Triad A-67J question about "tie" instruction

[nbnb]

Hey guys,

I've got an A-67j hanging around and I thought I'd try it out on a small D.I. box configuration just for fun. On the trafo's legend, it states:

PRIMARY: Blue and Red & White
- does this mean input signal to Blue; ground to Red & White?

TIE: Red to Blue & White
- does this mean solder Red to the Blue&White wire?

Obviously this is the first time I've worked with one of these and just trying to understand their notation.
Thanks so much for you help and patience with us guys who are just learning!

 

[Khron]

How many wires (and what colours) are coming out of the bottom?

Are some of the wires two-coloured, actually?

Looks like the two primary windings are blue and blue-white, and red and red-white, while the two secondaries are green and green-orange, and black and black-white. The "beginnings" of the windings are the solid colours, while the "ends" are the two-colour ones.

At least that's how i'm reading those connection instructions (for 600 ohm you series up each pair of windings; for 150 ohm you parallel them).

 

[nbnb]

Thanks for the reply....

There are 9 wires:

- red
- red & white
- blue
- blue & white
- green
- green & orange
- black
- black & white
- Ground

Looks like the two primary windings are blue and blue-white, and red and red-white, while the two secondaries are green and green-orange, and black and black-white. The "beginnings" of the windings are the solid colours, while the "ends" are the two-colour ones.

At least that's how i'm reading those connection instructions (for 600 ohm you series up each pair of windings; for 150 ohm you parallel them).

I'm not sure at all how you're reading that, could you be specific about it? Here's what I see:
600 ohm Primary: Blue and Red-White --- but you've written "blue and blue-white" ... how did you get that? Also, my confusion is really what the "TIE" instruction means. What exactly does that mean?

Any help would be very appreciated. Thanks guys!

 

[Khron]

I'm gonna guess "Ground" is connected (only) to the actual metal outside can of the transformer.

"600 ohm primary", as you may or may not have noticed, is NOT the only option.

I'll have to assume you haven't measured the resistances of any of the windings. But in case you haven't realized yet, that transformer has TWO primary windings and TWO secondary windings. That's where my wire-colour pair-ups came from.

As such, you have those four ways of wiring the transformer up: 600-600 ohm (1:1 ratio), 150-150 ohm (also 1:1 ratio, but for lower impedances), 600-150 ohm (2:1 step-down) or 150-600 ohm (1:2 step-up).

Don't freak out about the numbers - if you'll read through transformer basics, you'll find the impedances vary by the square of the ratios (for example, 600 is 4*150, but the winding ratio is "just" 2:1).

https://www.bristolwatch.com/ele4/xformer.htm
Figures 2, 4 and 5 are probably the most relevant in this case.

 

[nbnb]

Thanks so much! That is an excellent read (I'm going through it right now) ... and it just dawned on me - duh! - that this particular transformer is not especially suited for a direct box build. Perhaps it would be better suited for something like a decoupling box or something else, but the ratio is all wrong for a D.I. ...

Thanks for the link again. Do you have any recommendation for this little triad trafo?

 

[Khron]

It could still very well work for a DI box, but definitely not a passive one - you'll need some sort of high-impedance buffer there, which then drives the transformer out.