I'm currrently building a preamp for my sister, using the Constant Current Source schematic in the back of Bruce Rozenblit's Beginner's Guide to Tube Audio Design. The design uses an 12AU7 for each channel and looks to be a very simple build. Other than it being simple, the other attraction is that its different from the usual Common Cath/Cath Follower design, and I was very interested in hearing what it would sound like.To date, my exposure to tube preamps has been limited to CF designs, based on 12A_7 tubes. Never heard octals, and nothing outside of CF's. So I'm wondering if anyone can share their opinions on the various preamp topologies and tubes. Any favourites out there?
Thoughts on the follow designs: CF, Constant Current Source, SRPP (Shunt regulated push pull), Grounded Grid? Does the use of octals vs. 12A_7's really make a difference?
Thanks,
Gar.