more heater wiring questions

[bitsandvolts]

Hey folks,

I started my heater wiring...and I'm running into questions...I've got the 2 preamp sockets and 2 power amp sockets wired and I'm scared I might have already botched it!

My heater wiring is black and blue (on the phone with apexjr, I told him that I didn't care if he didn't have green...as long as it was a color other than black).

Anyway, the black is going to pins #9 on the preamps....and pins #4 on the el84s.

The blue, is going to pins #4 and #5 on the preamps and pins #5 on the el84s.


Then, as I was about to wire the recto....I noticed that Nik's layout @ceriatone is similar to how I did it. But the heater wiring for the november over at AX84 has it reversed...where the wire that was on pins 4&5 on the pre amp tubes is on pin 4 on the power tubes...

Does this all matter? And if not, I assume that it's at least important to maintain consistency throughout the heater run, correct?

Thanks,
Frank

[allynmey]

I used Nik's layout on my TMB and everything worked fine the first time on startup. I just used green cloth covered wire for the heaters and and marked one with a sharpie on the ends so I know which is which. And what you described above is correct according to his layout for 18 watt Trem and TMB ans correct for the heaters period. Pick one way and stay to it and don't mix and match builds. Nik's kits have subtle differences than some others but that is the way he designs his kits. If you use his kit use his layout. Thats just my opinion.

Allynmey

[bitsandvolts]

Well, I'm not using his kit....

I ended up having an "Uh oh!" moment after I was successful wiring the two 12ax7 and el84 sockets that I might have botched it...so I started referencing various layouts that show heater wire.

Assuming of course, there are no issues with Nik's layout (since it was successfully used by allynmey) I'm going to proceed forward with the idea that the heaters as I have them now, are ok.

-Frank

[JonFrum]

I"ve seen this discussed - maybe 2-3 years ago. I think that as long as you keep all the preamp tubes the same and all the power tubes the same, it doesn't matter which power tube lug is connected to which preamp tube lug. I wouldn't bet my dog on it, but that's where I'd start. I just rewired my tube heaters to clean up the layout, and it's not a killer job. I have 9 going to 4 - sounds fine.

[bitsandvolts]

Thanks Jon!

I actually went ahead and did just that....Things look good.

Got the PT in, wired 80% of that up...and I'm off and running!

-Frank

[coondog]

The power tube sockets on a push-pull amp are already humbucking so any noise you get there should be cancelled out assuming you have matched tubes . The pre-amp tubes are the ones that must observe correct polarity from one to the other or twisting those heater wires won't achieve the desired affect (a quiet filament supply)

[zaphod_phil]

That's not quite true. You will *only* get the hum cancellation effect in the push-pull power stage, if the heaters of the power tubes are wired in the same phase. If you swap phases between the power tube heater connections, the heater hum in the tubes will actually add up, rather than cancel out.

One other little trick is to connect the heater center tap on the PT to the EL84 cathodes instead of to ground. This provides a useful amount of DC elevation to the amp's heaters, to make the amp that little bit quieter.