Amplifier Progress Update

As I mentioned, a new batch of tubes arrived this past Monday, from Electron Tube Enterprises in Maine. ETE is owned and operated by Dick Bergeron, whom I worked with for a few years about 12 years ago. Dick sells NOS (New, Old-Stock) and used vacuum tubes at very reasonable prices. I picked up enough tubes to finish repopulating the amplifier with it's full complement of tubes.



Box of tubes, waiting to be installed



The AO-29 amplifier, with all tubes installed

Tuesday night I put the new tubes into the amp and gave it go. The good news is that the percussion and bass pedals are working! The bad news: there is now some rushing and crackle-y noises in the audio output from the amp. It seems to be worse when the organ is cold, and mostly goes away once the amp is warmed-up. So more work there to chase down the source of the noise. I have also found that the lowest pitch drawbar for the lower manual is somewhat intermittent and touchy. Probably some dirty contacts.

The percussion feature is pretty cool. The addition of percussion makes this a "3" level model, just like it's big sister the B3. Percussion in this case has nothing to do with rhythm - its an extra amplifier stage that adds some harmonic content to the beginning of a note that is played, giving it some extra "pop" or percussive sound. Here's a pretty lame video of me playing around on the organ with and without percussion... remember, I can't actually play keyboard yet so be kind 8):