Marshall style transformer orientation?

[Normster]

Is there a "correct" or "best" way to orient transformers when using a Marshall-style stand-up PT? Morgan Jones shows the least flux leakage at the center of the coil with the PT being the biggest offender. That would lead me to believe that Marshall got it right with their orientation.

Fender, OTOH, always orients the lams of their OPT towards the tubes...something that Jones advises against.

Now enter Dumble who seems to violate all rules with the 150watt. (see pic)

Anyway, enough theory. Has anyone tried different transformer orientations and come to any conclusions? (BTW, I've seen pictures of Gary and Gil's builds and they both chose different orientations.)

[Structo]

Then perhaps using the headphone trick is the best way to choose where or how to put it?

[Normster]

I can do that to find the least amount of coupling between transformers, but I'm still not sure about flux leakage to the power tubes. It probably doesn't matter either way, but I thought I'd poll the brain trust before drilling holes in the chassis.

[Normster]

Anyone home?

[Funkalicousgroove]

As long as they are not right next to or touching eachother The coupling factor diminishes exponentially as you move them apart.

I have had 2 Dumbles through my shop that had the orientation like the above pic, neither seemed to suffer any because of it-

[collinsamps]

I've always gone with the endbells at 90 degrees rule and never had any issues.

[Normster]

I've always gone with 90 degrees as well, but I'm curious about flux leakage to the power tubes based on transformer orientation. Especially in the Dumble photo above, it looks like HAD was more concerned about the transformer's relationship to the tubes than to each other. As Brandon pointed out, the trannys are probably far enough apart that coupling is not an issue.

I'm tempted to build a "sacrificial" chassis just to experiment with this.

[collinsamps]

I'd flip the OT 45 degrees if it was mine, or get an X mount PT & leave it.

[talbany]

As long as they are not right next to or touching eachother The coupling factor diminishes exponentially as you move them apart.

Anyone here want to tell Ken Fisher that the transformers shouldn't touch each other.. I wouldn't even think to put them this close to each other much less jam a dowel between them.. Offering up a conduit of vibration between the 2.. Francheska Express.. about 30K..



Tony VVT

[collinsamps]

The orientation and distance is fine, the dowel.........no friggin idea.

[M Fowler]

To help keep the chassis from caving in from the weight. Cheap Bud Chassis.

[talbany]

I think he put it in there to keep the chassis from buckling.. (Hammond aluminum).. is all I can figure.. The copper shield over the laminates work surprisingly well at controlling stray fields..Also other things susceptible to stray fields emitted from the power transformer are the small transformers in reverb tanks.. If you ever mount one in a head make sure the tanks output is furthest away from the PT as this end is very low level, higher in impedance and has a fair amount of amplification attached to it that is really sensitive to stray fields.
Don't mean to hijack the thread carry on!!

Tony VVT

[M Fowler]

He used the AC-425 Bud chassis not Hammond.

[Normster]

Ah, but we digress...

Sooo...no experiments on how the transformer placement effects tube function? Guess I'll be breadboarding.

[Funkalicousgroove]

As long as they are not right next to or touching eachother The coupling factor diminishes exponentially as you move them apart.

Anyone here want to tell Ken Fisher that the transformers shouldn't touch each other.. I wouldn't even think to put them this close to each other much less jam a dowel between them.. Offering up a conduit of vibration between the 2.. Francheska Express.. about 30K..



Tony VVT

Thing is, they are 90 degrees of eahother, and an express Hums a plenty- we just deal with it here in guitarville