I'm building a Combo Amp for someone.

The cabinet is Pine 13" wide x 15" tall and 11" deep. All glued together and used a 1/2" roundover bit in my router for the edges.

The speaker is a vintage 10" Utah 15W 8ohm. The amp is my dual Im386 chip bridged amp design. Can run on 9volt battery or walwart and output is 1 to 2 watts.

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After sanding and routing I cut a hole for the control plate on top at the back edge. Decided to burn the wood with a propane torch and finish with Truoil.

Started burning with the torch and discovered that my old torch was leaking when the whole tank and torch went up in flames. Got the fire out with blowing up and threw away the old torch. Went to Tractor Supply and got a new torch, went home and finished the job. Pics before the Truoil.

Making the speaker baffle and rear access door out of 3/8ths" plywood. Rear door will be hinged to allow access or to have open back cab sound if that is wanted.

Being an ex steel/metal fabricator, I'm use to this kind of thing happening. Just blow out the flame with a air compressor or smother the flame out and then turn off the gas. If you panic, things get worse or you get hurt.

While waiting for the Truoil to dry, I moved on to the speaker baffle. Got the speaker mounted on a 3/8ths" plywood baffle and it's time to cover the baffle. I looked over the stores that sell fabric for blue denim, but all the material I found was too thin. Kept looking and came across 2 that looked decent. One is a blue denim with a white threaded strip pattern and the other is a greenish gray solid color. Does anyone have a preference between the two?

My wife and I were leaning towards the blue one too. Got the material for 5 bucks each, store closing sale. Bye bye Hancock Fabrics.

My original circuit has 2 tone capacitors on a switch to allow a regular guitar amp tone(.047uf) or switch to a (.1uf) capacitor for a bass/darker tone. I'm removing the switch and adding a second input jack. Each input jack will have it's own tone cap(.047uf for the high and .1uf for the low) for a old style High/Low input choice. This way enables two instruments or a instrument and microphone or keyboard to be used through the same amp. Might suck a battery dry quickly, but a walwart will be fine.

The way this works is the input jack goes to a JFET-then to the switch-choice of cap-then to the volume-then to the chip.

So I have to add a second JFET-run a jack to each JFET-each JFET to it's cap-and both to volume-then to chip. Switch is deleted.

As far as electronic knowledge is concerned, I'm an amateur that knows how to avoid some danger an probably get into more danger. LOL


Lesson learned on spreading Truoil on a large surface. Thin coats is best wiped on with a folded paper towel. Brushes of whatever type soak up too much of the Truoil. Had to sand back the finish with 400 grit and reapply with the paper towel. One more coat will do it, then I'll add some pics.

Got the rear door painted Black. Have some brass hinges and hook & latch.

Need to got back to the store for some tack strips to put the grill cloth on.

Got the back door on.


Have you thought of just Velcroing the back door on? It's gonna get in the way when you build your DIY Sound Enhancer...:-)

Yeah that would be funny. A snake on a spring reverb.

Got the the controls laid out, drilled and installed. Need to find a way to label everything.

From left to right: walwart jack and 2-way switch for 9volt battery use, lighted on/off switch, 2 input jacks for HI/LOW choice, 4 pots V1 - G1 - V2 - G2 and stereo out jack for headphones with shunt for speaker cutoff.


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