Tubes Asylum

Tubes for Nagra VPA

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I have just bought used pair of Nagra VPA power amps. To check conditions on the tubes, I removed one of side panels and found that there are 3 tubes in the input stage, One E182CC by Mullard and two 12AX7 by EI. (But the J. Scull's review for VPA in Stereophile, there are two tube in each monoblock, one 12AU7 and one 12AX7).
My Question,
1. Any VPA user help me what is the real tube nagra originally provided (12AU7 or E182CC)?
2. If nagra stock tube was 12AU7, can E182CC be used without any troble ? I know that 12AU7 and E182CC(7119) is totally different.
In the picture provided by Nagra USA (http://www.nagrausa.com/nagra_VPA.htm), one tube in the left looks like E182CC, because it is taller than the other two 12AX7 tubes. The height of 12AX7 and 12AU7 is same as we know.
Any information would be highly appreciated.
JWK

http://www.nagrausa.com/nagra_VPA.htm (Open in New Window)

Follow Ups:

Re: Tubes for Nagra VPA - 1derful 13:04:02 02/04/04 (1)
Your pair is of later version than the one reviewed in Stereophile.
Don't ever even think of replacing the E182CC with 12AU7!!!
Replacing the stock 12AX7s and you'll be surprised. NOS Telefunken tubes should be a good start.
Pls be careful when swapping tubes. There's a microswitch on the top front corner and the side cover must be attached in order for the unit to function properly.
- Re: Tubes for Nagra VPA - chris found 17:00:58 02/06/04 (0)
  In response to the valve change, the E182CC is a higher current /voltage valve in comparison to the 12AU7, it also has a different pinout so swapping the valve with the original will not work properly in the circuit for this amplifier.
  The E182CC valve has been used by other manufacturers in ciruits for driving the 845 output tube, so it has a good history, I would expect the new version to sound better than the old one expecially in the mid and top where a higher current drive is needed.
  I would recommend that if you wish to play with valves here, be aware of pinout changes and compare specifications, as the VPA is a very expensive amplifier and I am sure Nagra would not warranty any faults or damage presented by this move.
  Best Regards
  Chris Found

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