ECC40 instead of ECC83 rimlock valves build

[VMUNIX]

Another idea: If you've got yet some ECC40's, but no EBC41, you'd want to completely rearrange the PI section around the triode pair from the original LTP to a voltage amplifier plus a Concertina, see page 4, Fig. B in the yet mentioned Philips ECC40 datsheet. Total voltage gain will be about the same as with a ECC83 LTP, and as EL41's are frugal to drive, a Concertina will work as well. But be aware of it's poor PSRR, i.e. provide good plate supply filtering!

Best regards!

I just saw your reply and thank you for taking your time to answer. Yes I do have a couple (but not 4) EBC41 and I already drilled the holes for the ECC40 and heater wiring
But definitely a good idea, too late I guess. And yes I know from experience what happens with the Concertina when the B+ is not well filtered, no idea why that happens though.

work in progress

An externally hosted image should be here but it was not working when we last tested it.

There's also this:
http://www.valveheart-bg.com/Scans/pp_i10w.gif

but that phase inverter looks odd, or primitive, with a voltage divider driving the second triode

 

[Kay Pirinha]

It's never too late !


As said before, you can use the same tubes, but you may want to rearrange the PI section around your ECC40.


PSRR of a Concertina is bad due to it's arrangement as a voltage divider (as seen from plate supply), and is even worsened due to the different impedances at the tube's cathode and plate.


Best regards!

 

[Kay Pirinha]

There's also this:
http://www.valveheart-bg.com/Scans/pp_i10w.gif

but that phase inverter looks odd, or primitive, with a voltage divider driving the second triode

Given that R9 = R10 = R11 this is quite a good phase inverter - a self balancing paraphase! You could also build that, if you find out the components' values.

Best regards!

 

[stocktrader200]

ECC40 would be much closer to a 6922 performance wise

 

[Kay Pirinha]

Are you really sure about that? The modern (relatively...) 6922/6DJ8/E88CC has nearly five times the gm of the really vintage ECC40.

Best regards!

 

[Ketje]

Let me propose some mod's and values keeps me bizzy
If you don't need the tone control, skip the EF40 and put the volume control on the first grid of the ECC40.
Mona

 

[rifraf50]

or this ?

I would go ef40 to channel one , ecc40 channel 2 then use another ecc40 , one section to boost gain and one as cathodyne PI and then another ecc40 to drive each el41.....put your tone stacks after the first ecc40 and ef40....play with the resistors until the volume balance is good between the two channels

Ive done this myself but with 7 pin tubes 6c4 , 6at6, 6aq5 Quad , good results 20+watts cheap too ...

I know this thread is old but this is where people look for ideas....