Help Phono 2 PSU HT High

[colin.hepburn]

Originally Posted by colin.hepburn

Hi all
Well ordered a new DMM just another cheap one for the time being I think it’s got overload protection but not sure if this means for setting the wrong range or not
I have always avoided a really good DMM for use on valve stuff maybe am auto ranger is with i should go for

Well the DMM is here complete with Chinese destructions
will try not to fry this one day one and the count down begins
plase you bets now

[colin.hepburn]

Hi all
OK CF pre up and running playing music
WD PSU 2 phono HT out is 347v preout HT is now 212v under load
Pre valve anode is 155v due to a resistor and extra 100uf cap in the pres umbilical cord i think
However, I can only plug one input in at a time switching from phono input to CD is making the speakers oscillate and sound terrible unplugging the phono and CD works fine And vice versa

I also got a belt when unplugging the phono not good
Any ideas as to what is happing
This is Strange too input selector input 1 is not switchable it’s direct through input 6 is on selector 3

[bob orbell]

Have you connected one input to the tape out socket Colin?, I know there are no markings on the back panel, not wanting to offend you, looking from the rear of pre, from left to right, the socket inputs are Phono, CD, Tuner, Aux, Tape in and Tape out,there is no mute, it all worked fine this end, and because of the PCB input, its impossible to go wrong, or am I reading your post incorrectly. I would also lower the voltage to Phono, it should be 250v, I did give you some 18k resistors for that. Think you need to go over PSU again, I take it that you have build instructions, if I can help, don't hesitate to ask. BOB

[colin.hepburn]

Hi BOB
AH right I was looking from the front left to right I have now label the input temp for now I had forgot all about tape loops these days
, all input now working fine by the selector switch
But we have a gain issue between phono and CD volume the phono Volume 10/11 o’clock CD @ 2/3 o’clock
And all but the phono inputs have a mains hum @ End of Pot Travel
PSU Pre HT Out 212v under load
Valve Anode voltage @ 155v need to change the resistor in the Pre can you suggest a new value to bring the voltage up to nearer the 200v
PS Yep forgot to change out the 18k for the phono job is in hand

[pre65]

Originally Posted by colin.hepburn

can you suggest a new value to bring the voltage up to nearer the 200v [/size][/font]

Ohms law dear boy.

Work out the voltage drop across the present resistor = current.

How many volts do you need to drop = voltage

Ohms law will give you resistance.

[bob orbell]

Hi Colin, and all, I use 1k resistor in both pre and phono, voltage taken from anode= 194v, voltage across the valve= 110v, Neal says 95-100 volts across valve so not far out. Cant understand how you need more volume on CD (2volt) my volume with CD is at 11 to 12oclock and that very loud, , Phono just a tad more. Switched mine on this morning, full volume, just a small amount of noise. What power amp are you using?. BOB

[colin.hepburn]

Hi BOB
Yes it maybe the DAC and the FET buffer that is dropping the out vol its not so bad thought
Phono out is fine

The Amp is my Je labs SE 6SL7/KT66 with its volume pot removed so is now a power amp which has a 0.1uf poly and grid resistor fitted now
The noise on the pot end stop is what I take to be DC not sure why thought

but it’s at the full volume stop so likely not an issue
Even with the lower Anode voltage, I like its sound works well
On load HT now 265v on phono and 220v on pre
Yes, I have 1k in phono so will fit it in pre as well

[colin.hepburn]

Well today I Changed out resistor on Extra cap in the CF pre for a 1K Also added a 0.1uf poly bypass cap to the extra 100uf Cap
New Voltages
PSU HT 210v
All other Voltages are in Red Text See Schematic are about right

[colin.hepburn]

Opps forgot to say which Valves i used 6922/6n1p see updated Schematic for voltages

[colin.hepburn]

Hi All
Well last night I decided to try a bigger choke in the WD PSU 2
This has made a clear difference to the sound of both pre and phono2 in my system the inky blackness is blacker and low level detail come out cleaner and sound stage seem deeper