Emission Labs 20A Mesh - UX4 Base (Pair)

For these tubes we use a very fine gold grid wire, with a gain of 21x for the 20A and 20B, and 32x for the 30B. It is recommended to use these tubes transformer or choke loaded. This is because you can use them at normal supply voltage then. Of course you can also use them resistor loaded, but then you need a supply voltage of 700V or more. The 20A, 20B and 30A tubes are based on a very old principle, where high gain tubes have much wider Anode distance. This is still the ultimate way to make a very linear DHT high gain tube. Miniaturization has always been the enemy of tube linearity, specially with DHT. The 20A/20B/30A will outdo any small size tube. We encourage you to check the tube curves of any miniature tube, like 6SN7, ECC88 or ECC82, and you will see this series presented here is much superior. However this results of larger dimension tubes is a higher working voltage. For this reason, tubes like this were not made any more after 1935, when miniaturization of tubes started to