The Astrotube Story Born During the Pandemic
In 2020, during the uncertainty of the Covid-19 crisis, we started an ambitious project: building a truly classic tube microphone similar to the U47.
We knew we wanted a circuit based on the great vintage designs. Our main inspiration came from Stanley Church, an engineer who famously modified the original U47 to better suit the needs of the American cinema industry.
Here is what Stanley Church did to create his legendary “CineMic”, he started with the core Neumann parts: the M7 or KK47 capsule, the grill and the body. He then cut down the body, designed a new shock mount, and changed the internal circuit to use American-made components. He chose the 6072 tube (a low microphonic tube) and the Triad JO-23 output transformer, with a 5.8:1 ratio.
Our goal with the Astrotube was to follow this spirit of custom engineering.
Triad JO-23
Hermetically Sealed transformer*
| Primary Impedance (Ohm) | 20 000 |
| Secondary Impedance (Ohm) | 600 – 250 – 50 |
| Ratio | 5.8 – 8.9 – 20.0 |
| Max Level DBM | 10 |
| Frequency Response (Hz) | 50 to 15 000 |
| Case | JOB |
Source: Triad Transformer Corp. Catalog
We chose to build upon those foundational ideas. This was a necessity, as the original Telefunken VF 14 M tube is unavailable today. Crucially, the 6072 tube is still produced by reliable manufacturers like Electro-Harmonix and JJ Electronic, ensuring the longevity and serviceability of the Astrotube.
The M7 Transducer
When it came to the capsule, we carefully auditioned the difference between the M7 and the KK47. While the KK47 is an excellent capsule, we weren’t aiming for its sound.
The Astrotube mic aims for the deepest, darkest, and most emotionally rich sound. If you are seeking the most technically “flat” or clinical microphone, brands like DPA or B&K are better suited. Our goal is to capture and translate emotion.
After testing many options, we chose our favorite: the Fortin D7 capsule, a M7 proudly made in Québec, Canada.
Affordability Meets Excellence
However, our pursuit of the best sound is balanced by a commitment to value. The Astrotube must be affordable. We are doing everything possible to bring you maximum quality at a minimum price. Where we see no major sonic difference, we opt for the most cost-effective path. Where compromise is impossible, we invest to ensure the Astrotube delivers true excellence.
Shortened Path, Pure Sound
Unlike traditional tube microphones, the Astrotube features the XLR output connector placed right on the microphone body. We made this choice for purity and performance:
- It shortens the crucial audio path directly to your mic preamp.
- It skips the proximity of the power supply voltage, minimizing potential noise or interference.
This design immediately allows you to use your preferred XLR cable, ensuring the absolute best connection quality from the start.