Marshall Amp Forum - View Single Post - V1 preamp tube in a JTM-60

MartyStrat54 · 06-22-2009, 03:32 PM

For a long time people (including myself) used a matched (balanced) tube for the PI slot. However, you do not need to do this. Any good 12AX7 will work in the PI slot. All of your preamp tubes should normally be 12AX7's. They can all be interchanged in V1, V2, V3 and V4.

As far as your power tube? Swap the tube around and see if it still does what you described, or if it is now affecting the good tube. If it stays with the "cold" tube, then it sounds like it's time for a power tube replacement before other problems are created.

Marty

06-22-2009, 03:32 PM	#13 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: V1 preamp tube in a JTM-60 For a long time people (including myself) used a matched (balanced) tube for the PI slot. However, you do not need to do this. Any good 12AX7 will work in the PI slot. All of your preamp tubes should normally be 12AX7's. They can all be interchanged in V1, V2, V3 and V4. As far as your power tube? Swap the tube around and see if it still does what you described, or if it is now affecting the good tube. If it stays with the "cold" tube, then it sounds like it's time for a power tube replacement before other problems are created. Marty __________________ MARTY 2009 Gibson Explorer-Hell Raising Machine 1989 Fender Strat Plus USA 2008 Fender Tele USA 2004 Schecter Elite w/DiMarzio's TSL100 with custom 4x12 cab. TSL122 with Man 'O War Speakers. TSL602 #1 with JBL D123 Speakers and 602 #2 with Altec 417 Speakers. "Oh so sweet my friends." DSL401 #1 with Red Fang Speaker and 401 #2 with JBL D123 Speaker. Tubes: Let's just say they are NOS that kick ass.