Large format Coaxial designs

[cclark65]

Sorry to cause an issue, I know that this isn't the typical subject for this board, usually we are chatting about home stuff. But, since I have a ton of Altec stuff and am using it, I am confident that I can get some knowledgable answers from the "live" sound guys that are on here. Over on the prosoundweb board it gets pretty flaky sometimes, not to mention that if you aren't one of the favored few, you get pounced on like they were rabid animals!

That EV cabinet and the Altec cabinet I originally specified are about the same, with the 2 exceptions of the EV is a 15" and has ports on the sides.

I would really prefer to use the 12" drivers for the midbass/midrange horn. I prefer 12's over 15's for vocal clarity. The 12's aren't RCF ones, they are the eminence version. I wish they were the RCF!

I was just wondering how the horn in front of the cone affects the sound. I have 4 of the smaller Mantaray 60/40 horns laying in the garage, if it worked out and they sounded good, I would find 4 more and build 8 cabinets so I could stack them 2x2 per side. No flying cabinets for me since they'll be home grown.

Also, these would be replacing my current speakers, not in addition to them. On the other hand, I do get a lot of compliments on the sound, how clear it is and how well the speakers project is getting to be well known in this area. I know they don't look like much, but they sure do put out a lot of pretty high quality sound! I might just end up making new midrange cabinets that I can splay with the 60 degree horns stacked on top. The midbass cabinet's wouldn't have to splay at the frequencies they handle.

I run the subs at about 95 or 100Hz (analog crossover). I tried running them off an aux once, but I didn't have a good crossover for it and didn't like it. I have another identical to my main 4way one now, so maybe I'll give it another shot. I run my PA in mono, so I was running subs on the left, mains on the right, and panning everything right except kick, bass, and keyboards, which got panned center.

[LICORNE]

As originals the duplex horn do not effect the woofer . If you intend to make a reproduction with some 12 inch driver and put a 60/40 horn in front you won't have the same result/efficiency.

one :the horn driver could block the woofer sine waves.

two: you will have to RTA the horn to the woofer.

If this had been feasable Altec would have gone this route.

Off topic:
Ps :Altec was once owned by EV so wich is the real DTS system ? I'll ask Todd White to answer this one.


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[Old Guy]

Charles I think it comes down to how large the horn is and how high you go with the crossover.

Sound becomes more directional as you go up in frequency and less likely to flow around objects.

It will work better with larger the mid bass horn relative to the HF horn. IE- if you are blocking 20% of the horn mouth it's gonna be better than blocking 50%.

Another option- consider building a 2-12" bass horn and mounting the HF horn in the center between the speakers. There was an old Altec corner cabinet that was essentially the horn later used in the 817. We built a bunch of those (slightly shortened) with 2-12's back in the "70's they worked quite well. Mounting the driver thusly would prevent some of the interference. This makes a box 25 1/2 tall by 30 by 24" deep. We sealed the back box since it was mid bass and not bass anyway.

So I would figure the mouth size of the mid bass and plot the percentage of area you are disrupting. If it comes to a high number go another route.

If you have eminence drivers yes they will be overhung. Not bad speakers, just inexpensive ones.

[Old Guy]

I didn't mean to imply the EV and Altec boxes are identical. They aren't The Altec uses a duplex driver, the EV has a seperate horn.

As much as I love Altec, I can't give them credit for the first coaxially mounted LF and HF horns. Community did it in the early 70's. I'm sure someone did it way earlier. The idea is just too obvious.
Agree with Charles about using 12's for midbass- this is far and away the dominant application in current SR.

[LICORNE]

As far as speakers are concerned, the Altec Lansing DE boxes would help out in any situation needing some reinforcement or replacement. Because of their wide pattern, they can also be mounted sideways and still obtain the same coverage. It's going to take a few days to match them with your main's

Specs:review:
A factory installed passive crossover is set at 1.5kHz, with a tweeter protection device attached, to avoid over-powering the horn drivers. According to the preliminary manual, the super efficient Duplex? system has a coverage of 110 degrees horizontal by 100 degrees vertical at 1kHz. The nominal pattern of the Vari-Intense? CD horn and the high-powered 12? is 90 x 90 degrees. Frequency response reaches wide from 80-20,00Hz and dips quite low for a box so small. According to Altec Lansing, up to 123 dB can be attained, with only 200 watts long term power input.


