building a Vox AC30 from the Tino Zottola book!!!

[Curranproducer]

OK I will review my layout and wiring, I do have the Aspen Pittman book, so I can find the schematic in there for sure. I am only building the amp side of the AC30 without the tremolo section. so there are only 3 12ax7's and one tone stack. the little sparks I saw in the power section of off of the tube sockets, could this be from the power section resistors that go to pin 9 and pin 2 on each el84 being to close to each other? they are not touching BUT they are deffinitley in super proximity to one another. Could they be arcing? should I shrink wrap these bad bears just on principle?

[M Fowler]

I would only be guessing but it could be bad solder overflowing to another pin or to ground. It could be wiring error, there is a lot of voltage flowing to those power tube sockets. You have high voltage for plates and screens and filter cap as well. The filament wires has 2A to 3A current flow too.

Make sure your 50 ohm bias resistor is connected and make sure you have the positive side of bias bypass cap going to tube socket not ground.

I use a lighted magnifier to check for problems.

Mark

[rock_mumbles]

The screen resistors go from the power supply (high voltage) to pin 9

The EL84 input grids are pin 2 they connect to the phase inverter

[Curranproducer]

OK, I have done the super review of the circuit double checked some things, went back , fired her up ANNNNNNNNNNNNNNND, she is working!! now there are some definite problems, LOTS of noise. I am pretty sure my heater wires are run very poorly through the amp, so I willrevisit this later in the week. I also have ALL of the pots wired backwards(I will switch the outside wires and this should fix my issue. I will post pix of my layout and wire runs for you guys to laugh at and go "well DUH there's noise". But all in all I feel like I am more than half way to having an incredible amp. Even with the noise/buzz/humming, I can tell this thing is going to sound amazing!!!
Another thing, the power tubes PULSE when I riff on the amp with my guitar. Like my own little tube amp light show. is this correct? non of the plates are red or blue, but the filaments ARE nice and bright.

[Curranproducer]

shouldI have fiber washers between my jacks and the chassis? I bought switch craft jacks instead of those plastic marshal types, and I am wondering if they are causeing a ground loop. and should i do a grounding bar across all the pots? doesn't seem like I should need to since they are all contacting the chassis

[M Fowler]

Make sure you either have a filament supply center tap to ground or if no center tap wire then use a 100 ohm resistor off each filament supply wire to ground at first tube socket or pilot light if 6.3v type this will cancel or balance the filament hum.

Don't need buss wire across the pots most use that as a anti-rotation method nothing to do with grounding. Make sure you only have one ground location not random grounding. You can get by with two grounding points preamp to near the input jack area and from the PI on back to power amp and filter caps grounded near PT. Or isolate the input jack and run all grounds to one ground point near PT.

Power tube imbalance can also cause noise.

Mark

[Curranproducer]

I am going to post some pix. I have grounds gong everywhere in this amp. I think both of my tranny's have CT on them and they are all going to ground, just not ONE ground spot

[Curranproducer]

alright!!! after a few wire moves to get the volumes and the tone stack going the correct way, things started to sound better!!! then I looked at my input jacks and saw that I had never grounded the inputs!!!! got that done, things started to get quieter!!!! then I went into the schematic to double check what I may be missing. Even with a CT on the power tranny the schematic still called for the 47R divider on the filament heaters. SUCCESS!!!!! now I have an amazing vox ac30 on my hands. I am very happy!!!! NOW I want to understand something. BOTH volume comtrols have some effect on the other. If I am in the normal channel and turn up the bright volume i get a little hiss and high end SHHHHHHHHHHHHHHHHHH . and vice verse for the bright being affected by the normal. now if this is a normal tube amp thing then fine. I did not use shielded wire into the 1st 12ax7. would this be an issue? I am not getting any radio interference at all, and no oscillations when I peg all the knobs

[Curranproducer]

I did the 47R from each filament 6.3v to the 1st filter cap can ground off of the pilot light. this cleaned up everything I think.

[Reeltarded]

There is nothing to stop the signal of the channel you aren't plugged into. That added hiss is normal.

[Curranproducer]

then I have a CHAMPION AC30 rager of an amp!!!! woo hooo!!!!

[M Fowler]

Good job getting you amp going. The amp will be even quieter when it is in a cab.

Mark

[Curranproducer]

http://youtu.be/7SbVdEDWB0U

here is a youtube link walk through of my new amp

[M Fowler]

You have a red/yellow HT center tap but not a filament center tap green/yellow wire so you needed those 47R balance resistors. Saw your video where you talked about this.

Builder of S7 guitars huh, kool

Mark

[JazzGuitarGimp]

What?! You went and BBq'd BEFORE recording some sound clips for us?! Sheesh!