• www.partsexpress.com -- RCA female jack, small toroidal trans  and OFC wire
• www.hndme.com -- Nichicon capacitors, shrink tube, silver-plated hook up wire, etc.
• Local Radio Shack -- any immediate supply, such as silver soldering.

I purchased the case from Taiwan (www.diysong.com).  It is meant for general amp use.  The price, including surface shipping, is about $70 USD.   The case came only with AC IEC outlet hole and fuse hole.  I have to drill the holes for XLR, RCA, enlarge the fuse and power switch hole.  The good thing is that Aluminum is not that hard to make holes on it.  The challenge one is the XLR holes.  My suggestion is to use a Drill press, whenever possible.  The hole will come out nicely, if you have one!

If you are drilling the XLR hole manually, then buy the big hole drill as shown on the left photo.  When purchasing one, buy with the diameter a little bit smaller, as it will move around when you drill it.  In my case, I bought one drill of 22 mm for the 24 mm XLR in the spec.  Again, it is better to drill it with a drill press whenever possible!

• All MOSFET IRF610 (Q1 & Q2) are matched to 0.01V.  Q101 and Q102 does not need to be matched, but they tend to run very hot!  Be sure to add additional heat sink to it!
• For matching the device, you can Nelson Pass' article in his diy website or a discussion here.  The resistor I used is 2.2K.  500 Ohms is also fine.  When matching, make sure to test it until the digits stabilized!  I tested each one for about 20 minutes each, but I noticed that 10 minutes is good enough! 
• Make sure you always discharge your electrostatic when handling transistors!  Use a Electrostatic wrist strap is a good idea!

The Plitron transformer has epoxy sealed in the middle, whereas the Avel does not!  I added my own epoxy to the Avel transformer (and drill a hole in the center later).  I hope this will reduce the vibration from the trans!

This is the PSU.  I have increased the PSU capacitors from original 1000uF to 1500uF/160V.  I also add two bypass 0.47uF/220V Polypropylene capacitors (at bottom, not shown).   Refer to here to see why adding a bypass capacitor in the PSU?

As I mentioned above, the Q101 & Q102 tend to run very, very hot!  I set the mosfet upright and add the heavy duty heat sink to make it cooler!  I buy these from Radio Shack as they work better than I parts used in the article (from Digi-key).

This is the initial setup planning.  The case has plentiful space to hold the BZLS.   The power line is protected by the Thermistor built-in on the PSU board already; therefore, there is no need to add one in the transformer AC primary side; although, adding one more on the primary AC is not going to hurt, either!

This is the power configuration setup from diymania.net.  On this figure, not however, that there is a 12V out from the secondary output.  If you don't have customized transformer, you can use a separate transformer, like I did.

Make sure to ground the Thermistor as shown.

I used the Input Select board from diymania.net from Korea's DIY site.  It has 4 sets of RCA unbalanced input, 2 pairs of XLR balanced input and 1 Tape In.  To drive this board, I use the Avel Lindberg 12V toroidal transformer as shown above.  Since I do not have balanced Input device, therefore, I did not install the XLR input jack (female).  I shorted the -In to GND because of not using XLR Input.  (Notes: I added one set of XLR Input connector on July, 2004.  It works great!)

You can also see the wire connection here for the inputs.

I used two 10K 24-steps Attenuator for full balanced volume control (at the output side).  The quality of these two attenuators is very good and not very expensive!  The control is very precise.  What I would like, if possible, is to have more steps than 24, but so far it is more than I can ask for, in terms of price and performance.  No complain what so ever!

You can download the gerber file from passdiy.com.  I got the boards from the Korean diymania.net, plus the Input Select board designed also by the diymania.net's diyer.  Except the the capacitors, C3 & C4, I am using the 3300uf/63V, all are the same spec as in the BZLS article.

I raised up all the mosfet to make them cooler with bigger heat sink.  To do that, I need to connect the Drain pin to the C1 & C2, because they are electrically live.  If you are designing your own PCB, make sure this is following the design.

