Mic Preamps Are All the Same?! — My Response to Jim Lill

Yes, there’s a lot of fuss over Jim Lill’s new video, and rightly so. The entire consumer culture of mic preamps has been called into question, and many are now questioning their own gear purchases. I’d like to weigh in on the matter from an acoustical standpoint.

If you haven’t, I encourage you to watch Jim‘s video all the way through: https://youtu.be/K-vIeA7yy6Q?si=FCMLEyjcyPXYJ1Ju

I’ve been testing the frequency response of my gear for years, and under normal operating conditions I have found the difference in tone between preamps to be negligible, if not non-existent. Of course, using EQ filters will instantly reveal the difference in color between other EQ’s, but this is a tangential discussion and one of many that Lill already covers in his video. But, I have always asserted that the first device in a recording signal chain—the microphone—is the single most influential on tone.

This is where things get interesting. Yes, the truth is that your mic pre does not in and of itself color your tone, in fact it’s designed not to. But, its input impedance can physically change the performance of your microphone. Yes, you read that correctly. Physically. When your ribbon mic is loaded down by a preamp’s low input impedance, the ribbon is actually inhibited from moving as freely and much of the natural resonance of the ribbon becomes over-damped. In simple terms, the mic will sound more dead and tight than its designers intended. Of course this only applies to passive microphones like dynamic mics (in their mid range) and especially ribbon mics (in their low-end). This can result in losses of up to 20dB or more at certain frequencies.

Check out the graphs proving this loss of tone in my previous article: https://www.pitmanmic.com/post/impedance-how-low-can-you-go

Jim Lill rightly acknowledges this caveat, albeit too briefly. This change in resonance is not only quantifiable but noticeable, and can have a big impact in the mix of a song.

See this video for some impedance comparisons : https://youtu.be/ak8Cj3uZB88?si=IL6r7B7UdRVUmOzQ&t=447

When selecting a mic preamp, I would prioritize clean transparent gain, low noise, and high input impedance especially for ribbon mics. This, combined with the need to protect your ribbon from phantom power is why I designed our Pitman FET Preamp upgrade. It preserves the natural performance of your ribbon regardless of what comes next in the signal chain, effectively making any ribbon mic “preamp-agnostic”, as one customer put it.

Check out upgrade pricing here: https://www.pitmanmic.com/services

To Jim Lill I say, "Bravo. You are doing an enormous service to the audio world, and doing a pretty damn scientific job for 'just a performer'." There are and will be many too stubborn to face the possibility of being misguided, and remain susceptible to the un-scientific snake-oil of audio gear marketing.

"It's easier to fool people than to convince them they have been fooled."  -Mark Twain

Please share your thoughts and feelings in the comments, and let me know what topics you’d like me to discuss next.

Until next time,

—Luke