Thanks to Nelson Pass for sharing his wonderful, patented design to the DIY world!  None of this will happen without your intelligence and your generosity!  Photos below are the original Aleph 5.

To study Aleph 5, you can find the Owner's and Service manual in Pass Labs web site.

(Notes: You can click the the photo that has a border to see in greater details.)

This is the heavy-duty speaker binding post I use and the gold-plated RCA female connectors.  I bought the binding post from Taiwan and the RCA female from Partsexpress.com.  Both are very good quality products!

If I were to do it again, I would separate the binding post wider than shown in the left figure, as this will make it more flexible to accommodate any kind of speaker cables, especially the thicker one!

• All Input MOSFET IRF9610 (Q1 & Q2) are matched to 0.01V.  Q3 does not need to be matched, but I still use the nearest value I can get.  I purchased 20 pieces and I can easily match to what I need for my Aleph 5.
• For the Power and Bias output MOSFET, IRFP240, I matched them down to 0.01V.  I purchased 40 pieces and I can easily get the 4 x 3 pairs for my Aleph 5.  
• There is an article about how to do the matching from Nelson in here.  There is also a discussion forum for matching the device in diyaudio.com and  you can refer it 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!  

The tape at the bottom is only for me to pin point the mounting hole.  I removed it after the hole is done.  The capacitors is fixed in place by the capacitor clamps and the copper plate as shown below.

The capacitors I used are 4 Nippon Chemi-Con 68,000 uF/50V.  I purchased it at a very good price with my friend.  For the PSU coupling capacitor, I use two 4.7 uF/100Vdc Electrolyte cap (I changed it later.  See below for more details).

I use a 2 mm, pure copper, plate for the common connection among the 4 capacitors.  It also help fixing the capacitors in place!

You can also use CRC (using 0.5R/40W resistor, for example) to lower the cost a little bit.  I did not use it is because I think the current in Aleph 5 is a little bit higher for CRC to handle it.

I did wanted to add the Speaker delay relay circuit, but the space had limited my choice.  I had to give it up; instead, I always turn the volume down to minimum on preamp to prevent signal spike when turning on and off of the amp.  I saw one user use a toggle switch for the speaker.  I prefer a cleaner signal path as I can!  Therefore, I leave it as-is in the original design.

Time constant (sec) = R * C (R in ohms and C in Farads)

(Notes:  The actual formula should be: t = -ln (Vc / Vo) * RC ).

So if you have a 25,000 uF of cap and you would like 15 seconds of discharge time, your R = t / C = 600 ohms.   The power (P) dissipation of the resistor will be P=V^2/R. V is the unreg supply voltage.  I recommend double P value of the resistor...as this will get hot.   You can use this resistor before working the innards of your amp so you can bleed off stored energy and avoid a nasty spark or shock.  (some quoted from diyaudio)

Do not connect the main board right after you power down the PSU!  Drain  your capacitor's charge before doing so, or you might shock and burn your main board!

I use 3 Nichicon Muse ES Bi-polar 220uF/50V capacitors for C5, C9 and C10.  All resistors are Dale 1% resistor.  For C7 I use the Wima 0.047uF MKP capacitor.  The output resistors is a series of 5-0.5 ohms/3W resistors, instead of 4-0.47 ohms resistor, because they are out of stock when I ordered them.

Actually, you can use the same board for all Aleph series amp.  The following chart are the different parts for each different Aleph amp.

The resistor R19, I change it to use the Vishay 500K ohms VR.  This gives me the advantage to adjust the bias voltage on the output board with ease.  

For Q4 and Q5, the most common error is when using other common transistor, the pin setting might be different from the MPSA18.  Make sure you notice this, if you want to use other kind of transistor!  This tiny difference may cost your amp and is hard to debug!

R1 is original at 10K.  I changed mine to 2.2K for my blue LED.

Our group purchase also made the Bias and Output board, instead of p2p.  I feel this is more organized than the p2p one.

The IRFP240 is the TO-247 package, which has the plastic around the screw hole for isolation to the chassis.  This saves me from using the transistor mounting kit.  I use the mica insulator plus the thermo paste to mount the mosfet.  All output board wire are 12 ga, OFC power wire.

I found an old PCB to use it to hold the Inductors, the 2 channel boards and serve as the shield from the transformer.  I plated a sheet of copper as the shield at the bottom of the PCB and ground it.  I also put a layer of paper tape for isolating the potential parts that may cause the problem of un-intentional short from the PCB!

This is how it looks like before all components are installed into the case.

After the PSU is tested and approved, I start assembling the case and then put the PSU in place.  The heat sink on both side is then added on to it.  A simple job of tightening the screw can be quite challenging, in a tight space like this one!  

Make sure also to mark the wires to prevent wrong connection!

