Members skaaks Posted August 9, 2006 Members Share Posted August 9, 2006 For all you VHT gurus out there: The UL tube spec sheet says that the earlier versions specify to use a 12AU7 instead of the currently used 12AT7 in socket V6. Does this mean that you can still use a 12AT7 if you want to, just that it's not marked as such on the amp? I'm not sure of the differences between the two types to know if they're interchangable. Thanks in advance. Link to comment Share on other sites More sharing options...
Members skaaks Posted August 9, 2006 Author Members Share Posted August 9, 2006 Bump Link to comment Share on other sites More sharing options...
Members Giga Posted August 9, 2006 Members Share Posted August 9, 2006 If I'm not mistaken an AU7 is even lower gain than an AT7. I also seem to remember reading somewhere Steve F is strongly advising against replacing that AU7 with an AT. Giga. Link to comment Share on other sites More sharing options...
Members vchizzle Posted August 9, 2006 Members Share Posted August 9, 2006 they are interchangable. 12Awhatever7 tubes are technically interchangeable, they vary in amounts of gain. 12AX7 highest gain 12AT7 12AU7 low gain the suggested tubes by VHT for your amp is the best bet. many VHT users agree that the suggested tubes by VHT seem to sound the best. check this place if you haven't been there, http://vhtusers.com - everyones pretty helpful over there. Link to comment Share on other sites More sharing options...
Members SteveVHT Posted August 9, 2006 Members Share Posted August 9, 2006 Just DO NOT use a 12Ax7 in that slot.... The 12AU and AT are interchangeable... Your best bet is to call Steve or Email him with your serial number and he will let you know what to use. Steve Link to comment Share on other sites More sharing options...
Members tequila_titan Posted August 9, 2006 Members Share Posted August 9, 2006 The AU7 will not affect the gain, it's the driver tube(?) and Steve Fryette told me on the phone that it will keep the low end tighter, and drive the power stage better, it won't flub out. I have an old Pittbull One Hundred that I sent back for some servicing and Steve was right, it does sound better with the AU7. Do you have this same amp? Link to comment Share on other sites More sharing options...
Members skaaks Posted August 9, 2006 Author Members Share Posted August 9, 2006 No, I've got one of the older Ultraleads. I was just curious because all of the newer models use 12AT7s while the old ones use 12AU7s. I also thought there was something in the history of the UL document on the vhtusers forum about why he chose to go to the 12AT7s in the newer ones. Link to comment Share on other sites More sharing options...
Members Paragraph51 Posted August 9, 2006 Members Share Posted August 9, 2006 Originally posted by skaaks For all you VHT gurus out there:The UL tube spec sheet says that the earlier versions specify to use a 12AU7 instead of the currently used 12AT7 in socket V6. Does this mean that you can still use a 12AT7 if you want to, just that it's not marked as such on the amp? I'm not sure of the differences between the two types to know if they're interchangable. Thanks in advance. The AT made it harsh sounding, which is why the 12at7 is scratched out and 12au7 is written in marker above it on the first 10 or so ULs ever made. Link to comment Share on other sites More sharing options...
Members vchizzle Posted August 10, 2006 Members Share Posted August 10, 2006 Originally posted by SteveVHT Just DO NOT use a 12Ax7 in that slot.... The 12AU and AT are interchangeable... Your best bet is to call Steve or Email him with your serial number and he will let you know what to use. Steve yeah, a 12AX7 is a no-no in the driver tube slot. i was talking preamp tubes in general, not thinking in terms of the tube position in context. sorry about that. Link to comment Share on other sites More sharing options...
Members Primex Posted August 27, 2006 Members Share Posted August 27, 2006 Hello, I Link to comment Share on other sites More sharing options...
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