I also add the 0.47uF/250V bypass capacitors to C3 and C4 (at the bottom of the board). 

I use the jumper pin for P5 (and not the pot, as this is optional) and therefore the gain is about: Gain = (R1+R2)/R15

I initially set my VR to 430 ohms, which will roughly gives me about 10 dB of gain (gain is 20*log[3.48]).  (You must set VR value first before soldering it on).  If you increase the R15 value, the gain decrease!  Remember this is the gain for balanced output.  (as Unbalanced output will be less gain).  The gain is also depends on the efficiency of your power amp and speaker.  You can adjust this value to match your system.  For me, 10 dB gain is good enough for my Triangle Polaris floor speaker system (sensitivity: 90 dB).

If you can, put the "socket pin" for the VR.  By doing this, you can always pull out the VR and adjust it and then put it back.  As the VR is in the series of resistors, by measuring it directly will not reflect its true value!

• The XLR connection is different than we are used in USA.
• I use the second 12V transformer for the Input Selector board.
• I only use the Attenuator for output and skip the input one.  (See the passdiy article for details).
• I skip the Balanced input XLR connection, because I do not have any balanced input device.  For this reason, I have to short the -In to the GND.

   Steps of my installation testing:

1. Add the Thermistor in the transformer's primary AC line to protect the circuit.  After I completed the Power Supply and measured the output is good at about +59.6V and -59.7V in rail.  (Schematic is +/- 60V).  I added the Power LED and it can also act as the Bleeder for the remaining current stored in the caps after power off!
2. Connect the V+, GND and V- lines to the main boards.  Remember, if you are using the board made from passdiy's gerber file, you need to connect both lines in V+ and V-, as they serve different circuit path.  I did my initial test without running both lines, the result is a burning smoke and a flash!  I burned one zener and one resistor and it took me a day to debug it and fix it right!
3. After the connection lines is done, power up with cautions!  Measure the Drain pin again GND.  It should have the voltage around +30V and the Source pin to GND should be -4V.  In my case, they all are within tight 1% tolerance of these voltages.  I am very happy with it!

4. The next thing is to connect the output line for the Output Attenuator.  I used two 10K 24-steps Attenuators to control my output.  On the output, I am using XLR male connector and its pin 2 share the positive pole with RCA positive pole.  Both RCA and XLR ground are connected together and into the chassis ground.  (I use star-grounding into one ground point, except for the ground from the RCA and XLR ground line to prevent ground loop buzz).  I did not install the Input side attenuator.  As for reason why, Nelson did explained in his article.

5. Connect the Input Selector board as shown above.  I do not have Input balanced source, therefore, I connect the -In from both channels to the GND.  I did not do this when I first test run it and there is no sound output at all!  After a good while and I noticed that I need to do this and sound flow out smoothly!  It was a wonderful feeling at the time you hear the music came out!
6. Connect the Input select switch.  

7. Add the LED for the Input display.  The circuit is simple!  I bought a circuit board from Radio Shack and connect the lines according to the figure above.  It works great!  (I feel that Ø3 mm LED may looks better than my currnet Ø5 mm LED.  You can try it yourself!)

I brought my BZLS to my friend's house, who has a pair of Aleph 2.  The sound now feels a little bit on the hard side.  I hope once I burn-in after a while, the sound will be more soften!  A month later (Jan. 2004), I finish my Aleph 5, as shown on the left photo.  Now I am using my Balanced Zen with my Aleph 5.  Both machine are in burn-in mode now.  I hope I can share with you a few months later how the sound goes then!

(After Notes: I upgraded my BZLS to X-BZLS in August, 2004.  You can refer to my DIY Journal here for more details).

• Nelson Pass:  Many thanks for your wonderful design and generosity to share your intelligence!
• Boards are supported by diymania.net.  Case from ACSP in Taiwan.
• Russell Sun:  My friend who taught me all things about Audio and he is the person who persuaded me to buy my first amp and speaker!
• My family's support in DIY hobby!