Nagra VPA 845 retubing


Hi. I have a pair of Nagra VPA monoblocks with 845 tubes. I bought these used. When I contacted a local dealer I was told that I should only buy tubes from Nagra, because Nagra supposedly ensures that they are perfectly matched and are fully compatible with the amps (they costs 900 a pair!). Is this true, or is this a racket? Has anyone tried other matched 845 tubes than those sold by Nagra? If so, any preferences? Thanks
obrennan1963

Showing 2 responses by philipwu

my dealer said the VPA need tight specs tubes so to work properly and flavorly with their amps. he come across one of his customers whom send back VPA for repair and was inform by Nagra that his customer had used third party tubes and cause certain part of tube rectifing circuits to burn out gradually.
Obrennan1963,
according to my dealer, he said tubes start deteriorating from 3000hrs onwards if you are using Nagra tubes. You would hear noticeable differences from 5000hrs onwards. Best is to use their own tubes because they(Nagra) will buy and burn-in all tubes for 24hrs then throw away those which dies off. Tubes that survive the burn-stress test will go through tube tester to discard those out of specs.. and further match & pair individually. That's the labor & quality involve.