Audiophool's Truepath Assembly Guidelines

Preliminaries
Getting Started.
Ownership of this document.
Nomenclature.
If you get stuck.
Comments and Feedback.

Overview
Maedos Solution

The drawings
Schematic.
PCB Component Overlay
SMT Sheet
Base Truepath
Optimised Truepath

Customization

Assembly
ESD.
Coils.
Coil shuttle.
Preparing Coil Ends
A better way to prepare coils ends?
Fit the SMT Components
Remote Mute
Fit Through-hole Components
TA3020 Socket.
Additional note for optimised Truepath.
Clean the PCB?

Learn about Truepath
Thomaseliot's Truepath Navigator
Watch the video.

Power Up and Test Procedure
Test Resistors.
Setup for the Test
Test V5.
Part 1: Before TA3020 is fitted.
Part 2: After TA3020 is fitted.
Test VN10
Troubleshooting VN10
Test VNN and VPP
Set Offset Adjust
Hisses and Hums
Load Test.

Final Step: Enjoy the music.

Building a Complete Amplifier Around Truepath.
41Hz Basic Configuration.
Tbrick Configuration
SMPS Configuration

Acknowledgments

 

Preliminaries

Getting Started.

If you are building your first Truepath then it is in your interest to take time to build the amplifier slowly and carefully. This document may look long, but you could spend days trying to find a fault caused by a single bad solder joint. Take the time to follow this document meticulously and the chance of problems will be minimised.
This document assumes that you:

• are competent at soldering.
• have the appropriate tools to build and test the amplifier. Here is a list of tools that Audiophool uses.
• have and know how to use appropriate power supplies.
• have basic fault-finding skills.

This document does not assume that you have:

• knowledge of electronics beyond the basics.

Ownership of this document.

This document belongs to Audiophool. You are welcome to use it for the purpose of getting your own Truepath based amplifier working. It is not to be used for any other purpose.

How to read this document

Nomenclature.

Here are some terms that are used in this document which are not commonly used on the forum or in Tripath documents.

This	Means This
Base Truepath	The amplifier PCB built entirely from components built from the Truepath kit. It is configured for 2VRMS line level source, 48V main rails, and 4 ohm speakers.
IPP	The current that flows from VPP power supply
INN	The current that flows into VNN power supply
IN10	The current that flows from VN10 power supply
I5	The current that flows from V5 power supply
main rails	VPP and VNN power supplies
auxiliary rails	V5 and VN10 power supplies
Optimised Truepath	A Truepath configuration  with customised components and schematic which is provided by Maedos
<To Do>	This part of the document is incomplete and to be written.

Optional sections of the document

Some parts of the document are optional. They are easy to identify because they are boxed-out and colour-coded as follows.

Suggestions - Stuff that you may be interested in.

Comments related to Optimised Truepath

If you get stuck.

There are plenty of experienced members on the 41Hz forum who are willing to help you. If you browse through the forum, it is clear that those who ask a succinct question are much more likely to get a satisfactory response. Suggestions for posting:

1. Explain what you have done, preferably in terms of this document.
2. Mention which testing tools you have.
3. Use generic names when referring to components.

If people clearly understand your question without having to refer to paperwork they are much more likely to reply promptly. Compare "I'm using 27k for R101/R201" to "I'm using 27k for RF". Any experienced builder will immediately understand the latter statement to be the feedback resistor on the input stage an will easily be able to reply to your question. Not many builders would recognize this from the reference to R102/R201 without looking at the schematic, and therefore would be less likely to reply to your question.

Comments and Feedback.

Suggestions on improvements to this document are most welcome. Please post them here or contact audiophool.

Overview

Building a complete amplifer is a lot of work. This applies to a Truepath based amplifier as it does to any other ampifier. Along the way there are many options and decisions that have to be made.

The following diagram shows an overview of the process of building a complete amplifier, and highlights where this guideline document fits into the overall process. Please study it carefully.

Maedos Solution

Solutions to many of the options and decisions are already addressed by Maedos. This is called the Maedos Solution. It is described in the following table, along with comparison with with the Base Truepath. Note that Customize, Assemble, Test, and Build, refer to the main steps of the above drawing. They also refer to the main sections of this guideline document.

