5E5A layout discrepancies and grounding scheme

[Fifthstone]

I am resuming / restarting a 5E5A build project and have all parts I need except the resistors and capacitors.  The only other amp I've ever built is a 5F1, which turned out pretty well.  But this build looks much more complex.  In addition to the excellent article on Hoffman's site, I am referencing two layout diagrams to figure out my approach:

http://www.kbapps.com/audio/schematics/tubeamps/fender/pro5e5alayout.html
http://www.ceriatone.com/images/layoutPic/fenderLayout/5E5_A_Ceriatone_100508.jpg

My plan is to go ahead and use a buss ground, wiring most of the leads off the board to a buss wire soldered to the back of the pots and to the four input jack grounds. 

There are some differences between these two layouts.  For one, the coupling of the treble to bass pots is different.  The Ceriatone layout joins these two with both a 220K resistor AND a 0.01uf capacitor, while the original Fender layout simply uses the 220K resistor, and sends the 0.01uf capacitor to ground.

Question:  Can anyone explain the benefits / downsides of both approaches?  I'd like to try and stick to the standard Fender layout where possible for authenticity's sake if possible, but not at the expense of a quiet and toneful build.

Also, my understanding is that the primaries off the PT and the ground leads off the rectifier and power tubes should go to a PT mounting bolt.  Or do I need to keep the AC pre-rectifier on a separate ground than the DC coming off the power tubes?  Looking at the Ceriatone layout and photos, they seem to add a lug to the power tube mount points and ground the resistors off pin 8 to the lug?
Question: Which approach is better and why?

A major difference between the two layouts is how the 12AX7's are wired up.  The Fender diagram sends a lead off the #9 pin to ground, while the newer Ceriatone layout runs a lead from the grid of the 2nd 6L6 to the #9 of each 12AX7. 
Question: Why such different approaches?  Which is the "better" way of doing it?  If the Fender approach is better, do I run the ground lead off the #9 pins to the ground buss bar on the volume pots, or do I attach lugs to the 12AX7 mounting bolts and ground directly to the lugs?

Lasty, the grounds off the pots themselves.  Do I solder their capacitors to the ground buss bar?  The Ceriatone layout appears to run the 0.1uf capacitor off the presence pot to a separate ground on the bolt which secures the circuit card? 
Question: Which should I do and why?

If you've read this far, thanks for your patience.  I am intimidated at the prospect of starting this build.  I'd like to do it right and first time and understand why what I'm doing is the right way to do it.  I just picked up a Fluke 177 and am about to order the resistors and capacitors.  I've been reading a few books and researching online and while the information I'm finding is good, I'm overwhelmed by the contradictions (even knowing there is no one absolute truth or correct approach).

Thanks for reading and for sharing your opinions and knowledge!

[sluckey]

I would stick with the Ceriatone layout because it incorporates several improvements over the 60 year old Fender layout. It may be confusing to work from 2 different layouts. But if you must be authentic, stick to the Fender layout, except for the filament wiring as discussed below.

A major difference between the two layouts is how the 12AX7's are wired up.  The Fender diagram sends a lead off the #9 pin to ground, while the newer Ceriatone layout runs a lead from the grid of the 2nd 6L6 to the #9 of each 12AX7. 
Question: Why such different approaches?  Which is the "better" way of doing it?  If the Fender approach is better, do I run the ground lead off the #9 pins to the ground buss bar on the volume pots, or do I attach lugs to the 12AX7 mounting bolts and ground directly to the lugs?

You're talking about filament wiring here. The Fender layout uses old technology and is inferior to the Ceriatone layout. Ceriatone uses a centertapped filament winding that has much less 60Hz hum than the old Fender filament wiring. Even Fender soon changed to the same filament wiring that Ceriatone uses. Use the Ceriatone layout.

BTW, you said "the newer Ceriatone layout runs a lead from the grid of the 2nd 6L6 to the #9 of each 12AX7." That's not true. Look again. Ceriatone connects pin 2 (filament) of the second 6L6 to pin 9 (also filament) of the 12AX7s.

[ThermionicEngine]

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I am resuming / restarting a 5E5A build project and have all parts I need except the resistors and capacitors.  The only other amp I've ever built is a 5F1, which turned out pretty well.  But this build looks much more complex.  In addition to the excellent article on Hoffman's site, I am referencing two layout diagrams to figure out my approach:

[http://www.ceriatone.com/images/layoutPic/fenderLayout/5E5_A_Ceriatone_100508.jpg[/url]

There are some differences between these two layouts. 

  I'll say there's a difference!!!  I would hit the brakes on the Ceriatone layout.  I see an unusual connection there.
1. The layout shows the outputs of the PI going to pin 5 of the 6L6's with the grid stopper resistor going from pin 5 to pin 6.  The wires from the PI should go to pin 6 and the 1K5 resistor from pin 6 to pin 5.  These resistors do not need to be 2 Watts- better if they are 1/2 Watt. They fit easier between the pins and if the screen or plate shorts to the grid, hopefully the resistor will burn open and save some components upstream. As shown, the grid stoppers do nothing but add noise.
2.  The center tap from the OT is connected to pin 4 of the 6L6's in to screen supply.  I know this is the 5E5A design but they didn't keep it and I would stick with the 5E5 setup or better yet the 6G5 and have the OT CT to to the B+ before the choke.  If you want quieter operation add another filter cap, in parallel with the one before the choke - I would use 20 or 22 uF 500VDC caps (I won't suggest a brand!!). for the filter section.  I think it is an improved power supply but should still capture the 5E5 tone.
3. I think the adjustable fixed bias is, like the filament supply, an improvement worth keeping.  Note the 1 Ohm resistor off the cathode can be used to read the cathode current (V=IR) by measuring the voltage drop accross the resistor.

Have fun with your build.  PS Hint: the 1K5 resistors should be soldered between pin 6 and 5 with as little lead between the resistor body and pin 5 as possible. 
Larry

[sluckey]

Good catch on the grid resistors on the Ceriatone layout. We just had a discussion about that same error on a Ceriatone 5E7 layout. How soon I forget!

http://www.el34world.com/Forum/index.php?topic=11193.0

[Fifthstone]

BTW, you said "the newer Ceriatone layout runs a lead from the grid of the 2nd 6L6 to the #9 of each 12AX7." That's not true. Look again. Ceriatone connects pin 2 (filament) of the second 6L6 to pin 9 (also filament) of the 12AX7s.

Thanks for the catch.  Yes, my eyes were getting blurry from too staring at the layouts closely for a long time.  Not quite an optical illusion but close.  They are of course filament. 

[Fifthstone]

So after struggling with the differences between the Ceriatone and the vintage Fender layout and the issues with both, I'm going to use the Weber layout.  Appears to be the best of both worlds.  Here it is:

http://taweber.powweb.com/store/5e5a_layout.jpg

[ThermionicEngine]

IMHO, you can't usually go wrong with Weber.  I miss the guy.  I would send Ted an email at 1:00 am asking a question or making a suggestion.  Later in the day I'd check my email and find his answer time stamped 2:15am. "The guy never sleeps" was the literal truth.

He uses a brass plate for a grounding buss.  I use an 18ga tinned wire on the back of the pots and it runs to a main ground point on the chassis.  All grounds from the board and caps off the pots go to the wire.  Some pot covers require sanding to get a good solder joint.  It's a pretty quiet setup and it has resolved some unintended oscillations.  I still think the B+ to the OT should go a different route but I already pled that case... Good luck!