Page 2 of 9
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 6:02 am
by vh junkie
vanhalen5150 wrote:The more I look at this grounding it makes total sense to have #6 as the wall ground only. Tieing that in with other grounds surely would cause excess noise.
Strat78 wrote:I love this grounding scheme! Those pictures are a huge help for those of us who need visuals. Ground #6 is to the PI filter lug?
Yes, #6 is for the AC Ground. It could be placed in the PI filter mounting bolt closest to the wall; though technically there should be a dedicated screw for this ground.
vanhalen5150 wrote:Thinking ahead...I'm adding a Lar?Mar. Which speaker output should be used? Away from the impedence switch? Drill another hole?
Yes, speaker hole away from the imped sel... might want to route the speaker ground wire to the between the two speaker jacks in anticipation of this upgrade. Could drill an new hole, not sure how close this would come to a typical FX loop location though.
Strat78 wrote:Robert, for the OT primary's, you have the red and white going to V5 and V6, should it be the brown and red (that's how it is shown in Georges directions, but perhaps Chris' tranny's are different here)?
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 7:38 am
by vanhalen5150
Strat78 wrote:I love this grounding scheme! Those pictures are a huge help for those of us who need visuals. Ground #6 is to the PI filter lug? Anyway, here is how I ended up working with the existing 68 chassis holes for the 2" core OT wires: I shaved off a little from one of the OT'a feet to allow for the grommet. The OT sits a bit off the chassis anyway, so I mounted it partially over the grommet. Seems OK (a small piece of tape on the OT to prevent the metal from chaffing the wire sheathing), but will having the wires that close to the core cause noise? I'm waiting for some chokes from different manufactures to arrive (3H, 3.6H, 5H and a 7H) before I get started again.
Strat78, so did you reverse your tranny wires like Roberts, or did you do them like the last build? Im still confused on that. Have the extra legs going on mine so I cant do that little mod you have going on there so Ill have to drill another hole. I got a bell covered 3h choke from Mojo. Has 4 legs instead of 2. My chassis is starting to have a swiss cheese look.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 8:17 am
by vh junkie
Let me just point out that this is critcal to get right... the center tap(brown) splits the B+ thru the two sides of the OT primary to the plates of the power tubes. Your OT should have come with the two plate wires (white and red twisted together). Like I said you can check this with an ohmeter, and check with ****** if you have doubts.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 8:17 am
by vanhalen5150
What's going on here?
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 8:20 am
by vanhalen5150
vh junkie wrote:Let me just point out that this is critcal to get right... the center tap(brown) splits the B+ thru the two sides of the OT primary to the plates of the power tubes. Your OT should have come with the two plate wires (white and red twisted together). Like I said you can check this with an ohmeter, and check with ****** if you have doubts.
Yeah, thats how mine came.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 8:34 am
by vh junkie
The 6v indicator connections to the heater wires?
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 8:36 am
by vanhalen5150
No, the 2 resistors with the sheilding on each side.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 8:57 am
by vh junkie
Old style grid stoppers.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 10:02 am
by vanhalen5150
The setup with the 4 5.6k resistors, the way everyone does it, looks like 4 big antenna sticking up. I often wonder it laying them down and shielding a bit would also help with some noise reduction?
Perhaps Im overthinking things a bit, but getting this new one to be as quiet as possible is the priority. Tone wise, we have this bugger licked somewhat IMO.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 11:17 am
by vanhalen5150
Email from C.M. Your correct Junkie.
PRIMARY:
WHITE= plates (pin#3 for V6 and V7)
RED= plates (pin#3 for V4 and V5)
BROWN= Center-Tap (goes to the B+)
SECONDARY:
ORANGE= GROUND
YELLOW= 4 Ohms
GREEN= 8 Ohms
GREY= 16 Ohms
Best Regards,
Chris ******
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 12:20 pm
by Strat78
You beat me to it, Chris just wrote me back too!
I was not doubting you Robert, I just need to have things repeated several times to get them through my thick head.
That would have been quite an explosion the way I had it wired up.
vanhalen5150 wrote:Email from C.M. Your correct Junkie.
PRIMARY:
WHITE= plates (pin#3 for V6 and V7)
RED= plates (pin#3 for V4 and V5)
BROWN= Center-Tap (goes to the B+)
SECONDARY:
ORANGE= GROUND
YELLOW= 4 Ohms
GREEN= 8 Ohms
GREY= 16 Ohms
Best Regards,
Chris ******
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 12:32 pm
by vanhalen5150
Well, before you correct it, do a short soundclip for us.
Re: 12xxx Larry Ground
Posted: Wed Feb 09, 2011 12:48 pm
by Strat78
vanhalen5150 wrote:Well, before you correct it, do a short soundclip for us.
OK, but I need to form the caps first.
Re: 12xxx Larry Ground
Posted: Sat Feb 12, 2011 5:42 pm
by vh junkie
Here's where we are before putting the mainboard in.
The choke wires will be separated and split between the screen wire and the HT fuse/OT CT wire.
The Vols Gnds will get an extra lug with the V2 cathode and "one of the PreAmp Caps".
Decided to completely shield the main inputs(two of the 68ks on the main board will be fakes?)
Re: 12xxx Larry Ground
Posted: Sat Feb 12, 2011 11:57 pm
by Strat78
So you are buypassing the board and going dirrectly to V1 from the maine inputes? I really like the look of the darker boards on this build. Also, that little black wire that connects the mains filters with screens filters is not necessary if the screens are grounded to lug 3?
