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Discussion in 'Amps and Cabs [BG]' started by jim nolte, Aug 1, 2019.
Been posted plenty of times here...
Remember my earlier comment about UNDERSTANDING what the specs really mean???
The 99dB senistivity is not 1 watt but is 2.83 volts into 1 ohm which is 8 watts so the stated sensitivity must be corrected to the 1 watt value in order to compare with other drivers that use the 1 watt (2.83V into 8 ohms) value. The 1W value for this driver is only 90dB/1W/1M. If you compare this to say a JBL 2242 which is a medium high performance driver with an average sensitivity of 99dB/1W/1M and a rated EIA 2 hour thermal power of 800 watts, the JBL wins out on maximum SPL with less input power. JBL: 128dB/800W/1M versus B&C: 124dB/2500W/1M. This is an example of why engineers/designers pay attention to the math behind the published data.
Regarding the damage number, that's for hard mechanical limits. Cumulative suspension system damage will occur well before that number is reached.
Sorry I missed that. Normally I check and just got carried away. Makes sense that a speaker primarily used as a sub would have lower sensitivity. 22mm xmax still seems cool, but 2500 watts would lead to a lot of thermal compression. And 1200 usd seems like a lot for a raw driver. I could buy a mesa bass cab for that.
I remember reading about it in one of the old electronic rags. Probably either Popular Electronics or Radio-Electronics magazine. Never saw one in the wild however.
Back in the 70s a friend of mine had a 500 pipe,3 keyboard pipe organ in her drawing room of her house.she had a 32 ft pipe run from the basement to the attic and had a 30" speaker to simulate the 64 ft pipe. It was awesome to jam with......
I seem to recall John Paul Jones talking about how he tried a 30" speaker.. and blew it up almost immediate.
If I remember right, rated power was 30 watts.
2500 watts MAY lead to thermal compression, but usually as much compression comes from mechanical factors. Note that the VC is freekin' 6" diameter so there's a lot of area to radiate from, and the gap is very tall too so there's plenty of thermal "conduction" to the gap metal. Now that VC diameter doesn't come without a penalty, there is magnetic losses plus the total flux is limited which compromises flux density. This is where the point of diminishing returns starts to rear its ugly head
So since you know the basic design flaws of this speaker, if someone wanted a kick a$$ 30 inch speaker could you personally design them one, I mean if money was no object???
One of my oldest and best clients has a theatre pipe organ in his "man cave" (a 2500 square foot structure), what a beautiful instrument. We designed, fabricated and installed an LED lighting system which at the time was one of the largest LED installations (600 watts) on the west coast. This was ~15 years ago, there weren't even real electrical codes to go by, but since it was an "outbuilding" we were allowed to design/build it to commercial/industrial standards. It used industrial redundant SMPS with PWM dimming control very much like the SMPS/class D technology I use today in bass amps. We were able to hit about 80 lumens/watt which was mind blowing, now this sort of installation would run about 120 lumens/watt, that's a monstrous increase in efficiency over the best 15 years ago had to offer.
I'm wondering whether the design wouldn't be nearly as difficult as the manufacture QC, since it involves a very large pliable object (the speaker surround) holding a small object (the voice coil) within a relatively tight gap.
Upset that this didn’t show up until page two. Shame on all of you.
Yes, I probably could, and with today's materials would be a lot better than the original BUT the sacrifice in sensitivity/efficiency would make it a poorer performer than say ~2 x 18" drivers.
It would be "easier" to manufacture today, using neo magnetic materials and a dual voice coil (JBL's differential drive technology would be an obvious choice), and double spiders and high strength/temperature adhesives, but it wouldn't be commercially viable.
When I was an engineer for the Navy in the Bahamas AUTEC we had a 10 ft speaker with a steel cone and thousands of watts that was waterproof and deeply submerged in the ocean to talk to submarines. you could hear it for miles.
BIGGER SPEAKER MEANS BIGGER BASS
So could the Russians, except for the little bit about encryption
I'm surprised nobody is barking up the servo drive tree , yet.
That would be another (expensive) way to do it.
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