Folks, i have a bad habit of collecting projects. Many years ago i was at a thrift store and found a Madisound box full of Foster wide-range woofers. 24 of them to be precise.
Just like the ones in this thread:
2422-264-00504
There was also a huge pile of Onkyo tweeters that were glued into 6x9 plastic frames - presumably they were originally to have been mounted on 6x9 speakers. I snoozed on those tweeters and someone else bought them.
Today, the era of 50 cent Apex Jr tweeters is long gone. The cheapest i could do looks like maybe $1.70/ea out of Alibaba. With no specs other than nominal impedance.
Frankly, arrays of tweeters never made any sense to me, short of a carefully calculated Bessel array, possibly. Because treble interference is destructive, not additive. Comb filtering makes it seem like a waste of tweeters.
Of course, Parts Express has no shortage of extremely efficient PA tweeters.
Is a linear array of 12 woofers with one loud tweeter (with good dispersion) halfway up a terrible idea?
fwiw i have the Dayton version of the Behringer calibrated measurement mic, a deq2496, etc, just no actual experience taking speaker measurements yet.
Just like the ones in this thread:
2422-264-00504
There was also a huge pile of Onkyo tweeters that were glued into 6x9 plastic frames - presumably they were originally to have been mounted on 6x9 speakers. I snoozed on those tweeters and someone else bought them.
Today, the era of 50 cent Apex Jr tweeters is long gone. The cheapest i could do looks like maybe $1.70/ea out of Alibaba. With no specs other than nominal impedance.
Frankly, arrays of tweeters never made any sense to me, short of a carefully calculated Bessel array, possibly. Because treble interference is destructive, not additive. Comb filtering makes it seem like a waste of tweeters.
Of course, Parts Express has no shortage of extremely efficient PA tweeters.
Is a linear array of 12 woofers with one loud tweeter (with good dispersion) halfway up a terrible idea?
fwiw i have the Dayton version of the Behringer calibrated measurement mic, a deq2496, etc, just no actual experience taking speaker measurements yet.
I've been trying to get that to work for years, including just the past week.
If you simulate it, the second you remove the center driver in the array, the response goes to hell.
I've only found two options that seem practical:
1) put the tweeter in the center of the array, but to the left or right of the woofers. By doing this, it insures you don't have a hole in the array.
2) put the tweeter in the center of the array, coaxially. By doing this, it insures you don't have a hole in the array.
If you simulate it, the second you remove the center driver in the array, the response goes to hell.
I've only found two options that seem practical:
1) put the tweeter in the center of the array, but to the left or right of the woofers. By doing this, it insures you don't have a hole in the array.
2) put the tweeter in the center of the array, coaxially. By doing this, it insures you don't have a hole in the array.
A single tweeter would be either small and not very loud (= unable to keep up with the max. SPL of a lot of woofers), or big, which pushes the membrane resonance into the audible range (can be avoided with Beryllium & co., but which is expensive). Practical solution would be a compression driver on a large horn to get it to play low enough to be able to XO cleanly to the woofers; but this seems to be a budget option, and I dunno if you can get a driver-horn-combo that will play down low loud cleanly on a budget.
Tweeter arrays need to be tightly spaced to avoid destructive interference at very high frequencies, where wavelengths are in the low single cm area. If you can manage that, I see no issue there; except maybe again to how low you can XO them (small cheap dome tweeters usually don't have any mid frequency capability). You can curve the array physically or via filters (shading) if you desire a wider vertical beam.
Tweeter arrays need to be tightly spaced to avoid destructive interference at very high frequencies, where wavelengths are in the low single cm area. If you can manage that, I see no issue there; except maybe again to how low you can XO them (small cheap dome tweeters usually don't have any mid frequency capability). You can curve the array physically or via filters (shading) if you desire a wider vertical beam.
