for outputs if money isn't an ishue go for luhndall's
maybe edcor is also good. i didn't test them yet.
if you have 2 pairs you could go for parallel single ended
and the in triode.
and keep it simple!
when you parallel the tubes your impedance of the tube halves and if you use triode mode id gets even lower.
ofcourse the power becomes less.
tdsl says for one tube in SE that you can get like 6w (@ 8%thd) so 4-5w rms would be more likely correct
now thats for one tube so when you use a pair you will get like 8-10 w rms pure class A triode. and really that can be enough.
tdsl says for one tube the impedance has to be like 3k and the B+ is 375v
the current running trough the tube is 70mA and it is cathode bias with 370ohm so 25.9v is lost there that gives a dissipation of 24.437watts. we have to know that the second grid dissipates some part of this! so don't be scared that the anode dissipation is only 25watts
in triode it is a little more and i looked in a datasheet and they say that dissipation without signal is 27.5watts so it will hold.
for 2 tubes you will have
B+375v
140mA current (70mA per tube).
1k5 primary impedance. (you will need a gapped output transformer for a current of 140mA! that isn't that cheap tough)
output power is like 8-10w rms
you could also use the tube in penthode. but you have to lower your B+ and i think you wouldnt benefit that much powerwise. it will probably get you 15w or something.
as input tube it depends on how much gain but the 5670 or 2c51 i have heard in hifi amps sounds pretty good. you could also use the 6sn7 (or 12sn7 beceause hifi freaks have lifted the price for 6sn7's).
for triode you need a swing of 18,9v. take 19v for instance.
so a simple good preamp tube will do. maybe lookout for miller.
then if you want it balanced for studio use or something i recommend a transformer. 1-1:1 or something. after that you could use a pot or attenuator before the grid of the first tube.
then for supply you will need like 375v
use a CLC filter! the use of an CLC filter works great with SE amplifiers.
so we have got like 375vdc on the plates after that filter.
let see that will be a transformer of around 270v and i think it's quite standard. of course that is if you use solid state bridge rectifier but i think you should but use some good diodes. i use avalanches diodes last time i think. they don't have much switching noise. and don't use a big capacitor after the bridge! use like 47µF or maybe 100µF beceause in total you will be needing 140mA per channel and thats enough so 100µF won't hurt. after that use an L of 10-20H yes that big. and it has to be minimum 140mA but probably 160mA is better to have some reserve.
now as a capacitor after the L you can use a bigger one. the B+ will come in slowly beceause of the big C afther the L and the smaller one just after the bridge doesnt make high current spikes so those spikes we'll be small and will not make much trouble. the C i mostly use after the L is 470µF
then after that als make sure u use 100nF c's over the elco's in that way the spikes that are left are surely out of the way. i alway build a supply that way and it works great.
then after that you can use an RC filter where you can calculate the R by nowing how much B+ you need on the preamp tube and how much current will be drawn. as a C for that filter use something like 47µF.
so thats the supply. i would uce AC heaters simple and just use a 100ohm wirewound 5w pot to adjust if you have hum. works perfect.
hmmm gotta go know but i will update with a schmatic if you want. and it will be readable this time
check out the site from luhndall maybe
i think the LL1627 or LL1623 can be an output.
the 140mA current is a lot the 1627 cant take it but the primary is only 1k2 so a little low maybe but in triode it should work.
the 1623 has the problem that it can only hold 120mA so the bass responce will be less. i would go for the LL1627.
for an L you can use a LL1638 or if you find something similar.
you should use 2! one for each channel.
if i had to choose i would use a seperate supply for each channel and maybe even a seperate mains transformer but thats maybe over the top.
speaking of mains transformer. thats like 280mA dc current only fot the output or more or less you will need 400mA @ 270v
for heaters you have 4 tubes that draw 1,5A or 6A! @ 6.3v
so roughly thinking it will be a mains transformer around 200w
look maybe at hammond or so they have more choice then luhndall for that.
succes, and try to keep it simple and use good components.
btw, you will get like 20w of power in total and you will be using like 150w of power
class A you where saying
thats like 13% of usefull power
