Thank You,(now w/ pics)

[jeff]

 I've just completed a new build. Cool sounding amp. This was the first amp I've ever built that had no problems to go back in and fix - move wires around, hum,etc.! Straight, outta the gate! The amp is super silent just idleing, no hum, just a (very,very)little speaker blow when the gain is cranked(and that goes away when you turn the guitar vol to 0). Unless you're playing, you hardly know it's on. There's not a super over the top amount of distortion so it's not the amp I'll use when I'm in a mean mood, but it's prefect for rock and blues(I did use 12AU7s so maybe..... naw!). I played a little "whole lotta love" through it and it sounded awsome to me. I know my playing didn't get better but the right tone makes all the difference in the world.

I think all my past builds and questions you've helped me with have led me to this moment. I'm pretty happy with it.

 I couldn't have done it without all your help. You guys are the best!!! Thanks so much for all the advise and putting up with all the stoopid questions.

Thank You, Thank You, Thank You!!!
                    Jeff
                    

[Geezer]

Congrats!

Well, are you going to share with the group? What is it? 

Any schematics or pictures (or sound clips?)

G

[jeff]

No time now, I'll try to get pics(if I can learn how to use the digital camera) and schematics up.

It's a PP 6V6 with some "mutations".
Probally nothin' new or innovative but it's not a straight up clone of somethin' else.

[bluesbear]

"nothin' new or innovative but it's not a straight up clone of somethin' else"

That's my idea of the perfect amp! Sounds like every good amp Fender or Marshall ever built. Every time they tried to be "new or innovative", the results pretty much sucked. Amp technology moves forward in tiny steps, not huge leaps. It's bound to be that way with a technology that's 50 to 100 years old.
There's nothing like playing with an amp you built yourself, is there?
Dave

[stingray_65]

I've experienced that feeling just 1 time.

I don't care that it was a 5F2A, Straight up Fender clone, 3rd 5F2A build in as many months.

IT WAS AWSOME!

I cannot begin to even contemplate how proud you have to be feeling right now!

[jeff]

Here's the schematic. Soon as the battery is charged(and if I can figure out how to use the camera) I'll have some pictures.

 I think the reason this amp is so quiet is how everything is grounded. Each tubes plates, grids, and power cap are grounded to one point on the chassis(X,Y and Z) with the exception of the power tubes. Their grids and cathode are grounded at one point and their PS caps at another.

 I was reading about grounding on the valve wizard site and it made a lot of sense to me. Before, I daisy chained all the grounds and grounded that wire. So the current going to the first tube is sharing the same wire as the current to the last tube.
 
 Before, I grounded the pots to the back, so the cathode ground and the grid ground are in different spots. If the grids are grounded at the pot and the cathode wire picks up hum, you'll get hum, but if the cathode and the grid are grounded at the same point, any hum on the cathode will also be on the grid and the grid to cathode voltage will be the same.

Now all the resistors that need to be grounded are going directally to a star ground, with a different star ground for each tube. No two resistors are sharing a wire to ground. I kinda tried to illustrate that in the schematic. Every ground symbol is a different location on the chassis. The jack is an isolated jack grounded at X.

Weither this makes a difference I don't really know but it makes sense to me and this is the quietest amp I ever built.

Another thing that may have made a difference is the chassis was divided into three sections. The preamp is in one section which is shielded from the PI and power tubes in the next, which is shielded from the power supply in the next.

[jerrydyer]

looking at that schem,,, looks like it would ROCK. 

try all 12ax7
and 12at7 in the PI   for fun see how much it changes.

[jeff]

I do wish it had a touch more treble though. I usally have the treble knob pinned. Not really a problem because it sounds good but say I want that little push over the top....Ideally I'd like to build an amp that sounds best to me with all controls at 5, that way you  have wiggle room up or down.

I had to use what I had on hand so I may change some values when I get more parts.
I used a 250pF for the treble cap. I probally should have changed the slope resistor to 56K or used a 500pF.
Things I may try:
Change the PI's coupling caps from .1 to .02.
Add a .68 bypass cap to the second tubes cathode resistor
Try a 500pF treble cap or use a 500K treble pot
Bypass the 470K in the voltage divider feeding the 3rd tube section with a cap.

I put the master volume after the PI driver's gain stage instead of after the tone stack just fo more distortion. I don't get to crank that much and need preamp distortion. It's not really too much, I think, because I'm using 12AU7s.

I went with the 12AU7s just because I had them and was running out of 12AX7s. Besides my other amp has 12AX7 and this is a good change to set the two amps apart.

[jeff]

 

try all 12ax7 and 12at7 in the PI   for fun see how much it changes.

Didn't try the 12AT7 yet but I did try the 12AX7 for kicks. The 12AX7 is a little too much and kinda ratty sounding. Maybe because the extra stage after the tone stack but before the master volume. It does sound good up to a point but that point is similar to the 12AU7 fully cranked. The 12AU7s sound good at any setting.

I kinda like the fact this amp uses different tubes from all my others. Besides all my 12AX7s are in amps right now so I'd have to constantly be swapping them out or spring for new ones. I think I'll keep it 12AU7s for now, it is what it is.

I notice in a lot of high gain amps there is usally a small cap in parallel with the first sections plate resistor. Is this just to keep the tubes from oscillating at the cost of some high end, or is this to roll off some high end to make the distortion smother? I've always thought if you don't need them to stablize the amp, don't use them and kill your highs, but maybe it makes for a better/smoother sound. It might be something to try.

