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AMI 'Dumb Luck' (what is this?) UPDATE

Posted: Wed Jun 14, 2023 11:58 am
by andrewsrea
Introducing my big project, by request of a long-time client from Fairfax, VA: The AMI 'Dumb Luck'. The name is an amalgamation of 'Dumble' and 'Vibrolux.' Basically a reliable amp that sounds like it is 120dB loud, at 90dB and fits easily in a car with other gear.

My friend gigs heavy in the summer, playing pedal or lap steel & guitar. Equally adept on both. He prefers Fender amps, has about 10 different amps and sends them to me in St. Louis for all repairs and set ups. He has often left me artistic freedom, gives me his desires, we chat and I design. he also has pedals and most of his pickups from me.

He requested the ability to have two inputs that can be used simultaneously (guitar and steel), with the steel side more midrange, a 20w amp with a high headroom, sweet clean channel and a dirt channel that blooms (foot switchable). Both channels having shared reverb and separate tone. He had this Virbrolux chassis and cabinet as the starting point. Even though this is 2x10", he wanted a sound more akin to an EVM-12L. So I am going for two of the 1980's Pyle 10" 100w speakers, which Derek Trucks favors. The transformers are being custom built to my specs by Musicalpowersupplies in Tennessee.

For those who are tech oriented, this will some of my new and old innovations: soft (subtle) limiter / high headroom FET buffer / mixer on the input, separating the steel and the guitar inputs (so the controls and pickups of both instruments don't interfere with each other). A separate B+ power for each of the 2 channels. Solid-state, fast acting rectification with large caps to make the amp responsive and articulate. KT-66 power tubes and cascading preamps based on my AMI Lil Giant. Silent channel switching.

Definitely channeling Leo Fender and Howard Dumble on this one.

A very expensive build, to which I already have two other players who desperately want one. I'll try and keep updating here for progress.
AMI Dumb Luck 1.jpg

Re: AMI 'Dumb Luck' (what is this?)

Posted: Wed Jun 14, 2023 1:15 pm
by tonebender
Awesome and a serious undertaking.

Re: AMI 'Dumb Luck' (what is this?)

Posted: Wed Jun 14, 2023 1:52 pm
by golem
I've heard about this. I'm looking forward to seeing it come together.
From Mesa I've learned I just slightly favor SS rectification when there's a switch available to go between the two. I only yesterday learned that my Filmore uses SS in that spot (no switch).

Re: AMI 'Dumb Luck' (what is this?)

Posted: Wed Jun 14, 2023 5:22 pm
by Partscaster
wow. how many might you make ?

Re: AMI 'Dumb Luck' (what is this?)

Posted: Thu Jun 15, 2023 10:57 am
by andrewsrea
Partscaster wrote: Wed Jun 14, 2023 5:22 pm wow. how many might you make ?
Made to order. Right now 1 order and 2 seriously interested. I am fairly sure that the 2 will want one after they play it.

Re: AMI 'Dumb Luck' (what is this?)

Posted: Thu Nov 09, 2023 9:13 pm
by andrewsrea
I am still working on this one. Sounds spectacular. The clean channel is uber clean and the gain channel sounds like a Two Rock.

I just figured out the source of a nasty hum in the reverb. It has taken me three days to figure it out, but it ended up being eddy currents in the chassis messing with the panel mount RCA connectors. Isolated the jacks from the chassis and it works like a charm!

Re: AMI 'Dumb Luck' (what is this?)

Posted: Thu Nov 23, 2023 10:30 am
by andrewsrea
Well this was my last big challenge to the AMI Dumb Luck amplifier I am building.

It is the interface/ channel control pedal, which is phantom powered by the amp. it inputs and tweaks two instruments and switches the amp's between the clean and overdriven channels. Pictured are the schematic, component layout and enclosure, all prepared from my feeble mind which started with a concept provided by my client. I start construction later today.
AMI Dumb Luck Interface and FS.jpg

Re: AMI 'Dumb Luck' (what is this?) UPDATE

Posted: Sat Dec 02, 2023 11:02 am
by andrewsrea
My good friend TJ Clark and I finished the amp's front panel. Sandblasted & repaired a dent, painted with Cerakote (high-temp baked-on paint used to paint guns) which we blended to a color which went with the oxblood grille cloth and then laser etched my graphics onto it. The laser is super cool and allowed for some really cool effects.

Re: AMI 'Dumb Luck' (what is this?) UPDATE

Posted: Sun Dec 03, 2023 5:22 pm
by tonebender
Man oh man.....nice amp.

Re: AMI 'Dumb Luck' (what is this?) UPDATE

Posted: Wed Dec 06, 2023 4:44 pm
by Buddha Pickups
This is not an easy job by any means
Looks great 👍