These are very efficient speakers .You should hear every nuances of your music.

As for the 421 as a matter of preference I would
go for 515 recones. The difference is in the voice coil compared to EAW the vC is underhung.
again you will gain in clarity and efficiency.

I don't think you can just change the center horn with a 60 degree horn .If I read you correctly you want to put these 60 degree horns on top.

It's up to you more trouble to align. Flying them is an alternative and works quite well
I have a preference in flying my speakers. You get better coverage and you can adjust the angle downward .

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[Old Guy]

1100 shouldn't be a problem. Lots of guys want to bring their horns in at 1600- that might be.

Normally with a horn like that I'd do 1200- so we're in the same ballpark. You're right new horns are small. I tend to be a bit wary of running them too low.

I've got a couple of pub systems- 18" Sub, 12" Eminence Delta pro mid(x2) and 299 on 40x60. They run at 100 and 1200 hz.
The delta pro are probably close to what you have.

[cclark65]

The Delta Pro is exactly what kit I used to recone the blown ones. EAW wants a fortune for them to recone. I bought a lot of them from a guy, and he gave me the blown ones for shipping costs pretty much. What I have found out is that all the blown ones are bad in the exact same way, the wire going from the tinsel lead down to the voice coil is broken. I contacted EAW and they said it might be an issue, but I would have to send all the blown ones in that I haven't ripped apart yet, and that's only 3, so it's not worth the trouble. I am just getting them reconed with eminence kits and they are working great. I have since blown 4 of the good ones I bought from the guy, and they have all gone the same way. Stress fractures from what I can tell, not heat.

Are you running yours horn loaded or front loaded? (Are you using the type you described based on the corner horn? If horn loaded, do you think a phase plug is necessary? I have the phase plugs for the, but haven't installed them yet.
I would love to see a photo of your setup!

[LICORNE]

Hi Old Guy,

You quoted : "I didn't mean to imply the EV and Altec boxes are identical. They aren't The Altec uses a duplex driver, the EV has a seperate horn".

According to the EV brochure the FRX is FUll coaxial design.

I want to know who came out with the Idea first Altec Or EV. Since Altec was owned by Ev for a while before they shut it down.

As for duplex technologies it wa invented way back in the early 40's by All Technical. Or Altec Lansing.

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[LICORNE]

Hi Old Guy,

Charles quoted:"I do a lot of live PA work, and just wanted to play with the design. Right now I have a pile of 421's that I could recone as 515's, but I am going to be more inclined to use my EAW's in them".


Anny intelligent sound engineer would choose 515 recones over "Eastern acoustics works sometimes" unless your EAW speakers are in good working condition and wou want to save money.

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[Old Guy]

Are you running yours horn loaded or front loaded? (Are you using the type you described based on the corner horn?

<font size="2" face="Verdana, Helvetica, sans-serif">The two pub systems are just basic vented boxes. Front load confuses me, I always think of front loaded horn, front mounted has become synonymous with front load.

They keep up with the 299's OK. What we used to run back about 10-15 years ago was a dual 12" horn. Altec made a 2-15" corner horn with ,If my brain still works, an 800hz multicell on top. We essentially used that horn but used 2 EVM 12"s.
Just basically made it a sealed box, we did line them with 4" fiberglass, that seemed to give the flattest response. We had one of the old"70's model HP/Altec real time analyzers so we we played around with packing. That reminds me- I may still have that thing. Note to self- check attic. Major difference is going to be less bass, which you don't need, but probably 4-6 db more output.

At one point we had some 30 or so of those. We rented them and used them ourselves.

If you want I'll try and find a set of prints for that box. The curve and so forth is pretty much identical to the 817. The 817 horn was stretched to fit the larger 16" woofer frames- we went the other way to fit the 12's.

The pub stuff will be hard to get pics of, it usually goes out with one of the college kids. I don't do pubs unless it's a good blues or jazz act, perhaps one of the better oldies acts. I did do the Ventures a few years back in one of the locals- it was a blast. I don't drink, used to do to much of it, so I stay out of pubs. It's been so rainy here we haven't been able to do any parking lot testing. I'll try and get some pics of the big system in June we have a couple of outdoor festivals. My first sunburn of the year! (groan) Let me know if I can help more. Feel free to email if you need, give me a couple days to answer. I coulda been Slow Guy just as easily.