vox sounds from a marshall
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JoshBernstein
- Posts: 289
- Joined: Tue Jan 27, 2015 1:31 am
- Location: Key Largo, FL USA
vox sounds from a marshall
Wasnt sure where to put this, but garage talk seems like an okay place. Is there any kind of modification i can do to a marshall 2061x build to get more of a sparkly ac30 top boost tone? Would a treble booster or an eq pedal get me in the realm?
Not really
Re: vox sounds from a marshall
Josh,
1) the PI on the 2061 is quite different. I would consider changing it over to the standard 1k2/47k arrangement used by Vox. Some of the crispy tone of the Vox is attributed to that PI.
2) You could just use a single input and cascade the input tube (making a single channel), biasing each stage with 1k5 and 22uF (or at least the input gain stage), and make the second 22uF on V1b switchable to tailor the gain to your taste. If you play humbucking guitars and 22uF is too bloated or ill defined, lower to 1uF-2.2uF or to taste.
3) Change the 470k/470k grid leak resistors on the power amp to 220k/220k.
4) Change (or add if your 2061 lacks) screen resistors to 100R.
5) Depending on your EL84 plate voltages, a bias resistor change might be considered. 2061s run higher plate voltages so that might be best left alone.
6) Add a Cut control (4n7 -> 250kA) after the PI coupling caps.
7) Change R19 on the 2061X Schematic to at least 100R 10W to dump some voltage and induce some rectifier tube like sag. Consider higher values, tuned to taste, and also the desired EL84 plate voltage (see #5 above).
8 ) C2 (V1a coupling cap) may need lowering from 22n to 10n if distortion is bloated and not smooth...or not. Tune by ear.
Just some ideas.
1) the PI on the 2061 is quite different. I would consider changing it over to the standard 1k2/47k arrangement used by Vox. Some of the crispy tone of the Vox is attributed to that PI.
2) You could just use a single input and cascade the input tube (making a single channel), biasing each stage with 1k5 and 22uF (or at least the input gain stage), and make the second 22uF on V1b switchable to tailor the gain to your taste. If you play humbucking guitars and 22uF is too bloated or ill defined, lower to 1uF-2.2uF or to taste.
3) Change the 470k/470k grid leak resistors on the power amp to 220k/220k.
4) Change (or add if your 2061 lacks) screen resistors to 100R.
5) Depending on your EL84 plate voltages, a bias resistor change might be considered. 2061s run higher plate voltages so that might be best left alone.
6) Add a Cut control (4n7 -> 250kA) after the PI coupling caps.
7) Change R19 on the 2061X Schematic to at least 100R 10W to dump some voltage and induce some rectifier tube like sag. Consider higher values, tuned to taste, and also the desired EL84 plate voltage (see #5 above).
8 ) C2 (V1a coupling cap) may need lowering from 22n to 10n if distortion is bloated and not smooth...or not. Tune by ear.
Just some ideas.
Awesome post
Tip my hat to ya Dave,Your a awesome amp builder!!Mikey 
Custom Built Amps for Sale!http://faithamps.weebly.com/
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guitarmike2107
- Posts: 303
- Joined: Fri Dec 12, 2008 10:51 pm
- Location: East Scotland
- Contact:
Re: vox sounds from a marshall
I just modified a 18w amp for the same purpose,
Biggest change was first stage coupling cap has to be small, 0.001uf to 500pf depending on volume pot value and your taste and then you will need to add the cut control as it will be much brighter.
next, if it has a 500pf cap on the tone control reduce that to 250pf
Overall these changes give a really chimey top boost type tone and reduces the gain a bit too
Biggest change was first stage coupling cap has to be small, 0.001uf to 500pf depending on volume pot value and your taste and then you will need to add the cut control as it will be much brighter.
next, if it has a 500pf cap on the tone control reduce that to 250pf
Overall these changes give a really chimey top boost type tone and reduces the gain a bit too