I'm still new to circuits, so I'm trying to educate myself by reading, but I found this circuit course on youtube. I like the guy's method of teaching and he has good examples. Tell me what you guys think:

https://www.youtube.com/playlist?list=PLM-mlLBFTjG3SDttCBXrabyhgLLo_RuwZ

So I picked one of these up from a local music store after listening to some videos and trying it out in the store.
Here is a schematic for it:    http://www.drtube.com/schematics/marshall/5010.gif

There are two issues that I have with it. First, the preamp control doesn't gradually increase the overdrive. The overdrive suddenly "kicks in" at about 9-10 on the knob. I'd like the overdrive to have a more gradual increase instead of that jump at 9-10.

Second, the overdrive has a decent Marshall-like sound to it, but there is a fizziness that colors the sound over top of it. Also, when a chord is left to ring out until it fades, the fizz will suddenly drop off.

I plugged into both the high and low inputs, but STILL hear the fizz.

I have tried plugging into the headphone jack to eliminate the possibility of the speaker being the culprit and I STILL hear the fizz.

Finally, here's a sound sample of a guy who apparently had the same exact problem:       https://www.youtube.com/watch?v=y1osT39OSjs

The amp seems to have really good potential, so any help would be greatly appreciated!!

Hey guys. I'm absolutely new here. I would like to get into building SS amps with an eventual goal to build a SS copy of the Marshall Plexi 1986 bass 50w head that Duane Allman used back in the day.

So my question to all of you is this: is it possible to get close to or in the ballpark of the sound of the original tube circuit? Whether it is possible or not, I still want to learn how to build a good sounding SS amp.

Since I am more of a visual learner, and since I need to start from the absolute beginning, what is the best way to get started? I've read some of the stuff in the Newcomer's Forum, but I still have questions about what each component is and does. Any help would be great. Thanks.