New build with a Dumble twist

[gloziersm58]

This is my first post to the site, I'm a guitar player who's a working tech, over the years I've worked on a lot of different amps and never really clicked totally with any. There's always some shortcoming that leaves something to be desired. So I figured build my own! I've built a few based on idea's I had, ones a hybrid, full tube font end with a single rail transistor output stage about 40 watts. Which actually was rather nice. But I kept looking for something better. That's when I ran across this site. Well I borrowed some of the preamp topology and joined it to a Kelly output design I had seen and liked with a pair of 6V6's running with a bit over 500v on the plate. This beast sang right from power up and has been my main amp for a while. However, this post is about a new build with a different choice in output tubes. Tubes can be expensive, far more than they should be. I went looking for alternatives. Here in Australia a couple of brands built in the 60's used the 6DQ6B which produced a nice tone in keeping with the time. I found a reference to the EL36 which piqued my curiosity and obtained some NOS winged C versions. Odd tube but with a 400v plate and a 200v screen will produce up to 60 watts a pair
into a 3.5k load. I've built it with a full dual channel setup and tube reverb drive and return and a tube effects loop. I've used fet channel switching for convenience because I'm not using the PAB switching or the channel chaining for drive. I've included a couple of photo's for interest sake. I've still got to build its case. At some point I will record some samples. So far I'm pretty happy with the tone. The wiring looks a bit busy but I was pretty much building on the fly. I had to create a regulated 200v screen supply which needed to be relatively isolated so built a discrete high voltage fet regulator which I'm happy to say worked well.

[ampgeek]

Welcome!

Now that is on-the-fly creativity at its best. Very, very cool!

Which Dumble circuit served as your guide?

Any chance that you could share your regulated screen supply schematic/component choices with us?

Rock on,
Dave O.

[gloziersm58]

Thanks for that Dave, I've got to do a schematic for the whole beast anyway, otherwise I'll lose my place the next time I have to dive in to fix something, New amps always go through a debugging phase, there's lots of solder joints I'll try to get some in focus shots as well, my eyes don't work as well as they used to. I've included a shot of the front of the unit and a shot of another I've just completed. This one is a single channel with a gain and master volume. Its got 4 stages of triodes to add a bit of crunch and harmonics but will has good intelligibility when driven hard plus good touch. 2 6V6's giving me about 25 watts just enough to gig. Also for a first time I used a accutronics/belton digital reverb. I had planned this one to have an 8" speaker so would not have had room for a tank.(Not to mention another 3 tube stages) I'm pleasantly surprised by the sound. I actually ended up using a 10" B&C neo woofer I had sitting on the shelf which actually sounds amazing. A bit pricy for a guitar amp though.