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OPT for PSE 6c33c tubes

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The optimum operating point for a single 6C33C in SE is ~220V and 200mA which means that for 2 tubes operating in parallell you would aim for 220V and 400mA and a primary impedance of ~300ohm.

The only 6C33C PSE output transformer I have seen was from Tango but I think ISO Tango that has taken over the production only make this type on special order.

I have somewhere a circuit diagram of a 6C33C PSE amp designed by Dakesue, (he was the one who "discovered" and started to import 6C33C to Japan in the late 70:ties) in that amp they use the operating point I described.

I am curious, where did you get the 800mA from?

Regards Hans
If you would consider going parafeed I can think of two sources of output tranneys currently available--- ourselves (magnequest) and
Lundahl. Our primary impedance is nominally 800 ohms while the Lundahl's nominal primary impedance is 600 ohms IIRC.

We have matching plate chokes available rated at 10 henries and 300 madc.

If you chose operating points at the 220v and 200madc that has been recommended in this thread--- the plate choke could be made a bit smaller and perhaps with a bit more L--- though 10 henries should be sufficient for a 6c33c.

also--- I may be making a parafeed output for two 6c33c's in parallel--- have an inquiry from an oem manufacturer for this application.


Hi Tubetvr
Ok I was in a hurry and i didnt proof my message it should have read500 mA. I had read a thread from 4 years ago and I dont think a schematic was posted for pse. Given the datasheet the anode current is 450 to 630 mA at 120V so i just doubled that figure without taking into account the 120 V anode voltage. A trap for young players as it where.
My reading suggests that the 6c33c can sound lovely and has the cahoonas to boot.
I have gone offf building a 300b due to cost of tubes but more importantly their reliability.
I dont mind paying big dollars for tubes but I have a friend in albury who bought some 300bs and thier measurements on his avo deteriorated within months... then theres the dc thing on heaters et al.
To MQracing.. when will you know re the parafeed for parallel 6c33c's?

The only person I know who has operating amps with this tube is Romy the Cat. He is quite difficult to deal with, if you are easily offended, or his malapropish english gives you trouble. The amps are quite good though. Here is a link.


I have designed and built a number of OPT's for this tube. Romy only uses amorphous core Lundahl transformers and I don't utilize that type of core. PM me if you want to explore the things, but read Romy's pages first please.

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