Heaters not twisted on Brand name amp!

[Guy77]

I had a DR Z Maz 38 on the bench to fix a noise that turned out to be a bad 12AT7 tube.
I was looking at the AC heaters and noticed that they were not even twisted! Just looped around and the amp was not even that noisy!
Heaters are the Red and Black wires against back wall. I attached the pic below.

Heaters.jpg

I always go nuts when I twist my heaters but I guess we don't need too?

Cheers

Guy

[sonicmojo]

Interesting theory. I wonder if some designs are more prone to noise than others. Look at this Mesa Boogie bass amp bare wire rails for the heaters.

[romberg]

Because each side of the filament winding is 180 degrees out of phase with the other the EMF fields produced by the out of phase currents on the wires will cancel
each other out if the wires are reasonably close to each other. Twisting is just an easy way to keep the out of phase wires close. There is nothing magic about the twist
itself.

In this particular case, it looks like cost of production won out over noise reduction. But maybe not. In some proven designs this may even make sense. If one
has built examples of the circuit with and with out twisted filament wires, there is no major benefit from twisting and the layout will be repeated over and over again, then it is not really worth doing. For one off amps, it is often better safe than sorry.

Mike

[Guy77]

Wow that's an interesting looking amp pick Sonicmojo! So many huge caps!

Thanks for the excellent explanation Romberg, it makes sense.

Cheers

Guy

[roberto]

I've never twisted my heaters' cables, just tried to keep those wires close to a corner of the amp, far from low signal-to-noise areas and keep ther wires perpendicular.

[M Fowler]

I've been in a lot of Dr Z amps and never had noise issues due to lazy loop filament wires.

The other amp above most likely has DC filament supply.

[Guy77]

I've never twisted my heaters' cables, just tried to keep those wires close to a corner of the amp, far from low signal-to-noise areas and keep ther wires perpendicular.

Looking more carefully at those red and black heater wires they are actually crossing each other perpendicularly as they loop towards the back wall of the amp.
Grazie Roberto!

Guy

[mwelch55]

I don't twist my heater wires and I have built two identical high gain marshall style amps that are very quiet.

[Bill Moore]

I quit twisting my heater wires after obtaining a "94 Twin" chassis in a trade. Since then I have built 2 AB763, and 1 5E3 that are very quiet!

DSCF0457.JPG

[roberto]

Looking more carefully at those red and black heater wires they are actually crossing each other perpendicularly as they loop towards the back wall of the amp.
Grazie Roberto!
Guy

Prego Guy, but I noticed a missing "o" created some misunderstanding.
It was supposed to be:

I've never twisted my heaters' cables, just tried to keep those wires close to a corner of the amp, far from low signal-to-noise areas and keep Other wires perpendicular.

So I keep the heater wires very close and possibly parallel, while other cables perpendicular to them.

[Reeltarded]

After 50 conversations with Bob S, I started shrinking the pair against the ouside corner and had less hissing that we attributed to shorter runs. If the deck to bottom of the chassis plane is farther, running them above is a better idea, even.. maybe.

[RockinRocket]

Twisting just adds more lead wire.. potentially making a bigger noise issue I would think.
Twisting holds them together parallel but a piece of heat shrink tubing would benefit more.

That Z amp in the OP though I have never seen.
Ken liked the lazy zoop too and I use them in my Trainwreks..maybe this is the idea behind it.

[Malcolm Irving]

Many amps seem not to bother with twisting (or even keeping the two wires very close together). I think Soldano is a classic example. Recently I've been twisting the wires from V1 and V2 and just use close parallel after that - it works fine.

In theory, twisting helps to cancel both the magnetic field and the electric field from the heater wires.

According to EE/physics theory there is no way that the heater wiring can influence hiss, just hum and buzz. But once Mojo enters the equations - who knows!

If the heaters are DC there is no need for twisting or close paralleling, of course.

[brewdude]

I’ve been using heat shrink tubing to keep the heater wires neat and parallel.

4C2EDC9F-D8B9-4405-A48C-CE478638D9DD.jpeg

[Guy77]

Thanks for all the informative posts and pics and great explanations everyone!
I have learned more about heater wiring from this post then anywhere else on the Internet. Maybe we should make this a sticky!
The learning never stops!
I like the idea of just keeping the wires close and using tiny zip ties.

Regarding the history of this Dr Z Maz 38, it was built in 2006 for a Guitar store called MusicToyz.com in Maine and then after trading hands a few times sold to a friend of mine here in Toronto. It was built as a 1x12 combo with a Vintage 30. This speaker sounds perfect with this amp. Great sparkly cleans like a Rocket, needs a pedal to overdrive.

Cheers
Guy