Lee Jackson mod
Moderator: VelvetGeorge
- Guitar Adjuster
- Senior Member
- Posts: 1560
- Joined: Mon Oct 31, 2005 8:34 pm
- Location: San Antonio
For those who want to build this, drop the 1000pf off the plate resistor, drop the 470K/470pf off the low input, add a .47 or .68 cap across the 820 ohm resistor on what is now V3A, drop the 1000pf bright cap, keep your filtering at 50/50 and use a 10H choke---I will guarantee this thing will rip your head off with either EL34's or 6550's. I use the 47k/470pf tone stack with mine and it kills. This is pretty close to the lee jackson mod......
Allen
Allen
-
- Senior Member
- Posts: 1304
- Joined: Sat Jan 21, 2006 9:17 pm
- Just the numbers in order: 13492
- Tone Slinger
- Senior Member
- Posts: 6520
- Joined: Thu Aug 24, 2006 10:31 am
Yeah that additional, or fourth gain stage was the "magic", so to speak, of what I was after back in the 80's, but nobody around here were doin those mods at that time.I hear alot of preamp gain on Pritchards rhythm, as well as lead. Sounds like 75 watt celestions as well. I tell you, the Splawn Quick Rod can get very close to Pritchards sound, here again basic 1959/800 design, with that fourth stage of gain.
-
- Senior Member
- Posts: 1304
- Joined: Sat Jan 21, 2006 9:17 pm
- Just the numbers in order: 13492
- rockstah
- Senior Member
- Posts: 12481
- Joined: Thu Sep 15, 2005 12:28 pm
- Just the numbers in order: 7
- Location: Austin Texas
plexi - 3 stages of gain but you only use two at any given time with either your brightor normal channel.
2203 or marshall master volume amps take that extra stage and cascade it so what you give up in not having the normal channel anymore u gain in an extra gain stage for a 3 stage preamp.
the lee jackson mod adds yet another stage for a total of 4 stages of gain - (shred city.)
Mark
2203 or marshall master volume amps take that extra stage and cascade it so what you give up in not having the normal channel anymore u gain in an extra gain stage for a 3 stage preamp.
the lee jackson mod adds yet another stage for a total of 4 stages of gain - (shred city.)
Mark
-
- Senior Member
- Posts: 862
- Joined: Wed Jul 19, 2006 4:15 am
- Just the numbers in order: 7
- Location: Bancrupt Euroland (Germany)
- rockstah
- Senior Member
- Posts: 12481
- Joined: Thu Sep 15, 2005 12:28 pm
- Just the numbers in order: 7
- Location: Austin Texas
-
- Senior Member
- Posts: 371
- Joined: Mon Sep 11, 2006 11:45 pm
Most of Lee's mods where 3 gain stages. The added tube is for an added gain stage after the tone stack. He did do one with 4 gain stages but the one with 3 is the mod that most people had. Its a split cathode 1959 type(2 gain stages same values) circuit then from the treble wiper to a 220k w/a 220pf-470pf over it to the input of the added tube 100k/.022 to a 1meg master.Cathode for the added tube is .68/2.7k some I'v seen with 820ohm too. So Lee would only use 1/2 of v1 and 1/2 of the added tube.
Last edited by MarkCameron on Wed Dec 20, 2006 2:53 am, edited 2 times in total.
-
- Senior Member
- Posts: 1304
- Joined: Sat Jan 21, 2006 9:17 pm
- Just the numbers in order: 13492
This 3 stage mod would likely not add alot of distortion, but still crunch the preamp ? I would say that is the mod I'd be interested in. 4 gain stages is likely too much distortion for the tones mentioned above (Dave prichard) since i;m getting plenty with 3 stages. i just need that extra crunch. Can anyone translate this 3 stage mod to a diagram.
- Tone Slinger
- Senior Member
- Posts: 6520
- Joined: Thu Aug 24, 2006 10:31 am
- Guitar Adjuster
- Senior Member
- Posts: 1560
- Joined: Mon Oct 31, 2005 8:34 pm
- Location: San Antonio
- Devon8822
- Senior Member
- Posts: 436
- Joined: Thu Nov 02, 2006 5:55 pm
- Just the numbers in order: 7
- Location: Toronto
- rockstah
- Senior Member
- Posts: 12481
- Joined: Thu Sep 15, 2005 12:28 pm
- Just the numbers in order: 7
- Location: Austin Texas
take a look at a plexi layout .Devon8822 wrote:Can you get higher gain stages with pedals? like for example a ts 808 and a plexi?
Could you get a 2 stage to 3 stages with a pedal? or a 3 stage to a 4? is that how it works or am I confused?
think of a gain stage as half a tube a cap and 4 or 5 resistors = gain stage.,( in any given 12ax7 we have two tubes in one)
from left to right we see the first tube = 2 gain stages. one for normal channel one for bright channel.
the next tube is gain stage( tone circuit ) and a cathode follower.
the next tube is the phase inverter.