511E vs. 311-90

[chip_junior]

There are a number of documented mistakes in Altec lit...usually dimensions..


Note the A is shown as huge too...8" taller than a B...

Here is an interesting pic...looks like a cut off and welded on flange to me...

Oh, just interestingly found out my horns is here.

I'll provide some more information about these511E vs 511B and comparing to 311-60 tonight.

I've also did some measurement on the frequency response of the 511E with the original 288D too.

[chip_junior]

I have both. The 511E's I have, have the original dark grey color, aquaplas coating and original stickers with serial numbers on them. They are nothing more than modified 511A/Bs...trust me... I have viewed the catalog you referred to that intimates larger size... but until someone has a set and can provide incontrovertible proof....I'm convinced the catalog is garbage.

I totally agree with Steve, who also have both 511E and 511B. To me, 511E would be a modification of the 511A/B series.

Cause they are just a modification, they just cut the throat shorter, solder the bigger mouting flange, add some alquaplas and that's all.

My 511E pair have 2 horns made in different time and they also showed some interesting difference! However, both of the having the same size and also the same size with the 511B except the shorter and bigger throat.

[chip_junior]

If you go to Altec Pro which is still up, and look at the PDF's...

The PDF labeled 511A states 500 HZ cutoff.

The 311-90 PDF states 220 Hz cutoff.

I don't understand and don't believe that Altec innocent enough to cross their horn at it's cut-off frequency (as with the A7-500 with N500 cross) in case the public 500Hz cutoff of the 511A horn is correct.

Looking at how they named their horn, which all horn have cutoff frequency lower than the nominal lowest working frequency of the horn, we have ground to believe that the 511A/B horn should have lower cutoff frequency than 500Hz.

Of course, 511 can not be compared to 311 cause the first number has already show their norminal working frequency already.

[Old Guy]

I don't understand and don't believe that Altec innocent enough to cross their horn at it's cut-off frequency (as with the A7-500 with N500 cross) in case the public 500Hz cutoff of the 511A horn is correct.

Looking at how they named their horn, which all horn have cutoff frequency lower than the nominal lowest working frequency of the horn, we have ground to believe that the 511A/B horn should have lower cutoff frequency than 500Hz.

Of course, 511 can not be compared to 311 cause the first number has already show their norminal working frequency already.

Can't argue with that logic...I was more trying to show that anybody who states 511E and 311 have the same specs is a liar or a fool...

I would suspect the 511's cutoff to be between 400-500, I could calculate it but am too lazy. At my age you pick your battles.

[Altec Best]

At my age you pick your battles.

But still sharp as a tack Thank You !!!!!

[chip_junior]

I would suspect the 511's cutoff to be between 400-500, I could calculate it but am too lazy. At my age you pick your battles.

I've done some basic frequency response measurement for the 511E with 288D driver using RadioShack dB meter. It look like that the 511E might not be suitable to be crossed above 750-800Hz.

Here is the picture showing that the horn start to be rolled-off below 800Hz. The 511E+288D combo was actively crossed at 450Hz-LR24 and 8.5kHz-LR12.



Look at the response, I think the 511E properly has higher cut-off frequency than the 511B due to having shorter throat as well.