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Tubes for Nagra VPA

I have just bought used pair of Nagra VPA power amps.
I found that there are 3 tubes are in the input stage, One E182CC by Mullard and two 12AX7 by EI. (But the JS'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 looks like E182CC, because it is taller than the other two 12AX7 tubes.

Any information would be highly appreciated.

JWK
bwv1004

Showing 3 responses by bwv1004

bwv1004 OP
3 posts
 
Thanks for your kind information.

I have some more questions for my used VPA.

1. The tubes life of 845 and E182CC and E83CC in VPA ? In case of Nagra PL-L preamp, 5000 Hours of each tube(ECC83 & ECC81) life is specified in the manual. But for VPA, I could not find any information for the tubes life.

2. So, I consider changing tubes bacause my VPA have used a couple of years. How to set the bais ?? The owner's manual did not provide full infomation of setting the bais.

Thanks in advance,

JWK
bwv1004 OP
3 posts
 
Thanks for you guys help.
I have just bought used pair of VPAs and have listened only 3 days, actually around 10 hours, and using them with Meridian G08 CDP & Clearaudio TT, Nagra PL-L preamp and B&W Signature 805 speakers. And also, My VPA has only XLR input and they provided adapters to use single ended input.
Up to now, the performance of VPA is a little fall short of my expectations. therefore I doubt tubes life and want to know how to set the bais.
To "Kleech", please send an email to "bwv1004@hanafos.com" regarding setting the bais. I found a black button to the side of the volt meter and 4 screws in the left panel, but I do not know hot to used them to set bais.
Thanks again you guys help and look forward to further information to set bais.

JWK
bwv1004 OP
3 posts
 
I checked ex-owner's bais setting when MUTE mode and found that the red arrows are below the green zone. Therefore, I moved red arrow to the middle of the green zone in accordance with Kleech's instruction on the above. And then, I moved speaker cables to 4 ohm taps from 8 ohm taps and connected Discovery Essence XLR interconnects between Nagra PL-L and VPA.
The result was very impressive, my disappointment for the VPAs was almost disapear and I could listen my favorate Keith Jarret Trio and Casandra Wilson with satisfactroy. Thanks for your help ~~~

[p.s] To Kleech, I have one more question that what is the role about the rest two holes on the middle of left side of the amps. And have you ever changed input tubes (E182CC and/or ECC83) to the famous NOS TFK, Mullard, Amperex, etc ?
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