Metropoulos Forum

It seems that Mercury Magnetics is really big on selling their "super stack", oversized transformers. MM hypes up their trannies, saying out more iron is better.

Why is more iron better?

I have some Heyboer trannies that are much smaller than their MM counterparts and they seem to do the job just fine. Is there a point where the extra just become wasteful and is more of a gimmick or hype?

In terms of performance, I feel that the Heyboers do a great job, as does the MMs, but I can't understand what the extra iron does on the MM. Can a smaller transformer be just as good as one with more laminations? What does the extra laminations give you?

In terms of voltage sag and current, the Heyboers perform the way I want them to. I never got a chance to A/B a Heyboer with a super stack MM for the same amp, which is why I ask.

I've been curious about this too. Though I can't explain it, I culled this from a Marshall forum thread:

"This is from MM website

"FatStack™ (SuperStack):

FatStack transformers are custom-designed Mercury Magnetics transformers that have extra iron. In an output transformer it extends the bass frequencies response. I the case of a power transformer it can minimize tone drift giving your amp more stability and headroom. Our SuperStack is similar but built higher to accommodate smaller mounting footprints."

...and on the second page of the Metro Transformers and Chokes forum: transformer "stack" question

hope that helps

Using more iron makes a transformer harder to saturate. This is where the "extended low frequencies" comes from because it's usually the lows that saturate on an OT before anything else does.

While "OT saturation" has been used as a marketing ploy for years, in reality it's not something that sounds very good. The bigger the core, the better it can handle low frequencies without reaching the point of core saturation.

As with anything else there does come a time when you reach the point of diminishing returns.

To me, the FatStack super size trannies sound like a marketing ploy. For guitar, I can't imagine needing more lows.
Does anyone have decent A/B clips?

ive used a lot of hybrs. and MM's (pt's & ots).... MM is the last choice for me. frankly, i think they are simply over-priced. sure, manuftring quality is good. but so are hybrs! a couple MM's i didnt even like....shrill on top..not smooth. ~~~but those were "tone clones", not the 'fat stack'.
whatever- just my experience