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Saturday, February 27, 2016

Grid Choke

In the past, we've mentioned about two coil choke for power supply, now this round, let's talk about Grid Choke. 

Grid choke is a small-medium size, high inductance choke for tube amplifier use. The choke is built with a single coil, tapped at the center for various usages, for grid load (replacing resistor), for phase splitting, or for special grid bias scheme. Since it is for audio usage, it is wound with a special low capacitance coil winding methodology. 

Center Tap Grid Choke
Low capacitance coil winding methodology will be needed to the load is consistent across audio frequency spectrum. 

Grid choke is sensitive to pick-up of noises from the surround such as magnetic field emitting from surround transformers and therefore needs to be shielded or potted to prevent such events. Also, mount it further away from transformers to avoid hum pick up. 

We have the following standard 3 types for your considerations, and of course, low levels such as Level 1 and 2 are available too if Level 3 is over budget.


Level 3 Nanocrystalline Double C core choke, potted
- Low current, high inductance grid choke, U$690 per matched pair (ex: 5687, 12AU7, 12AX7, 13E1, 300B, 2A3, 45)
- Medium current, high inductance 304TL grid choke, U$690 per matched pair (211, 845, 212, 304TL, 805, 811)
- Universal grid choke, U$1290 per matched pair (for all tubes) 
- Others sizes, please email us

Specs: 600H - 1200H, 1mA - 20mA, DCR = depends on user requirements, size


One size does note fit all since there shall be varying grid current being drawn for different tubes. So, it is critical to select or use the correct grid choke for the accompanying tube to avoid saturation

For pre-driver stage, use smaller grid choke, for power stage, use bigger grid choke. Voltage swing is another consideration when using such chokes. Smaller choke will tolerate ~50Vpp, and bigger choke will tolerate more. When order, please specify to us so that we can ensure what you get fits what we build for you.

What's the benefit of using grid choke? 
* Better voltage swing (peak to peak) compared to grid resistor. 
* Better low frequency response compared to grid resistor. 
* Different tonality compared to grid resistor (User comments: more solid and stable imaging, 2D -> 3D).

If you do not see what you need on our website, please do not hesitate to contact us. We are expert in custom made transformers. Do note that our custom made department are always fully loaded with projects and therefore lead time is long. Please order early to avoid disappointment or long wait.

J&K Audio Design
2/28/2016

Product Lists  

Level 0

Level 3: depends on type, size and complexity. Email us for details.
Iso-trans: link 1, link 2
* Finished amplifiers, DACs, audio gadgets, upgrades and repairs - this is not our core business and we do it out of passion. We do not have fixed models, fixed price and we customize for each individuals. The sky is limit of creativity.  
* Our product lines are always improving and increasing. If you do not see what you want, contact us!  
* Please email for volume discounts, distributor and OEM pricing.


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Product Lists

Product Lists

Level 0: link 1

Level 1: link 1, link 2, link 3, link 4

Level 2: link 1, link 2, link 3, link 4, link 5, link 6, link 7, Link 8, link 9

Level 3: depends on type, size and complexity. Email us for details.

Iso-trans: link 1, link 2

Power-trans: link 1

* Finished amplifiers, DACs, audio gadgets, upgrades and repairs - this is not our core business and we do it out of passion. We do not have fixed models, fixed price and we customize for each individuals. The sky is limit of creativity.

* Our product lines are always improving and increasing. If you do not see what you want, contact us!

* Please email for volume discounts, distributor and OEM pricing.

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