can I get more garageband instruments without updating my OS?

Most of the instruments in Garageband 10's additional content are instruments you already have in GarageBand '11.

And the Smart Instruments will not work with GarageBand '11.

You could try to install Mavericks in a second partition or on external drive. This way you can install GarageBand '10 and buy MainStage 3 from the App Store. MainStage 3 will install all five JamPacks with plenty of instruments.

The problem is, to be able to buy MainStage 3 from the App Store, you need a Mac with Mavericks. You simply cannot buy it with your current system.

You could try to contact the Apple Store from the Store Support page and try, if they will offer you to purchase a redeem code for MainStage 2. That will work well with Mt. Lion. I have never tried to contact Apple Support for older software, but it has been reported, that they occasionally will help.

Piers61 wrote:

Hi, my son and I are trying to get more instruments on garage band 6.0.5 (428.5) [...] without updating my OS

here you'll find some free SoundFonts (5,000 ish):

http://www.bulletsandbones.com/GB/PlugInsSoundFonts.html

how to install them (short story):

http://www.bulletsandbones.com/GB/GBFAQ.html#installsoundfonts

(Let the page FULLY load. The link to your answer is at the top of your screen)

how to use them (short story):

http://www.bulletsandbones.com/GB/GBFAQ.html#usesoundfonts

(Let the page FULLY load. The link to your answer is at the top of your screen)

install and use tutorial (the long hand-holding story):

http://www.bulletsandbones.com/GB/Tutorials.html#allaboutsoundfonts

(Let the page FULLY load. The link to your answer is at the top of your screen)