Transformers: Is Bigger Better?

[softwareguy]

This question comes from my limited knowledge of EE, which is almost entirely based in maintaining and trying to understand my old guitar amplifiers.

My question is, is it always better to have a big, powerful tranny in play? I know it will support bass information better, but I keep thinking about the sound/desirability of Fender Supers and Fender Pro's, which have much smaller output tranny's than the Fender Twins/Showman line (even considering the power differential). The Showman is a wonderful bass amp, but this circuit never develops the transformer saturation that a Fender Super or Pro does, and as a result, it never has the same compression, sweetness, and midrange richness that those amps attain when dealing with higher frequency material such as guitar (think of a Fender Twin vs. a Super). Is the output tranny on a preamp analogous? Should I be trying to get some pre's that are useful for "full range" like a Showman and others that might get squishy on bass but are really amazing for mid and high frequency material? Do preamp designers ever consider such "limitations" to be desirable?

Thanks for your thoughts.

[David Kulka]

"Bigger" specs are usually better, as transformers frequently run out of iron and go into clipping. A bigger footprint or heavier package isn't necessarily better -- it depends on what's inside. As for whether transformer clipping or compression adds to sound or tone I would say "no, it's more the opposite".

(Some might disagree, though calling distortion "a desirable artifact" would seem to undo the persuit of quality.)

If you're asking about power transformers, then it's a whole other question.

[Tim Farrant]

As David points out, the size depends on the type of metal used for the core. Older metals meant bigger transformers to acheive a similar output level before saturation compared to the modern core types in use today. Most transformers will saturate at low frequencies first, hence the "warmth" that is actually low freq harmonic distortion. But yes, generally speaking, a bigger trnaformer will handle more level before saturation.

Cheers
Tim.

[softwareguy]

Thanks for your input, guys. I guess what I'm really asking is not whether better transformer specs make for more accurate sound, but whether there aren't some instances where the saturation that takes place in transformers is desirable as a coloration. In particular, can a transformer that doesn't do as well on bass material because it saturates too soon nonetheless add a lot of richness and vibe on midrange and treble material such as guitar and voice?

And since we know that trannies saturate on low frequency material earlier, would it be possible that there could be a preamp tranny that was optimum for mid to higher level information just as the Fender Super tranny is optimum for guitar even though it saturates too rapidly for bass?

I know that the preamp ideal is DC to daylight, but as I look at how guitar amps, and particularly their trannies have evolved, it seems that there could be a case to be made for a preamp that was more deliberately limited in its optimum frequency applications.

[softwareguy]

Maybe another analogy is to some classic gear that is not really that swift in the replication of extremely high or low material but due to whatever combination of tranny windings, rail instability, etc, brings huge mojo to everything between 100 and 10,000 cycles. It's just striking me that the tranny in particular might be an example where it is really the limitations that make the magic.

[David Kulka]

It's interesting that people often expect gear specs that extend from DC to microwave with near zero distortion, yet value old transformers with rather severe limitations on the high and low ends, and then push them beyond their design range. Distortion = magic?

[softwareguy]

An important aspect of transformer "warmth" (distortion) is that it is stimulated by, and therefor tracks, the frequency of the input. EQ, by contrast, boosts or cuts a specific frequency range that remains static, whatever the input does. The frequencies added by a good-sounding transformer will always be based upon the frequency (and overtones) of the input at that moment in time and will change as the input changes.

I think that this is why transformers remain attractive to us. They can add color, richness, overtones, distortion, whatever, that tracks the musical content of the input. Kind of like an aural exciter, but much more complex and much less cheesy.

I think it is this effect that makes transformers "magic" and also why their limitations might be their most important features.

[tINY]

When thinking about this, don't forget to consider hysterisis as well as saturation.....




-tINY

[softwareguy]

OK, bearing in mind my limited skills, I'm guessing you mean that, even before a transformer goes into saturation, hysterisis is going to be impacting the sound transmitted by a transformer, as reflected in that transformer's BH curve. And that the BH curve for a smaller core/fewer turns/more vintage/less perfect transformer is going to show this impact earlier and more dramatically.

I'm sure I've pretty thoroughly hashed that up, but is the general idea correct? In other words that even prior to saturation, the two transformers will impact the signal differently?

[tINY]

Close enough.

The upshot is even order harmonic distortion on lower frequencies and some intermodulation.



-tINY

[softwareguy]

Tiny,

Thanks for SCHOOLIN me! Seriously, this is exactly the kind of thing I'm looking for. So you're saying that as a result of greater hysterisis, earlier in the curve, you're going to hear more even order harmonic distortion which is, as we know, that stuff that we perceive as "sweet" sounding or "euphonic." I'm diggin it! And the fact that the transformer's response on the BH curve is frequency dependant means that the transformer will especially add this distortion in the lower frequencies, which we perceive as adding "warmth" or "grunt" or all those other ridiculous terms that we use.

Let me know if I got this all wrong, but I think I just understood something for the first time!