Why the 300Hz horns?

[Panomaniac]

That's way groovy. Yeah, can see them as stand alone horns - on a pole.
If they make such good midrange horns, I'll have to keep an eye out for some 290 divers. I know someone here who has a pair.

FWIW, my 803 with the Radian driver is anything but flat. Very 2K~3K dominant. Takes a good bit of work to tame them. Nice 6dB/octave roll off above that. Cal, maybe that's why your 1803's sound so "in your face." But you have better drivers than I.

Thanks again for the info guys.

[Todd W. White]

The system I refurbished at Razorback Stadium in Fayetteville years ago was an updated version of a huge system originally installed in the early 1960's.

The original system had two 210 Bass horns on their sides, with 11 - that's right 11 - 203B 2-cell Multicellular Horns mounted on top of them in a semi-circle. HF drivers were 290's of the era. LF's were 515B's.

The updated system, which was installed by WestArk Sound out of Ft. Smith, used MRII542A's, coupled with 290E's, and had 4 817A Bass Horns with 3156's in them.

Not as impressive.

When I was called in to repair and update it further in the late 1980's, all of the 290E's had suffered water damage, and the woofers were shot.

We replaced the 290E's with 290K's, and properly waterproofed them. Many years later (something like 10 or more), only one had leaked. The woofers were reconed with 515GHP-series cones.

The entire system was driven by a huge set of 1590C's with SeQur amplifier couplers in 200-volt mode using 16-gauge wire (another WestArk contribution to the system). They ran hot and full throttle all the time. It's a wonder they got ANY sound to the scoreboard cluster from the PressBox at all, but Frank Broyles wouldn't spend the money for the relocation of the amp racks I recommended, so we did the best we could...

Overall, the new drivers and reconed woofers were a vast improvement, though not as effective in the vocal range due to the MRII542A Horns. However, the system worked so well that it was left virtually unchanged until the UofA "bowled" the stadium not so many years ago. In fact, you could understand the announcements in the upper deck on the Home side, even though we didn't have any speakers aimed up there at the time.

After the revamp, calls and letters came into the UofA Athletic Dept. congratulating them on the wonderful "new" sound system!

I think it's all JBL or EV or something stupid now - it's loud, but intelligibility is not good.

At least to my ears...

[Panomaniac]

And speaking of PSYOPS in 'Nam - what are the horns and drivers used in the famous Kilgore Helicopter attack scene in Apocolypse Now?

You can find clips on youtube. In this clip:
[nomedia="http://www.youtube.com/watch?v=vHjWDCX1Bdw"]YouTube - Apocalypse Now - Helicopter Attack- Kilgore[/nomedia]
.. --you'll see the horns starting at about 3:20 in.

They are using horns with what looks like 12 drivers per horn. But I can't tell what the horn or drivers are. Someone here knows, for sure. They may not be period accurate, just wonder what they are.

I used to know what the R2R deck in the 'copter was. Panasonic IIRC. When the film came out we had the exact same R2R in the radio station where I worked.

So just for fun - what are they?

[Horn Savant]

a good time to ...maybe experiment with 350-400 Hz XOs if a HIFI/HT app.

GM

I notice pre WWII Western Electric had 300hz X/O (TA*7777, TA*7375/6 crossover) but some in the 1940s were 400hz (TA*7473 - 1939 design)

"

[Panomaniac]

Hey guys - I didn't think this would be such an interesting topic.

I'm right there with the 500Hz x-over, Vathek. So far that is what sounds the best on my setup. My driver drops like a stone under 250Hz, so an octave above that works great. I once tried to figure out some sort of "rule" of cutoff frequency from the published specs of many horns. Could not do it. For a given mouth size the specs were all over the map. Except Altec - their horns were always massive for the given low end cut-off.

GM, what sort of amp do you mean? A high output impedance tube amp? How high? I could build one, I guess. Doubt horns would need anything more than an EL84 or an SET.

H-S - thanks for the crossover schema. "retard" coils, indeed!

EDIT: Looking at that "Theatre Apparatus" again, it sure is a 300Hz, 2nd order Butterworth 2-Way for 16 ohm drivers. Do you know who the patent is granted to? A certain Mr. Otto J. Zobel of AT&T. Filed in 1920, granted in 1925.

[bfish]

An important factor we HIFI geeks often forget or ignore is the symbiotic relationship our favorite gear had with the telephone system. "Loudspeaking telephones" were the forebearers.

Telephone bandwidth has historically been ~300-3,000Hz. While that seems to be a coincidentally-similar BW to the Giant Voice systems, it's really more than that, as the GV control/signal was fed to the remote amp/speaker stations via dual, twisted pair, simplexed phone lines. As an added precaution, the 290s each had a 15045A xfmr for low frequency attenuation and driver protection.

Bell and others have done exhaustive research on speech intelligibility. While the 3kHz BW has long survived for practical adequacy, it's well known that consonant intelligibility is signifigantly improved by extending the BW up to ~7kHz. Coincidence that that happens to be the be the FR of 290s and 300Hz systems? I think not.

OTOH, try telling 755 cultists that the object of their passion is merely an output-limited wideband telephone receiver, and you'll be left picking up your own bar tab.

[Panomaniac]

It all goes back to the telephone, always....

And for you 300Hz horn fans, this guy has just put a few up on eBay.
One pair of 1003B, two pair of 803B. I wouldn't mind having the 10s.

Altec 803B 300hz Horns w/ 288/291 Throat Adaptors WOW!! - eBay (item 160337313633 end time May-31-09 18:29:00 PDT)
Altec 803B 300hz Horns w/ 288/291 Throat Adaptors WOW!! - eBay (item 160337314017 end time May-31-09 18:34:00 PDT)
Altec 1003B Multicell 300hz Horns Impressive Classic!! - eBay (item 160337314730 end time May-31-09 18:37:00 PDT)

Some other Altec stuff, too. All in Ohio.

[Horn Savant]

300Hz, 2nd order Butterworth 2-Way for 16 ohm drivers.

The one with the matching autotransformers at the output is for vatious combinations of TA-4181 woofers (introduced 1936) which are 12 ohm and there could be one or two or four, thus the option for 6 or 12 ohm in series/parallel combinations. HF was one or two @ 24 ohms speech coil like early Altec 288's


Picture of 300 hz X/O horn (mid 1930's)
LF & 300 hz horn

[Panomaniac]

Ah, yes, I see. Running the numbers thru another calculator shows those are the values for 300Hz on 12 ohm drivers. I wasn't too far off....

[Horn Savant]

[quote
Picture of 300 hz X/O horn (mid 1930's)
LF & 300 hz horn [/quote]

Looking at this picture again, I see superb lower Midrange loading with the 25A horn (40" x 26" face = a 100 hz horn !) and that long exponential taper with the elongated model 20A 'Receiver Attach' for 555 - good loading to way below 300 hz (exponential has better LF performance than CD,Tractrix). I once discovered this same set up in a theater in Sparta,WI !

Some good ideas here for home construction/experimentation (overall length of 25A+20A+555=35.5")