I am putting together a bedroom system and wanted to build a pre from scratch. I have seen may passive pre's out there, but impedance matching can be an issue sometimes. So I decided on the Nelson Pass B1 buffered pre http://www.passdiy.com/pdf/B1%20Buffer%20Preamp.pdf
The schematic looked very straight forward, and the good thing is that it can be built on any budget. Mr Pass had the cad files on his website, so I downloaded and etched the board at 85% size (to fit on a radio shack board). I used all metal film 1% resistors, 2SK170 fets, Solon and some other caps from Futurlec. I soldered all of my connections under the board, and I am using a Compaq 18.5 2.7A wallwart. The sound is very transparent, with my source on pause and I crank up the volume -silence-.
Now I plan to use an AM/FM tuner and TT, so for the TT section I went with a solid discrete gem. Tony van Roon has many wonderful circuits for DIY folks and his RIAA circuit brings out great detail form my Grado Green. The circuit provides "1-volt output from a 6-millivolt input at 1KHz, and provides equalization that is within 1 dB of the RIAA standard between 40 Hz and 12KHz." (Tony van Roon, 1994) http://www.sentex.ca/~mec1995/tutorial/ ... xtor5.html
I drafted the circuit up in Eagle and have provided the files for those who want to download and etch the boards. Thanks to Tony for a great design.
The third part of my pre is one of my hybrid headamp builds. It is actually the prototype I made, the new project is much smaller and will fit in a radio shack project box. Since the power supply is 18.5, I threw a 7812 between B+ and the filaments. Since the final stage of the headamp is Class A, it will crank out a bit of heat, but the sound is wonderful.
With all DIY circuits there tends to be some turn on thump, I have a mitigated this issue with two delay circuits, the first is of Pass Labs and can be found on page 5 of the Zen light build http://www.passdiy.com/pdf/zenlite.pdf
The delay will turn the headlamp on 3 seconds after the B1. Further, I wanted to protect my headphones from thump of the MOSFETS, so there is another delay circuit for low voltage signals..
Now all of this is enclosed in an old Dynaco tuner chassis. I used the existing switches and 20k linear pot. It will fit nicely in my room. Will post pics of the rack when it is totally up and running.