JD
Well-Known Member
Nightmare of the Day!
We have a very nice pipe organ at Trinity, but the lowest stop is a 32 foot "speaker" stop. It appeared to contain four 15 inch speakers and four 18 inch passive radiators. The suspension on the 15's is shot. Went to take one out and Woooo! They are not "speakers" after all! The diaphragms are driven by a servo motor! So, they haven't been built since the 1980s and there are no replacement parts available! Just to make matters even more fun, each cabinet weighs 120 pounds and is 12 feet up inside the pipe chest with about 4 inches of clearance to work on them... This is going to be a fun project...
In any case, my options are limited. As far as I can tell, the manufacturer "ServoDrive" is long gone. (Contra-Bass is the model) The only option I can think of is to pull the servo guts and mount standard 15's in all 4 locations. It is going to be a real hit-or-miss in Passive radiator cabinets. My only thought is to find drivers with the lowest possible free air cone resonance. The JBL 2235 looked nice at 20Hz, but is discontinued. Foam surround on them as well, so used/old would be a bad idea. I figured before I headed into this one, I would try a post here on the off chance that one of the old-timers knew or had any experience on servo-drive speakers.
Any Thoughts?
We have a very nice pipe organ at Trinity, but the lowest stop is a 32 foot "speaker" stop. It appeared to contain four 15 inch speakers and four 18 inch passive radiators. The suspension on the 15's is shot. Went to take one out and Woooo! They are not "speakers" after all! The diaphragms are driven by a servo motor! So, they haven't been built since the 1980s and there are no replacement parts available! Just to make matters even more fun, each cabinet weighs 120 pounds and is 12 feet up inside the pipe chest with about 4 inches of clearance to work on them... This is going to be a fun project...
In any case, my options are limited. As far as I can tell, the manufacturer "ServoDrive" is long gone. (Contra-Bass is the model) The only option I can think of is to pull the servo guts and mount standard 15's in all 4 locations. It is going to be a real hit-or-miss in Passive radiator cabinets. My only thought is to find drivers with the lowest possible free air cone resonance. The JBL 2235 looked nice at 20Hz, but is discontinued. Foam surround on them as well, so used/old would be a bad idea. I figured before I headed into this one, I would try a post here on the off chance that one of the old-timers knew or had any experience on servo-drive speakers.
Any Thoughts?