Saturday, March 30, 2024


The Legend, the Man and the Tubes. The TUBES? What?


If you spend any significant time reading articles about tube gear on internet pro audio forums, you are bound to run across a mention of “Bowie” as THE GUY to see for quality, good sounding vacuum tubes from the Golden Era of tube manufacturing. Bowie keeps a low profile and does not post or promote himself or his company. He is so low key I wondered what his allure is and why people continue talking about getting tubes from him. 


It was quite by accident that I saw a mention of “Christian Whitmore” in a forum post and a single additional word that led me to try emailing him; Bowie. That email led me to connecting with Christian Whitmore and his company called “Pro Audio Tubes”.

This is not Christian Whitmore but it's a great big tube

I emailed him about acquiring a “microphone grade” EF86 vacuum tube for an upcoming mic shootout. He quickly responded with his thoughts about the tone of the various tubes available and their respective prices, they're not cheap. 


When it comes to using vacuum tubes in microphones, “microphone grade” is an important term because the piece of gear that comes right after the mic is a preamplifier with 30-60 dB (or more) of gain added. If you have a tube that is hissing or spitting or making other noises these problems will be amplified by the preamp stage.

MXL Revelation Tube Mic


The two microphones I was preparing to review:

  • MXL Revelation

  • Warm Audio WA-67

These two microphone models use the same tube-type and given the price of the vintage replacement, I was interested in a tube I could move in and out of both microphones during the test/shootout. Both microphones came equipped with modern production Electro-Harmonix EF86 which are manufactured in Russia. Both microphones sounded good when I started the testing, neither was exhibiting disturbing noise. I told Christian that I'd be interested in a tube for the MXL Revelation which might deemphasize sibilance if that was possible. After we discussed the price range of the replacements we got down to specifics and with that, he told me to give him some time to evaluate what he had in stock. 


The Tube I received with custom packaging

Christian does things different, and by different, I mean better! He is using modern, state-of-the-art, digitally controlled vacuum tube testers, but that is just part of his total service. The exclusive part is having his ears evaluate every tube audibly. Normally I don't like describing sounds with written words but Christian has a way of making the sound produced by the tubes come to life through his written descriptions. 

My EF86 N.O.S. Amperex tube

When he contacted me a few days later he had identified a few EF86 in his inventory that he thought were “microphone grade” (quiet enough and excellent tone) and he was very up front about the pricing. He gave me a wide range of prices and based off the description of what I was looking for he pointed me at a 1959 Amperex EF86 made by LRT in France for $135, it would have been more if he had the original box ;-) 

Russian EHX on left, French LRT on right

I ordered the tube based off his recommendation. I've used it and done preliminary A-B test recordings before and after tube swap in the Revelation microphone. To my ears the vintage replacement tube has a slightly different sound, richer in the midrange, with more depth and detail. 

MXL Revelation Mic, Click to enlarge

The Revelation microphone is not fun when it comes to swapping the tube. To their credit there is a clamp which holds the tube solidly to prevent mechanical noise. The screws that must be removed are difficult to get loose (even harder to get them back in); then there is a little rubber sleeve around the tube to provide a tiny amount of vibrational isolation. My new vintage tube is slightly smaller in diameter than the modern counterpart. 

Revelation Mic Tube Clamp, Click to enlarge

TESTING.....1, 2, WOW

For the comparison test recordings I'm using a Neve 1073 preamp with identical settings before and after the tube swap. The preamp is patched directly to the digital-audio interface line input without any other processing. The only variable was the tube used to record the test vocal track.

Evaluating vacuum tube sound reproduction objectively is tedious because the improvement is very subtle. What you're recording is also important to consider. If I was recording acoustic guitar or pretty vocals I would want the vintage tube. The 3D depth of the vintage Amperex could be heard every time once the listener became accustomed to listening for the additional details in the sound not just tonal differences. The modern Russian EF86 would probably be satisfactory to the vast majority of people. If you're listening on a phone or car stereo the extra depth from a vintage tube would be virtually impossible to perceive.


I'm older and when I hear or read the word Bowie I think of the 19th century, American pioneer, “Jim Bowie”, the inventor of the Bowie knife. 

Rare photo holding the Booee Mic

I asked Christian directly about his Bowie nickname and he explained that a vocal teacher back in college thought he sang like David Bowie. Christian told me there is a circle of people in Nashville who just refer to him as “The Tube Guy”. He's ok with any of these names. 


I'm still working on my EF86 comparison study and the vintage Amperex will be climbing inside my new WA-67 tube mic for more A-B testing very soon. Meanwhile I'm already plotting my next vintage tube purchase, a GE6072 to compare with the Russian tube that came in my new Warm Audio WA-CX12 microphone.

If you have a tube-driven vocal microphone exchanging the tube for a vintage manufactured part is one of the easiest and most simple modifications. Where your tube was and what it's been doing for the last 50-60 years is the question. If you're young and have boundless time and energy then you should try everything. If you're older and don't have time to waste then by all means engage an expert like Christian Whitmore of proaudio tubes. 

To get your own tube from "Bowie", aka Christian Whitmore, email: proaudiotubes at AOL dot com.

Thanks for reading High on Technology, Good Music To You!

©March 2024 by Mark King. It's not ok to copy or quote without written permission from the author.