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How to build your own Poweramp 5 audiophile / studio quality stereo power amplifier using the PA5C component kit. (For info about the kit, click here.)
have made these instructions very
detailed so that anyone who can read english and use pliers and a
screwdriver can build their own top-quality power amplifier.
We recommend a case made from insulating material
(plastic or wood) unless you are very experienced and know exactly what
you are doing, in that case you can of course use metal if you are
careful and keep the distance between the metal and parts with mains
Recommended case material:
20-22 mm square, solid wood:
When screwing, both when assembling the case and
when doing electrical connections, do not use an electric
screwdriver. Do all screwing by hand.
Paint / varnish / surface the parts before assembly.
We recommend painting the wood blocks black, as they will be visible from the outside.
The same applies to the sides of the base. They are also visible (when looking from the side of the case).
Front and top, which are visible from the front can be finished the way you want. We used matte black spray paint, it came out rather well. But of course you can choose real wood or plastic if you want to.
However, if you want to use metal for the case, it is important that you know exactly what you are doing as the amp is powered by mains voltage.
The instructions here apply to a case made from the material list above.
This page shows how to install the electronics, instructions for the making of the case, click here. (PDF)
First of all:
Mount the feet on the bottom board. The feet should be 10 - 14 mm high.
Then screw the wooden blocks onto the front and back plate.
Now screw the bottom plate into the underside of the blocks on the front, so that the bottom and front are joined together.
Make certain the bottom has the same distance to the right and left edges of the front, and that it is close to the front when they are screwed together.
Put away the front/bottom until later.
Now take the back plate and screw the contacts and sockets in place.
The picture shows the back plate as seen from inside when ready. RCA sockets to the left, mains input socket with integrated fuse holder on the right, and the two loudspeaker sockets inbetween.
Place the AC socket so that the fuse holder is below the cable connector, see left picture.
Seen from inside the mains socket has one connetor over the other on the left side, and one (the earth connector) in the middle above, see the right picture.
RCA sockets: Black = left channel, red = right channel.
Mount the socket from the outside, then (from the inside) first the black wire with its ring, then the spring washer, then the nut. Be careful not to tighten the nuts too hard, it may damage the threads. Just make sure the sockets don´t turn when connecting / disconnecting an RCA cable. You could use glue between the socket and the back plate to ensure this if you want to.
Then twirl the wire pairs this way:
Put the back plate aside for now.
Now you screw the thicker wires onto the 10 terminal block on the PSU board. This is the way it will look when the wires are in place. (There are also some thin wires, they will be used with the volume controls later.)
The wires come in two lengths, and are connected like this:
(Letter on the terminal block, from left to right: Wire colour / length)
H Black, short
H Black, long
D Yellow, short
G Yellow, short
X Not connected, unless you need earth connection for front and / or top, såvida man inte har delar som behöver jordning, t.ex. front / lock av metall
X Yellow / green with a female spade connector in one end.
G Yellow, long
D Yellow, long
A Red, short
A Red, long
Long wires will be connected to the right amplifier module (and mains socket), short to the left amplifier module, that is why long wires go to the right and short ones to the left in the picture above.
Then screw the PSU board onto the bottom plate. The 10 terminal block with its wires facing the front, the 4 terminal block facing the back.
Do not tighten the screws too hard to avoid the PCB from cracking.
There are four holes, but only two screws are really needed, placed diagonally.
After this, hold the back plate edge-to-edge with the back side of the bottom plate as in the picture, make a marking with a pricker through the holes, drill 2 mm holes in the wood blocks and then screw the back plate in place.
This is the way it should be, seen from above:
Now you screw the amplifier modules into place with the terminal blocks upwards.
Viewed from the side it should be about 5 mm of the wood block visible both above and below the heatsinks. If you followed the instructions in the PDF document, it will be so.
When the amplifier modules are in place, the back part of the case can be unscrewed to simplify the mounting of the transformer, as in the next picture.
Start by sticking the long screw through the hole in the base plate from below, so the screw head is on the bottom side of the bottom plate.
Inside, place the transformer items on the screw in this order:
Rubber washer - transformer - rubber washer - metal washer (with sinkage downwards) - nut.
When screwing the nut in place, do not tighten too hard. You should still be able to rotate the transformer at this point.
It will look like this. (The transformer´s secondary wires are green and yellow in this picture, but will probably have other colours in your kit.)
Now connect the wires from the PSU board to the power amplifier modules. Screw by hand, and just enough so the wires sit firmly. The short wires go to the left amplifier module, the long wires to the right. Leave the yelllow/green earth wire, it is not connected yet.
This is the way the colours should be:
Red to A. One yellow to D, one yellow to G (either one, not important). Black to H.
Left module, short wires:
Red wire from A (on the PSU board) to A (on the amplifier module).
Yellow wire from D to D
Yellow wire from G to G
Black wire from H to H
So, it is rather simple -- A to A, D to D, G to G and H to H
Right module: Exactly the same, but with the long wires.
When this is done it is time to connect the transformer to the 4 terminal block on the PSU board. The thicker secondary wires (low voltage) are marked with 1, 2, 3 and 4 marks. The wire with one mark goes to terminal 1, two marks to terminal 2, three to 3, four to 4. Screw by hand until the wires are firmly connected.
Turn the transformer so the wires are kept within the area of the bottom plate. Like this:
(Do not mind the colours, they vary from time to time, just connect the one with one mark to no 1, two marks to 2 and so on.)
