SMPS for tube pedals

[printer2]

The module with my two penny heatsink is doing well in a Champ type of circuit at 350V and 45 mA from 11.5V.

[merlinb]

Adorable! Do you notice any buzz being picked up by the output transformer?

[printer2]

Adorable! Do you notice any buzz being picked up by the output transformer?

Absolutely none. I was concerned about conducted or radiated EMI when I started this, part of the reason for making the amp. I planned to do a P-P amp with the module and started this amp to see what pitfalls I might find. Just never thought it would take this long, thought it would only take a week. I also made the tone stack switchable from the regular Fender response to almost a flat response. It is different from using a tone stack lift in that the bass and treble controls still work but with less range. Also when switching from one to the other I do not get the massive gain boost but rather the same volume but with the hole in the response filled in.

I originally had a smaller speaker in it and was going to make this a SS amp but when I tried the speaker in the cabinet it sucked. So I shoehorned in the smallest 8" speaker I had (70V PA speaker) and thought the Blackface curve will give it some bass given the small cabinet. Or make it less boxy sounding. I have only played through it for a short time but it seems to work. It can not be mistaken for a full size cabinet but it is fine as a practice amp. At first I though switching to the flat setting sounded quite middy but after a touch of EQ it sounds fine. As it is set right now I can switch between both settings and I can not bother tweaking the EQ. I did want to use a 250k pot for the treble but when I looked in the bag that was suppose to have 250k pots in it I had 500k's. Thinking right now I guess I could have used the pot for the bass control but at the time I thought using it in the treble position would make it easier to do a point to point wiring of the stack.



With the 250k pot. The 500k circuit has a 100k instead of the 82k, 22 nF instead of the 75k (68k on the schematic, did not notice the difference before creating the image), 33 instead of the 47 nF.  With the same relative signal level between both settings I do not have to bother adjusting the volume control going between either.



Otherwise it is a basic Champ other than using the 10k/500pF input filter. I spaced the controls as close to each other as I could to give me more sonic options. I would like to have an Orange Squeezer on the input and a slap back delay after the volume pot. If I feel really ambitious I might stick in a reverb instead, but these are winter projects. Right now it is sitting beside my TV and it is easy to overlook. Because the amp is so quiet the only noise I hear is from the guitar I built with a single coil pickup. Now I am going to have to put a noise canceling coil in it to get it quieter.