Altec Lansing

[Pano]

The 511 can be crossed circa 600Hz if you use some EQ. But it's better at 700-800Hz or above.
The main problem I found was that midrange bump, the 1-2K octave you mentioned. Flatten that and a lot of the honk goes away.

[steve71]

Originally Posted by Pano

I have not measured the 1505, but the 1005 starts dropping above ~7KHz with my drivers. That's about where I bring in the tweeter.

I wonder about those Westrex drivers that Mr. Hiraga has on his A5s. They are supposed to be equivalent to the 288, but they don't look like them. And I never ran them with tweeters, even tho Hiraga did. The tweeters did add something, but I found them unnecessary. Maybe the Westrex have a better top end?

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.

[Pano]

I dunno, but it's a good question.

A lot of talk in hifi and pro circles about how the multi-cells lobe and comb filter. If they do, I just don't hear it. Nor have I had anyone comment on it when listening to a pair.

But maybe some ears are more sensitive to it than others.

[steve71]

Originally Posted by GM

Nope.

djn appears to have a very reverberant room, so combined with a pair of such large multi-cells, I imagine he sits well within their near-field, probably even closer than with the 825, so a very spacious, if not near holographic presentation, is possible with a good stereo recording. I experienced it regularly when I had stacked 511s on top of 211s. Telephones ringing, doors slamming, chairs being slid around, etc. off screen and behind me on some movies and TV shows would sometimes have my head jerking around involuntarily.

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?

Originally Posted by GM

Just one more reason why I advocate large mids systems with low XO points, though I still contend that multi-cells per se are a bit too 'colorful' for all but the largest HIFI/HT apps if not XO'd to a super tweeter system in the 3 kHz region, in which case the basic horn without all the individual cells should suffice. Such a horn should be easy to DIY, so rather surprised no one on any of the forums has done it AFAIK except 'in the round'. GM

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.

[steve71]

Originally Posted by Pano

I dunno, but it's a good question.

A lot of talk in hifi and pro circles about how the multi-cells lobe and comb filter. If they do, I just don't hear it. Nor have I had anyone comment on it when listening to a pair.

But maybe some ears are more sensitive to it than others.

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.

[Altec Best]

[QUOTE]

Originally Posted by Cal Weldon

Cal's are 1803's

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 !!

[QUOTE]

Originally Posted by GM

Hmm, the old data I have says all the large format multi-cells can be (1) or (2) driver loaded depending on the adapter/throat combo and the 1004, 1504, 1804 can be loaded with (2) dual driver throats, i.e. (4) drivers, making for 100+% eff.! with 290s.

All the literature I have seen says they are all dual throat the (1803-1804's). GM that link appears to be broken.

Well, the 511E is an alternate way to reduce it somewhat since its 1" throat is sawed off and re-flanged to accept a 1.4" throat driver, but the trade-off is reduced HF extension, so for some (many?) folks it's not an acceptable alternative.

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. And why I'm going to stick with just the 511E/288.But I really like my 1005A tar-filleds the best though.And am seriously thinking of using the 1005 Multi.It is just so darn heavy and big,were the 511E is nice and compact.With the boxes already being 20 cubes I really would like to keep the horns as small as possible without trading quality of the output.

[GM]

Originally Posted by Pano

I wonder about those Westrex drivers that Mr. Hiraga has on his A5s. They are supposed to be equivalent to the 288, but they don't look like them.

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

[Cal Weldon]

Originally Posted by steve71

Just thinking out loud here, but aren't multicells a lobbing nightmare if you run them too high?

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.

Originally Posted by steve71

that comb filtering, once sufficiently complex, act just like the peaks and dips present in room modes and as such our brains ignore it.

Perhaps, or maybe it's not really there?

Originally Posted by Altec Best

I Don't know were I got that though. Sorry Cal !!

No problem my friend.

Originally Posted by Altec Best

I have both 511B's and 3 pair of 511E's.
And the E's sound much,much,better IMHO

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.

[djn]

I've got a pair of big *** Yamaha pro compression drivers. Were they made by Altec?

[Pano]

Originally Posted by GM

Westrex had the WE drivers

Well the Westrex drivers look a lot like the WE drivers. Including the nifty handle on top to lift them by!