511E... factory or DIY?

[bfish]

Can anyone reliably identify the "real" 511E out of this pair on eBay?

http://cgi.ebay.com/Altec-511E-Large...QQcmdZViewItem

The black one appears to me to be a 511B DIY conversion. Having never seen a factory 511E, I'm wondering about the grey one. The aquaplas on it looks correct, but the throat appears to be the length of a 511B...

I'd be interested in a matched pair of factory 511Es if anyone here has some spares. Will buy if reasonable, or swap other Altec gear...no hurry.

[bowtie427ss]

LOL............ spotted those yesterday and remembered some informative reading on this board from a while back where it was discussed how much the 511 had to be shortened to get the mounting flange at the right point in the horn's taper.

Does the real 511E only have one mounting lug back by the flange as pictured, or has one been removed?

What's anybody's guess with regard to the damping material on the horn that appears NOT to be an authentic "E"?

Were there factory damped 511A's and B's?

That 4th mounting bolt hole threw a red flag.

[GM]

Greets!

Hmm.........

OK, my SWAG is that the short black one is the chopped up 511 used on the 9848 studio monitor which is a 31189 in the '75 system components listings and why the need for only the one mounting tab. This style was (erroneously?) listed as a 511E in the only other auction I've seen, but after a little research the longer one appears to be a true 511E. So this begs the question, did Altec initially market the 31189 as a 511E before apparently making a whole new design?

Another thing of interest is the 511E appears to be a bit larger in the photos and if the '76 catalog on the various widths/heights is correct, then it's a completely different design (which it should be) that just looks like a 511 at a glance.

For sure though due to the different throat configurations, they won't perform the same up high or down low regardless of the lister's assertions. With personal experience limited to a demo of the 9848 though, I can only theorize how audible the difference is.

Anyway, one can look at the 9848's response to see how the 31189 performs with a 700 Hz XO and the 511E appears to be a 311-90 replacement of sorts, so maybe performs 'close enough' to it.

GM

[GM]

Originally posted by bowtie427ss:

What's anybody's guess with regard to the damping material on the horn that appears NOT to be an authentic "E"?

Were there factory damped 511A's and B's?

That 4th mounting bolt hole threw a red flag.

<font size="2" face="Verdana, Helvetica, sans-serif">Greets!

They both appear to have the rubbery Aquaplas coating used on the later multi-cells with the black one just having less on it.

I've seen a pair of Aquaplas coated 511Bs that had the rubber inserts between the vanes. No 811s though.

Not sure what the fourth hole would be for except that so does the 21216 1" - 1.4" adapter, so apparently the real 511E (if I'm right) was designed with both large and small format drivers in mind (as they should have).

GM

[Old Guy]

IMHO, the fourth hole is probably to mount an EV 1.4 driver using two of it's 4 bolt holes....

[bowtie427ss]

I'm always floored by the amount of knowledge that surfaces here.

511E, according to the dimensions in both 1975 and 1978 pro catalogs is definitely larger than 511B. But, what's with the vast difference in depth between the 511B and the 511A and E?

I'm sure i've read about the "E" version having to be shortened in the throat area to put the mounting flange where the throat was 1.4 inches in dia, maybe another board i spose.

And i don't for a moment believe that 511E is over 16 inches tall as the catalogs suggest, the pics of it certainly don't suggest an aspect ratio of less than 2 to 1, but the published dimensions do.

http://www.lansingheritage.org/image...pro/page_9.jpg

http://www.lansingheritage.org/image...pro/page13.jpg

[GM]

Greets!

The 511A's dim includes its long mounting bkt: http://www.lansingheritage.org/image...orns/page2.jpg

Regardless, various dims are wrong and me and bfish had some fun awhile back about what sort of 'meds' the marketing dept. was on back in the '70s as there's a lot of seriously misleading typos.

Yes, we had this conversation awhile back and one of the posters made this and other remarks about his '511E' horns, but unless the 31189 was initially marketed as such, then his weren't 511Es IMO since they were just sawed off 511Bs with a larger driver mtg. flange welded on. I assume this is why the 9848 had a 700 Hz XO since it was anything but ideal for mating to dual vertically oriented 15" woofers, just look at the published directivity plots. Frankly, I never understood why they would bother to market such a beast for studio apps since this layout makes for poor coherence in the ~nearfield due to the HF/LF acoustic centers being too far apart, not to mention the heavily rolled off HF response of a large format driver.

As for the 511E being larger, we know it's longer than the 31189 and this alone implies a larger mouth, which it apparently has according to the auction pics.

GM

[cclark65]

Originally posted by Old Guy:
IMHO, the fourth hole is probably to mount an EV 1.4 driver using two of it's 4 bolt holes....

<font size="2" face="Verdana, Helvetica, sans-serif">Let's not forget that the Altec 906 was a 4 bolt 1.4" driver.

Off on another tangent - I know many don't think much of the 906 driver, and I don't know if it was manufactured by EV for Altec, or by Altec and EV just renamed it and modified it some. Eventually it turned into the DH1A when they enlarged the magnet structure, a very highly respected driver, which is now the Dh7 (Neo magnet I think). The EV DH1A and DH7 diaphragms will fit directly into the 906 magnets and perform fine, with a slightly less sensitivity due to the smaller magnet. Most of the drivers I use are Altec 906's with DH1A diaphragms on them.

ok, back to your regular discussion about the 511E!

[Old Guy]

That Altec driver WAS an EV.

[Old Guy]

That driver is an evolution of the EV DH 1012.

It was completely an EV desing, just rebadged as Altec.

Frankly I sold a lot of them- hundreds in fact, they were cheap and sounded decent. Not 299's, but better than a lot out there.

FWIW, that driver was first developed for Kustom.

Kustom sold it in the seventies as the MF 1012, several years before it appeared in the EV line.