View Full Version : 604 in back loaded horn?

12-10-2005, 07:41 AM
Did Altec used 604 in a back loaded horn?

According to this (http://www.ominous-valve.com/altec.html) site back in 1945 there was model A6 using 15" duplex.

12-10-2005, 08:43 AM

I have some reservations concerning that post. The 604 could be mounted in a bass horn unless the horn tweeter was extended to the front of the bass hprn like the DTS system. Here is s sight with the description of the A6 in the 1940's.


12-10-2005, 08:51 AM
Take a look in the Library to see what they have



12-10-2005, 09:03 AM
His word "this" is a link and there is a chart at that site listing an A6 with a Duplex.


12-10-2005, 09:40 AM
Back in my large-scale cabinet building days I made a pair of single scoops with oak plywood for a client. The baffleboard behind the mounting panel needed a special recess made to clear the driver but it turned out to be a killer system for the guy.

He complained that his old marantz tube components needed too much service and he wanted me to take them in trade as junk...I said "no room" and declined.

Man that was a mistake of youth...:(

Charley Rummel
12-10-2005, 10:04 AM
That sounds like an incredible idea! In all the years I've been into scoop designs I never considerred one with a provision to allow clearance for the back of a 604, since thay are deep to begin with. Without looking up the numbers right now, I'd think likely candidates would be the 604E and earlier versions for such a proposition.


Tom Loizeaux
12-10-2005, 04:48 PM
Even JBL's current 2155H duplex could sound great in one of those cabinets!
Anyone tried it?


12-10-2005, 08:23 PM
Altec VOTT line were all for the most part front loaded horn cabinets except for A8 and more recent models like A10 A12 A6 1993 year.

I would be surprised if the year 1945 A6 was a rear loaded horn.

Someone with more past experience should look into this matter.

The web site "another Altec page " does indeed state a duplex in a A6 cabinetfor the year 1945.

The Marketing brochure of that year shows otherwise. ( front loaded horn ).

12-10-2005, 08:48 PM
Right. They could have altered the back of the cabinet to fit a duplex in the place where the woofer would have been.


12-10-2005, 08:57 PM
Speaker Dave I don't quite get what your trying to say about alterations. You either have a front or rear loaded horn cabinet . A front loaded cabinet cannot be be altered into a rear loaded cabinet just like that. They are two completely different shaped horn cabinets.

12-10-2005, 09:21 PM
The duplex mounts, as I said, where the woofer is usually fitted, and is front loaded, with the little concentric horn peeking out at you. I believe the back of the cabinet would need to be altered because the duplex is so deep. Otherwise it would be unchanged. It seems to me we have a photo of such on our site. I'll look.


12-10-2005, 10:03 PM
I'm not finding anything. I think there is confusion in this thread from the beginning, and the original poster has not come back to clarify. He mentions back loading and then refers to a speaker that front loads. I don't know if he means front load with a horn and back load to bass reflex (what the A6 would do) or what. I've looked on our site and done some searches at Great Plains Audio forum and have not come up with anything. I've also looked again at that site he links to and I don't think it is totally reliable.

I'm going to drop the whole question.


12-11-2005, 09:50 AM
Tom Loiseux said :Even JBL's current 2155H duplex could sound great in one of those cabinets!
Anyone tried it?


Well first of all it is not called Duplex but Coaxial ,Second the 2155h is a ceiling speaker with fr. 60hz-17 khz. Not HI FI to me.

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12-11-2005, 12:18 PM
The 1945 Altec catalog does indeed show an A-6 with a duplex. The model # duplex is only listed as "special".
The enclosure appears to be the same H-110 used in the early model A-5, larger than the 825, smaller than the 210.
It is the usual VOT type front horn load, rear bass reflex load.
I don't know how they handled the depth of the duplex speaker. All VOT enclosures I have seen don't have very much clearance behind the shallower 515 series woofers.


12-11-2005, 12:41 PM
Thanks for that. You may have a catalogue not in the library here. A scan of it would be much appreciated. One of the moderators may chime in and say how it can be sent in.



12-12-2005, 02:17 PM
Back in the late 1970's, I worked sound for a band from Marietta, Ohio. The band, called Calabash, actually played a gig in CB-GB's, in NYC. The bass player, whose name was Mark something or other, had a single scoop-
style rear-loaded horn cabinet that he'd modified to allow mounting an Altec Duplex. He also sometimes played through a K170 mounted in a Leslie cabinet (!). The Altec modification didn't sound half-bad, but, to the best of my knowledge, no such rig emanated from the factory. I'm pretty sure, from the old literature I have lying around, that all its several iterations were reflex cabinets.

04-06-2006, 03:12 PM
"The 1945 Altec catalog does indeed show an A-6 with a duplex. The model # duplex is only listed as "special".
The enclosure appears to be the same H-110 used in the early model A-5, larger than the 825, smaller than the 210."

I would love to see a scan of that 1945 catalog..

Have a pair of Duplex 605Bīs waiting for enclosures.

The famous Tannoy Westminster Royal loudspeaker is a front + backloaded horn made for their 15" dual concentric driver: http://www.tannoy.com/WestminsterRoyal

Best regards,

Steve Schell
04-06-2006, 11:37 PM
Interesting link to the A6 brochure, Convergence. I was not aware of that system. I think it is a bit later than the 1940s though, as to the best of my knowledge the one piece cast 811 horn depicted didn't debut until 1952 or so. Also, the 825 style boxes shown have the slanted inner horizontal horn wall. The late 1940s model 800 small VOTT boxes had parallel horizontal walls.

04-08-2006, 01:06 PM
Hi Steve,

Here is the link to the A6 front loaded bass horn duplex speaker from Altec.