Or get a 5/8>3/8 adapter and a 3/8>5/8 adapter and screw then together. That will get you a little over 1/2 inch rise. Put two sets of those together and you can X-Y most any pencil mics. That's what I have.
If the knobs at the end of your bar are 3/8 with an adapter on them up to 5/8, remove the adapter and get a 3/8X16 coupling nut at Lowes/Home Depot/etc. and a 3/8X16 stud. The screw the 3/8>5/8 adapter on the stud. That will also make a nice riser. It doesn't look fancy but will be perfectly functional.