There’s been quite a bit of exciting work going on on the lab lately! I’ve been working on my second tube-amp project, which I call The DEUXamp.
I thought I’d post a few shots of the progress so far for the DIY’ers out there that enjoy this sort of thing.
A quick note about the amp circuit I’m using, and why I’m building another tube amp project instead of plowing forward with more creepy steampunk-skull pieces.
My original Steam Amp created quite a stir, and I had quite a few folks that were interested in perhaps purchasing it… Interested that was until they found out it was based upon a relatively inexpensive ($250.00) kit. When they found out about that, they promptly lost interest and were never to be heard from again.
If that had happened once, I’d shrug it off, but it happened more than a few times. I guess they thought for 1200 bucks it was going to be a McIntosh tube amp on the inside or something… and I get that, 1200 bucks is a lot of dough, but if you want a high-end tube amp.. go buy one! The steam Amp is first-and-formost an art piece, and the fact that it actually functions (and sounds really, really good) is an added bonus in my book.
Well, never being one to be dissuaded by a slight or a challenge (wether real, or most likely in this case, imaginary), I began scheming another steampunk-ish tube amp project, but this time it would be a decidedly much more high-end tube amplifier project. Thus The DEUXamp was born. Or hatched. Or popped into existence through a rip in the space-time continuum.. whatever.
“I’ll show those doubting Thomases!” I cackled at the rafters in my lab as I wrung my hands in evil defiance. Thunder arced across the sky, the wind blew, and somewhere a child cried a single, solemn tear.
This project is actually a pair of mono amplifiers; wheras most amplifiers are stereo, (two channels in one box), this one completely separates the two channels into tow discreet circuits, giving a much better audio soundstage. It also looks cooler, dude.
These tube amps are based upon the Dynaco MKIII kit amps of DIY lore. I bought the amp kits minus the driver boards and chassis from a wonderful place online called Vacuum Tube Audio. VTA sells a wide array of cool amplifier kits, as well as modified driver circuitry kits to bring these old amp circuits into the modern realm of high-end audio.
I opted for their Octal Driver Kits for my MKIII’s, mostly because of the way people spoke about the upgrade to the sound over the original driver boards, and partly because I prefer the look of Octal tubes over some of the other types. Hey, this may be a kick-ass amp, but it’s still an ART project, so aesthetics are important.
In the end I did away with the VTA PC board that came with the driver kit, and direct-wired the circuit into the amp. I didn’t want to have a PC board cluttering up the underside because I wanted to use clear-acrylic bottoms under the bases so people could “look under the hood” if they were so inclined. (Hey, it took forever to wire that thing up, I wanna be able to see it!) I also plan to have some UV LED’s inside there so the amps will have a purple glow under them. Not that I’d recommend trying to just pick these things up and flip them over.. they weigh a TON.
On to the Building
I started with a 12″x12″x.125 sheet of copper and laid out all of my holes on the top with a fine-point sharpie and began drilling! The large octal tube socket holes were made with a 1-1/8″ knockout punch. What a godsend these little babies are, they make life working with sheet metal almost pleasant!
After getting all of my holes taken care of, I wet-sanded the crap out of the top of the copper sheet with 400 grit sandpaper, then 800, then 1200, then finished with 2000 grit. After that I buffed the surface with jeweler’s rouge to get it as close to mirror-finish as I could. This was a real pain in the arse, and I wasn’t able to get it quite perfect, but I think I did a respectable job.
After polishing I cleaned it carefully with lacquer thinner, being careful not to touch the surface with my hands for fear of fingerprints. I then sprayed it with a few coats of a special lacquer called Permalac, which is formulated to seal metals like copper and brass so they won’t tarnish.
Most of my pieces I’ve finished using Renaissance Wax, but for these amps, I wanted to have a finish that wouldn’t need any maintenance, so I went with the lacquer. I have to say that I’m very impressed with the Permalac, it dries to a very smooth finish, and doesn’t have the annoying plastic look of most clear store-bought spray cans.
The next step was to attach all of the tube sockets and transformers attach the copper plate to the wooden base and begin wiring! The wooden base in these photos is red oak, and after finishing two of them, I decided I was sick of looking at red oak, and I decided to rebuild them using some nice Walnut. Talk about picky… I’m glad I don’t have people working for me, I’d be dead by now.
At any rate, the next set of photos will show the newer version of the bases, and will hopefully also show the transformer covers in some sort of finished state. I have designed a pair of matching speakers that I will of course share in the coming months, but first I have to finish these amps..
Until next time…