Here you can see original data for all 3 versions produced. The closest parameters has 6C33C-B (6S33S-V with latin letters). -B means made for military. This version has less tolerances (very little less), but also has shortest expected lifetime, only 750h. Remember - all of 6C33C are produced for military purposes (aircraft and missile electronics, power supply regulator tube, nuke proof), it really doesn't matter, what version you use in your audio amp. Just pick closest tubes for pairs.
It is allowed to use the 6C33C with one side heater turned on only. In this case you can get parameters close to 6C41C. If you may have interest to try this (I can't see why one should, but...)
It is allowed to use the 6C33C with one side heater turned on only. In this case you can get parameters close to 6C41C. If you may have interest to try this (I can't see why one should, but...)
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Knoberik,
Are you saying that the 6C33c can be run with one or two heaters so we can reduce power for night listening?
I only just realized what you had said. LOL
That’s interesting.
Regards
M. Gregg
Sure thing
As you can see here on oem datasheet framed in red, I will translate:Anode max current:
by using single cathode: 350 mA
by using double cathode: 600 mA
Anode max power dissipation:
by using single cathode: 45W
by using double cathode: 60W
So it's not a monday morning blue vision
Just ask, if anything else on this datasheet seems interesting to translate.
Hmm....
Thats not a bad plan, but a little concerned about the cathode-idling-current, May be a little high for just one cathode--may also need to change/make switchable the cathode-resistor to compensate...
Dunno---
My 'breadboard' of this still usable (Although gone through more variations than a Ford Transit) so I'll play around with the 6C33 valves and one cathode only....
Thats not a bad plan, but a little concerned about the cathode-idling-current, May be a little high for just one cathode--may also need to change/make switchable the cathode-resistor to compensate...
Dunno---
My 'breadboard' of this still usable (Although gone through more variations than a Ford Transit) so I'll play around with the 6C33 valves and one cathode only....
Yes sorry (No Tx) wrong terminology, I was thinking about the change in output impedance and power transfer to the 8 Ohm / 6 Ohm speaker.
Regards
M. Gregg
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If you want to reduce the effects of single-cathode operation and lower the O/P impedance, a nominal amount of global-feedback can be applied into the grid of the first stage, a la Tim-Mellow OTL.
Use a 33K in series with the vol-pot wiper to G1, and a 470K from O/P to the G1 of the first-gain stage.....
Ive tried this, and although it does reduce the overall gain somewhat, it will minimise the effects of a higher o/p impedance using 6C41C or single-cathode 6C33C operation at lower powers
Try it with, and without GNFB, Vary the amount even--See which you personally like the best, Thats the great thing about DIY-Audio....
Personally, I think I prefer without, but I'm giving it a few days listening now with to decide....
Thank's, 
I notice the 120 - 120V Tx is not so easy to find.
Have you ever used Airlink Tx's
Transformer Manufacturer UK - Airlink Transformers - Home Page
Wondered if they HUMMMM like a wasps nest?
Regards
M. Gregg
I notice the 120 - 120V Tx is not so easy to find.
Have you ever used Airlink Tx's
Transformer Manufacturer UK - Airlink Transformers - Home Page
Wondered if they HUMMMM like a wasps nest?
Regards
M. Gregg
A quick look, and Ive found this--
9639 : 300VA 230V 1 x 110V toroidal transformer
You would need 2, one for each 150V rail, but they will happily supply both channels...
Prob cheaper than using/getting made a custom jobbie...Being toroidal, noise/hum should be minimal...
--I'll look around for summit better anyway....
There's this one too, bit bigger and more expensive, but has 115-0-115V, so you'll only need the one...
-It seems to have a pretty good spec and shielding etc, looks like it was originally made for some fairly noise sensitive equipment rather than general use. Should be nice and quiet...
http://www.airlinktransformers.com/transformer/tt0913-cased-transformer.asp
9639 : 300VA 230V 1 x 110V toroidal transformer
You would need 2, one for each 150V rail, but they will happily supply both channels...
Prob cheaper than using/getting made a custom jobbie...Being toroidal, noise/hum should be minimal...
--I'll look around for summit better anyway....
There's this one too, bit bigger and more expensive, but has 115-0-115V, so you'll only need the one...
-It seems to have a pretty good spec and shielding etc, looks like it was originally made for some fairly noise sensitive equipment rather than general use. Should be nice and quiet...
http://www.airlinktransformers.com/transformer/tt0913-cased-transformer.asp
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