When the wires are in place, like in the picture, you can tighten the nut holding the transformer. Just so that you cannot turn the transformer by hand anymore, not tighter.
When the transformer is fixed, you can attach the back plate again.
The two volume controls are connected to the wires from the two RCA sockets and to the four remaining thin wires (short white, short black, long red, long black).
Important: When you screw the wires to the terminal blocks on the potentiometers, hold the terminal blocks, not the potentiometer, with the other hand. Otherwise the stress on the potentiometer terminals could cause problems.
Left channel volume control connections:
Connect white wire from the black RCA socket to potentiometer terminal 1. (Screw by hand until the wire is firm, but not too hard.)
Connect white short (separate) wire to terminal 2.
Connecty both the black wire from the black RCA socket and the short (separate) black wire to terminal 3.
When this is done, twirl the black and white short wires together, as you did with the wires from the RCA sockets.
Do exactly the same with the right volume control, but red wires instead of white ones, and long instead of short.
(Red from RCA socket to terminal 1, red separate wire to 2, both black wires to 3.)
It will look like this:
These wires will soon be connected to the power amplifier modules, but first...
Fasten the volume controls / potentiometers to the front using pliers.
This time, hold the other hand on to the potentiometer, not the terminal block.
Let the terminals face straight upwards.
Now you connect the unconnected wires from the volume controls to the amplifier modules.
Black wires from the volume controls are connected to amplifier C terminals (short to the left, long to the right). White (short) to left B terminal, red (long) to right B termina:
Now you connect the wires from the loudspeaker terminals to the amplifier modules.
The red wires to the E terminals, the black wires to the F terminals. (Same on both sides.)
When this is done, the module connections are ready.
Now only the mains voltage part remains.
Start by pushing the power switch onto the front (from the outside, of course).
Notice the small protruding piece on the yellow plastic (where the arrow points in the picture below).
It is important that it is below, not at the top. It should look like this:
Push the female blade connectors on the transformer primary wires (red, flexible) onto the power switch, the two connections to the right of the arrow above (those closest to the middle of the front). See also the next picture.
Hold the power switch in place with your other hand on the outside of the case, so it does not "pop out".
Then push the two yellow wires with female blade connectors onto the other two contacts of the power switch, the ones closest to the right edge of the front. (Left in the picture above.)
When done, it should look like this:
The other end of the yellow wires are then connected to the blade connectors of the mains outlet this way:
Important! Make sure you connect to the blades on the left in this picture, not the one in the middle on top.
To the one top-middle you now connect the yellow - green earth wire from terminal 6 on the PSU board.
It will then look like this:
This is it! All connections are made and the amplifier is ready. However, before screwing on the lid, do a thorough walkthrough of all wiring.
Here is a check list:
First, check the wiring between the 10 terminal block on the PSU board and the amplifier modules:
A to A (red wires)
D to D (yellow wires)
G to G (yellow wires)
H to H (black wires) .
Other connections on the amplifier modules:
B: White wire from left volume control, terminal 2.
C: Black wire from left volume control, terminal 1.
E: Red wire from left loudspeaker terminal
F: Black wire from left loudspeaker terminal.
B: White wire from right volume control, terminal 2.
C: Black wire from right volume control, terminal 1.
E: Red wire from right loudspeaker terminal
F: Black wire from right loudspeaker terminal.
Left volume control terminals also have wires to the left RCA socket: Black to terminal 3, white to terminal 2.
Right volume control terminals also have wires to the left RCA socket: Black to terminal 3, white to terminal 2.
The power switch, viewed from the inside of the case. (The back of the amplifier turned towards you.)
The small protruding piece on the yellow plastic downwards.
The two red wires from the transformer to the right, the two yellow wires from the mains input to the left.
(If these are reversed, the control lamp in the power switch will not turn off.)
Finally (and this is very important for safety): The mains input socket:
Viewed from the outside, the fuse holder should be below the contacts.
Viewed from the inside:
The two blade connectors to the left, one above the other, go to the two yellow wires from the power switch.
The middle / upper blade connector goes to the yellow - green cable from the PSU board, terminal X.
If everything looks correct, screw on the top plate to close the amplifier before connecting to the mains voltage.
Connect to the mains using a cable that fits the mains input socket of the amplifier. It is the same 3-wire type that is normally used for desktop computers, and should be easy to find in any electrical shop or department store.
Everything was OK? Then connect a signal source (preamplifier, computer, CD or DVD player, smartphone, tablet, DAC, Bluetooth music adapter...) and two 8 Ohm speakers.
Turn the musik source on, so you have a signal before turning the amplifier on.
Set the volume controls to about 1/4 of their maximum position.
When turning the amplifier on, the music should come at once, without any delay.
If it doesn´t, turn off the amplifier immediately, disconnect the mains cable and wait a minute or two before opening the amplifier, so the power supply has time to uncharge before you check (and correct) the wiring.
If you see nothing wrong, check the signal source itself. If it is silent, so is the CM-100-17, the noise level is very low.
If you have an old electrical system where the wall sockets have no ground terminals, and there is a small humming sound from the speakers because of this, you can ground the amplifier by connecting a wire from something grounded (like a water heating element or the kitchen sink) and one of the X terminals on the PSU board.
Or maybe just one of the minus (black) connections on the speaker terminals, or the ground (outside) of the RCA sockets. (We have not tested this ourselves, as we have no big transformers, electric engines or other noise sources nearby.) As there is no current passing through such a ground wire, the wire area is not important.