X-Can v3 circuit ? tubes just voltage amps ?

[fatgaz]

Hi,

anyone know anything about the X-cans v3 circuit ?

from the photos, I can't see any high voltage supply for the tube plates, if they are run normally as triodes you would see 150+ volts on the anode BUT the supply is 12 or 24V AC and I don't see any transformers on board or anythiong that looks like a cascaded voltage doubler to produce the high B+ DC.

Also there seem to be 4 pairs of MOSFETS mounted back-to-back (for temperature regulation I guess) - I assume these are the current (=power output) amplifer stage ? So the tubes are probably uses as a voltage (pre-amp) stage ? can;t see if these are run parallel or cascode or as a triode/ cathode follower buffer.

so, anyone know what tube topology is used ?

I have a limited electronics background, but i have build guitar valve amps before.

I'm thinking of buying a 'phones amp but I'm not sure which to get at the moment.

cheers all,

Gareth

[fatgaz]

I've just seen something on the web that claims the circuit is a type of discrete OP-AMP circuit; the valve is used as one of the differential pairs. any comments ?

seems a world away from something like the earmax circuit.

G.

[PinkFloyd]

Hi Fatgaz,

It is a hybrid, this should give you a better idea www.rock-grotto.co.uk/x-canv2.pdf that's the v2 but not dissimilar to the v3. The v1 was even more zany with opamps, transistors and valves

[fatgaz]

cool, i'll have a look over the schem tonight as I sit the garden with a beer.

is the much difference in the V3 ? i know it has a nicer case and a better big alps volume pot. maybe a better power-supply too ?

I'm tempted by either the senn. hd600 or hd650 phones, but i need a 'phones amp because my musical fidelity pre-amp ( A3-CR ) has no pho nes out.

any idea if i could drive a pair of phones directly from the pre-amp out puts? M.F. do brag that their preamps can output over 1 watt of power and at a high voltage ? the output impedance will probably be comparitively much higher I guess ?

cheers,

Gareth.

[fatgaz]

Pinkie,

have you got a copy of a V3 schematic at all ? - i'd like to compare it to the ouput stages of my A3-24 dac and my A3cr preamp.

I have a copy of the output stage of the A3-24 dac and it is very similar to your V2 schematic.

I guess since MF refer to the 'nuvistor and trivistor' in all the marketing blurb, this shouldn't be a shock !

thanks,

gareth,