ultra class A superdrive power amp

[lumpymusic]

Super fun build.

How did you build the "tube"?
Did you cut the glass on a 12xxx?

Beautiful concept and execution.

Lumpy

[KerryF]

^-I remember reading somewhere that he did cut open the tube.  He said it took many tubes to finally cut one without it breaking.  Then he put the transistor in there in a socket, and an LED to model the glow of a tube.  I think he said its a Blue LED to show a "backlit" tube glow.

[dano12]

just curious dano, but what was the enclosure originally used for? (I.e., where did you find it)

Pretty cool by the way 

It is a standard Hammond. I forget the size number, maybe "J". Check out the hammond site and you should be able to find it.

Also, a little bit more on my build at http://beavisaudio.com/Projects/HalfWattClassA/index.htm

[Caferacernoc]

How would you use 3 transistors in this circuit as stated a couple posts back?  Thanks!

[lumpymusic]

Also, a little bit more on my build at http://beavisaudio.com/Projects/HalfWattClassA/index.htm

Would you care to discuss a little about how you built the "tube"?
Specifically, how did you open, reassemble the glass?

Thanks -


Lumpy

[KerryF]

^- Yea I would like to know too.  It seems like he probably cut it low, and then when he fixed it up, he put it in a socket with a little shield on the bottom to hold it together.

[bancika]

Here's link for micro power amp by joe davisson
http://www.diystompboxes.com/analogalchemy/amps/microamp.html

[dano12]

Regarding the tube, it was an evening of frustration and glass shards, punctuated by colorful language and multiple trips to the beer fridge.

I had a gaggle of burned out 12A*7 tubes. I first tried a manual glass cutter--disaster. The final solution was to use my dremel tool with a cut-off disk. Even that took 5 or 6 tries. I found that plastic base of an XLR connector fit in the bottom just fine and used that as the base for both the transistor and the backlight LED.

It takes a lot of work to do silly stuff

My experiments in picture frames and plexiglass went a little better:

[RLBJR65]

Thats really awesome no mater what it sounds like

I did a vero layout for Joes amp a while back, haven't got a chance to build it yet.

Here it is if anyone wants to give it a go.
http://aronnelson.com/gallery/Richard-Boop-RLBJR65/JDMCA

[Threefish]

Has anyone tried either of these mini amps with headphones? I know there will be an impedance mismatch (speaker 8 ohms, my headphones 32 ohms)

[oldrocker]

Yes I'm working with that right now.  The Ruby works great with headphones.  I'm building a Ruby that is fed by a Muff Fuzz in one box.  When I'm done I can plug in headphones or plug in a speaker which clips onto my belt or guitar strap.  I added a toggle to turn on the Muff Fuzz.  I should have it finished Monday and I'll post some pics.