[mgsboedmisodpc2]

Are 12FV7 RCA USA Tube drop in replacements for 12AU7 for prima luna prologue model 5 amp.  I ask because there specs are different

12FV7 
Base Noval, B9A 
Filament Vf 12.6 Volts / If 0.45 Ampere / Indirect / 
Description Durch Heizfaden-Mittenanschluss auch Betrieb mit 6.3 V und 0.9 A möglich. 





12AU7
Base Noval, B9A (Codex=No 15) 
Filament Vf 6.3 Volts / If 0.3 Ampere / Indirect / Parallel / series AC/DC / 
Description Centre-tapped heater permits operation at 12.6V 0.15A. 

[JakeJ]

THe 12FV7 is not a direct replacement for the 12AU7.  You would need to make changes to components around the tube to correctly operate it.

Here is a great resource for tube data and substitutions.
http://tdsl.duncanamps.com/

[mgsboedmisodpc2]

good to know but some ebay listings are just confusing "12FV7 RCA USA Tube 12AU7 12AT7 Instant plug-in upgrade Long Box Plate NOS" 


http://www.ebay.com/itm/12FV7-RCA-USA-Tube-12AU7-12AT7-Instant-plug-in-upgrade-Long-Box-Plate-NOS-/261479610593?pt=Vintage_Electronics_R2&hash=item3ce16638e1

[avahifi]

Well, since the 12FV7 pulls three times as much heater current as a 12AU7 (.45 amp compared to .15 amp) I certainly would not consider it a drop in replacement unless you have a very robust heater current supply at least.

Oh well!

Frank Van Alstine

[FullRangeMan]

Thanks for explain. Both are similar, the gain is around u20.

[FireGuy]

6V6 and Yankees... = happiness