One thing I could try is adjusting the 5K cathode resistor for the PI driver stage. This may make it sound better when using a 12AX7 in the first position. Since I moved the master volume to after this stage it's getting slammed with the gain up. I think adjusting the bias of this stage would definately change the sound. I only used the 5K because I took the values for the PI off a schematic for an amp using a 12AU7 PI and 6V6 power tube with similar voltages. The usual Fender value for a 12AX7 is 1K5. I'm not sure if a 5K was used instead of a 1K5 because it's a 12AU7 or it was an attempt to have the tube more center biased. I could just tack a resistor in parallel to play with it, or better yet a 10K pot and twist to taste.

....camera's still charging......

[jerrydyer]

ive been wanting to build a 6v6 amp for a long time. like a francesca with 6v6 (trainwreck type ) that tube when pushed just perfectly does some really cool stuff. I remember way back replacing a volume pot on my father in laws 64 blackface deluxe, the pot was basically stuck wide open. I turned it on and hit a note, I said so whats wrong with it. this thing was the most awesome classic rock tone Id ever heard to that point.

that first 360pf can be changed to 500 and your treble cap to 500pf and the 33k to 56 like you said,   more treble.  maybe even try bypassing the 470k iwith a cap too. before 2nd stage?

[OldHouseScott]

Bypass the 470K in the voltage divider feeding the 3rd tube section with a cap.

This should give you enough treble. If not, diddle with the tonestack some more, or bypass the V1a cathode, just like you mentioned.

[jeff]

Pics removed due to bad quality.

[John]

Cool! Does your chassis have some sort of covering, or is that a paint effect? Either way, nice!

It is cool playing through something you built. I was late to work this morning because I was noodling around on mine for just a few minutes and somehow the clock got turned ahead 30 minutes.

[jeff]

 The box is painted a cool military green. It looks grainy like that because I changed the quality of the pic to make it smaller, that's not a covering or a paint effect. It's kinda cool because the box has a flip top lid(now the bottom)
Originally it contained two flood lights and some replacement tubes. It was some type of repair kit. My friend bought it for me at a tag sale because of the tubes but they're not anything I can use. But hey, a metal box is a metal box.
Just poke some holes for the pots and tubes and bingo.

 I love repurposing stuff like that. I have a SE amp built in an old motion detector box(in fact it was given to me by the same friend). My grandma just got a bigger fuse box installed in her home so I think I got a box for my next project.

Anyone know how to resize pictures? I can't post any of the other pics because they're too big.

[John]

Depends on what version of Windows you're running, but maybe you can re-size through Paint. Try right clicking on the pic and then choosing something from the drop down menu.

Right now my "cabinet" is just some scrap lumber I screwed together quick.  It looks like a poorly built produce crate or something, but it's easy to flip it over and get to the guts, since I'm still tinkering with it.

[jeff]

Thanks I'll try.
There's something cool to that rustic look. I don't like stuff that's too fancy shmancy.

These pics are only a test. Still trying to figure out camera and how to post pics.

[jeff]

See what I mean about the sections? It's cool, preamp in one, PI and power tubes in the next, power supply in next.

[jeff]

Here's a brighter pic. Still learning the camera.

I know this is like a stranger coming up to you on the street and proudly showing you his baby's pictures. It means more to him than you and you think "So what it's a baby, seen one you've seen them all, I don't know who this is.", but I just gotta show it off.

[John]

That depends. Sometimes the other guy is a new dad himself. 

[jeff]

True.

Thing's gonna be a pain in the butt if I ever have to replace a resistor.
Check out the layout of the preamp. Everything is tied to that standoff and all the plate resistors cathode resistors and PS caps are in a straight line(as opposed to the PI section). It goes against every thing I've seen about good layout but it was all I had so I figured I'd try it and if it squeals like a piggy I'll redo it. If I said I was going to do it this way you could have slapped me across the face and be well within your rights, but I saw the rat's nest in the stereo I was harvesting the parts from and thought maybe this will work. Amazingly it works and is stable at full tilt(as far as I can tell, don't know about supersonic oscillations but it sounds like there's no problems).

Oh yeah those extra holes in the chassis aren't misakes where I drilled in the wrong spot. They were there when I got the box and were for the mounting the clips I had to remove.

The reason the gain is over to the side was because of the dividers inside the box. I couldn't space the knobs equally and figured it would look better if it was spaced twice as far apart instead if a little bit off.
Kinda like there is space for a knob in between and if it was there everything would be equally spaced, instead of wierdly spaced.

[jeff]

Alright, I'll stop blabing about my amp now.

Thanks for looking, thanks for the replies, and thanks for all the advise.
Couldn't have done it without you guys!

     Jeff

[stingray_65]

Great looking build!

love those minty green chicken heads!, very aesthetic.

Brag all you want! unlike a stranger showing baby pics, I could just choose not to read and you'd not be the wiser.

LOL, think its hard to get the "perfect" tone for yourself? try building one for someone else! double hard when they can't describe  what they want!

Way cool look, and yeah I can almost hear how its sounding from the schemo, but whats important is how you like it.

You've built it as a head, This is good (my opinion only) gives you lots of speaker choices, you may find your extra treble there.

[jeff]

Thanks

You've built it as a head, This is good (my opinion only) gives you lots of speaker choices, you may find your extra treble there.

True I just tried it out with some speakers I boosted off an organ. More treble, weak bass but the distortion wasn't as pleasing.

My brother gave me those green knobs and I thought,"what the hell am I gonna do with these ugly things" but I think they kinda fit. That's why I never throw anything away. Right after you throw something a way you always find a use for it. It could be on a shelf for 20 years, but a week after it's gone.......
 Of course, I should be featured on an episode of "hoarders" but I've always got somethin' up my sleeve.

[tubenit]

Creative build with the sections. Good job!  Looks fine.

With respect, Tubenit