Truepath amplifier

Module assembly and testing.

Here I will briefly go over the assembly and testing process.
The order of assembly and testing will not be the same as the order in which I chose the components, but do not fear, it is not that hard!

Soft start module PSU1-SS

The softstart module was the first thing I assembled as it would allow me to power up my transformer without blowing any fuses (yep, I actually DID try to power the toroid without a softstart).
Also, it is not too complicated!

For this module I simply chose the classic assembly procedure of mounting the lowest components first. That got me from here... here. Softstart completed. Since I was now able to actually power up the toroid that is where I headed next!


There is really not much to the transformer part as I ordered a custom-wound toroid to suit my needs

~8kg's of pure goodness... What does it say?

Looks like they got the specifications right, but that should not satisfy us. LET'S MEASURE!!!

OK now, this is important, DO NOT POWER ON A TOROID THIS SIZE BY PLUGGING IT TO MAINS DIRECTLY!!! I did and my mains relay switched off so definitely not a good idea. In the picture above you can see that the toroid is fed mains voltage through the softstart module. Well, with everything powered up lets get on to those measurements...

Apparently we are not entirely off, measurements were done with no load.
Here's a tip for you, if you shorten the leads on a toroid, make sure you remove the layer of lacquer, or else you will be wondering why your amplifier seems not to get any power at all. I forgot and all of a sudden it seemed I had no connection between the two leads on the primary side. I got afraid I had burned something but after some troubleshooting I found out that it was due to the insulating layer on the leads. I sanded it off and all of a sudden it was alive again.
Affirmed that the toroid was on spec I proceeded to the power supplies.


The Tbrick was my first ever encounter with SMC's, but I took care and followed the instructions by Audiophool. After some soldering I ended up with a Tbrick.

This is the assembled Tbrick, ready to be "T-broken" into the two pieces that would provide the Truepath with its "household" voltages!

And finally here is the Tbrick broken into the two modules and hooked up to the toroid for testing of voltages. All went fine here so I felt it safe to proceed to the main power supply.


This is where things started going a bit slow... I put the components on the table before I started soldering to check if it was all there... Can you find a thing missing in the picture below?

Yeah, I bet you noticed straight away, but in case you did not, let me help you.

Yup, that is one resistor less than there ought to be, so no soldering that night... Actually, no soldering for a long time, since I never had a reply to my support request (and still have not at the time of writing this, more than two months later). Oh well, let us not linger too much on the horrible after sales support I experienced, since a forum member of stepped in and actually sent me another 8 resistors so I could get on with the project. Those guys on that forum... well... THUMBS UP!

This is the assembled PSU1-PS, a word of caution here... Soldering those capacitors on that PCB can cause a bit of trouble... You will need PLENTY of heat if you want to get the job done properly, so turn up the heat or you just might be in for trouble!
I now connected the power supply to the toroid and verified that I had the correct voltages from the power supply. All set I now braced myself for the big challenge...


The Truepath was actually the last module I assembled as it was also the hardest one.
My components bags were not numbered for starters, so I had to figure out what was in the bags.

So, this was my starting point, the bag to the upper left is the "accessories" pack I ordered from Audiophool

As I ordered the "Optimized components" from Audiophool I also received this. It may not look like much, but it proved VERY helpful. To the left you see the "optimized components" provided and already held in place with some double sided adhesive tape. To the right you can see the sheet filled with all components after I figured out what was in each bag...

Time to get started, so being a good little boy I finished my oatmeal and had my first (of many) cup of coffee for the day.
I will not go through the entire process of placing components step-by-step, but I did hit a few curbs on the way...

#1 Forgetting to short "J2" and "J3" was not too clever. This caused me a bit of troubleshooting to find out why those test resistors got so damn hot in no time when I first powered the amp.

#2 Winding those toroids is easily one of the most annoying tasks during the entire project, so to keep the windings in order whilst I removed the insulation from the wire strands I came up with this. Put a wire strip around the toroid and a battery through the hole. An AA size with a little tape fits perfectly and will prevent the windings from going loose whilst you work. Actually the battery alone should do the trick so go hunting for one at this time in the project. If you cannot seem to find one, look in the Missus night drawer and pray you do not find D-size batteries!

Otherwise, just follow the instructions provided on the 41hz website or the guide provided on and you should end up with something like this (oh, but WITH jumpers 2 and 3 shorted correctly of course). Some clever asses out there might realize I ended up not using the connectors (sockets and plugs) provided in the "accessories" kit from Audiophool but as it turned out I realised I would not be needing them for this particular project.