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Stacking transformer

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Posted on March 21, 2017 at 04:05:31
Tube747
Audiophile

Posts: 419
Joined: May 11, 2004
I have 2 identical toroid power transformer with the following specification for each transformer:

Secondary #1: 225v @0.15A
Secondary #2: 9v @1A

Any advantage to stack these 2 toroid transformers as I have seen some solid state amplifier with 2 x power transformer stacking? Refer to what those solid state amp designer claimed that stacking power transformers sounds better......

I guess 2 transformers after stacking:
Secondary #1: 225v @0.3A
Secondary #2: 9v @2A

Any comments?

 

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RE: Stacking transformer, posted on March 21, 2017 at 06:11:11
Triode_Kingdom
Audiophile

Posts: 10011
Location: Central Texas
Joined: September 24, 2006
There's no advantage. In fact, I remember reading some years ago that combining the windings of separate transformers in this way requires derating their individual power ratings. It's only a useful technique if you don't have the correct transformer for the job.


 

RE: Stacking transformer, posted on March 21, 2017 at 09:17:49
Tube747
Audiophile

Posts: 419
Joined: May 11, 2004
What the stacked power transformer sounds like I wonder? Good or worst or no difference.

 

RE: Stacking transformer, posted on March 21, 2017 at 09:45:19
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
What are the power requirements of the device the singe transformer is powering?

If the single transformer meets the requirements with a comfortable overhead, then there is no advantage to adding a second transformer.

You need to get away from this idea of "what it sounds like". That's not how electrical engineering is done. Sure the engineering certainly determines how something will sound. But you have to do the math first. Not just throw components in and see how it sounds.

 

RE: Stacking transformer, posted on March 21, 2017 at 10:47:53
Please remember that when stacking transformers you can get weird and/or unpredictable results if you do not connect primaries and/or secondaries in parallel.

In other words, if you connect in parallel the outputs (in order to double the VA output), you might also connect in series the two primaries to adapt for example from 110V to 220V AC mains.

If you connect in parallel the AC mains inputs then you might as well connect in series the outputs to double the voltage.

If you ever connected in series primaries and secondaries it will be pure fun: more or less the same unpredictable voltage division that happens when connecting in series similar capacitors without parallel resistors.

In case of tight mechanical stacking do not forget the magnetic forces that tend to vibrate the assembly. The mechanical forcse are strong also in case of toroids (even though the magnetic leakage is very low), as the magnetic vector potential is wild across the toroid center...







 

Also Phasing - ruin the transformer, posted on March 21, 2017 at 11:47:52
gusser
Audiophile

Posts: 3649
Location: So. California
Joined: September 6, 2006
And if connecting secondaries in parallel, you have to consider phasing. Same applies to paralleling primaries.

If you operate a transformer for more than a few seconds with paralleled misphased windings you stand a good chance of burning out the windings.

 

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