should OT primary and secondary wires be kept apart?

[iknowjohnny]

I'm asking because i have the OT right across from the impedance switch and i put a hole directly below the switch so i can have the secondary wires outside the chassis and come in right below the switch. But the primary wires will be on the front panel side of the chassis near the master and presence. So i don't want to have them come in there, and the hole for he secondaries would also be perfect fro the primaries since 2 of those go to the tube plate and the hole is directly between the power tubes. So the simplest and best place for the primary wires to go would be outside the chassis and then thru that hole just like the seconaries. But i need the question answered....is it ok for them to be run together? They would only really be together at the point they all go thru the hole, but not before or after that. Is this ok or could it be problematic for noise or tonal considerations?

Heres a pic of my intended mounting of the ot. Of course i'd tie things up nicely or use heat shrink on them. By the way, should i twist the primary wires till they each go off to their separate destinations, or just twist the secondaries?

[img:800:819]http://i24.photobucket.com/albums/c39/dazco/ot.jpg[/img]

[Structo]

I twist both primary and secondary on the OT.
But I have never ran them together like you show so I can't tell you if it will be noisy.
My guess is it will.

[Phil_S]

It's kind of like getting half of the question. I get the gist of what you are saying, but can't really visualize the problem. Can you post a picture of the guts so we can see what you are describing?

Even without seeing it, my gut reaction is to turn the transformer 90 degrees, and make two holes. If there is a turret board there, raise it off the floor with standoffs. That will give you plenty of room to bring in the wires and distribute them to the intended terminals.

[David Root]

I agree. Two holes, one for primary leads and one for secondary leads, separated by at least two inches and preferably more; and turn the OT 90 degrees so the bells face lengthwise along the chassis.

[iknowjohnny]

I was told to face it the other way...bells towards the front/back. I already did it like that, plus looking at a marshall chassis thats the way they did it. I'll just take the primaries thru the chassis under the board like my last build. Maybe shield then till they split off to their destinations.

[Structo]

Well you probably know this but traditionally, you want the core laminations to be 90 degrees to each other.
Has to do with the magnetic flux of the iron.

Have you heard of the headphone trick?
Since you are at the early stage you could still do that for the quietest placement.

[iknowjohnny]

Yes, and i have done the headphone thing on my last build. This time i'm aligning them the opposite tho just because thats the way i see marshall doing it and someone told me to do it that way. Always 90 degrees off from each other, but this time with the OT lams pointing forwards and rear and PT lams pointing side to side. Don't know why thats the proper may compared to the opposite, but either way is quiet so i went with what i was told and have seen.

[Phil_S]

Well, then, get some very small size grommets, the one wire size. Drill three holes: one on each side of the OT and one in front of the OT. Bring one plate wire through each side hole and bring the B+ wire through the one in the middle.

I readily admit that I am not sure if bringing all the wires through the same hole is a problem, but, to me, it looks like trouble. If you must bring them all into that vicinity, see if you can drill a second hole right below where the secondary wires emerge from the bell. I would do something to separate them.

As a last resort, bringing them all through one hole, I would braid the two bundles and try to keep them from intermingling.

[iknowjohnny]

I thought about that. (single holes for each primary) It would surely be the best way as far as avoiding issues. I could have each emerge into the chassis right at it's termination point. But i think thats probably being anal about it. So i will just do it the usual way and put all primaries thru one hole hole where they emerge from the OT and run them under the board to thier destinations. I'm not worried about noise anyway. My other amps are done normally and the wires cross othe wires in the amp, yet none of them are noisy at all. I mainly am concerned with tonal issues of the kind you DON'T hear. In other words, phase issues or anything that might compromise the tone w/o even knowing it.