Comparison of Preamp with and without output transformer

[ChuckS]

I did a recording to try to get a sense of the difference when I use the transformer coupled output or the solid state output of my preamps. The preamps I have are the Speck 5.0 MicPre. The Jensen output transformer can be switched in or out of the output stage.

In order to do the comparison using the same take, I recorded the preamp output with the transformer in the circuit as well as another output available from the preamp that does not go through the transformer.

The recording used 3 Zigma cardioid SDC mics in a spaced pair arrangement. Each mic into a Speck preamp, and each preamp having two outputs recorded (transformer coupled and solid state). The preamps had their high pass filter set at 50Hz, and this HPF was in the circuit for both outputs. No effects or EQ. The transformer outputs were a couple dB different than the solid state output so I normalized the transformer output recording and the solid state output recording independently.

I'd be curious as to your thoughts on the differences, and if you have a preference on this song. The songs on soundcloud were uploadeed as 16 bit wav files and downloadable.

Thanks

https://soundcloud.com/chuck_s/her-f...ng-solid-state

https://soundcloud.com/chuck_s/her-f...ng-transformer

[runamuck]

The differences are so minute that they're irrelevant to me.

[ChuckS]

Originally Posted by runamuck

The differences are so minute that they're irrelevant to me.

Thanks for taking a listen. Your feedback isn't exciting, but useful; not considering the preamps options and not recording both outputs would simplify things.

[rick-slo]

I don't hear a difference. If it is also a balance versus unbalanced output you might hear a difference with long mike cable lengths and possibly some external radio frequency noise, but these two samples sound the same to me.

[ChuckS]

Originally Posted by rick-slo

I don't hear a difference. If it is also a balance versus unbalanced output you might hear a difference with long mike cable lengths and possibly some external radio frequency noise, but these two samples sound the same to me.

Thanks for listening. All the preamp outputs are balanced. Not too surprising that little/no difference is being heard as the Jensen transformers are low distortion.

[sdelsolray]

Originally Posted by ChuckS

Thanks for listening. All the preamp outputs are balanced. Not too surprising that little/no difference is being heard as the Jensen transformers are low distortion.

I haven't listened to your samples in the studio yet, so I won't comment on them yet.

I do know that there is a difference in the transformer balanced and non-transformer active balanced outputs of the Speck MicPre 5.0. As you know, Chuck, I have a pair of the same Speck mic preamps and have spent quite some time with them. The differences (like many things) are subtle and less noticeable at lower gain settings. Run a null test with the two files to isolate the difference.

As an aside, the difference between the transformer and non-transformer outputs from the Speck ASC parametric equalizer is more pronounced. Dunno why.

Regardless, the Speck MicPre 5.0 is a great unit.

[Bob Womack]

This is, indeed, an old topic. I started on wonderful transformer-iso'd Neve consoles in 1981. About three years after I came into the profession digital arrived and everyone began yelling that we needed to get all that "awful iron" out of the signal chain. Three years later people began buying transformerless consoles to replace their transformered consoles. Many discovered that transformerless inputs had their own share of problems and so ended up ordering a raft of new Jensen transformers to allow inputs to be iso'd. But no kidding, we went through a phase where EVERYTHING, including mics, was re-engineered to remove the transformers and increase the slew rate of the electronics. Engineers stood about for hours scratching their heads and trying to tell if transformerless was inherently superior. It was different.

After a few years, all those classic, transformered consoles suddenly began fetching astronomical prices and their preamps began being removed and sold for astronomical prices as well. Why? As we settled into digital recording, transformerless preamps (and mics) were now deemed "harsh" and "brash." These day engineers proudly carry around their "500 Series Rack" with a collection of those 1970s transformered preamp modules that I grew up on, assembled and displayed as an "Add-a-bead" badge of their savviness. They are great preamps. Why? Because they are "warm" sounding. Of course, transformerless preamps can be pretty cool as well...

Now, to your question, first a disclaimer: Monday I celebrated thirty-five years in the field as a recording engineer. Surviving for that long means two things: 1) I have probably learned to listen pretty well, and 2) I am definitely "of an age" where I am experiencing "presbycusis," *ageing ears*. That phenomenon that ALL "people of a certain age" experience usually shows up in loss of high-end perception. Hopefully the latter doesn't cancel out the former!

One more thing: When I entered the field as a young buck, I read an article in Recording Engineer/Producer Magazine (RIP)* that as an aside addressed a professional malady of recording engineers: Ask a highly experienced engineer which mic (or frankly any device) is better and he will probably scratch his chin and say, "It depends..." and stare off into the blue.

With all that said (and scratching my chin, staring off into the blue), I put your files up on the marvelous, big, powerful monitor system here at the studio and gave them a listen. I may, may, may, have heard a tiny bit more "air" in the high end of the transformerless mic. I tried not to pay attention to which was which but it was virtually impossible and pure psychological associative effect may have biased my listening. However, the more I went back and forth between the two ignoring the labels, the less difference I perceived. And that, my friend, might be a great example of William James' maxim , "A difference that makes no difference is no difference at all."

I wish I could give you something more stellar and definitive.

Bob

* Issues now available for free download ONLINE!

[Timothy Lawler]

I downloaded the wav files and had a listen. KRK V6 speakers, treated room. Does the transformer version have a very slightly rounder lower midrange? I'm probably imagining it because I'm looking for a difference, heh. I have a Great River MP2 with similar dual outputs for each channel and have always thought there wasn't much of a difference.

[ChuckS]

Thanks to all who listened and responded. While this was fun and interesting, I guess it's time to focus on some things that will have a bigger impact on my playing and my recordings.