A real Ba****d – Part 1

Yes, the name is maybe not so fortunate in today’s english-speaking world, but the design is still interesting – mainly because of its simplicity. Originally published by (long-gone) Danish magazine “Ny Elektronik” (which incidentally means “New Electronics” 😉 ) in 1989, “The Bastard” is a preamp made up of a tube line stage and a solid-state RIAA-stage. The line stage is based on a somewhat unorthodox design with a single 6J5 tube per channel operating at just 40V anode voltage, while the RIAA is a single-supply job based on more pedestrian BC550/BC560 transistors.

This is another design that has fascinated me for a long time, so I have made my own PCB layouts and tried it out. I started out with the line stage and this is what I will be presenting here (the RIAA pcbs have arrived but I need a few “odd-value” parts before I can start assembling them, so they will have to come in part 2 later). The PCB layout was designed to be more or less as compact as possible, with 10cm being the largest dimension (also helps keep the price down at the boardhouses 😉 ) For the tubes I use GE 6J5s in metal cans.

Eagle layout

Silkscreen rendering from the Gerber files. Made with http://www.circuitpeople.com – thanks guys!

I have only had this connected briefly to my desktop amp and speakers and I probably won’t get around to casing it for a while, but it does sound promising. Since I ordered a few extra boards, I may try building two more for a balanced version.

Assembled board with test wiring

Closer view of the assembled board and tubes.

PS: If you want to read the original build article (in Danish) you can read it here (20MB pdf)


5 Responses to A real Ba****d – Part 1

  1. Pingback: A real Ba****d – Part 2 | theslowdiyer

  2. Pingback: Project files: The Bas***ds | theslowdiyer

  3. skrodahl says:

    Just wanted to let you know that I built the Ba****d (or The BSTRD, as I called it), incorporating the feedback discussed on Hifi4All: http://www.hifi4all.dk/forum/forum_posts.asp?TID=59789&KW=bastard

    It is one sweet BSTRD, that’s for sure. 🙂

    The Eagle files for The BSTRD and the PSU that I made for it are freely available, and you can find the whole project here: https://hackaday.io/project/16944-the-muffsy-bstrd-valve-preamp

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