Input transformer shootout!

I thought #1 stood out. It had a fullness that the others lacked.
Putting them in order of best to worst, 1, 4, 3, 2.
4 and 3 were close but 4 had a bit more depth to the sound.
2 sounded a bit flat compared to the others.

Matt, you know what I like.

Thanks for putting in the time to put this test together, I for one haven't been privy to a transformer shootout and so never really could appreciate until now the oft times not so subtle difference they can truely make in a signal path. That said, I first thought that it was a younger Lowden Wainwright III singing, and outside of that similarity thought that the singer has a killer, distinctive voice.

#1 for the clarity and the way it might stand out in a mix for how it defines the transients, then in close order as they all seemed variations of a common theme, 3, 4 and finally the darker 2. My guess is that #1 is the Jensen as it to me sounded the outsider of the group.

I preferred the fullness of #1 as well.

Cinemag CM75101 - 150:15K, max 20Hz -5dBu
Cinemag RE0887 - don't find any data
Cinemag CMMI10C - 150:15K, max 20Hz +5dBu
Jensen JT-110K - 150:9K6 max 20Hz -2dBu


Headphones from laptop, hardly a critical listening session:

1 - sounds the most pillowy and distorted, has some high mid restriction/cloudiness compared to the others, seems slightly rolled off in very top, but that may be due to distortion enhancements in lower registers. Sounds the most 'like a transformer'.
2 - sounds quieter than the others, maybe the most 'invisible'.
3 and 4, I can convince myself I'm hearing various things that change on subsequent passes.

Most of the differences between 2-4 are easily differences in the mics more than in the transformers.

I'd add to the test with program material fed through appropriate pads at appropriate levels as another benchmark.

What is the load resistor, and is there a Zobel? What are the mics?

Using a 150k so a 1:10 vs 1:8 is 1500 vs 2300, plus or minus minor winding variance. No zobel on any of them. I’m using 3U CM127s because it’s the only thing I have four of.

I’ve done frequency response testing on all of these. Unsurprisingly we’re talking about a difference of generally less than a dB, almost all of it in the low lows and very highs. The entire range of frequency response on these four is around 0.7 dB at 20Hz and all are within a few tenths at 20k, with the exception of the CMMI10C. From 300 to 3k they are almost identical.

It gets down to how you like your distortion.

I would be skeptical that all four microphones sound identical, even those matched pairs. There could be as much sonic variation between capsules and head amps as there is between the transformers.

I'd just go with the Jensen. Can't think of a company that has contributed more to "new" transformer designs in the past 40 years than them.

My feelings exactly!

Just use a standard 20dB pad.  Three $0.12 resistors.  As I suggested above.  The higher the attenuation out of a pad like this, the greater the high frequency roll-off from what I've seen.  12dB might be a more ideal combination of series resistance and shunt, combined with lowered levels driving it.