Twist or not twist OT leads?

[markmalin]

Just curious - do you guys twist your OT leads (i.e. twist the 2 primarys together but not the CT, and twist all the secondary wires together)?

Mark.

[glasman]

On my amps I never twist the primary side. Reason, I feel (never verified) that there would besome signal cancellation due to the phase difference. I also keep the grid wires away from one another for the same reason.

I try to keep them as separated as possible.

The secondary wires are not twisted, but encased in heat shrink up to the jacks.

Gary

[odourboy]

Interesting thread here on the topic.

https://tubeamparchive.com/viewtopic.php?t=3467

[jelle]

I was gonna reply with the Novosibir link (Where are you, Larry?!) but after hearing the Glaswerks amps last weekend...whew! That sounds awesome. Congrats Gary!

I must admid that my best sounding amps have seperated OT primaries. I'm also not sure it has anything to do with it.:lol:

jelle

[Stanz]

I had an AC15 I built that I did not twist the OT secondaries. Bad fizzy sound behind the notes. Especially an issue because the chassis was pretty tight, everything was packed pretty close to each other. There was the moment when the light bulb went off, of yeah, it's an AC signal. Twisted pair solved the problem.

[briane]

interesting question.

Lately I have been twisting the primaries about 2 turns, and secondaries a bit more, about 1/2way to the jack, maybe 6-8 turns or so....My theory was that it was the secondary that would be more subseptible to stray fields than the primary....And I do make sure both of these are well away from any other wires, especially the nfb.

I'm going to have to try this out a few different ways now. Ive seen some big impacts stray capacitance and phase cancellation can have on the PI wires feeding the power grids, and where those wires are placed, and the type of wire used. I now use 18 gauge or larger stranded & twisted from the PI to feed the grid resistor. solid core always had stray sounds leaking in, and sheilded wire just dulled down the sound to much.

[glasman]

I was gonna reply with the Novosibir link (Where are you, Larry?!) but after hearing the Glaswerks amps last weekend...whew! That sounds awesome. Congrats Gary!

jelle

Thanks Jelle, Hope the boys gave you some time to mess with the amps.

Tot ziens
Gary

[markmalin]

interesting question.

Lately I have been twisting the primaries about 2 turns, and secondaries a bit more, about 1/2way to the jack, maybe 6-8 turns or so....My theory was that it was the secondary that would be more subseptible to stray fields than the primary....And I do make sure both of these are well away from any other wires, especially the nfb.

I'm going to have to try this out a few different ways now. Ive seen some big impacts stray capacitance and phase cancellation can have on the PI wires feeding the power grids, and where those wires are placed, and the type of wire used. I now use 18 gauge or larger stranded & twisted from the PI to feed the grid resistor. solid core always had stray sounds leaking in, and sheilded wire just dulled down the sound to much.

Interesting, this whole stray capacitance thing. I mentioned this to a friend who's an EE (and a guitarist) and he said stray capacitance only is a factor when you're talking about frequencies on the order of MHz. I'm not sure what to think, but I'd like to follow good amp building techniques, especially from experienced builders.

[jelle]

Mark,

As a guitarist, he should know better...
IMHO, amps get stiff and dry because of these issues.

jelle

[Fischerman]

My theory was that it was the secondary that would be more subseptible to stray fields than the primary...

I would think the secondary would be least susceptible to stray fields...it sits almost at ground. But I think due to the high current in the secondary it might induce stray fields...and because of the high signal on the primaries I would think they would too. In other words...I would consider the OT wires to play the role of 'transmitter' more than 'receiver'. I would consider any grid wires to be the biggest 'receivers'.