More A7 questions

[RonSSS]

You can also use EQ.
But build a spacer to move the woof back from the cab. Otherwise the cone will hit. Ask me how I know.
Simple with 1/4" ply and a sabre saw.
A7's will go low with EQ.
Otherwise add subs.

Here is a great one!

http://www.altecpro.com/pdfs/vintage...%20Speaker.pdf

I can't find the PDF for the system.

Ron

[Altec Best]

Here is a great one!

http://www.altecpro.com/pdfs/vintage...%20Speaker.pdf

I can't find the PDF for the system.

Ron

Try these. It is at the bottom of the PDF :2thumbsup:

http://alteclansingunofficial.nlenet...osurePlans.pdf


http://www.lansingheritage.org/image...pro/page08.jpg


http://www.altecpro.com/pdfs/vintage...%20Systems.pdf

[VolvoHeretic]

I plugged that speaker into an online calcuator and with its suggested box size of 4 cu ft, the frequency responce nosedived at 50Hz and was off of the chart at 30Hz. Increasing the enclosure to 12 cu ft, but not knowing the vent size and just guessing, there was a faster initial drop, and then a rise, but it still dropped off of a cliff by 30Hz. I would have hoped for better. How much is that woofer anyway, I can't find the price anywhere.

I have been equalizing thus w/ 8-3" piezo super tweeters per speaker;
--25Hz---40--63--100--164--250--400--630--1KHz--1.6--2.5--4--6.3--10---16
+12db __+12__0__-3___-3___-3___-3___-3___-3____-3__-3__-3_-3__+10_+10

[GM]

Right, for typical prosound apps back then and still to a great extent today in touring sound, 60 Hz was/is the lower useful limit with 40 Hz being typically at least -24 dB, so its seeming too small vent for its rated power is more than adequate.

For HIFI/HT apps, tuning 12 ft^3 to Fs to as low as 17 Hz should be fine combined with some room/boundary gain and maybe some EQ, though it takes two of these to match up to a single A7's mid-bass horn's sensitivity.

GM

[VolvoHeretic]

When I bought my 16-3" piezo super tweeters from Radio Shack long ago, they came with no data or wiring instructions. The only thing I knew was that ohms were halved in parallel and doubled in series, so I wired up 4 in parallel to 4 in series. I know realize that their resistance is something like 1000 ohms and no worries in that regard. I have been reading this thread on piezo tweeters indicating that I need resistors to protect the amp from high frequency feedback. Can anyone dumb this thread down so that I can duplicate what they are talking about? I don’t need an L-pad, just a wiring diagram in plain English. My only wiring experience is with using plumbing solder and a Bic lighter.

http://www.audiokarma.org/forums/showthread.php?t=79659 Specifically post #30 with it’s thumbnail image and on. (edit; opps, I guess I forgot about the wiring diagram in post #32. So I don't need the 8ohm reisitor, just the 20-50 ohm resistors in series before each tweeter.)

Thanks a bunch

How dumb would it be mounting 7 of these things in a 12” globe or basket ball centered over the horn and woofer voice coils?

[VolvoHeretic]

How about this for the encloser sound deadening reenforcing? The interior 1/2" sound board is sandwiched inbetween the A7 plywood and 3/4" MDF, bolted together with a rubber washer assembly to totaly isolate the two. I would still use single plane forming plywood on the outside of the curved horn bell with the same technique to reinforce the curved bell since there is no room to add any solid piece of wood to the inside of the bell. ???

[bfish]

That's quite the Death Star you've got there. I'd OD on that math though. Hell, it might work.

Your constrained layer looks good, but what keeps the bolts centered? Maybe a snug nylon sleeve would help.

[Panomaniac]

How dumb would it be mounting 7 of these things in a 12” globe or basket ball centered over the horn and woofer voice coils?

In theory, pretty dumb. Comb filtering and who knows what else. But a lot of stuff like that is not as bad in practice as it might seem. Multi-cell horns, for example. I'd try it and see. Might be cool.

[VolvoHeretic]

Right now I have two rows of 4 tweeters each artfully duct taped to the mid range horn bell lip. I would like to try to sound phase array the horn, and tweeters to the woofer as per some other thread. I can't remember, but I think that the tweeters are arrayed at 40 degrees from each other around the 12" radius. Maybe arrayed at a larger radius would be a better match to the tweeters dispersion angle. I will have to see if I can find that data.

[VolvoHeretic]

Your constrained layer looks good, but what keeps the bolts centered? Maybe a snug nylon sleeve would help.

I JUST thought of how to center the bolts; I could just use 1 1/4" long pieces of 1/4" rubber hose. Now to calculate the weight of this extra material, but the heavier-the harder to steal.