6V6 line preamp

[stajo]

Found those little beads. You think theyll work? Just put ower wire socket side?

 

[Zen Mod]

put two of them , no harm

yup - on wire , right to socket pin ( not practical to open da tube and put them inside )

 

[stajo]

you can blame only your self for that ........ matter of physical layout ;

if you proceed in that direction , you must place some local decoupling near tubes ; say that anything more than 10cm of wires between shunt reg and tubes is critical , in my book ;

how you'll do with high S toob ? you would have fireworks

My first thought was to use an umbilical from SSHVs to tubes as I have seen many people do here on 26 amps for example but I changed that idea in the middle of my test build when I saw Andrew T post something about that. So I putted the SSHVs just under the toobz instead. Those connects with 11-12 cm ethernet twisted pairs now.

All this info needs a burger to melt together with. Hotdogstand, here I come.

 

[stajo]

dunno for SSHV ground in/out topology ( Salas is da man for that ) but it seems to me that you must have separate diode blocks to chassis on both GND points on right side , deleting that existing one

you can't make half dual mono gadget , then make gnd loop with (usually) source having same gnd on both outputs ; that's same as little pregnant

if SSHV is having GND traces organization in perfect way , you are not having difference in potential between in and out GND and you can make it as shown

if case is different , each SSHV must have separate rectifier and filter

As far as I understand the SSHVs are just passing the ground thru, thats why I made it like this. Theres one PSU and two SSHVs with separately connecting audio grounds

 

[buzzforb]

FWIW. I had trouble with tube rectifier and noise, but i don't know **** about tubes or anything else, for that matter. MY SS bridge was dead quiet.

 

[Zen Mod]

Salas will know what to answer , even if I'm not doubting his layout

thought - more pics of your harness will not harm

 

[stajo]

Salas will know what to answer , even if I'm not doubting his layout

thought - more pics of your harness will not harm

Heres some. Beware its a dummydoll, no comments of that please

First is PSU doll, second shows how I place the audio circuit on that, third trafo/filter side, 4th PSU star ground, 5th SSHVs, and 6th the audio circuit again.

I will do things in steps, starting I think with filament css to audio gnd point. Tho I know now that I made a mistake on that. Two LM317 is sharing same PSU. That means there could be the loop.

 

[iko]

My first thought was to use an umbilical from SSHVs to tubes as I have seen many people do here on 26 amps for example

Nobody does that. The regulator is placed as close as possible to the load. The umbilical cable is to bring power to the regulator.

Loud hum must be a ground loop.

 

[iko]

I don't see the cathode chokes in the last picture. Those chokes if they're anywhere near the psu they'll pick a ton of 50Hz hum.

 

[stajo]

I don't see the cathode chokes in the last picture. Those chokes if they're anywhere near the psu they'll pick a ton of 50Hz hum.

Second pic is the cathode chokes

 

[stajo]

If I'm to build a dualmono LM317 filament CSS to be able to truly separate their grounds, how cruical is the input voltage from trafo? Salas has dual 10 VAC secondarys and I cant find any. Single 9 volters and single and dual 12 volters is what I find now.

 

[iko]

If you have enough current on the single 9V secondary it will do.

 

[Zen Mod]

9V will do

provide fine tuning for current , to get 6V3 ; each toob needing readjust ; final check of voltage after 5min or so and it will stay like that for years

 

[stajo]

Is dual graetz considered ok for ground separation or should I dig harder for a dual 9 v trafo, or use 2 single trafos maybe?

 

[Zen Mod]

what ground separation ?

there is no gnd separation needed for heating indirected heated toobz

 

[stajo]

what ground separation ?

there is no gnd separation needed for heating indirected heated toobz

If I am to try and connect the filament ground reference to the 2 audio ground stars instead of the single PSU ground star I need 2 separate grounds. Last time I connected the filament-CSS it had one common ground that was connected to single PSU ground. The dual LM317 had one common PSU/ground.

Or maybe I could just connect CSS PSU ground to big PSU ground and connect filament zero to each audio ground

 

[Zen Mod]

choose one "side" of HV PSU , after or prior to reg , make explained voltage divider on it

it's irrelevant which one

potential is potential , no need to do same thing twice

 

[stajo]

Ok. Im on chokes now. Didnt find any suitable shilding so im trying with twisting kathodechoke wires instead.

I've never messed with ferrite beads. I guess there must be isolation between them and the wire?

I had B+ voltage divider when I tried ac to filaments, even an adjustable one between 5-95 volts over gnd. Didnt make much of a difference, but it might do to css fed dc.

 

[stajo]

Cathodestoppers on chokewires in the form of dual ferrite beads mounted on both channels. Now to some professor balthasar walking around thinking of CSS circuit and potential divider.

 

[Salas]

As far as I understand the SSHVs are just passing the ground thru

Correct. They just pass the ground doing no further tricks. You can even star ground them. When picturing them in a system think of the force 0 line carrying the PSU ground path to the load. Don't loop that twice at the load.