A blog of my tube amp design and modification work. Primarily my own builds, but occasionally I feature work I've done on others' amps (with their permission.)

Sunday, March 10, 2013

5E3 Pictures

Raw cab; not a scratching post!
 The cat's been unusually interested in the raw tweed fabric. I'm keeping it in a box until it gets warm enough to spray nitro.

So, I forgot to take a picture of the chassis with nothing installed.

By the awesome power of reflection, I show you my heater wiring!
 That white lead goes to a center post in the noval socket, supposedly grounding it helps reduce noise and crosstalk and such. I've never noticed a huge difference but it's cheap so what the hell. Also I alternated phases on the heaters for the preamp tubes (and kept the phases the same for the power tubes), another thing that supposedly can help to reduce noise but if it does it's not really noticeable.

Ceramic sockets.
Above the board wiring instead of the traditional "sandwich" style. 
 Yes, all these leads are way too long but I hate this solid-core nylon cloth-covered wire and have no problem wasting it. I trimmed them before soldering to their various connections. I actually made the bright channel's volume control lead too short, which is a first.

Populated board.

PT progress.

More PT progress.
Input jacks and tone/volume controls.
 Since I didn't have a brass grounding plate on which to wire up the jacks and pots outside the chassis, I mounted them to the outside of the chassis for wiring. The piece of paper protects the face from scratches, blips of solder and/or flux, and general "whoops" moments.


Closeup!


I soldered on the underside of the board going for a better mechanical connection as that's where the leads fold over the lip of the eyelets.

Output sockets almost finished.

PT almost finished.
 I went a little nuts with the zipties. Really hard to get these PT leads to hold a tight spiral; I think next time I'll just leave them straight and ziptie every inch or so. The twist itself doesn't matter, you just want to keep the corresponding pairs close together.

Controls mounted.

Jacks.
 I gotta say, it's a real pain to try to take pictures of something so shiny.

Mounted the board.
 Still waiting on my replacement pilot light holder in this shot.

DELICIOUS SPAGHETTI
 I was tempted to just box it up at this point and see if anyone would notice.

Output sockets done. I think?

Ready to go!
 Here it's got the stock tubes in it, and an old stock 5Y3. I've since put in all old stock tubes. The 6V6s I have aren't matched (the horror!) but they're both dissipating safely at 10 and 12W.

Preamp sockets.

Output sockets totally done this time.

Standby, Fuse, Power, Pilot.
 So, I don't like standby switches, but I dislike ground switches even more. The hole's already there and labeled "STANDBY" so what the hell.

Pots all wired up.

Jacks all wired up.
 Man, those two white leads connecting to the bottom jacks were A REAL TREAT, especially as I hadn't trimmed them before I mounted the board. This cloth wire really sucks too; did what I could to get rid of the fuzzies (burned them off with a lighter) but this wire was just fighting me the whole time. They also didn't send enough colors to have a consistent color scheme. They included the slightly thicker (18 AWG?) stranded white and black wire for the speaker cable but nuh-uh, I've got 16 AWG lamp cord for that. The red, green, and yellow wires are all solid-core.

Done!

Done!

Donnnnnne!
 Oh yeah, the cathode resistor on the power tubes is now a 300R/10W because I didn't have a 5W lying around. I could (should?) probably go a little colder but it's not a priority. I'd need a matched pair of tubes but I've got a few old stock 6V6s and a half dozen of cheap recent ones so that's not going to happen any time soon.

Aw, yours goes to 11? That's cute.
So there you go! Not particularly hard but a little frustrating at times. I spread the build out over a number of nights, maybe 15 hours or so in all. 

And dear god is this a sweet amp. I knew there was a reason why so many people build these but DAAAMN. I can't put the thing down.

I should measure the output on the 'scope. These are usually quoted around 12W which means it's too loud for bedroom playing but not quite loud enough for being onstage by itself. Of course, most venues have PA systems these days so being quiet isn't a problem.

Oh, and I guess I should mention the hiss/hum/buzz noise. There isn't any. There is some slight hiss when you turn the volume up past six - it's not the quietest build I've ever done but I think it's still impressively quiet. There are other things that could be done to kill the last little bit of his - shielded cable on that huge grid lead, grid stoppers, screen grid stoppers, actually shielding the back of the amp too but it's not really necessary.

Fun, fun little amp.

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