Question about heater supply

[JoeTele]

I'm considering my first stereo build (have done 4 guitar amps) and if I do it will join a forum that is more specific to that but I've one preliminary question I'm hoping someone can help me with. I'm looking at building a Mullard 3-3, which ideally wants a 3.15-0-3.15v winding for the EF86 and EL84 tubes and a 6.3v winding for the EZ80 rectifier. It does say that a single 6.3 winding is workable if it has enough amperage. My question: Can a PT with a 6.3 winding (center tap available) like we see in guitar amps be set up to supply all 3 of the tubes in the 3-3?

Thanks!

JoeTele

[Phil_S]

it works fine in my 18W build. That's 3 preamps, 2 EL84's and one EZ81 on a single 6.3VCT winding.

[David Root]

Yeah, it'll be fine. The EZ81 is a separate cathode and heater design so it works with a regular 6.3V winding.
This is why separate dedicated 5V rectifier windings exist on PTs. A lot of 5V rectifier tubes are filamentary cathodes ie the heater filament is also the cathode, so these types need special construction on the 5V winding.

Otherwise you could just drop the 6.3V supply down to 5V and use it. Try that with a 5Y3 or a 5U4 and you'll get a nasty surprise!

[JoeTele]

Great! So just ground the heater supply CT and daisy chain them as normal?

Joe

[Phil_S]

That's right! Simple as that.

[Malcolm Irving]

Yes, the EZ80 and EZ81 were designed specifically for the lower-powered, less expensive consumer goods, such as the smaller radios and record players. The idea was to allow manufacturers to specify a power transformer with one less secondary winding (and thereby save a few pennies).