Live Sound Mixing book cover


Take another little piezo my heart now baby

All Rights Reserved © 1995 Duncan R Fry


At a recent exhibition, I was busy poring over a display of old compression drivers, and musing on the fact that what we used to throw away as a load of old shit is now eagerly sought after by collectors. Seeing all that old stuff there reminded me of the first horns I ever had in my PA system.

They were Altec multicells, with dual 291 compression drivers on a Y adaptor on each one. It's possible that the old 291 wasn't the world's most inefficient driver, but it sure as hell couldn't have been far off. Still I was in desperate need of them as I had the whole PA system assembled apart from some horns. It was a basic pub system - two bathtub W bins, 4 of the ubiquitous 4560s - all I needed were some horns to sit on top of them and I could get it out there earning a dollar.

So I did a deal with their owner and swapped a Mini Minor car for them.

They were enormous things, mounted in square steel tubing, looking like a geriatric audio person's walking frame, and covered in a skin of plywood.

They sounded tolerable...nothing much above 8 KHz, but a couple of piezos sitting on top fixed that up. The main problem was that they were very inefficient and had very limited power handling. As long as you didn't work them too hard they were fine, but since replacement diaphragms cost about four times the price I got for a gig, I had a vested financial interest in nursing them along as much as possible.

The bands were all very happy with them, though. It was a time when bigger was definitely better, and you couldn't get much bigger than these buggers! Then I got myself a great deal on four new Emilar drivers, and these were everything that the Altecs weren't - super efficient, much louder and sweeter and they went out to 18 KHz at least. Far further than my hearing, anyway!

So I made four fibreglass versions of the big JBL 90 alloy flares and stuck the Emilars on the back of them. They sounded great and what's more they didn't give you a hernia putting them on top of the stack.

But what was I going to do with the multicells? The market for them was pretty low, but they still worked, and I was reluctant to give them away or just leave them sitting around not working.

So I stuck them in the rehearsal room.

I still had my original pair of chipboard 4560s I had bought years before. They had grown a bit in size since they had been left out in the rain and the chipboard had swollen, but they still were holding together, and the famous NoNamo brand 15s still worked most of the time.

I sat the things up on a couple of old packing crates with a black drape around them, and the whole thing looked like a pretty mega system. Certainly one that more than justified the incredibly low rehearsal price I was charging.

The first band to come in was very impressed with these black monoliths standing like sentinels in each corner of the room.

I think the compression drivers lasted about a week in the rehearsal room before the last one of the 4 died!

I was really stuffed now. I had this mega rehearsal system but no horns. New diaphragms were out of the question.

Then I remembered I still had the piezos from the main PA. With the new Emilars I didn't need them any more, so they had been either holding the studio door open on hot days, or been used as a horn chock to angle the PA horns downwards.

So I ripped them out of their little boxes and got out the hacksaw. I carefully sawed the little plastic flares off the front of the piezos, but left the long skinny phase plug still sticking out the front.

Then I gaffer taped them onto the back of the big multicell flares, sealed the joins up with silicone, and connected them up.

Well, they didn't work perfectly, but they did work! But they were way too small. I figured that no-one would take them seriously being so small, so I got some takeaway Chinese food containers and glued them over the piezos!

Now they were the right size! I figured if it was good enough for Celestion to do it with the early G12M speakers, then it was good enough for me!

A quick spray with matt black paint, and they were all set to go. It looked like the multicells each had a pair of really beefy (with noodles?) compression drivers on the back.

The customers loved them. Not one of them complained that the system didn't sound right. In fact the opposite was true. Most of them said that the horns sounded better for some reason! Personally I didn't care how they sounded, as long as they never blew up!

I suppose I should have called the place Piezo Hut!


This story first appeared in Connections magazine

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