Here's another idea for consideration. I made these and put them in my wife's greenhouse without taking measurements. But damn, the high end sounds clear and there is plenty of it. They use really cheap 1/2" tweeters that you can get for less than 50 cents each in quantity. Maybe we should call this RAST technology (redundant array of sh*tty tweeters). Someday, I'll measure these, but I can say that the approach works far better than I expected. The 9/16" CTC spacing is small enough to minimize comb filtering, and there is enough total surface area to keep excursion low to minimize distortion.
Each tweeter is sitting in a small chamber filled with cotton and then hot glued in place. It takes a while to wire up 96 tweeters (192 for stereo).
Each tweeter is sitting in a small chamber filled with cotton and then hot glued in place. It takes a while to wire up 96 tweeters (192 for stereo).
Huh? That SZ-2T looks like the "ribbon" tweeter that Apexjr sold for a while (https://t-linespeakers.org/drivers/ribbon.html). It is 1-1/2" in diameter, and the response is very rough.
The "tweeters" I used were Parts Express #289-2036, but they are no longer available at PE. They were sold as "1/2" Mylar Full-Range" speakers for less than 35 cents each in bags of 100. These are still available, and they might work as well: https://www.parts-express.com/1-2-x-1-Speaker-Pair-50R-A14002-0401-65-289-2032
The ones I used look similar to these at aliexpress: https://www.aliexpress.us/item/3256805913525080.html The 13mm versions are 21 cents apiece. Next time I place an order at aliexpress I'll get some of those and take them apart to see if they are similar.
The "tweeters" I used were Parts Express #289-2036, but they are no longer available at PE. They were sold as "1/2" Mylar Full-Range" speakers for less than 35 cents each in bags of 100. These are still available, and they might work as well: https://www.parts-express.com/1-2-x-1-Speaker-Pair-50R-A14002-0401-65-289-2032
The ones I used look similar to these at aliexpress: https://www.aliexpress.us/item/3256805913525080.html The 13mm versions are 21 cents apiece. Next time I place an order at aliexpress I'll get some of those and take them apart to see if they are similar.
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That's the fifty cent tweeter that OP wanted to use, but can't 🙁
No, he had a cheap conventional tweeter as well. That's a tweeter from a Sawafuji speaker. I forget if the whole speaker was called Dynapleat or just the mid and woof. The dipole version was much better, and was available in 32r, which made a pretty sweet headphone driver if used properly. Suspiciously similar to planar headphone drivers found in Audio-Technica and Radioshack headphones that may or may not have been made by A-T. With some additional foam and a bit of felt, the Realistic Pro-30 can be excellent. Got two pair myself.
The 12mm speaker from aliexpress looks like it has potential.
Anacronym of the year !
Well done line...if I ever get back into lines, I hope you'll help tutor me! 🙂
Great idea, go for it 👍
Ivé just build one but with 8 woofers (5,9 inch) and a WG Audax "gold" tweeter.
Are in the final stage with last tweaks now.
measurement from 2,05 m
Attachments
It's just easier to pad down too much treble than to deal with not enough treble, yaknow?
Some years ago i bought a Kustom KMA-100 keyboard amp / PA with scratchy pots and no tweeter. I found the specs for the Celestion 15" in it and found a cheap compression driver and horn at PE, did some math, padded it down 9db with 10w resistors, and it worked GREAT. Also ended up replacing all of the pots, and replaced all of the njm4558 chips with njm2068. Gave it a 3rd order crossover where the original design just had a cap in line with the tweeter. Makes a very respectable bass amp.
I would be fine mounting a tweeter to the side, but after something like 15 years maybe i need to chew on this a little bit longer? 😛
Some years ago i bought a Kustom KMA-100 keyboard amp / PA with scratchy pots and no tweeter. I found the specs for the Celestion 15" in it and found a cheap compression driver and horn at PE, did some math, padded it down 9db with 10w resistors, and it worked GREAT. Also ended up replacing all of the pots, and replaced all of the njm4558 chips with njm2068. Gave it a 3rd order crossover where the original design just had a cap in line with the tweeter. Makes a very respectable bass amp.
I would be fine mounting a tweeter to the side, but after something like 15 years maybe i need to chew on this a little bit longer? 😛