The full schematic of the Lead 100 Mosfet can be found here: Building Marshall Lead 100 MOSFET
Attached the schematic of the AVT50.
Attached the schematic of the AVT50.
1) you can build what you want but it will not fit inside your AVT50 combo
2) for now, forget tube amps,a completely different game,and 10X more expensive than a 100W SS amp, Mosfet or Bipolar or Class D.
3) you will need not only a whole new power amp, but also a chassis to house it, heatsinks, a power supply to feed it including a large heavy power transformer, hardware and wiring (mains connector and cable, fuse, power switch, input jacks, etc.)
4) new speakers, which will need their own cabinet.
5) so although it´s definitely doable, it will take money, time, build experience and patience.Weigh all that before starting.
6) the bare "electronics part" is the simplest/cheapest by comparison, but you will NOT be able to just populate a PCB and replace the current power amp, you´ll need all I mention above.
Plus tools, space, carpentry skills, etc.
7) you have a fine amp as is, only you want more power, more speakers and larger sound.
Fine with me, but the practical way to do that is:
8) get 4 good (Emi/Jensen/Celestion) or 2 VERY good 12" Guitar speakers and build a cabinet for them.
9) build a 100 to 150W SS amp, Class AB or D ,maybe even use a ready made module from EBay, with its matching power supply.
Mount it in a suitable chassis+ case.
As an alternative buy a used rack type power amp, which is ready to plug in and use.
10) drive it from your AVT50 Preamp out.
Now for practice or small shows or rehearsals or Church you use the combo alone; for bone crushing shows you use the full system.
11) the MosFet 100 is a nice amp but you will NOT find real MosFets or pay way too much for them.
12) actual supply voltage is +/-32V for 50W RMS into a 4 ohm speaker.
+/-15V is the preamp supply.
2) for now, forget tube amps,a completely different game,and 10X more expensive than a 100W SS amp, Mosfet or Bipolar or Class D.
3) you will need not only a whole new power amp, but also a chassis to house it, heatsinks, a power supply to feed it including a large heavy power transformer, hardware and wiring (mains connector and cable, fuse, power switch, input jacks, etc.)
4) new speakers, which will need their own cabinet.
5) so although it´s definitely doable, it will take money, time, build experience and patience.Weigh all that before starting.
6) the bare "electronics part" is the simplest/cheapest by comparison, but you will NOT be able to just populate a PCB and replace the current power amp, you´ll need all I mention above.
Plus tools, space, carpentry skills, etc.
7) you have a fine amp as is, only you want more power, more speakers and larger sound.
Fine with me, but the practical way to do that is:
8) get 4 good (Emi/Jensen/Celestion) or 2 VERY good 12" Guitar speakers and build a cabinet for them.
9) build a 100 to 150W SS amp, Class AB or D ,maybe even use a ready made module from EBay, with its matching power supply.
Mount it in a suitable chassis+ case.
As an alternative buy a used rack type power amp, which is ready to plug in and use.
10) drive it from your AVT50 Preamp out.
Now for practice or small shows or rehearsals or Church you use the combo alone; for bone crushing shows you use the full system.
11) the MosFet 100 is a nice amp but you will NOT find real MosFets or pay way too much for them.
12) actual supply voltage is +/-32V for 50W RMS into a 4 ohm speaker.
+/-15V is the preamp supply.
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And the standard AVT power amp actually tries to counteract that by employing current feedback to artificially lower damping factor to magnitudes comparable to tube amps. The older discrete design, on the other hand, is a good example of a generic power amplifier design with very "hi-fi" and "transparent" performance.
Forget that it has MOSFETs, you won't "hear" them there like you didn't hear them being there in the TDA chip -based amp either. In these generic power amp circuits MOSFETs will never portray any of the "warmth" people maybe associate to them. The MOSFET output devices may make the discrete amp a bit more stabile thermally but that's it. Want to experience MOSFET tone? You need to try something like the TubeWorks MOSValve amp with its proprietary circuit design.
And speaking of thermal stability, the real issue of the TDA chip -based Marshall power amps is that they try to squueze too much power out of the chip with quite insufficient heat sinking for the job. If you want to improve and upgrade something in these amps then there's the spot.
If the amp is not "loud enough" replace the speakers with more efficient ones. Trying to make the amp louder by increasing output power won't be worth the effort.
Lastly, I would suggest OP to be less susceptible to marketing tricks that try to sell an image of superiority of things such as "MOSFET tone" or "tube power amp tone". You can mark "check" on both of those attributes with the current AVT power amp design: It has MOSFET output devices and it colours the output signal similarly to a tube power amp. I'm pretty sure in the end these characteristics weren't as hype-worthy you were lead to believe.
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This.
You've already got a speaker out on the AVT50: borrow or hire a marshall quad or a 2x12 with something decent in it and find something you like.
E.g. The Celestion V-30 is supposed to work with the AVT50 and it's 100db/w vs the 97db/w of the stock 12T-AVT which is usefully louder. But four of them will cost $$
Frankly, 50W with 97db/w is c. 113db/1m which is well into stupidly loud (as in, it will bugger your hearing rather quickly - ask me how I know
)
Don't mess with your existing amp.
Try RunOffGroove for some easy, cheap and interesting stuff.
If you want to go tube, go read Rob Robinette, starting with something simple, like a 1W amp.
Strangely enough, most of us are trying to make amps that are quieter, not louder!
Basically agree.Frankly, 50W with 97db/w is c. 113db/1m which is well into stupidly loud (as in, it will bugger your hearing rather quickly - ask me how I know
But to put it in real world perspective:
1) 50W to 80W single 12" Guitar combos are incredibly popular, for good reason, because they are:
* easy to carry everywhere with a single hand, fit in a car trunk, etc.
* loud enough to play besides a drummer, in a typical Club situation
2) yes, they are loud .... but then *the Drummer* is LOUD!!!!!!
Playing at home alone because of Covid is the exception, not the rule (I hope
)