It's hard to find good jam tracks. If you look for them on the 'net, it seems like most sites are trying to sell you lesson materials. There are a few out there with decent tracks for free if you can find them, but the tracks aren't exactly top quality either. My goal here is to provide a few good quality, free jam tracks for you to use. If you don't like mine, feel free to make some and send them to me! I'll post good ones here with a link to your site.
Most of this tune is in G major (E pentatonic), but it switches briefly in the "chorus" to the key of B (G# pentatonic). The drums change time on that part too, so it's easy to recognize where it changes.
Mostly G Delay Tune - Ben Holt
This jam track starts out in C major but emphasizes E Phrygian. The chorus changes to A harmonic minor. See if you can keep up, it's a fun jam track!
Em Rock Jam - Ben Holt
This Dorian-sounding progression actually makes a diminished chord sound decent! At least, I think so. Solo using modes in Gb or Eb pentatonics.
Ab Dorian/Diminished Rock - Ben Holt
Use the key of B minor/D major for this one. B pentatonic will work too.
B Minor Jam - Ben Holt
This is in the key of Gb major, but is modal and emphasizes the Bb Phrygian scale. Eb pentatonics will also work.
Bb Phrygian - Ben Holt
With a quarternote pulse throughout, this jam starts in the key of Bb (G pentatonic scales). The second part is a Bb blues, so use modes in the key of Eb (or Bb pentatonics).
Bb Ionian to Mixolydian - Ben Holt
A laid-back, groovy track in Ab Mixolydian. Solo with Db modes or Bb pentatonics.
Ab Mixo Jam - Ben Holt
These next two tracks will help you work on changing keys in the middle of a song. You must reacclimate yourself to a new set of modes several times throughout the song.
This one was a jam track I made for myself to test out a Joe Satriani type preset. If you want, you can hear the soloing version here. It's not that great, just an example :)
This is a modal jam. Use modes in the key of F major first (Bb Lydian), then when it changes chords use the key of C major (F Lydian).
Bb - F Lydian - Ben Holt
This one changes key from B minor (D major) to E minor (G major).
D - G Jam - Ben Holt
These next few tracks are from jamtrackcentral.com, a site with tons of great jam tracks. These few are free demo jam tracks (most other ones cost a few bucks) from their site which they generously gave me permission to host here. They're very professional sounding!
An uptempo blues jam in E. Use those E pentatonic scales with some tasteful chromatic notes thrown in!
Fast Blues - Jam Track Central
A slower, bluesy track in C minor in the style of "Tin Pan Alley". Use C pentatonic scales.
Slow Cm Blues - Jam Track Central
Funky minor blues in Am. Use A pentatonics or G major modes (to bring out the Dorian sound).
Funky Am Blues - Jam Track Central
A slow, Pink Floyd style jam track in D minor. Use D pentatonics or F major modes.
Floyd Jam - Jam Track Central
A 12-bar rock/blues track in the style of "With Jupiter in Mind" by Joe Satriani, this track is perfect for shredding. Use E pentatonic scales.
Satriani Shred Jam - Jam Track Central
Perfect for slow dancing, this rather sappy R&B track is good for soloing as emotively as possible. A good track to practice space and speaking through your solos, even if it does make you feel like smashing a wall in after listening too long :) Use modes in the key of G or E pentatonics.
G Major Sappy Jam - Jam Track Central
This great jam tune was created by Keith Moore, a guitar teacher in California. He has a few jam tracks on his site, but this was my favorite (I have his permission to post it here). It's a simple A ostinato, which means you can play in ANY key that has an A in it! You can use A pentatonic, F# pentatonic, and try others! For modes, you can use any mode starting on A! There are seven keys with A in it, and seven modes for each key, so this tune works with at least 49 different modes.
A Ostinato Jam - Keith Moore
I was watching this soloist and liked his jam track - it's a drone (in this case a root and fifth) played softly behind his soloing. This kind of thing is nice for messing with scales and chords and stuff - it gives you a reference. Middle Eastern music does this a lot. If you know your modes, try bringing out the different sounds of each while soloing over one of the tracks below. For instance, if you're soloing over A, try playing A Ionian, A Dorian, A Phrygian, etc (with other modes in the key, of course). Locrian will not work, since the tracks below all include a root and (perfect) fifth.
10 Minutes of A
10 Minutes of Bb
10 Minutes of B
10 Minutes of C
10 Minutes of C#
10 Minutes of D
10 Minutes of Eb
10 Minutes of E
10 Minutes of F
10 Minutes of F#
10 Minutes of G
10 Minutes of G#
These jam tracks weren't cool enough to make it to the top of the page, but you may find some use for them.
Blues in E - Ben Holt
Eb Major Happy Jam - Ben Holt
D Major Loops - Ben Holt
Bm - Cm Keychange - Ben Holt