Aikido power supply

[Nick]

This is the start of Steves pages about valve regulators

http://members.aol.com/sbench/reg1.html

[david C]

thanks Nick

you're making my brain work

[shaun]

hi dave

it took me a while to get my head around S Bench but i found that you realy dont need to get it ''all'' to build one. i found that i got more understanding from building them than just reading but i guess i'm a bit like that

i forgot to mention i also built a S Bench reg using el cheapo maplins TX 240-240 into full wave (not bridge). i used a 2.2uf befor the choke and 100uf after for a raw B+ 300v into the reg for 220v OP. i used a trimmer pot between the voltage devider resistors to have a bit of scope for adjustment to the OP. it worked for me



take care

shaun

now i've got to the whats better ss or valve rectification. i think i read that valve rectifiers have a higher impedance compared so ss. any thoughts

[david C]

thanks Shaun,
which of his regulators did you use?

[Nick]

now i've got to the whats better ss or valve rectification.

I don't know, but I have a couple of thoughts. If what I found about the sound of a reg is in any way valid, the impedance isn't the most important thing after its reached a value less than the cap that follows it.

One advantage that SS may have is the lower voltage drop, I have noticed that its interesting what happens before the reg, if you load it with a heavy signal, the supply is also loaded hard, if the combination of ripple and load causes the reg to drop out of regulation, the output drops like a stone for that part of the cycle, so there is the potential for problems, less with SS as the required drop across the reg is less. Chances are though, you won't in reality be loading the reg that much. What I did was short out the output TX in the 6c33c amp, and drive it from a sig gen, so the supply was being directlly loaded by the signal. Interesting as it gives a way of seeing how the outout impedance changes with frequency.

Down side of the SS reg, is I don't know enough to build one thats good for 150ma @ 450v. I am sure it can be done though. But without that I can't do a direct comparison.

[shaun]

hi dave

i used the one in section 3

starts '' there is a common circuit that has been around for (seems like) a 10,000 years'' this is a common circuit that shows up with different part values in many places'' with a 6080 instead of the EL509. i'm not up to speed with posting links but both quotes are from steve's Tube based Voltage Regulator primer.

altenatively you could do a passive supply so that you have something to listen to while you read

take care

shaun

[dave dove]

hi dave and all

if you check broskie blog 64
- i can't post URLs yet! -

it lists values for loads of valves at loads of different HTs
if you're going for 6n6p just read as 5687 - thereabouts
your 350-0-350 should make a decent choke input supply
and @300V should make you a jolly nice preamp
like shaun said - you have something to listen to while you read

bob's your uncle

dave

[Andrew]

Down side of the SS reg, is I don't know enough to build one thats good for 150ma @ 450v. I am sure it can be done though. But without that I can't do a direct comparison.

I've managed to get as far as 100mA @ ~220v so, yes, I reckon Nick's right, it's possible, my issue has been getting them quiet enough for a phono. The heat given off is quite impressive, large heatsinks and high wattage resistors required. The heat isn't a big deal with a valve, after all they're supposed to get hot, SS doesn't like hot.

-- Andrew

[shaun]

hi Dave D

nice to see you

[david C]

thanks Dave D

nice to hear from you,
this is a very cool place to hang out

Shaun, thanks, luckily I'm under no pressure to build the pre quickly so I can take my time and do a bit of learning

[david C]

as a matter of interest,
how do you deal with the heaters, is my tx 6.3vAC @ 4 amps enough to cover all the valves in the ps and aikido?

is it as simple as adding up all the heater currents?

thanks

[shaun]

hi dave

your TX sounds quite like the Hammond 350-350@ 110ma and so on i'm using.

i don't think the 4a fillament supply is going to be quite enough to power reg and aikido.

(if you decide to go with the 6080)

6080 - 6.3 @ 2.5ma fillament to cathode voltage max + or - 300v
ecl82 - 6.3v @ 780ma fillament to cathode voltage max 100v

(from memory so do check the specs for yourself )

so your going to run out of steam.

what i have is the 6080 and ecl82 powered from the Hammond biased to sit just above the cathode of the ecl82 at around 115v give or take a foot. the fillament to cathode max for the 6080 is quite large so i've tried to get the bias in a nice place for the 82. i have a seperate regulated supply for the Aikido 6n1p and 6n6p fillaments biased to 55v which is within the 6n1p and 6n6p 100v max range.

hope that makes some sense

take care

shaun

[david C]

what i have is the 6080 and ecl82 powered from the Hammond biased to sit just above the cathode of the ecl82 at around 115v give or take a foot. the fillament to cathode max for the 6080 is quite large so i've tried to get the bias in a nice place for the 82. i have a seperate regulated supply for the Aikido 6n1p and 6n6p fillaments biased to 55v which is within the 6n1p and 6n6p 100v max range.

thanks Shaun,
being stupid could you explain what you mean by biasing ,
how do you do it,

thanks

[shaun]

hi Dave

i guess what i mean by biasing in this case is creating a dc reference to ground by superimposing a dc voltage onto the heaters ac wave form. so for a 6.3v fillament supply @ dc ground = +3.15v and -3.15v and superimposing the 55vdc voltage onto the heater supply i end up with the AC voltage sitting across the 55v reference voltage.

i'm not to good at this explaining stuff and find that books do it so much better Morgan Jones - Valve Amplifiers is a goldmine

how i did it was quite strieght forward.

i used a voltage devider with a cap connected across it's lower leg. this was connected across the raw B+ and set to provide the required voltage.
then i just connected the ref voltage to the fillament TX centre tap.

there must be a better explanation any help would be good

take care

shaun

[david C]

thanks Shaun,
I'll do a bit of reading of Morgan Jones