Grounding Confusion DR build

[taddy]

Hi everyone,

I'm building a Deluxe Reverb without the trem using a PR chassis and using my own layout with tag board. But I am getting a bit confused over the details of the grounding scheme. This is my first build so please bear with with me!

GROUND POINT 1. So at the moment I've got a bus bar running between the pots and the board and attaching at a point on the floor of the chassis near the input (which is a standard non isolated switchcraft socket). Connected to this is volume pot bottom, tone stack bottom end, reverb pot bottom, cathode resistors and pots for the preamp valves (including the reverb) and also the bottom end of the phase inverter (this might be wrong - see below!). I'm also planning to connect the power caps grounds corresponding to points C (phase invertor HT supply) and D (preamp supply) on the DR schematic to this bar.

GROUND POINT 2. I have a second ground point near the power transformer and I'm intending to connect the bias circuit ground, the PT center tap, mains ground, power tube cathodes (via 10R bias resistors), and the power cap grounds A (OT center tap) and B (screen and reverb supply) to this point.

So my questions are: -

1. Should the phase invertor bottom end be connected to the second GROUND POINT 2? I checked Sluckey's Tweed DR and he has it connected at this point I think.
2. If that is true then should I also be connecting the 'C' supply filter cap ground (i.e. the HT supplying the phase invertor anodes) to GROUND POINT 2 as well?
3. Should 'B' supply ground (screens and reverb HT) be connected to the GROUND POINT 1 OR 2?
4. At the moment my reverb RCAs in and outs are just grounded to the chassis via non insulated RCA sockets. Should I also connect the grounds and run a cable to ground point 2? or 1?
5. Should my output jack socket ground which is currently grounded to the chassis (non isolated switchcraft again) also be connected to ground point 2? or 1?
6. I was going to run a couple of 100R resistors from the green PT heater wires to a third ground point on the PT screws next to the bulb. Is this ok or should I really be grounding them at ground point 2 as well?

Hope that all makes sense!

Thanks in anticipation.

[John]

Everyone does grounding a little bit different, but here's my 2 cents:
Q 1&2: I treat the PI as part of the preamp.
Q3 : I've grounded that "node" both ways, and at least in my stuff couldn't tell a difference. And, I'm not totally sure what the "right" answer is.
Q4: I think Hoffman has his RCA jacks grounded at chassis i.e. non isolated. Mine, I isolated them with those little plastic bushings that come with em, and then grounded each jack to the same point where the cathodes at each reverb tube did. Dunno if that's "right" or not, but it's quiet.
Q5: I think almost everyone grounds their speaker jack right to chassis like yours is.
Q6: I think you want to ground your artificial CT close to your ground point 2. Just an aside, I got in the habit of making an elevated ground for the heaters in almost everything I do now.


Don't take my answers as gospel, for petey's sake. ;) Wait for confirmation from someone that's been at it longer than me.

[jjasilli]

Taddy, I think your ground scheme will work as you describe it.  You can double check it against Doug Hoffman's grounding scheme in the Library Pages. 



BTW: I like the idea of 10R bias resistors.

[taddy]

Hey thanks guys. Ive got quite far with this thing now but beginning to have some doubts and get a bit unsure of myself so its good to have a bit of reassurance!
Sorry a couple more questions. Should the 820r nfb resistor be connected to the tip of the output socket?
The OT i bought has 4 8 and 16 ohm taps. Can i run each to an output socket and if so then how does the nfb system work?

[sluckey]

For a Deluxe Reverb that uses an 8Ω speaker, connect the NFB to the tip of the 8Ω speaker jack.