What is the purpose behind hollowing out the back of the fingerboard, and cutting slots in the soundboard? The fretboard seems a little bulky at 2x2. --Always unplug the mains cord before working. We have an educated guess, using the datasheet (see the previous step):1833 ohm for two tubes. yet to get my pots and hook it up and to be honest, the layout was just too tight for my liking, and suspect i may have overheated and probably have some solder bleeds. on Introduction. Every single other tool I used was a common woodworking tool. Again, this isn't as loud as a two-tube PP setup, but it's simpler. About: Go sit in the Faraday cage and think about what you've done... Want to build your own tube amplifier for guitar? That is awesome. An attractive alternative: change the hard-wired caps from 40uF and 15uF to 10uF for each. And nice sound too. I originally estimated the power output from the datasheets as approx 7+ watts. I figure the market can handle one more local. Power tube cathode bias : 5 to 10 watts I tried using the Duncanamps "Tone Stack Calc" designer, but it's useful as a starting point only. OK--it's a little "experimental," but that's good, right? If I make another it will be with power tools for sure, I only made this one without to enter a contest. Even less capacitance is an option...The Screen Supply SwitchAn additional source for the 6DG6GT screens has been added: the Edcor output transformer has a 40% screen tap. Would be nice to have a video so that we could hear how it sounds. --Coupling capacitors (and the grid-leak resistors following which constitute an RC filter.) The Tone / Volume Control Why? 200V : 4000 (Again, sorry for the lost formatting.) Thanks mappcs, Reply Question it has both a guitar channel and a bass channel and you can mod the holy living merciful Jesus out of it.. change the bass channel to a marshal guitar one, add tone stacks... modify the existing ones.... the good part of the schematic is that the power amplification stage is so isolated from the preamp stage that there is so much room for personal modifications, that would actually be a more than good starting place, isnt that where James Marshall started :), Reply Immediately, I rejected the use of a tube rectifier--what I had on hand wouldn't be as efficient as a solid state rectifier. A ground reference (false center tap) was provided by bridging the 6V by a pair of 180 ohm resistors, tied to the chassis ground. #1(rectifier) 5.0v @ 3a ct.It's 180V, but with a tube rectifier like a 5U4 instead of the SS bridge, the output voltage should be very near 200V. The bottom input, which is a ground reference followed by a grid stopper resistor, has a more "bassy" sound. Contest Sponsored by Dremel. So I started planning how to supply the filament voltage for two 50V and one 12V (or 6V, the 12AX7 can be 6.3V filaments, also) tubes. Since it's controllable, I'm OK with that, for now. Reply This is a timelapse video of a Les Paul style guitar that is made of reclaimed wood that has been salvaged from deconstructed buildings in Chicago. That's awesome! Now would be a good time to stain your dulcimer if you would like. They are a must for the power supply filter caps, and are also often used for cathode bypass caps. As a general rule, a higher (cooler) bias voltage results in a harsher distortion. ***If you don’t like the music please just turn it down. Figuring Load Resistance Mathematically (WARNING: Math Content) The two-diode trick works only for AC--current flows through one diode at a time, dropping that half of the waveform by the diode's voltage drop amount. Hi and welcome to my longest woodworking project so far. We'll stick with 150 ohm for now. Make sure your ruler is accurate and measure very carefully. We're at 190V, so it'll be slightly less than the chart. 5 years ago. But some of those are a little hard to duplicate...(that's why I'm always looking for junked amps, transformers, etc). With this chart alone, a very workable triode stage can be constructed. that should drop the voltage to less than 210V (vs. 322V for a rectified 230 RMS.) With all your sound holes cut, you are ready to glue this piece to the rest of the dulcimer body and let it dry while you work on the fingerboard. Hi , I am just starting out. (Gotta dig that crazy square root of 2...that 1.414 number pops up in so many places!) But it's not ideal--it's better used in the push-pull configuration, especially this close to it's rating. Put wood glue along the outside edges of the bottom piece and attach the lath sides to it. Don't make a new nut just to fix a low slot—fill it! As you can see, the coupling cap in the second preamp stage is missing. A single bit can drill holes from 1/4 to 3/4 in., and FAST, too!