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JakeAC5253 21st December 2009 07:05 PM

Marshall AVT50 Mods
Hey, what's up. This is my first post here, but I've been playing guitar for a while, about 7 years. I have recently just gotten into modding and I like it and want to learn more about it. I like it so much that I am changing my major to Electrical Engineering. Anyway, that's enough about me.

I am buying a new cab and I want to know what I can do to my amp to get a better sound out of it. It'll be a while before I can fit another amp into my budget so I'm looking for like a nice cheap mod, component switching/swapping and the like. Maybe increase frequency response, get more natural low end without it sounding too boosted or muddy (maybe both will be achieved by increasing the input impedance?). More headroom, more circuit clarity/transparency, more gain, you know the fun stuff :D I already swapped out the tube for a Tung Sol and as far as I can hear it's a good change, the EHX was a bit harsher in the highs I think. I'm not really going to look into a transformer/choke upgrade for it because that's very expensive and involved and I don't think this amp is worth it. I'll save that kind of modding for when I get a true all tube amp. I'm just looking for a way to spread this one out a little further.

Anyway I'm not even sure if any of this is possible, but I figured you guys would know.


nigelwright7557 21st December 2009 08:26 PM


Originally Posted by JakeAC5253 (
Hey, what's up.

I like it so much that I am changing my major to Electrical Engineering.Thanks

Electronic engineering would be a better start.

Enzo 22nd December 2009 07:43 AM

On this side of the pond we call Electronic engineering "electrical." At least in the naming of college courses. The local university now includes computer engineering into the department:
Electrical and Computer Engineering

Adding chokes to the power supplies I don;t think would be of much use, frankly. And remember this soloid state amp runs on split supplies, so you'd have to use two. There is no output transformer, and the power transformer seems to be up to the job, so not changing them is fine.

The power amps are TDA7293 based, not really the place for much tweaking in my view.

That leaves the preamps. You can mess with the gain structures of the stages, you can fiddle with the tone stacks.

A wonderful bit of free software is the Tone Stack Calculator over at Duncan's Amp Pages. There is a bunch of good stuff there. The TSC allows you so see a response curve for a variety of tone stack configurations. In real time you can watch how each control affects the curve. You also can edit the component values to see what a different capacitor in the treble does, for example.

AudioTerrorRegime 4th June 2010 04:33 PM

I know this post is a little old but thought I'd still pass along a quick upgrade that made a huge difference with my AVT50. I found a Mesa Boogie Black Shadow MC90 speaker on CL for $40.00. I actually bought it off Richard Gibson from the old DC hardcore band MFD. Anyway, it's 8 ohms and 90 watts. The magnet weighs a ton in comparison to the stock Celestion GT50 AVT speaker. It's at least 4 times the weight of the stock speaker. Bass and mids have come alive and the highs are much smoother. Better overall balance of sound. The speaker is likely more efficient and at 90 watts it also handles the amp's power better. This translates into the amp becoming louder and fuller. Cranking the amp around 4-5 is plenty to jam with a drummer. There's no farting out or change in sound due to "poor" break up. The sound remains transparent and clear. $40.00 and 10-15 minutes of your time will give this amp a new life that will be better than it's first one.

Enzo 5th June 2010 03:40 AM

Changing a speaker your guitar amp plays through will be the one thing you can do that will make the biggest change in sound.

clara 25th December 2012 06:26 PM

I'm convinced that this amp sounds better pushing 8 ohms instead of the 4 ohm stock speaker. When I tried the amp with a speaker cab at 4 ohms the old shrill honky sound returned.

Removing the back panel changes the frequency response of the speaker and it sounds better, but not as good as the Jensen Neos. I finally settled on an 8 ohm speaker with the bottom 3" of the back panel removed for a slightly open back cab.

clara 18th December 2014 12:46 AM

Update - try running a jumper from the Emulated Out to Effect Return - Makes the amp a bit smoother, less harsh

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