Hi DC,
I have developed a servo feedback Sub in conjunction with a friend in th US, It uses a secondary coil of 24ohms and reaches 12hz in room. The driver is 12" and achieves this in a 1.5cu foot box. I have sold 27 last year and the last home theatre i built has two of them. You will never reach this level of sub bass from an OB design. believe me I have tried them all. My Sub has been compared with the Velo DD12 and sounded better. I can give you the parts and you can build this as a kit if you like.
Best regards,
Stuart (SDA)
I have developed a servo feedback Sub in conjunction with a friend in th US, It uses a secondary coil of 24ohms and reaches 12hz in room. The driver is 12" and achieves this in a 1.5cu foot box. I have sold 27 last year and the last home theatre i built has two of them. You will never reach this level of sub bass from an OB design. believe me I have tried them all. My Sub has been compared with the Velo DD12 and sounded better. I can give you the parts and you can build this as a kit if you like.
Best regards,
Stuart (SDA)