Introduction: DIY Turntable With Amp Preamp and Buffer in Wooden Case
One day I found old and broken
dual hifi with turntable of funny shape. I checked mechanism of turntable and it was ok. Then the idea came to me that I can fulfill my dream of making my own hifi with turntable in wooden case with mechanism I found.
I knew in start that I want wooden case and that it can’t be just square box. When I saw that turntable it gave me solution for the shape of case.
I didn’t have any experience in electronics or woodworking before I started this project so it took me many long months in learning analyzing and frustration. I burned some electronic parts few times and made them from the beginning.
Turntable was not enough. I wanted also an amp, and with amp also goes preamp.
For amp I decided to go with ganclone lm3886 chipamp. After some digging through ebay i found 6n3 tube buffer and MV02 Motorized Remote Volume Control Input KIT. I love nixies and i knew that one would add up to steampunk look.
I also needed preamp for RIAA correction for turntable. I found Very Simple Phono Stage which was enough for me.
Step 1: The Turntable, VSPS and Strobe
The turntable have pretty good mechanics.
It has the pitch control, anti-skating, 33-45rpm, lift and returning hand at the end of vinyl.
The motor was easy to setup. It just needed 12v power supply. I made one with one rectifier, one electrolyte and lm7812 voltage regulator. I gave it power from the separate transformer.
For VSPS preamp I made PSU with 2x12v transformer and two rectifiers.
Strobe you can see on the picture is project from Vinyl engine DIY project.
Step 2: The Amplifier
I saw many solutions for the LM3886 and in the end I found a guy who is selling PCBs for LM3886 chipamps and I used his solution in the end.
After preparing another parts list I went on another trip to the electronics shop.
Step 3: The Buffer
After 30 days of waiting the DIY kit came from the china.
After some time assembling it I gave it a test drive with gainclone.
All pats came along. I only needed another 12v transformer and some wire.
Step 4: The Preamp and IN-4 Nixie
Another month of waiting and preamp was here.
Preamp came already assembled.
It has 4 stereo inputs, remote control, motorized volume potentiometer and output for led indicators that show which channel is active.
I didn’t get any documentation in package so i turned the web upside down to find schematic for it. After some time I found this link and some picture with instructions in Italian. In combination I understood how to make it stop turning volume down and up every time I change channel.
I wanted to use indicator that shows which channel is active but I dint want any LEDs on my steampunk case. So after some more research I found IN-4 Russian indicator tube that goes nice with my design.
Running the tube bugged me in the beginning but then I realized I only need to give it 180v to the anode and cathode of number I want to display. I made the power supply with one rectifier directly on 220VAC and 8 10Kohm resistors in series. I used eight of them because I wanted to split voltage drop across multiple resistors to prevent heating.
Then I made a project in Eagle for firing relays with 5v that would let on the other side 180v to the tube. Project is attached.
I didn’t manage to start relays with 5v output for LEDs so I took it from the power preamp gave to his relays for signal.
Step 5: The Case
And now to the dust!
I saw somewhere design of stacked plywood and decided to go with that one. I like the lines you get stacking sheets of veneer and stability. I didn’t put it on the scale but it is very heavy.
I printed out outlines for cutting and glued them to the ply sheet. Then I cutted it as close to the line as I could get. In the end I sanded to the lines by hand.
After making first layer it was easy to coy it with copy bit for router. When using copy bit keep router on the right side of the piece you are cutting or else the beat will go on its own. It took me 2 bits and 2 layers of ply to learn. Always go slowly with router, let the bit lead the machine. Don’t use highest speeds because wood will start burning.
I repeated the same for the second base.
After cutting everything out I glued every layer with white glue for wood and clamped it hard.
Next day when glue dried out came the hardest part, SANDING.
I didn’t align properly every layer and that was my biggest mistake. I had to sand through every layer to make them even. I used every type of sanding machine that I could find.
After few days of sanding with 60grit paper I managed to make everything even. Then I sanded everything again with 100, 180, 250 and 1000 paper by hand. 1000grit paper gave it very smooth surface, almost like some plastic.
I didn’t like the color of the outer veneer so i sanded it out to the next layer. I discovered on the second layer some shapes in the wood that looked more natural than "perfect" look that had the upper layer.
It looked nice but I wanted a nicer finish. So I made polishing pasta by heating and mixing natural bees wax and olive oil. When it cooled down I applied it to the case first by hand and then with cloth. The pasta gave it nice shining color.
EDIT: I attached PDF documents with cutout templates. They are huge and non-standard dimension of paper. I printed it out using "Poster" option in print dialog in Adobe Reader. Remember to turn on "cut marks" option when printing.
Step 6: Laying Elements
I started with buffer. I needed
to know where the tube can be positioned. I turned the socket for tube on the other side of PCB, applied it some color and transferred color to the inside of the case. Then I drilled the small hole in the center of where socket center would be and drilled a hole for tube from the outer side to the inside.
The second thing was volume pot.
I found the place where it can stand and drilled the hole for the knob.
Then i decided to put channel selector right most and drilled the hole for him.
Fourth thing was IN-4 nixie. I found middlest place for nixie and drilled a hole.
I didn’t have a socket so I made one out of CD case. I punched holes for pins with hot iron and two bigger for screws. Since the hole is a bit bigger than nixie and you can see the sides of the hole, I sanded them out and added polish I made.
Heat sink layed in only place where it can be.
Input board of preamp is next to heat sink since there will come tile with connectors.
After that I layed the rest of elements without any order.
At the top right of back plate I added power connector fuse and switch.
Step 7: Conclusion
From a piece of trash
to the beauty with beast inside!
It started from the broken hifi, developed as idea and finished as beautiful piece. Project took me few months and money out of pocket but it was worth.
I wouldn’t be able to finish it without my friend Vex who is specialist in audio and electronic field, my boss Rajko who is specialist in all sorts of electronics and my girlfriend Tasa which gave me support to finish this project.
I will give the price list but this is very rough since i lost count how many times i connected something wrong way and had to buy it again.
· Buffer - 20$
· Preamp - 50$
· Gainclone - 30$
· Sheet of plywood - 30$
· 12v 1A transformer for motor - 5$
· 12v 5A transformer for buffer and preamp - 20$
· 2x12v 2A transformer for VSPS preamp - 15$
· 2x30v 5A toroid transformer for gainclone - 40$
Sum: ~210$. But again, this is very rough calculation without tools and spare parts.