Defined benefit

Indication that if you have a "one-person" DB not covered by PBGC, your DC contribution is limited to 6 percent of compensation.

http://benefitslink.com/boards/index.php?showtopic=43751

Indications that if you have a Schedule C, your deductible DB contribution is limited to your Sched C earnings. Also, if you have a DB and DC, DC contribution is limited to 6 percent of compensation.

http://www.taxalmanac.org/index.php/Discussion:Update_to_defined_benefit...

Good articles on defined benefit plans :

Defined benefit maximum contribution and minimum compensation table :

http://automatedpension.com/minmax/default.aspx

Simple calculator showing DB vs. DC contributions in various cases.

http://www.pensiononline.com/poltools/netearn.asp

Simple DB calculator from Oppenheimer showing max DB contribution. Seems to be too low. For example, only $40K contribution on $200K income for age 46.

http://www.singledbplus.com/singledbplus/pen.asp

You can participate in plans from two employers.