Transformer Mounting..?

[Snatchman]

Hello..Question if I may. I've wondered, if any, what's the difference in sound/performance between a transformer that's mounted directly on the circuit board as opposed to one that's mounted somewhere in the chassis ( where I have seen some mounted )..?

 

[rock soderstrom]

what's the difference in sound/performance between a transformer that's mounted directly on the circuit board as opposed to one that's mounted somewhere in the chassis

From my point of view there is no difference in sound/performance with the same transformer for case or PCB mounting.

The position and orientation of a transformer can be relevant in terms of magnetic crosstalk, but this is independent of the mounting type.

 

[Snatchman]

Hello..Thanks for your reply..!

 

[john12ax7]

All things being equal the pcb mount version will perform better due to the shorter lead length, less chance of unwanted parasitics from the wires. This was also confirmed by Jensen when I asked them some years ago.

Now as rock mentioned the positioning might also have an impact, so you might gain more than you lose by using wires and mounting elsewhere.

In terms of sound it's subjective, so not really a better or worse.

 

[Ricardus]

All things being equal the pcb mount version will perform better due to the shorter lead length, less chance of unwanted parasitics from the wires. This was also confirmed by Jensen when I asked them some years ago.

PCB traces don't contribute as many parasitics? Aren't they just extensions of the transformer leads?

 

[john12ax7]

PCB traces don't contribute as many parasitics? Aren't they just extensions of the transformer leads?

A pcb trace will be more controlled and predictable.

Consider that you often have a pcb trace anyway, so what's better a pcb trace or a pcb trace plus an additional piece of dangling wire?

 

[Ricardus]

A pcb trace will be more controlled and predictable.

Consider that you often have a pcb trace anyway, so what's better a pcb trace or a pcb trace plus an additional piece of dangling wire?

If you keep the leads short, and the traces happen to be long, I'm just wondering if it isn't the same thing.

 

[john12ax7]

If you keep the leads short, and the traces happen to be long, I'm just wondering if it isn't the same thing.

I haven't directly measured it, but would imagine at a certain point it would be neglible. With proper lead dress you can build well behaved circuits into the MHz region.

 

[CJ]

we developed a wattmeter at work, took a year, pretty slick software, you could hook up 3 voltage leads and three current transformers to a 3 phase system in any order and it would automatically sort out what CT was supposed to go with what voltage lead, and flip the polarity of a CT if needed so that the power reading would be correct.
we were celebrating the first 6 units sent out UPS Red to our first customer,
all 6 pc mount transformers ripped loose from the board, not a good start to what turned into a big loss product for the company.
hmm, what's that rattling around inside the case?

 

[Tubetec]

Ive seen smaller pcb mounted input transformers with the pins ripped out due to taking a fall . The other thing is you wont know the best orientation of multiple transformers for minimum hum until you try it , if your input transformer is pcb mounted your stuck with that orientation unless you re-do the pcb . The thread mounting input transformers in the round mumetal can are most convenient ,as they have maximum flexibillity in terms of positioning ,relative to a nearby mains transformer for instance .

In something like a line or mic input transformer , the primary will have a cable connected to the input in any case , so a few inches of twisted pair inside the chassis wont make much odds , keeping the distance between the secondary and the following grid as short as possible when hi-z unbalanced is involved is always preferable . Theres no screening on PCB traces , where a short length of screened wire directly to the tube grid would help eliminate any leakages due to the pcb or other induced noises . Tubes mounted on pcb's can also suffer unwanted microphonics and resonances , although something like a guitar amp tends to be much worse in this respect than mic pre's .

 

[Snatchman]

Thanks for the replies..I sorta thought about this as I've listen to gear per si, a channel strip, with the units connected within the pcb board as opposed to a channel strip like a lunchbox going in/out with a cable..I seem to notice a slight difference..Could just be me.....

 

[MisterCMRR]

You can eliminate any magnetic field pickup problems from transformers with wire leads by just tightly twisting the wire pairs for each winding. Funny how the answer to both magnetic pickup and magnetic radiation from wires is twisting. The to and from currents create opposing and therefore, cancelling, magnetic fields. If the transformer is on a PCB keep the traces for each winding pair as close together as possible until they reach their destination (side by side or on opposite sides of the PCB, but very near each other).

 

[JohnRoberts]

we developed a wattmeter at work, took a year, pretty slick software, you could hook up 3 voltage leads and three current transformers to a 3 phase system in any order and it would automatically sort out what CT was supposed to go with what voltage lead, and flip the polarity of a CT if needed so that the power reading would be correct.
we were celebrating the first 6 units sent out UPS Red to our first customer,
all 6 pc mount transformers ripped loose from the board, not a good start to what turned into a big loss product for the company.
hmm, what's that rattling around inside the case?

I learned that lesson back in the 70s for my kit business... Since I sold the kits unassembled the loose transformer was fine, but if the kit builder mailed it back to me for repair the transformer would invariably break off at the PCB leads. After that I started using a mounting screw to secure the transformers....
===

A difficult issue was when I designed my drum tuner to keep the batteries from popping loose during shipping... I got it sorted but it was not simple.

JR