Heaters wiring help!

[cjkpkg]

OK...I need some help...I have hit the wall with this and I know it should be simple...

I am having a hard time visualizing the heater schematic for my build - 6N1P - EL84 PP amp.

12.6V heater voltage DC

Does it really matter +/- voltage on pin 4 or 5?

Does this scheme make sense? Is there a better route?

[kavermei]

It's better to keep the + and - wires twisted together at all times. To keep the required wire gauge down, you could use one twisted pair which goes to the two el84 at the left and then the 6n1p, and a second pair which does the same for the other channel.

[chrish]

Why 12.6 V DC? They are all 6.3 volt tubes. You are not building a phono pre amp here, so good layout with AC will give you no hum. I am re-working a 6N2P, EL84 amp laid out as yours is, but with AC heaters. I have no hum. With my latest 6L6 amp with regulated B+ I used AC heaters with absolutely zero hum.

Do you have Morgan Jones "Building Valve Amplifiers"? He goes in to great detail about heater wiring layout, RF decoupling with ceramic caps to chassis ground and lifting the heater voltage reference.

Applying technique here and with the grounding scheme is where you will get low hum.

Cheers,

Chris

[cjkpkg]

I am using JB's PS-4 PSU for this...and I have set it up for 12.6VDC.

I would have to wire the 6N1P's in series since they are 6.3V heaters. I guess I could run one wire set to the 6N1P's and another pair to the EL84's.

[DualTriode]

Originally Posted by cjkpkg

I am using JB's PS-4 PSU for this...and I have set it up for 12.6VDC.

I would have to wire the 6N1P's in series since they are 6.3V heaters. I guess I could run one wire set to the 6N1P's and another pair to the EL84's.

Hello cjkpg,
This plan sounds good. Also tuck the heater conductors into the corner and tight to the chassis. I also bypass the heaters at the tube socket with a 10 uf electrolytic and small monolithic ceramic capacitor. The PS-4 has regulated H output and should be near quiet to start with.
DT
All just for fun!

[cjkpkg]

OK...

One last thought...does this look feasible? There should be just shy of 3A available from the heater section of the PSU.

Wires would be twisted pairs...

[kavermei]

looks okay to my eyes

[cjkpkg]

OK...thanks guys...sometimes you just need to think outloud and hear what others think...

For some reason heater wiring always get me...

[kevinkr]

The use of black for + and red for - is the reverse of engineering convention, but frankly doesn't matter here.. Other than that fine.

Probably ought to float the whole filament supply on a dc bias of 30 - 40V (resistive divider from B+ with a cap from the floating filament bias voltage to ground) make sure there is a low impedance AC path to ground for your filament supply. Or you can use a resistive divider between +/- to ground with a pair of 100 ohm 1W resistors.

[cjkpkg]

Whoops...just a typo on my super awesome powerpoint schematic...

The heaters will be referenced to B+/4 roughly 80V...

Thanks!