Just quick note from Wikipedia about Woodstock 1969.
Do not think it is irrelevant to home listening.
JBL D140 drivers and Altec horns in good condition is almost impossible to find.
"Sound for the concert was engineered by Bill Hanley, whose innovations in the sound industry have earned him the prestigious Parnelli Award. "It worked very well," he says of the event. "I built special speaker columns on the hills and had 16 loudspeaker arrays in a square platform going up to the hill on 70-foot [21 meter] towers. We set it up for 150,000 to 200,000 people. Of course, 500,000 showed up." ALTEC designed 4 - 15 marine ply cabinets that weighed in at half a ton a piece, stood 6 feet straight up, almost 4 feet deep & a yard wide. Each of these woofers carried four 15-inch JBL LANSING D140 loudspeakers. The tweeters consisted of 4x2-Cell & 2x10-Cell Altec Horns. For many years this system was collectively referred to as the Woodstock Bins"
And now for people who hate math, but have money.
Horns are very simple to understand. Sound pressure is not a linear but logarithmic function:
1. You start at 1 watt.
2. To get first 10 DB above your speaker's sensitivity you need 10 Watt
3. To get second 10 DB you need 100 Watt
4. To get third 10 Db you need 1000 Watt
5. So if you draw the curve.
Your DB's are on vertical scale Y, and your Wattage on horisontal scale X.
From 0 to 1 watt it is almost steeply upward. First watt is the most linear part of the curve.
6. From 1 to 10 watt it is flatten up to ~ 45 degree (compression starts to build up)
7. From 10 to 100 watt the curve goes only 15 degree uphill
8. From 100 to 1000 watt the curve is almost horisontal. You pump 600 more Watts and get 1 db more. Ha Ha.
With horn I have 111 DB with one watt. Nondistorted linear 111db. To get those 111 db with the cone speaker (Sens. 85Db at 1 watt) I need to pump ~750 watt. Guess how heavy the coil will be to handle 750 Watt.
Think.