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Altec 615B/A duplex?

lattiboy

lattiboy

Well-Known Member
Hi everybody,

I’m debating picking up a pair of these, there is practically no information about them online except for the original ad flyers.

Some people say the 615 is the commercial version of the 605, others say the HF cutoff is 12K, so they’re worthless for HiFi.

These are in enclosures and have internal crossover. I’m going to demo today, but wanted to see if anybody had any additional info on them.


Thanks!
 
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If you have ever heard a rock concert sound good, thank Dr C Paul Boner and sons. The Don Davis mentioned was the vice president of Altec Lansing.
https://www.aes.org/aeshc/jaes.obit/JAES_V27_6_PG538.pdf

The 615 is a 605 except for the horn which makes it useless for hifi.

That teardrop shaped nugget intended to aid conical dispersion creates a big, on axis, null in the VHF. That rather sucks for aiming your speakers at a dedicated listening position.

Cut or grind that thing out of their and they would sound much closer to a 605. But, the conical shaped horn is still going to impart a different sonic signature than the 605, that might not be a bad thing.
 
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Maybe with the enclosures he can use them as woofers only?
What are they tuned to go down to?
Just a thought if op can get them cheap enough
 
Lotsa possibilities.

The LF is heavily based on 416 woofer. So for any given volume box, you can tune and enjoy a bit lower extension than 604.

If they could be bought right..

and you could source a pair of duplex horns(C thru G style)...

I'd try to have a speaker guru like GordonW for example, install the 604/605 style horns without having to replace any more of the LF moving assembly than just the felt dust guard. Not exactly a simple task. But, quite doable in the right hands.
 
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The 615 was designed to be used in distributed systems that were large and a ceiling that was very high. Yes the highs were sort of limited becuse of the tear drop placed in front of the horn to get the uniform circular distribution and the even distribution pattern. NMSU used them in their field house basket ball arena. The Cities convention center used the 604E instead. I preferred the 604's personally but the system at NMSU was a great system, too. With a touch of equalization the 615 will easily reach 18,000hz, which for us older folk is all you will ever need. You might want to use the more modern diaphragms, which will have lower distortion and handle much more power. Make sure you rebuild the crossovers. Call Great Plains Audio for more information. They are a coaxial speaker for sure being more like the Tannoys which use the cone of the woofer as part of the horn.
 
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Hello - I've been searching for info on these.
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I got a pair from the original seller - I think he felt bad because the guy who turned out to be a flipper got them from under me and I was really excited to give these a try. I'm pretty sure these were the last of 20+ he got from a Seattle hotel where he was working in 1968 when they took these out. They are in unvented 2 x 2 x 2 plywood boxes - right out of the ceiling. Sound big, full, but kinda mid heavy to me. I was advised to try new crossovers so I'm building them now. Just got the first one wired up today. If it sounds good, might build new cabinets.. I left out the l-pad.. I'll see what it sounds like first - I'm guessing I might need one. Interested to hear that the conic horn is generally considered inferior.
 
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OK.. Thank you.

How's this for a half-baked idea?:
remove the tear-drop, then add material to the inner diameter of the horn (fiberglass?, alum tape?, epoxy+paper? 3D print in plastic?) to maintain the same cross sectional area that was there with the tear drop. I.e. nothing added at the pointy end of the tear drop, then increasing in thickness (linear if the cone is linear) to the edge. Then ignore the half sphere opposite the pointy end - I assume that's just a close out. The goal being to maintain the "shape" of the horn, just without the cone.

anyone familiar enough with horn design to comment on what is specifically dumb about that idea?
I'm sure it would be better to find real 605 tweeter horns and adapt them, but finding those sounds difficult/expensive.

upload_2020-10-26_8-14-1.png
 
these are they btw:
upload_2020-10-26_8-24-26.png
upload_2020-10-26_8-24-41.png

can't say I heard any missing upper Hz relative to the Epos, but will listen closer when comparing my DIY crossover to the Altec N-1550.
 
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