VALAB 600H 20mA High-Bias Grid Choke
For Capacitor-Coupled 300B / 50 / 45 / 2A3 / 211 / 845 DHT Tube Amplifiers
Designed for High-Bias DHT Circuits
The VALAB 600H Grid Choke is not a generic low-current grid choke. It is designed specifically for high-bias directly heated triode circuits such as 300B, 50, 45, 2A3, 211, 845 and other premium DHT amplifier stages.
Unlike many traditional grid chokes intended for only very small DC current, this choke is rated for up to 20mA DC working current. This gives the choke generous operating margin and helps maintain stable performance under real amplifier conditions, including higher bias operation, startup behavior, overload recovery and specialized DHT circuit designs.
What Is a Grid Choke?
A grid choke is a high-inductance coil used to provide a stable reference path from the tube grid to ground.
In a conventional tube amplifier, the grid is usually referenced to ground through a grid leak resistor, typically 50kΩ, 100kΩ, 220kΩ or higher. A grid choke replaces this resistor with a very high-inductance winding.
For DC, the choke provides a defined resistance path to ground.
For AC audio signal, the choke presents very high impedance, reducing signal loading.
This allows the tube grid to remain properly referenced while allowing the music signal to pass with less damping than a conventional resistor-loaded input.
Key Specifications
| Inductance | 600H |
| Rated DC Working Current | 20mA |
| DCR | 13.6kΩ |
| Connection | Tube Grid to Ground |
| Application | Grid-to-ground choke after coupling capacitor |
| Optimized For | High-bias DHT grid circuits |
| Suitable Tubes | 300B / 50 / 45 / 2A3 / 211 / 845 / other high-voltage DHT tubes |
| Dimensions | 70mm x 60mm x 50mm / W x H x D |
| Weight | 1550g / pair net weight |
| Sold As | Please select quantity as required |
How It Works
Traditional capacitor-coupled input:
With VALAB 600H Grid Choke:
At DC, this choke has 13.6kΩ DCR, giving the grid a firm reference to ground. At audio frequencies, the inductive reactance rises strongly:
| Frequency | Approximate Reactance |
|---|---|
| 20Hz | ≈ 75kΩ |
| 100Hz | ≈ 377kΩ |
| Midrange | Extremely high impedance |
Engineering Advantages
- Stable DC reference for the tube grid
- Extremely high AC impedance at audio frequencies
- 20mA working current for demanding high-bias DHT circuits
- Lower risk of magnetic saturation
- Better signal transfer from the previous driver stage
- Less loading on the coupling capacitor
- Improved microdynamics and small-signal detail
- Natural midrange texture, especially valuable for DHT amplifiers
Sonic Character
- More open and relaxed soundstage
- Better low-level detail
- More natural decay
- Improved midrange presence
- Better sense of flow and musical ease
- Less resistor-loaded compression
- More vivid microdynamics
- More stable performance in high-bias DHT circuits
- Especially effective in 300B midrange performance
Custom Designs Welcome
Looking for a specification that is not currently listed?
We are always interested in developing new products for the DIY audio community.
If you need a custom inductor, choke, transformer, or another special specification, please feel free to contact us.
Many of our current products actually began as custom requests from customers around the world.
Your ideas help us develop better products for everyone.
Even if your project is unique, we would be happy to discuss it with you.
Many of today's Valab products began as customer requests and were later refined into standard production models.
Anode Chokes
Grid Chokes
Filter Chokes
Please message me with your requirements.
Important Application Note
This choke is intended for capacitor-coupled grid input or driver stages. It is connected from the tube grid to ground, after the coupling capacitor.
This product is NOT intended to be used as:
- Plate choke
- Power supply choke
- Output choke
- Interstage transformer
- Speaker crossover inductor
Recommended For
- 300B single-ended amplifiers
- 2A3 amplifiers
- 45 amplifiers
- 50 DHT amplifiers
- 211 / 845 input or driver stages
- High-bias directly heated triode circuits
- High-end DIY tube amplifiers
- Capacitor-coupled tube circuits
- Builders seeking an alternative to traditional grid leak resistors
- Audiophile tuning where midrange texture and microdynamics matter
Customer Feedbacks:
Trusted Worldwide
- Worldwide shipping
- Carefully packed for international delivery
- Selected and tested for serious audio builders
- Long-term support for VALAB audio products
- Designed for DIY tube amplifier enthusiasts and audiophiles
Summary
The VALAB 600H 20mA Grid Choke is a specialized high-inductance grid reference choke for capacitor-coupled, high-bias directly heated triode amplifiers.
It gives the grid a stable DC reference while presenting very high impedance to the music signal. Compared with a conventional grid resistor, this can reduce signal loading and help preserve the natural openness, tone, density, and microdynamic life of high-quality DHT amplifiers.
The 20mA DC working current capability makes it especially suitable for demanding high-bias tube circuits using 300B, 50, 45, 2A3, 211, 845, and other high-voltage directly heated triodes.