Finished modding my 2204 build today

  • Thread starter Thread starter ledvedder
  • Start date Start date
I’m glad I could help. Tbh this is what I love - helping others and explaining the theory behind what’s going on under the hood so that mods can be done strategically.

You did an amazing job on that amplifier and should be very proud of all of the hard work and patience! Seriously one of the best JEL modded tones I’ve heard. It’s got a lot of bounce and chew in it that I really dig plus the bark is still there. I’m sure it’s a blast to play!
 
Hell yeah! Sounds great. Classic Marshall tones right there.

The only thing I would play with now for fun is the NFB/depth. You can accomplish a lot with just that. But it sounds great as is.
 
FourT6and2 said:
Hell yeah! Sounds great. Classic Marshall tones right there.

The only thing I would play with now for fun is the NFB/depth. You can accomplish a lot with just that. But it sounds great as is.
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It’s funny because in PM I was answering a question he asked and said the same thing 😂
 
I do have a depth knob on it. 1M/0.0022uF. I tried an NFB knob with a 100k pot into the 47k feedback resistor, but it seemed to mess with the depth. I had it going 8 ohm tap > 1M depth pot > 100k NFB pot > 47k resistor. I pulled the NFB knob out and replaced the 47k with 100k.
 
Both the JEL and SIR#34 sound killer...plenty of gain on tap for sure. I'm glad you got it all sorted out!:2thumbsup:
 
ledvedder said:
I do have a depth knob on it. 1M/0.0022uF. I tried an NFB knob with a 100k pot into the 47k feedback resistor, but it seemed to mess with the depth. I had it going 8 ohm tap > 1M depth pot > 100k NFB pot > 47k resistor. I pulled the NFB knob out and replaced the 47k with 100k.
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That's a pretty solid setup already. 2200pF depth cap + 100k/8ohm.

Where'd you have the depth control set for those recordings and what speakers/cab?
 
FourT6and2 said:
That's a pretty solid setup already. 2200pF depth cap + 100k/8ohm.

Where'd you have the depth control set for those recordings and what speakers/cab?
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I had it set around 2 or so. Through my reactive load into Reaper, using Suhr IR's. Greenback on one side, V30 on the other.
 
burger said:
awesome. how did you end up configuring the switching?
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I'm using a 3 way dpdt switch. Middle goes to ground. One side grounds the 0.1uF cathode cap on the 10k, the 150k coming from the gain wiper, and the 1nF coming from the gain input. The other side grounds the 3.9k/0.68uF cathode bypass across the 10k, and the 220k coming from the gain input. I found I didn't need the plate bypass caps.

The only compromise is the lack of the 2.2nF treble peaker cap for the 34. I couldn't figure out how to bring that in on the same switch.

I did put a 470pF across the 100k cathode follower.
 
That sounds great, all three modes. And very Marshally too. Does this have a loop @ledvedder ? I've been considering one for my JEL mod.
 
SpiderWars said:
That sounds great, all three modes. And very Marshally too. Does this have a loop @ledvedder ? I've been considering one for my JEL mod.
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Thanks! I do have a Headfirst loop that I'm gonna put in. Haven't done it yet. I'm also thinking about adding some switchable zener clipping. Maybe 20v and some other value. I just have to wrap my head around implementing it. I know it goes between the cathode follower and the input to the tone stack, but I'm not sure how I'm gonna do it just yet.
 
I also have to give huge props to @burger! His Headfirst Amplification DIY Facebook group and all its members have been a huge resource as I've been learning the ins and outs of building and modding.
 
ledvedder said:
Thanks! I do have a Headfirst loop that I'm gonna put in. Haven't done it yet. I'm also thinking about adding some switchable zener clipping. Maybe 20v and some other value. I just have to wrap my head around implementing it. I know it goes between the cathode follower and the input to the tone stack, but I'm not sure how I'm gonna do it just yet.
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I'll look into that loop. His videos are great.

On the zeners, check out the difference between the way Friedman does it vs Jose/Cameron/et al. The Friedman way is much easier to implement if you already have a post tone stack Master. As to the sound difference, that's preference. If you do choose to put in a pre tone stack Master for the zeners then consider mounting your Treble cap point-to-point on the Master/Treble pots. Frees up a turret on the board for the big cap or 10k resistor, then just run a wire from the now free end of the 33k slope resistor to the pot. That's one way to do it.

The two Masters sound different. If you like more kerrangy, open Marshally tone (like you have) you might not like the pre stack Master as much. That's why Jose had switchable Masters on his full blown mods.
 
Think about where your loop would be inserted if you’re changing up where your master is located. Loop should be before master, zeners should be before loop. Otherwise you’ll be chopping up your loop tones with zeners and not adding effects to your zener gain tones. If the loop is after the master you’ll have level problems like many have (I’m guilty about it).

Take a step back for a second and decide what you want to do before you just throw it in there.
 
glpg80 said:
Think about where your loop would be inserted if you’re changing up where your master is located. Loop should be before master, zeners should be before loop. Otherwise you’ll be chopping up your loop tones with zeners and not adding effects to your zener gain tones. If the loop is after the master you’ll have level problems like many have (I’m guilty about it).

Take a step back for a second and decide what you want to do before you just throw it in there.
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I'm considering doing it like this, which is the method Headfirst recommends. The clipping is pre tonestack, but the master stays post. Then the loop will go between the treble and master.
Screenshot_20220912_132137.jpg
 
psychodave said:
This times infinity. People seem to forget how easy it is to fine tune an amp with the NFB and depth.
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I added a variable 1M depth pot with a 0.0022uF cap. I might try 0.0033uF and even 0.0047uF on it. I had a variable 100k NFB pot into a 47k feedback resistor, but it seemed to affect the depth in a weird way. So I disconnected that pot and put a 100k feedback resistor back in.
 
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