The Servodrive Subwoofers have been in service scince the Late 80's,  There are many pluses and minuses to them.  On of which is cost.  Another is they have higher distortion at very low volume levels due to moter and motion converter stiction and jerkyness.
 
     Check this site out.
www.servodrive.com
They still manufacture the BT7 and the Contrabass.
 
There have been a couple of what I'd call failures in the servo driven speakers like the Acoustic SB 2.6, and the cyclone subwoofer.
 
     I have no idea what year the recording bass is but I think it may be pre triumph bass.  So maybe 68-71?
 
Anyhow thanks again
Antone-

If anyone is interested, there was a Les Paul  Recording bass at Cowtown Guitars in Las Vegas a whle back. It was in mediocre cosmetic condition, but it played well. Heavy though!  No doubt about it being a big chunk of solid Mahogany.

And remember:  ServoDrive means never having to say . . . Metamucil!
 
J o e y

Hello All I have a just completed my for real Bass rig.  I have been unhappy with LFE of most available bass rigs so I decieded to research and develop my own Subwoofer with some tips from Jerry Steckling (My part time employer).  From my preliminary tests these subs are -4dB around 25Hz and have reasonable output down to 20Hz.       I have given the sub the Title of BS-212,  I am using some EVM15B's in TL606 Cabs for the 80-3kHz region.  I have ~1100Wats available for the Subs and 450 for the 15's.  LF Extension is incredible.       Here are a couple of Photos of the rig and some preliminary close mic test sweeps (White line is sub cone Yellow Line is Sub Port).  

 

 

       Yah Baby Yah  You ever felt a low A like that!?  Sum

Wow, speechless!

Wow.

Here is an outdoor sweep I did vs some other pro drivers.  100 Watts @ 10 Meters  There is 5-6 to hot a reading on the TAD, BS-212 and JB 2245 sweeps.  The JBL 2225 Is more accurate.  You can see my BS-212 sub beats out the rest between 20-30Hz by far.  And only 1.07% THD @ 20Hz wow!!!       All sweeps are 1/2 space on ground plane so treble info is inaccurate.  

  BS-212 Harmoic Tracking 2nd & 3rd  

  THD of BS-212  

Mmmmm... nice artwork!
I can use one of these pictures in my once new office to come! On large scale of course!
 
Paul TBO

Ummm Shure I guess?
 
     If your serious go for it!?
 
Antone-

Lows like that make bowel movements easy LMAO wow lows baby

Seismic Lows!