Of course, "budget" is a rather subjective term. For the sake of some truly usable options for ribbon microphones, let's consider budget to be under $1000.
For passive, traditional ribbon mics, the TRP from AEA truly is the way to go. Every ribbon mic benefits from this preamp. The extremely high impedance of this mic (18kOhms!) and the 83 dB of clean pure gain allow ribbons to breathe and have depth without experiencing the lower-mid bloating that is all too common with "regular" preamps. Plus you have enough gain to drive a vocal or acoustic string instruments. Keep in mind that this is a two-channel unit and that it is fantastic on tube and dynamic mics, too.
Another preamp that works well with ribbons is the Universal Audio Solo 610
, or the LA610mkII
for that matter. Considering that this design comes from a time when more than a couple RCA mics were the norm on a typical recording session, the 610 HAD to sound good with ribbon mics. The sound is a little on the big and round side in the lower register, but it's nothing that will ruin your day. A good high pass filter will cure it. However, I will say that the LA-610mkII will have one distinct advantage over the Solo 610
; selectable impedance. You can set the LA-610mkII to 2.0kOhms and a ribbon will come to life.