More close-up view of the inside.  My plan is to buy a better cap to replace the one use in the PSU shown in the future.  

For the main board, the common suggestion is to add the bypass cap (1uF ~ 4.7uF, as suggested  by Nelson Pass) on Z5 as this will make your sound better!  The result of this fine tuning is discussed below.

(Notes:  As I am using the same board as Aleph 2, you can refer to the wiring of Aleph 2 here.  Besides the different parts and the fact that Aleph 2 is a mono block, all the wiring are very similar!)

(Part of the figure are of the courtesy of diyzone.net)

This is the final assembly done using the steps I just described above.

This is the rear panel.  The only difference in my final version is that I added the toggle switch between the two XLR to toggle the XLR or RCA input (as few figures above).  If you are to do the Aleph 5, I recommend you to separate the binding post a little bit further on each channel.  This will make your speaker cables easier to connect.

   Steps of my installation testing:

1. After I completed the Power Supply and measured the output, it is about at +/- 33.6V in rail after adding the load (NP's design is +/- 34V).  I added the Bleeder Resistor, as the high capacitance of the capacitors is used (for safety!).
2. (Optional) I checked the AC ripple and it shows that the CLC filtering is working good!
3. Connect the Blue LEDs.  As I mentioned above, I used the 2.2K for R1, because of the lower mA blue LED I choose.  I connected the Power and Bias board on one channel and measure the bias voltage.  It should be 0.5V, according to Nelson Pass' design.  In my case, both channels are around 0.620V and the blue LED lit up OK, not too bright, not too dim!
4. I adjusted the R19 VR, so that the Bias voltage is around 0.5V!  Some suggest using (R19) VR for initial adjustment, then take it off and replace it with the fixed value resistor, as this will improve the sound quality!  This option is entirely up to you.  I picked to use the VR for convenience sake!
5. I checked the following voltages to verify my installation.  At Q3 (R11), Q4 (R14) and Q5, it should be 4 to 5V.  Q1 and Q2 Source to GND should be +4V.  I have all the voltages right!  Half of my worry is gone right away!
6. Once one channel done, I connected the other channel and repeats steps 3 to 5.  I am lucky that the second channel also have all the voltages right and I only need to adjust is the R19 to make all output resistors close to 0.5V bias.
7. Now comes to the time to test the sound output.  If you use RCA Input only, make sure to ground the XLR connector's pin 3 and pin 1 as illustrated above (if you don't do this, the difference is a loss of -6 dB).
8. Run-in the Aleph 5 for 1~4 hours and measure all the voltages again, make sure they are all correct and check the temperature of the heat sink.  They should be around 70ºC (or 158ºF).  In my case, they are about 55ºC to 60ºC after 1 hour.  The T1 thermostatic switch should kicks in and shut the Aleph 5 off, if the temperature exceed 75ºC.  I check the voltage multiple times after each couple of hours of listening.  I did the checking many times for the first week.  Everything is working fine according to the spec and I think I can conclude that my project is done.

The DC offset of my Aleph 5 settled at 56 mV for left and 48 mV on the right channel after about 1 hour. So far, the treble is pretty good. Midrange also is very good, but the bass didn't impress me yet!  I will change the PSU bypass cap to a better one and add the Z5 bypass cap to see how it goes!  One DIYer shared his experience using 1.0uF Black Gate N-type cap on Z5 bypass and that the sound is very good for both treble and midrange (bass is no change)!  I definitely will try this! 

(Photo at top left is my new Aleph 5 DIY and my commercial Aleph 3 amp.  Lego AT-AT is my son's DIY.  Photo below is my current setup).

My first impression to the sound that it is very similar to my  commercial Aleph 3 and I am yet to find out the difference of the two!  The balanced connection from my BZLS preamp to Aleph 5 does provide a clearer sounds!  I believe I need to break in the amp in order to hear its true performance!  I will keep you posted regarding the result of it.  It is now my standard of relaxation every day, after I return home from work!  It is really wonderful!  Thanks, Nelson!

(Added Notes on Feb. 07th, 2004):

I did the fine tuning on my Aleph 5 by changing the PSU bypass cap from the 4.7uF/100V Electrolyte capacitors to ERO MKP 0.47uF/400V.  I also added the bypass cap on Z5, according to Nelson Pass' suggestion in diyaudio.  I used the WIMA 1uF/63V MKP capacitors.  The sound seems to be more precise and with more concentration now.   

• Preparing Aleph-P 1.7 Preamp now...
• Aleph X project, or may be two Aleph 2 mono blocks....
• Rest and enjoy!

• Nelson Pass:  Many thanks for your wonderful design and generosity to share your intelligence!
• Brian Bell's PCB layout and PRBS in supplying the boards.  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!