Dieselpunk Stereophonic Amplifier

Step 7 Final Assembly

This last part consists of putting it all together and adding some finishing touches.

Wire the lid. The DC power and line-in go straight to the amp board. Make sure there is enough slack in the wires so that it doesn't bind as the lid opens and closes. Wire up the speakers. Pay attention to the left and right channels. Install the volume potentiometer.

The volume knob is from a knob from an old pot cover. It was shortened and bored out 1/4 inch bit to fit the pot shaft. Use hot glue to attach the knob to the shaft.

Next make the name plates. The nameplates are printed clear labels on 0.025 inch aluminum sheet. The plates are a chance to personalize the box. Attach the plates with Crazy Glue.

The V-emblem fills empty space on the grill. It is made from 1/2 inch angle aluminum. Using a hack saw, cut two pieces of aluminum at an angle. Using a file and or belt sander, finish them so they form a V-shape. Use masking tape to temporarily attach the two ends together. To permanently attach the two ends together take a piece of wire and form it so it fits inside the V-emblem. Place the emblem so that it sits level. Mix up some 5-Minute epoxy. Fill up the V-emblem with the epoxy. Let it sit over night. File and/or sand the emblem. Give the emblem a texture by lightly sanding the surface. Hot glue the emblem to the speaker grill.

The final touch is to age the box. Start by brushing black enamel in the edges and crevices.
It is okay to get messy. Next take paint thinner to remove and blend the black enamel to simulate grease.
Repeat until happy with the look.

Don't like the buzz? During the final assembly, I found that the DC power transformer was "emitting" a 60Hz buzz. Rather than build a notch filter, http://members.shaw.ca/roma/nine.html I decided to leave it. Another option is to run the amp from batteries. Use a 6 AA battery holder and connect up the 9V battery clip and DC Power Plug. Use this set up instead of the power transformer to eliminate the buzz.

Congratulations! You finished! :) Thanks for viewing my Instructable. I hope this project stirs up the creative juices for other Makers!

Comments

[Aiden1015]

have you tried connecting a capacitor between 12v and ground before the power input on the amp? it'll act as a low pass filter and should get rid of the hum

[garagemonkeysan]

Thanks for the suggestion. What value capacitor would you recommend?

[zack247]

I would think something along the lines of 16v, and between 10 and 470 uF, but i am not exactly sure, a 47uF @ 16v capacitor worked in my 6v version.

[garagemonkeysan]

Thank you! I will try it out. : )

[Thereyouhaveit]

You could try mine , LM7815A Because using a Lm7812 would only give you 10Vrms with a load .
With a 470uf elect. cap tied to the input and ground ( + to input , left pin , - to ground middle pin )
0.1uf ceramic cap tied to output and ground .

[garagemonkeysan]

Thanks for the suggestion! : )

[mnmitch57]

The reason why you're getting the hum is you've grounded the power input to the chassis of the case and did the same for the input to the speakers. If you replace the pipe fitting for the power input with a PVC pipe fitting (you can still use the metal end cap), it should alleviate the hum when you're running off of a wall socket.

[garagemonkeysan]

Thanks for the tip. Unfortunately the power ground and the audio ground are the same on the circuit board. So isloating the power input jack from the case won't do anything. I think. Thanks! : )

[RSR1]

AAAAAHHGGG¡¡

Sorry for my explanation was a complete mistake, I should be wrote (sorry for my english)

"separate the "line in" female plug, to aislate the common earth from the audio in", this should solve your problem, no need to open your power suply,

test it only desoldering :-)

sorry again, hope you´ll be not to lazy to do that, to see what happens

Kindly

[garagemonkeysan]

Thanks for the email! Unfortunately the common earth and the line in ground are tied together on the amp board itself. I think the amp kit was designed for battery use only. Thanks again! : )

[RSR1]

Guy, this is a beautiful design, I know why are you having the 60 hz hum, this is probably because your line in "earth", have the same that the others "earths" of your design, as a tip, try to test with a searate male plug that is not connescted to the complete sistem earth. this may be solve your problem

cheers

[garagemonkeysan]

Thanks for the email! I use a two prong wall wart type of power supply. With a two blade 120VAC input and 12DC output. I guess I am too lazy to crack open this power supply to try to isolate the ground. : )

[khayel]

dude its so cooll did u have the pdf of it or how much it cost if u make me one cus im not sure that where i live i can found the tda's :C

[garagemonkeysan]

Thanks for the comment. Unfortunately, I didn't keep track of the cost of the parts nor do I do any contract work. Sorry. : )