My Very First Ever Build AA764 Vibro Champ. (Cab is here)

[tribi9]

Thx Structo,

I don't have any shielding wire handy but after I reversed the OT's primary wires and plugged in it sounded pretty nice and there wasn't much hum. In fact I find it very quiet.

I'm running the input wire on top of the board as opposed to under like I had it but I don't know if that makes a difference. Also I placed the 68K resistors at pin 2 on V1.

[Structo]

Cool!

Yeah, unless you are getting radio noise or other things leaching into the input, you might be lucky and not need the shielded cable.

Glad you got it going.

[tribi9]

Cool!


Glad you got it going.

It wouldn't have happened without all of you guys helping me out every time I got stock.

Definitely looking forward to a smoother second build, and that 18 watt Marshall clone seems sooo tempting.

Cheers all,

Ronald

[M Fowler]

Tribi,

Remember that guitar cords are shielded wire and I often used old grey guitar cords as shielded wire until I got plenty of the good stuff. Every cheap amp or guitar seems to come with those very thin guitar cords and that works very well as shielded wire.

Mark

[tribi9]

Ladies, Gents...

Here's my amp. FInally done. I cleaned up the wiring last week but only got the cab today. Weber speaker on it's way to me. I just need to get some knobs and I'm good.

Thanks for all the help guys. If you don't mind I'm going to quietly lurk so i can hopefully pick up a little of what you guys know.

Now a couple of pics

Cleaned up the wiring a bit.

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02085.jpg[/img]

Front and back (Hadn't attached the back sticker on this shot yet)

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02088.jpg[/img]

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02087.jpg[/img]

The whole thing.

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02090.jpg[/img]

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02098.jpg[/img]

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02096.jpg[/img]

[M Fowler]

Yeah now your talkin buddy, that is nice and tidy and I love the cab color as well.

Mark

[Kregg]

That looks way bitchin' cool! I love it in baby blue.
What speaker did you go with?

[Structo]

Sonic blue tolex!

How cool is that!

[Rick]

So... pretty much I have to drill through the chassis? (Since there are no holes in the area the tagboard sits)

ARGHHHHHHHHHHH!

Get a step bit from 1/8" to 1/2". Get the titanium nitride coated or pro quality step bit like electricians use, it is about the handiest tool you can have.

[tweedeluxe]

Tribi, congrats on your first build! Feels good, doesn't it?

One thing to consider, most every Champ/Vibro Champ is incorrectly biased. Fender started using the higher voltage PT from the Princetons and never changed the cathode bias circuit, so the poor 6V6 tube would dissipate 15+watts.

This "mistake" may be responsible for the classic dirty Champ tone everybody loves, but I always redo the bias circuit and no has ever complained.

It's a simple modification- just replace the 470/500ohm cathode resistor with a 820ohm to 1K resistor, and replace the bypass cap with one rated for 50V or higher.

[spiralstairs]

that blue tolex looks great

May I say - I would suggest fender White knobs, would go really well with the look I think (although does not go with whats inside, but personally I dont care)

[tribi9]

Thx guys. Like I said before, i owe it to some the fine members on this forum.


Here's a pic of it complete.


[img:800:600]http://i114.photobucket.com/albums/n271 ... C02158.jpg[/img]

[M Fowler]

I do like that sweet looking amp Tribi.

Mark

[tribi9]

Hey guys,

So I haven't really played my amp much since I built it. (Well at least as much as a should) sounds good but isn't very loud but I did blow up a 12AX7 so i decided to open it to see what was up...

I noticed that I actually wired pin 9 on both 12AX7's to the 6.3 tap. The schematic shows that I should have just wired the heaters 4&5 but I mistook the grounds on the layout for arrows pointing to the where the wires needed to go.



Could this have something to do with the amp not being so loud?

Thanks guys and as alwaysd I appreciate your help. I still lurk randomly to pick up info from the site.

[IMG:800:600]http://i114.photobucket.com/albums/n271 ... c02024.jpg[/img]

[IMG:800:468]http://i114.photobucket.com/albums/n271 ... layout.gif[/img]

[Structo]

The original Fenders had the heater supply grounded off of pin 9.

That is not a good way to go.

you should have pins 4 & 5 connected together with one heater wire there and the other heater wire should go to pin 9.
You're good to go there from the looks.
You have the 100 ohm resistors coming off of each heater wire to ground.
That creates a virtual center tap for the heater winding.

I would check the preamp tubes and your cathode bias to see what it's set at.