Weber 6M36 brass grounding plate +

[Turmoil]

Hello great builders of fine amps,

I've placed my order and I'm getting my ducks in a row. Are there any opinions about using the brass plate that comes with the Weber kits? I have always used a star ground but I know Fender used brass to good effect. I have been reading about some stability issues with other 36'ers on this page, so I guess I'm just a little nervous.

Another thing of concern is, the layout on Ted's site shows the output tube grid resistors are mounted on the board, and not on the sockets where I would expect to see them.

I'm also planning (like everyone else I see) to install a half power switch. As of now I'm leaning towards a dpdt switch to change the primary impeadance and lift one of a pair of cathode resistors. I see alot of talk about grounding the grids of two tubes, but I am concerned about what that does to the bias of the two tubes that are left. What happens when you have two tubes working away and two more in parrallel sitting at idle? I'm having a hard time wrapping my brain around that concept.

Thanks for trudging through this.

Tim Earll

[csbradley]

I am using the 6M36 kit to build up an amp. Different than the 36 Watt, but similar.

I have never used the brass plates. To me, it's just not worth the effort of soldering to the large brass plate. Its the same concept as the ground buss that you typically see, but its 2 inches wide, and sits up against the chassis.

The output grid resistors on the 6M36 are identical to the placement of the grid resistors on the 18 watt.

A half power switch that just grounds the grids of two of the tubes will not do anything to the bias current of those tubes. The bias current IS the zero signal current, so there is no change.

CSB

[Turmoil]

Thanks for the help. I'll not be using the brass plate. And I will be installing a dpdt switch to ground the grids.

Turmoil

[LeeMo]

One possible use of the brass plate is as a template to mount your pots to , so you can wire them to the board on the bench as opposed to in the chassis. Might save some frustration.

LeeMo

[markd]

I'm also planning (like everyone else I see) to install a half power switch. As of now I'm leaning towards a dpdt switch to change the primary impeadance and lift one of a pair of cathode resistors. I see alot of talk about grounding the grids of two tubes, but I am concerned about what that does to the bias of the two tubes that are left. What happens when you have two tubes working away and two more in parrallel sitting at idle? I'm having a hard time wrapping my brain around that concept.
Tim Earll

Tim,
I think your idea of lifting one of the cathode resistors for the 18/36watt switch would be easier to implement than grounding the control grids. Grounding the control grids does solve the problem of the plate voltage rising when you switch to 18watts(see the 18/36watt bias thread). But with a single PI for both sets of tubes, when you ground one set of control grids you ground both sets of control grids. That would be a 0watt/36watt switch. ha! You would need to have two PI's, one for each set of power tubes, to be able to use the grounded control grids for a 18/36watt switch.
mdurham

[allynmey]

Hello great builders of fine amps,

I've placed my order and I'm getting my ducks in a row. Are there any opinions about using the brass plate that comes with the Weber kits? I have always used a star ground but I know Fender used brass to good effect. I have been reading about some stability issues with other 36'ers on this page, so I guess I'm just a little nervous.

Another thing of concern is, the layout on Ted's site shows the output tube grid resistors are mounted on the board, and not on the sockets where I would expect to see them.

I'm also planning (like everyone else I see) to install a half power switch. As of now I'm leaning towards a dpdt switch to change the primary impeadance and lift one of a pair of cathode resistors. I see alot of talk about grounding the grids of two tubes, but I am concerned about what that does to the bias of the two tubes that are left. What happens when you have two tubes working away and two more in parrallel sitting at idle? I'm having a hard time wrapping my brain around that concept.

Thanks for trudging through this.

Tim Earll

Hi all, so far the issues that I have had have been parts related NOT design related. I sourced a HOT tranny and have to compensate now for the extra voltage. My 36 watter runs and sounds great. I didn't do the ground buss across the pots because the pec's I have require a blow torch to solder to! The amp is VERY quiet and has no hum. It seems the 18/36 watt amps that have the switchable output seem to be giving people the trouble. I can recommend the Richie/Pete-layout/drawing in the downloads section. I followed Richies design and my amp sounds just like his in the Zzounds section

Allynmey