New build, could do with some advice! PICS

[Chris_P]

Hey all, im currently on my second build. I had some issues with hum on my last build, managed to get it down to a good level in the end, but for this build Ive done a lot of reading & come up with a whole new original layout, rather than recreating a standard 2204 amp.

Anyway, for this build (4 gainstage, w/CF) every tube has its own filter cap, I also have seperate caps for screens, PI & mains.. the idea is that all grounds go back to the appropriate filter return, these are then tied together in order and grounded at one point (sounds familiar eh). Im just drawing out a layout before I wire up the mainboard & Im not too sure if the master volume ground & treble will return to the ground of the cathode that drives the tonestack (which will then tie to that stages filter) OR if I should be grounding them at the PI filter (as they are feeding the PI).

Im using a jose master style layout, 10k res, .22, diodes & master then onto the tone controls. Im also fitting a Metroamp FX loop to this build, im planning to just ground that to the return of the PI filter that feeds it. One other thing, should the power tube cathodes go to mains or screens return? Im thinking mains?

Anyway, heres a couple of shots of what I have so far. Early days, but the power section is done & tested (I replaced the enameled copper bus for tinned stuff.. once I figured out you cant solder onto enameled copper, not easily anyway lol)







Cheers, Chris.

[catalin gramada]

Hi Chris
you're on the right way for sure. just two consideration with you permission: I prefer always to keep the filter caps under board, directly on the stages, for space economy reason. also I prefer to tin the bus wire before,to prevent corosion in time- it will looks more neat.
something like this:


nice job man , keep it on.
cheers Catalin

[Chris_P]

Ah, nice one! I might consider trying that with the caps on a future build, space is very precious in these JTM sized chassis that ive been using. The buss has been changed to tinned stuff now, I like how yours is laid out across the standoffs, nice chunky bit of metal there!

So, is that a layout you've developed over a few builds, or just straight off the bat? This one im working on now will be the Mk2, quietly confident that the next one will be the 'final', unless I end up satisfied with this one.. which would be nice!

Chris.

[catalin gramada]

Hi Chris,
It is a layout developed by me based on standard Plexi, using a real bus and not the chassis as grounding path. I can change in seconds from a parallel to cascade configuration or reverse. For the same reasons I chosed to use those terminals-to change and secure in place any components in seconds aso. On short, is a very practical layout for modding, not necessary the best one. Sorry for offtopic.
PS: one more consideration: the bus must be fixed as rigid as possible into chassis and same with all power supply and output wires to avoid vibrations, but saw you allready did it. well done.
For the rigidity reasons sometimes solid core wires are prefered, more important in paths where current is pretty signifiant.

Regards Catalin

[joey]

The MV, and ts ground will always go to the stage it feeds. Your only predicament is exactly where in the supply chain you are decoupling the loop. If you have no loop, it would be grounded where the phase inverter is. If you have a loop with series decoupling it will go to the loop, and from there the pi. If you are parallel decoupling the loop you now have to make a decision, most likely you would group them all and return them to the PI.

Powertube cathodes and bias return go to the screens! Why? The screen grid has more influence over the valves operation/varies widely than the plate does. From that grouping it then goes to where the plate is decoupled. You now have to choose where you want to actially put It to the chassis.

The biggest thing and most important thing to stress is that you have to make the current loop for the dc reservoir including rectiification as small as possible or all this work may not buy you a damn thing! There's actually quite a bit more that goes into this than what you might read at guitar amp sites, but for the most part it's covered fairly well as to what's practical. And another thing to point out that it may not be the quietest method to ground case to case, but it is the proper way meaning its the best way to get a predictable result everytime.

[joey]

Hi Chris,
It is a layout developed by me based on standard Plexi, using a real bus and not the chassis as grounding path. I can change in seconds from a parallel to cascade configuration or reverse. For the same reasons I chosed to use those terminals-to change and secure in place any components in seconds aso. On short, is a very practical layout for modding, not necessary the best one. Sorry for offtopic.
PS: one more consideration: the bus must be fixed as rigid as possible into chassis and same with all power supply and output wires to avoid vibrations, but saw you allready did it. well done.
For the rigidity reasons sometimes solid core wires are prefered, more important in paths where current is pretty signifiant.

Regards Catalin

The biggest problem is that you have multiple connections to the chassis. If you play your cards right the proximity effect migh work, or you might get a perfectly quiet amp, however it's just not a predictable way of doing it

He caps over or under board argument can go either way. If you have room, over board is preferable from a service standpoint, it makes changing, replacing (or even playing with) the decoupling capacitors easier. On the other hand yeah it saves space.

[catalin gramada]

The biggest problem is that you have multiple connections to the chassis. If you play your cards right the proximity effect migh work, or you might get a perfectly quiet amp, however it's just not a predictable way of doing it

He caps over or under board argument can go either way. If you have room, over board is preferable from a service standpoint, it makes changing, replacing (or even playing with) the decoupling capacitors easier. On the other hand yeah it saves space.

Sorry Joey but there are not. if you look carefully to my pics all standoff bolts are isolated from chassis with nylon washers/otherwise have not sense... The only conection to chassis will be at one of the end of the bus. Further, all my underboard caps are fast replaceable, they are secured only with a nylon strap and the end conections are soldered directly to the board terminals/it is the same think like mounting overboard...but in reverse, can change easy the caps without unmount the board, no incovenient. the criticism is not justified from you point of view...sorry if you don.t like it. it works for me fair well and share my ideea for anyone.
Cheers.
Catalin

[joey]

Sorry Joey but there are not. if you look carefully to my pics all standoff bolts are isolated from chassis with nylon washers/otherwise have not sense... The only conection to chassis will be at one of the end of the bus.

Fair enough.

Further, all my underboard caps are fast replaceable, they are secured only with a nylon strap and the end conections are soldered directly to the board terminals/it is the same think like mounting overboard...but in reverse, can change easy the caps without unmount the board, no incovenient. the criticism is not justified from you point of view...sorry if you don.t like it. it works for me fair well and share my ideea for anyone.
Cheers.
Catalin

First I was talking in general not specifically to your layout regarding capacitor mounting. second, you seem to be taking my comment too personally, at least thats how it seems to be conveyed. I never said I didn't like it either.