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CalyxRai
02-20-2005, 09:44 PM
the 12AT7 in the PI slot w say a 12ax7? My amp is modded so I know the circuit is designed to run a 12ax7 but curious why it would be a bad idea to run one on a stock amp? Rawk on -

Rai //
www.FarewellRadiance.com

tubebury
02-21-2005, 02:42 AM
the 12AT7 in the PI slot w say a 12ax7? My amp is modded so I know the circuit is designed to run a 12ax7 but curious why it would be a bad idea to run one on a stock amp? Rawk on -

Rai //
www.FarewellRadiance.com
Hi Rai! Whussup? Here's some of the Steve Fryette talk on the evolution of the UL and why it now has a 12AT7 in the DRIVER position slot, not the PI tube slot. I don't know how your Voodoo modded UL is set up, though.... The link to this page is below.

I think the 12AT7 is used to voice the power amp tight and aggressively and give it a 12AX7's fatness.

"After a year of this, the UL went back to tow tubes in the drive/phase inverter stage, but with a difference. A new driver design using a 12AT7 in place of the 12AU7 for the driver. The idea being to restore the tightness and aggressive UL trademark but retain some of the fatness of the 12AX7 only style. By then the Sovtek KT88 became available and that became what is still the standard tube for the UL: New Tube config:

Preamp, 1 Sovtek 12AX7WB, 3 Chinese 12AX7A.
Power amp, 1 Chinese 12AX7A, 1 Chinese 12AT7.
Power Tubes: 4 Sovtek KT88.
Output power: 120 watts."

http://vhtusers.com/phpBB2/viewtopic.php?t=12

Man, I need to get a life...... :roll:

CalyxRai
02-21-2005, 03:23 AM
Thanks man! That's kinda what I figured that they used the 12AT7 for tightness and warmth in the Power Amp Section. The current config is what I have in my 2001 UL. Trace modded the PI based off of an old Fender Silverface design (from what I remember) and fattened/warmed it up some. This was just one of the mods he did. Now you say the 12AT7 was in the driver spot? What is the function of the Driver? I always thought the 12AT7 was for 1/2 the PI and 1/2 for the FX Loop and that the first 12ax7 (in the power amp section) was 1/2 of the FX Loop, and dah! I can't remember now. But basically it was worded to me that the FX Loop (maybe this is the driver?) was split btwn the 2 preamp tubes in the Power Section.

This is what was explained to me or how i remember it (as I wrote it down)

V1- Initial Gain stage
V2 and V3 - Directly impact the tone and are responsible for the dirty channels
V4 - Clean - when in clean v1 bypasses V2 and V3 going straight to V4.
V5 and 6 - see above

Based on all this info I have-

V1 - GE12ax7
V2 and V3 - RFTECC83
V4 - Ge5751
V5 - GE12ax7
V6 - Mullard 12ax7

Def. sounds sweet but it'd be cool to get an understanding on the 2 preamp tubes in the power section.

Thank you much again!

Rai //
www.FarewellRadiance.com

tubebury
02-21-2005, 03:33 AM
Thanks man! That's kinda what I figured that they used the 12AT7 for tightness and warmth in the Power Amp Section. The current config is what I have in my 2001 UL. Trace modded the PI based off of an old Fender Silverface design (from what I remember) and fattened/warmed it up some. This was just one of the mods he did. Now you say the 12AT7 was in the driver spot? What is the function of the Driver? I always thought the 12AT7 was for 1/2 the PI and 1/2 for the FX Loop and that the first 12ax7 (in the power amp section) was 1/2 of the FX Loop, and dah! I can't remember now. But basically it was worded to me that the FX Loop (maybe this is the driver?) was split btwn the 2 preamp tubes in the Power Section.

This is what was explained to me or how i remember it (as I wrote it down)

V1- Initial Gain stage
V2 and V3 - Directly impact the tone and are responsible for the dirty channels
V4 - Clean - when in clean v1 bypasses V2 and V3 going straight to V4.
V5 and 6 - see above

Based on all this info I have-

V1 - GE12ax7
V2 and V3 - RFTECC83
V4 - Ge5751
V5 - GE12ax7
V6 - Mullard 12ax7

Def. sounds sweet but it'd be cool to get an understanding on the 2 preamp tubes in the power section.

Thank you much again!

Rai //
www.FarewellRadiance.comHi Rai! I know all this is a pain in the ass and after all, we're only guitar players!! Fuckin' A, dude! :wink:

Here's a link that shows all of the valve slots in the UL. It helps me understand it better!! Rawk on and grab a beer!!!! Look under the UL notation!

Brian

http://www.vhtusers.com/documents/