Kenetek T4B Opto-Attenuator




The Kenetek T4B is a direct, drop-in replacement for the Teletronix, Universal Audio and Urei T4A, T4B and T4C opto-attenuator modules. The result of over 20 years of testing, the Kenetek T4B is the highest quality opto-attenuator unit available today.  The electroluminescent panel (EL panel) is custom built to our specifications and provides a smoother, more musical attenuation curve than T4B units from other vendors.  T4B units built with these panels are much more musical and will restore the classic behavior of your LA-2A, LA-3A or BL-40.  Your unit will be smoother and more versatile, and you will find it becomes a pleasure to use again.

Kenetek T4B's are built to the highest standards in the industry. Over 50% of the photocells tested are rejected. Photocells are tested no less than three times during the build process, and usually more like four or five times, unless we get lucky and find an unusually well-matched set early on. Click here to visit the Kenetek website for complete information on Kenetek T4B units.

Kenetek has been building, servicing and restoring Teletronix and Urei LA-2A Tube Limiters for 20 years. By necessity, we had to exhaustively research the components, materials, suppliers, construction and history of the T4B unit.  We discovered that the modern EL panels built by the "Original Equipment Manufacturer" (which was at least four times removed from Grimes, the original manufacturer of the EL panel used in the original LA-2A and LA-3A units) has updated their materials and manufacturing techniques to provide a brighter, more efficient and reliable EL panel.  You see, the primary use for their panels is for instrument lighting in aircraft. While the "improvements" they made may benefit pilots, they were actually detrimental to the performance of the opto-attenuator units used in LA-2A, LA-3A and BL-40 units.  Modern panels have a much lower threshold voltage and put out more light at lower voltages than the original panels. The result is that opto-attenuator units using these panels exhibit a sharp knee at the threshold of compression, and the unit goes into heavy compression much sooner than the classic units. It is difficult to dial in the exact amount of compression desired, and the musicality and versatility of the compressor is diminished. Kenetek found a supplier that was willing to build EL panels to our specifications, and these panels more closely resemble the curves and behavior of the EL panels from the 1960's.  T4B units built with these panels are much more musical and will restore the classic behavior of your LA-2A, LA-3A or BL-40.  Your unit will be smoother and more versatile, and you will find it becomes a pleasure to use again.

The Kenetek T4B is hand built from specially selected components and is guaranteed to be the most accurate T4B you can buy. The photocells, EL panels and finished units are graded and matched using our custom-built, computer-driven T4B tester, which gives us unmatched precision and accuracy when testing T4 units. Each unit is delivered with screenshots of the pulse and dynamic range tests performed on that unit.  The test data on each unit is archived. Do yourself and your classic limiter a favor. Try a new Kenetek T4B opto-attenuator in it.


Kenetek T4B Electro-Optical Attenuators are warranted against premature failure due to material and manufacturing defects for a period of three years from date of purchase. Simply return the unit to Kenetek and we will, at our option, repair or replace the unit at no cost.  You are responsible only for shipping expense to our facility. This warranty does not cover damage or abuse. The warranty seal on the unit must be intact and undisturbed.

NOTE: International shipping varies by country. Right now, the web store is overcharging some people for shipping. Don't worry; I do not make a profit on shipping and will refund any excess shipping fees. I am working on getting this problem corrected, but in the mean time, please use the Contact Us form if you have questions or concerns about shipping costs. Thanks!!!.

Also take a look at Inside the Teletronix LA-2A - The most complete information available anywhere

Add to Cart:

  • Model: KENETEK-T4B
  • Shipping Weight: 0.5lbs
  • Manufactured by: Kenetek Pro Audio

This product was added to our catalog on Wednesday 22 February, 2012.