2204... mostly

[sepulchre]

Here's my latest, a 2204 variation:

[img743]http://i269.photobucket.com/albums/jj55 ... 9655a6.jpg[/img]

[img768]http://i269.photobucket.com/albums/jj55 ... ed82b9.jpg[/img]

It's very similar to Jana's with a few minor changes. When I first fired it up it instantly started Howling at the top of its lungs around 100 or 200Hz and making a mess on the floor. (oh, that was me ) I checked everything until I was blue in the face. No joy so I hit the "books" (online) and read everything I could find. Then a fellow named Tilly Dog asked if I had checked the NFB phase. Nope. Hit the books some more and finally got it straightened out (swapped the OT primaries, pretty simple).

Now it's singing like a . . . okay, not like an angel, though it does have more nice cleans than I thought it would. And not quite as much gain, but it's kind of loud in this little room so maybe when I can really crank it I'll get a bit more gain. However, it's pretty sweet with the Master down too. I'm still playing with a few things on it but I've got a cab all ready and waiting. Pics of that when it gets installed.

[rsi]

Nice work. What did you use for that bus bar?

[HeeBGB]

Looks like what i use. I take very thin solid core wire and strip off all the insulation. About 4 feet. I fold the length in half once and put the ends together in a vice. I put the fold in a cordless drill chuck and spin the drill until the wire is wound nicely. Cut to the length i need and tin with solder and viola....instant bus bar.

[Reeltarded]

Coolness! Not as gainy as you thought it would be?

I am doing everything I can not to build every amp like a Marshall and having to back up 2-3 steps at a time to make the Rocket not a Marshall. That thing is very Wreckish!

[Bob S]

Congrats - that makes mine look messy !
That layout looks good to me.
The 2204 circuit seems to be forgiving - a good thing in my case.
A definite must have.
Well Done.

[M Fowler]

Nice job.

What size filter caps did you use 40-47uf all the way through?

Oh and one can cap I saw 50/50?

Mark

[sepulchre]

Thanks, Bob. It's a good thing me that 2204s are forgiving too.

Mark: they're 47uf except for the initial can which is a JJ 50-50. I had the F&Ts from a previous attempt so they've found a home.

Miles: I've been hearing so many of these with Pauls that my Strat, well it's not so fat. Now that I've played through it a bit more, well it's got plenty of gain. I don't do the shredding stuff anyway, but I was thinking - if somebody wanted one that is more gainy what would I do. There are a plethora of mods for it in that unlikely event.

HeeBGB & RSI: that's just stranded wire that I stripped. 18 gauge IIRC.

Thanks guys. This was fun. But actually the fun is just starting. My wife said, "Now you better get out there and show it off."

Heh, heh, heh! Guess I better.

[Reeltarded]

She is kicking you out!?

[sepulchre]

Hahahaha! Guess so!

[jon]

I actually just converted a Roctal (octal power tube Rocket) into a 2204. It is a total beast I love it. Mine has very little clean though. Mine also only has the high sensitivity input.

[sepulchre]

Well, I was more or less mistaken about the gain - it's got plenty! I'm just still getting used to it. It's a very sweet sounding . . . monster; plenty of Loud too.

And with the switch on 'Low' it cleans up nicely, albeit not as loud (that's what the knob's for, dummy). Oh yeah, this'll do just fine!

That said, I was looking at Reel's tone stack changes coupled with the CF 50K cathode resistor that's bypassed. His description of how it sounds is very tempting.

Mine's got a 68K on it. I didn't go less because I was under the impression that lowering Rk on a CF strains cathode/filament voltage tolerances. I found a JJ ECC803 long plate in an old box - don't remember when or why I got it - so figuring it's tougher I put it in the CF slot. Any thought about that?

But right now I'm waitin for the weather to clear (some day) so I can take it out and give a real test. Having fun playing on it though. Sure is nice.

[martin manning]

Mine's got a 68K on it. I didn't go less because I was under the impression that lowering Rk on a CF strains cathode/filament voltage tolerances.

The Rk value won't affect the heater-cathode voltage much in a CF like this one, it's really determined by the grid voltage. Smaller Rk values will drive the current up, though, so watch the plate dissipation.

[HeeBGB]

Not intending to Hi-jack the thread but here is a pic of the bus bar I described earlier.

[sepulchre]

That's nice! What gauge?

[Reeltarded]

The Rk value won't affect the heater-cathode voltage much in a CF like this one, it's really determined by the grid voltage. Smaller Rk values will drive the current up, though, so watch the plate dissipation.

After all my foolishness and still no catastrophes here. I tried a .005p bypass over a 47k once and I could tell that was not going to last long though.

I can only imagine how that would look on a scope.

Sounds awful!