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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
brf
1,699 posts
 
$900/pr for current production 845 tubes is a lot of money. What make are the Nagra supplied tubes?
sunnyboy1956's avatar
sunnyboy1956
423 posts
 
Online prices range from approx USD 95 for a single tube to 950 or so for a pair depending on the brand etc. Nagra prices don't appear to be unreasonable .
All the best
Pradeep
brf
1,699 posts
 
Nagra at one time used KR Audio 845 which retail in the 900/pr range but I thought Nagra dropped them due to reliability issues and started using Chinese sourced 845.

Which version of the VPA do you own? Does it have the built in tube protection circuit?
philipwu
204 posts
 
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.
brf
1,699 posts
 
Philipwu, I believe that was true with the first generation VPA and especially with KR Tubes. Nagra later fix this problem in the second gerneration VPA which allowed for a wider variance of 845 to be used.
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