John Halliburton wrote on Mon, 28 December 2009 18:54 |
Ask if the motors are still working on them. After that, cones and belts are the next things to check. They can be rebuilt, but getting motors fixed would be the major hurdle. Finding surplus might be easier. $275 for a working BT7 is a deal. Best regards, John |
Art Welter wrote on Mon, 28 December 2009 21:03 | ||
The BT-7 is basically the same horn as the Lab Sub, and it is not difficult to retrofit the chamber for Lab 12 speakers. If I needed subs, I’d be inclined to by the lot, retrofit them with Lab 12s, then sell off the Servodrive parts which are Unobtanium now. Art Welter |
Ivan Beaver wrote on Mon, 28 December 2009 19:22 | ||||
Are you sure the lab 12's will fit? The original "drivers" in the servo products were 15" cones-but no magnet structure and the chambers behind the rear of the cones were very close to the rear of the speaker frame. In my SDL5s the bolts that attached the rotary to linear converters actually dug little holes into the wood in the back. In those cabinets, there was no way you could fit a lab 12. Maybe there is more room in the BT7's, but I am not inclined to believe there is. Maybe you could fit a very shallow 12", but then the parameters may not be right for the particular horn used in the BT7-but you might get lucky. |
Art Welter wrote on Mon, 28 December 2009 20:56 | ||||||
The BT7 basket looks like it is about 6 inches deep, the Lab 12 is 6.44 inches deep. With one or two “donut” adapters that depth difference could easily be made up. I once replaced a Servodrive unit with an EVX-150A. I didn’t get to hear the cabinet before the DJs burnt up the Servodrive motor, but the cabinet sounded quite good with the EVX-150A. Art Welter |
Eric Dodson wrote on Tue, 29 December 2009 03:13 |
We've got 6 of these Servo Drive BT7's! All working, with spare belts and cones! In the hopes that this thread will find someone who wants them; Call Us...! <http://www.specialeventaudio.com> Thanks. Eric Dodson |
Whit Hutchinson wrote on Mon, 28 December 2009 23:23 |
Please enlighten me on why you (or anyone) would be willing to get rid of such a "perfect" sub woofer. I have always wanted these (albeit wanted 4 (2 per side for my rock bands and DJ gigs)) But were unable to afford them back when this was the only real high powered bass device around. Now, I see them for this price, but thinking on it, there are still VERY few subs (if any) that can go to 30hz with little power at huge levels. I understand that they are big cabs and you have to be SUPER careful with them as to not burn them up but it is my understanding that an old school Macrotech 2400 on a pair was sent from god him/herself to run these subs without worry. I am sure there are many amps since then but I refuse to buy Chinese bullshit anymore so I will stick with my old iron until then. |
Milt Hathaway wrote on Tue, 29 December 2009 10:57 |
If you are primarily reproducing sine waves, they are great. However, due to the mass of the motor/belt mechanism, their impulse response was really lousy. They might be really cool with an upgrade to real drivers, though. |
John Halliburton wrote on Tue, 29 December 2009 14:22 | ||
Milt, After running QA TEF sweeps on a few hundred Servodrive subwoofer products, I am afraid I have to disagree on the impulse response statement. They are quite good at it actually, and Tom also did plenty of head to head comparisons in the shop at the time with other competing products. They still produce some of the best percussion instrument reproduction in the frequency range I've ever heard-and I still have my pair of Contrabass subs as reference. I do agree however, that refitting the Basstech 7 cabinets for sale in Dallas with "proper" drivers is definitely a workable project. Best regards, John |
Milt Hathaway wrote on Tue, 29 December 2009 10:57 |
If you are primarily reproducing sine waves, they are great. However, due to the mass of the motor/belt mechanism, their impulse response was really lousy. |
Ben Outerbridge wrote on Mon, 31 January 2011 19:45 |
I own 8 BT7's. The summer I got them I went through a ton of belts. (I was overpowering them) Once I sorted that problem out, the metal rod that the belts spin on got corroded (Bermuda salt spray air) and was chewing through the belts nightly. Anyway, I got irritated and investigated on how to load the cabinet with regular drivers. 6 months later I got over it, cleaned the rods, and ordered some more belts. I couldn't find any 15 or 12 that could fit where the servocones are attached. If anyone has managed to do so I would love to hear about it. |