mumbling, grumbling about something. Until I realized it was not the neighbors but the piano player! Probably Keith Jarrett
. Really sounding like he was out the window 30' behind me at the neighbor's house.As fun as that all was, it sure killed normal vocals recorded right in the center. So the wiring got put back "right".