audio Research REF 110 and KT 120 tubes

The KT-120 actually can run at a maximum plate voltage of 700-800Vdc! This is a very very robust tube. I have fitted a set in one ARC amp in warranty. It is taller, heavier, and the glass is thicker. Also on inspection, the plate of the tube utilizes heat sink fins. This is a very different tube then a 6550 and frankly sounds wonderful. I believe this currently represents the state of the art in tube design. Remember, unlike the U.S., the Russians never stopped making and designing tubes. That being said you will always get a random bad tube. It's the nature of the beast...

Hifigeek1...is there only one supplier of the KT-120s? From my conversation with ARC, they said they are not selling the KT-120s on a standalone basis for existing customers to retube their current production amps because they barely have enough supply to meet new amp deliveries that come with the new KT-120s. So it sounds like supply is pretty limited. Did you get yours from ARC or from a third-party tube vendor? Thanks.

Wow I guess my last post never made it on here. Cmalak, the reason I saw the KT-120's is I had to service in warranty a pair of Ref210's and they came with KT-120's. Understand that I can get KT-120's but they would not be ARC KT-120s. ARC runs all their tubes at hard labor for 24 hours to cull out the bad ones and then categorizes them based on their current gain etc. That way when I order tubes from ARC I have to give them the model of the product I'm repairing. Also, if any damage is caused by the ARC tubes within the warranty period, i.e. a screen or plate load resistor failure, it's covered under warranty. This tube represents the current state of the art in Russia tube design. You can email me gary.mf1@gmail.com and I can keep you updated as to when they will be available. Please be patient. Both myself and ARC know that people are chomping at the bit to get these tubes in their amps. This tube is so new they don't even know which amps these tubes will fit in. I just found out today that the KT-120's will not fit in the VT-200 as there's just not enough space. I can tell you that after just working on a Ref 110 the KT-120's will fit, and the factory tells me they work great! Additionally, any ARC amp that uses a 6550 regulator, that tube is not replaced with a KT-120.

Will the KT-120 tube fit in a VT100 Mk II ?

Mabonn.....I believe so.