Looking to start a DIY tube amp project without shelling out big bucks? You can do it if you follow a few tips from Bruce Brown, who built a high-quality tube amp for less than $150. His biggest purchase was the “iron.” Here’s how he kept the cost down.
The first step is to get the “iron.” Transformers can be very expensive, but if you watch eBay you can find some real bargains. Look for complete “off brand” integrated tube amps from the 60s using tubes that are no longer commonly available. These might include 6BM8, 7355, 7027, 7212, and the like.
Because tubes for many of these aren’t easily available, many sellers just want to dump the amps. If you buy a complete chassis, you might even be able to lower your cost further if the chassis includes switches, knobs, and sockets, in addition to the transformers. (This is always a challenge for me, because I prefer to see whether I can fix the unit rather than parting it out.) I found a set of output transformers and a power transformer from a Harman-Kardon A-100 integrated amp. I contacted the seller to see whether he still had the chassis and he said he threw it out (not much of a scrounger, I guess). I successfully bid on them at $62, including flat rate shipping.—Bruce Brown, “15 Watts per Channel for Less Than $150,” audioXpress, January 2010.
Editor's note: This article originally appeared in audioXpress, January 2010. audioXpress magazine and AudioXpress.com are Elektor International Media publications.