At this moment the only available downloads are this home made soundfonts that were recorded in mono 44.1 Khz using a Sound Blaster Live soundcard, a Peavey mixer and a Shure Beta-57a microphone.
Even though I didn't use any costly equipment I know they are the best sounding trumpet or trombone soundfont you will find for free over the hole web (based upon my own experience). If you want to hear a sample you can get a free MP3 here .
I have processed the sound the less posible (just a little bit of noise reduction) to keep the samples in its purest state because, if you are like me, you'll prefer to create your tracks first and then add all effects and EQ during the mixig process at your own measure and taste. I've tried several stereo soudfonts and, in my opinion, mono soundfonts sound fatter and more natural to make sequences using MIDI.
The trumpet one and the trombone one were recorded by setting the microphone in axis with the instrument bell, while the trumpet two and the trombone two were recorded by setting the microphone in a 90° angle in relation with the instrument bell. This soundfonts are not copyrighted so you can use them in any project you want.