Altec PA system, used weekly

[cclark65]

OK, I know the picture is a bit messy, but that's my garage, and it's usually full of audio stuff! Anyway, I just wanted to share with you all what I am currently using my Altec equipment for. You will all be happy (maybe?) that they get used several times a month for live events with anywhere from 50 to 700 people attending. I almost always get compliments on the sound. Here is a basic description:
The highs in the photo are handled with 902-8b drivers on 511b horns. I have since replaced them with 906 drivers on MR594 horns, much louder and better coverage. They are driven by an Altec 9442 amp. The mids are covered by Altec 417-8H series II. The cabinet is a shortened version of the 816 without the port. I didn't need it to have any bass, just project the midrange, and that it does! The midbass in the picture is handled by 421-A's, driven by Altec 9444 amps. They have since been replaced with Altec 3156 drivers for better power handling.(I have 3 blown 421's waiting to rebuild!) The cabinets are modeled after the 816, again without the port since I am using subs, I just needed them to project the midbass good. The subs (sorry to say) aren't Altec, so I won't go into the details on them unless somebody wants to know. However, they are driven by Altec 9446 amps, I have since retired the 4 9440's that were driving them. All I will say is they kick hard from 50 feet away! All cabinets are custom made by a friend and I, and they aren't perfect, but they get the job done quite well.
Comments? Suggestions? I am posting this so I can get ideas for putting together my next system!

[mbenterprizes]

Looks like my shop I've been running 3156's in 816's for a couple of years. Driving them with 1590C's.

I love the sound they provide. The bass really pounds your chest.

[Fitts]

Very nice looking system. I bet it is a pleasure to go to one of your events.

It looks as though your cabinets can be stacked without necessarily aligning the drivers in the same plane. I have found that having a HF horn forward or back of the LF driver by just mere inches greatly affects the sound quality. You may want to consider making sure the driver voice coils are all in the same plane by building cabinets with stacking notches that line everything up.

Just a thought,

[cclark65]

You are correct about the alignment, but I believe both the 15 and 12 drivers do line up with the horn driver inside the cabinet. The only thing I have a problem with is the bass horn, which is a Cerwin Vega based horn. I do have 3 TC3 delay's, and have played with the idea of delaying the other three cabinets enough to offset the sound coming out of the bass horns, I just have to figure out the delay needed. The bass horns are 7ft folded.

Also, this picture is a year or so old, and I have since replaced the horns with MRII594A's with 906-8b drivers on the back. They do align properly with the voice coils on the rest of the speakers.

As for a pleasure to go to one of my events, I guess it entirely depends on what type of music you like! I rarely take all 4 stacks of speakers out, usually I only need 2 of them.

And by the way, I am having 4 more sub cabinets built, the bass just can't keep up with the output of the mains, even with the horn loaded cabinets!

[cclark65]

I looked back at the picture, and I think I see what you are thinking about. The 2 cabinets on the right look to be separated a bit, and they are! I didn't realize it at first, but when I stack the mains on the subs, one of the corners rested on another corner, the other rested on the cabinet itself, causing it to be crooked. I cut some of the corners up and put just flat pieces on the sub cabinets, and that straightened them right up. I will try to take some more pics next time I use all 4 stacks.

[Fitts]

For a bass cabinet try a tube. I posted here a while back about getting a 12 foot long, 14 inch diameter construction sono tube and cutting it at 9 feet so that you had 3 feet left over. Mount a 15 woofer facing into one end of the long tube and then attach the short three foot tube to the back side of the woofer. You end up with long tube, woofer, short tube, the whole mess being just a hair over 12 feet long. This makes a great woofer that covers from about 25 hz to 125 hz and is absolutely thunderous.

Regards,

[Roland N R]

Charles:

Nice system, good work!!

Noticed you are going to make additional horn sub woofers. If it was me I would make Tom Danly's (of servodrive fame)free design of the LAB SUB horn woofer.` Search under High Efficiency asylum. These put out 107 dB/watt/m from 30+ to about a hundred Hz. Each uses 2 "lab sub" 12" woofers from eminence $150 each retail. From looking at the quality of your cabs making the Lab Sub should be no problem. Additionally I would consider making his top box the TD1 which is patented but you are allowed to make some for "personal" use. This multidriver in a single horn concept combines a 1" comp driver, four 5" sealed back mids and three 12" midbass into a single smallish horn all summing coherently down to the 80 Hz. Basically these two "compact" cabs offer a very high level of performance in a rather small package. You will need at least two Lab subs per side in open space for deep bass.

[cclark65]

Bass Tubes...similar to what Bose has done for theater subs, the tubes go behind the screen, and yes, they do put out a tremendous amount of bass. However, I am a one-man sound guy/road crew, and this all has to fit into my 12ft trailer! I don't think I would be able to handle the tubes very easily, and they probably wouldn't be easily setup in many venues.

LAB subs, I have looked them over several times, and considered them very much. I chose this style at this point in time again for the simple reason I do the entire show myself, and these are easily handled and stacked. Someday though, I would like to build 4 of the LAB subs. From looking at the design, they can't help but put out tight clean bass. 12" drivers are much quicker than 18's, and still quicker and tighter than 15's, so I am sure they put out a rock-solid bass line that hits hard and remains smooth. And with that compression chamber, no wonder they had to design a special driver for it! I would think that 4 of the LAB subs would outperform 8 of the subs I have now.