Support Report: Changing the Micro-Tubes on Your UAD-1
By Brett Patrick

Location of UAD-1 micro-tubes

Now that they've been out in the field for over five years, it may be time to swap the spurious micro-tubes on some UAD-1 cards. The micro-tubes are an integral part of the warm and musical sound of UA's unique plug-in algorithms. Although the micro-tubes have a life expectancy of ten years, it has been observed that they may begin losing fidelity as early as four years into their life, depending on the actual PCI bus power-supply voltage, bus speed and the amount of time computer games are played on the computer in question. Computer games are particularly troublesome because they cause video cards to run at high temperatures and generate an unusual amount of radio-frequency interference (RFI) inside the computer case. Excessive RFI can cause a warping of the plate within the UA micro-tubes. Universal Audio does not recommend playing computer games on UAD-1 equipped systems, especially first-person shooters.

Checking the Micro-Tubes
To check your UAD-1 card's micro-tubes, all you will need is a digital multimeter and a microscope. While an electron microscope is recommended, this procedure can be performed using a simple 400x magnifier. The micro-tubes are mounted sideways to facilitate easy checking without first removing the tubes.

WARNING! If you do not see exposed tubes on your UAD-1, DO NOT perform the procedure! You have the FET based model.

First, be sure you are wearing a proper grounding strap. Shut down your computer. Remove the UAD-1 card, and place it on the original anti-stat bag that came with your card. UAD-1 anti stat bags have a higher grade anti-static coating than most anti-stat bags. DO NOT substitute another bag. If you cannot locate your original anti-stat bag, DO NOT perform the procedure. Call Universal Audio for a replacement.

Locate the anode and cathode of the micro-tube and measure the resistance between the two, using the access holes on the back of the tube mount. If the resistance is over 20 k-ohms, then your micro-tubes are fine. Anything under 20 k-ohms is an indication that you are not operating at optimum levels and could be losing fidelity.

Changing the Micro-Tubes
If you do get a reading of less than 20 k and decide to change the user-serviceable micro-tubes, you may order them from UA. The part number is 0401. They are extremely easy to replace: all you will need is a pair of ESD safe tweezers, an ESD safe soldering iron, an ESD safe solder suction device, and an electron microscope. Simply desolder the micro-tubes from the UAD-1's circuit board and remove them with the ESD safe tweezers, being careful to note the alignment of the anode and cathode poles. Next, align the new micro-tubes and solder them into place on the circuit board. Using your multimeter, measure the resistance to make sure you have a reading above 20k. If so, you are finished changing the micro-tubes on your UAD-1 card.

Remove the micro-tubes with ESD safe tweezers