CineMag Transformers (on the WARM BUS-COMP)

[jemmons]

I keep hearing about transformers warming up sound, and I’m trying to figure out what that means. I realized my BUS-COMP has a transformer stage in it (the makeup gain can optionally go through a pair of CineMags), so I thought this would be the perfect test platform.

But what’s the best-case test for transformers coloring sound? Because right now, either my BUS-COMP is busted or I’m just not giving the transformers the right type of load such that they’re doing anything unusual.

Here are the samples of a triangle OSC straight from an A4 into my interface, for example:

And here’s the same routed through the BUS-COMP first (compressor and transformers engaged, make-up maxed out):

Those look near-enough identical, and indeed if I do a null-test everything cancels out (after adjusting gain) with the exception of an inaudible bump on the fundamental that I can only detect with the EQ analyzer.

So can my fellow Nauts help me out? Is the BUS-COMP junk that I should sell for a RNC + a couple hundred? Or is it fine and transformer color is just a myth? Or have I just not found the proper material to make it shine?

[Anfim]

I would do a test with more complicated material before you write it off, a triangle wave is not the most harmonically rich thing out there

[jemmons]

So I should be looking for changes across harmonics rather than, say, the clipping of distortion, the smoothing of EQ, or the folding of… wave folding? It’s more a frequency domain thing than a time domain thing?

Sorry for the ignorant questions, but in searching all I can find is that transformers are supposed to add “warmth” or “space” or “depth” to a mix, and that doesn’t give me much of an idea of what I should be listening listen for.

[jemmons]

So here’s what it looks like with noise on a spectrum.

Before flipping polarity:

With flipped polarity:

So interestingly, if this isn’t just noise or some other artifact of the compressor, all the actual change seems to be +4k Hz. This would jive with the claims of a transformer adding “space” but is maybe the opposite of what I’d expect for “warmth”?

[resonant_space]

The effects of transformers are influenced by the type of transformer, the circuits surrounding them, the source material, and gain staging. A good place to start would be hitting the input of the transformers hard, so they saturate. I’d use music rather than a single frequency waveform, and use your ears.

[d4ydream]

You may find some useful information in this Fabfilter Saturn 2 demo. I seem to recall Dan Worrall covering some of the differences between, tube, tape, transformer saturation etc.:

Introduction to FabFilter Saturn 2

If it’s not in that video than it’s in this one:

Beginner's Guide to Saturation

My understanding is that certain types will add even order harmonics and certain types add odd order harmonics. Others still will flatten the peaks of waveforms.

[darenager]

Yeah you need to be driving the transformer to get hysteresis happening in the core, which is going to create more low frequency harmonics, drive it harder and you can get a nice bit of saturation.

Different transformers will of course have different properties, and of course the surrounding circuitry is going to be a factor - in fact this most likely explains the slight differences you noticed when nulling.

[resonant_space]

Looking at the manual, the transformer control also switches in a different make-up gain circuit that feeds the transformers. Try cranking up the make-up gain–I think you should hear a difference. If the product engineers added the circuit, presumably it would be enough to cause some transformer saturation.

[jemmons]

@plastic_pizza

Transformers are mainly there as another way to get a balanced signal, and were used for this purpose back in the days before op-amp ICs were very common.

Ah, ok. This is starting to make sense now. Both in what the transformer’s supposed to be doing, how modern distrust of ICs has lead to mythologizing around analog windings, and how some original SSL comp in some console somewhere had transformers and someone abused them to get a certain sound that they then failed to recreate with opamps, so now they have to be in an “authentic” recreation.

@resonant_space

A good place to start would be hitting the input of the transformers hard, so they saturate.

and

@darenager

Yeah you need to be driving the transformer to get hysteresis happening in the core

This was the other missing piece. When I really wail on it, it totally clips. These saws never stood a chance:

And look at the goofy way it clips just the rising edge off the square:

It almost look like the “TRP” osc on the A4… which is a transistor pulse, which means I have more questions, but I’ll save them for another day.

Thank you all for your help! You’re wonderful and I feel much smarter now.

[BassesAndPads]

Sounds like you are dialed in now. I would just add that transformers are great but it’s typically a pretty subtle difference unless you overdrive the inputs. So you really want to be listening for extra weight and depth in your mixes. They shine on low end too - basses,kicks,etc. But it’s not a huge mind blowing difference or anything unless you clip it.