			Base Truepath	Maedos Solution
Customize		Drawings - SMT Sheet, PCB Overlay, and schematic	All drawings included in the Guidelines	Maedos calculates optimal component values for your system and provides customized drawings based on these
		Customizing Components	Uses components provided in the Trueapth kit	Optimized components provided by Maedos - prefitted to SMT sheet.
			Solved?	Solved?	Refer to
Assemble	Truepath / Optimizing Components	Truepath with pre-wound coils and IRFP4228 MOSFETS. Unassembled, or	No	Yes	<To Do>
		SMT soldering complete and tested, or	No	Yes	OS, OSA, OSAH: S means SMT soldering complete (Refer here)
		Fully assembled and tested	No	Yes	OFA, OFAH: F means fully assemblied (Refer here)
	Accessories	Plugs and sockets for all I/O	No	Yes	Accessories
		Mosfet mounting kits	No	Yes	Accessories
		PCB Standoffs	No	Yes	Accessories
		Gold-plated IC socket for TA3020	No	Yes	Accessories
		Mute jumper	No	Yes	Accessories
		SMT soldering practice kit	No	<To Do>	Accessories
	Tools	Needle nose pliers	No	Yes	Toolshop
		Pick and place tool - tweezers	No	Yes	Toolshop
		PCB Standoffs	No	Yes	Toolshop
		Sidecutters	No	Yes	Toolshop
		Cigarette lighter/ Small gas torch	No	No
		Sandpaper 80 grit	No	<To Do>	Toolshop
		Soldering iron with 1.6 and 2.4 mm tips	No	<To Do>	Toolshop
		Solder 1.2mm for through-hole components	No	<To Do>	Toolshop
		Solder 0.6mm for SMT components	No	<To Do>	Toolshop
		Desoldering iron with 1 and 1.6 mm tips, or	No	<To Do>	Toolshop
		Solder sucker, or	No	<To Do>	Toolshop
		Desoldering Braid	No	<To Do>	Toolshop
Test		Multimeter, or	No	Yes	Toolshop
		Panel meters	No	Yes	Toolshop
		Heatsinks - Correct size, drilled and tapped	No	Yes	Heatsinks
		Test wiring and switching	No	<To Do>	Dashboard
		Test resistors	No	Yes	Accessories
Build		Auxiliary power supply	No	Yes	Tbrick
		Speaker protection	No	Yes	Tbrick
		Front panel indicators, isolated from V5	No	Yes	Tbrick
		Pop supression - Shutdown	No	Yes	Tbrick
		Pop supression - Startup	No	Yes	Tbrick
		Main powrer supply - Capacitor/rectifier circuit	No	Yes	Power supply for VPP/VNN
		Main power supply - Transformer	No	<To Do>
		Main power supply - Soft start	No	<To Do>
		Panel switches, sockets, etc	No	<To Do>
		Ampifier case	No	No
		Amplifer build tools	No	No

 

 

 

The drawings

There are three drawings required to build  the Truepath: the Schematic, the PCB Component Overlay, and the SMT Sheet. In most cases you can click to download a high resolution version of drawings and pictures in this document. Click here for a single hi-res pdf containing the following drawings for Base Truepath: Schematic, PCB Component Overlay and SMT Sheet

Schematic.

There are two pages to the schematic which you can download from the 41Hz Downloads area (you have to buy at least one item from 41Hz before you can do this). Only page one of the schematic is posted in this document. It is posted because the coloured text in this schematic has been added to or modified from the original schematic. In particular, it is the schematic of the Base Truepath.

PCB Component Overlay

The PCB component overlay is the drawing which shows which components go where on either side the PCB.

SMT Sheet

The SMT Sheet is a place to stick components to organize them prior to the assembly stage. It alleviates you from having to organize or find components during assembly and allows you to concentrate on what matters most, ie, fitting the components in the right place and properly. The SMT sheet even contains the relevant information from the BOM, ie, which kit bags the components are located in - for example, how to locate the 33p capacitors is highlighted in this SMT sheet.

Base Truepath

When you get your first Truepath and download the schematic from the forum, you may be a little confused because the component values on the schematic do not match the components in the Truepath kit.  The "Base Truepath" is a Truepath configuration that uses a selection of the components supplied in the kit to provide an amplifier configuration that is suitable for typical applications and for which the values of the components used match the values of the components on the schematic. These are the specifications of the Base Truepath:

• 4 ohm speakers
• 35V RMS transformer which provides a VPP/VNN of +-48V.
• 2Volt RMS source voltage. This is the normal line level that is provided by CD players, sound-cards, and preamplifiers for non-professional equipment. 

All drawings in this document refer to the Base Truepath configuration. If you are building a Base Truepath then you can use the Schematic, PCB Component Overlay, and SMT Sheet directly from this document. In this case, ignore the green text because it is not relevant to the Base Truepath.

Optimization

<To Do : Add detail here>

Assembly

ESD.

Practice normal ESD hygiene as you would for any microelectronics work. Do not worry too much about any of the parts on the Truepath though. None are particularly ESD sensitive.

Coils.

Truepath requires two toroidal coils and these need to be hand wound.Read Jan's document Winding Toroids for the 41Hz Audio Amps for instructions on how to wind the coils.Some supplementary information and suggestions:

• Whilst the design of Truepath calls for 29 turns of wire on each coil, this number is not critical. Some Truepath builders can only fit 26 on and this is fine.
• Before you start winding, draw it through your fingers a few times bending it back and forth to anneal it. The wire will become warm and easier to work. Kinks will gradually disappear. Be sure to pull the wire alternately from both ends to stop the litz from bunching at the ends. Continue to draw the wire each time you pull a winding through so that it stays warm and soft.
• Start winding from the centre of the wire. Wind the 15 turns or so to the end, turn the coil over and then wind the rest of the turns from the other half of the wire. This saves a lot of time.
• There is a reason why people who get sore fingers tend to also have trouble fitting enough turns on. Wind each turn firmly but not tightly.

Preparing Coil Ends

Winding coils comprises several steps: splay, burn, sand, tin, wind, solder. It sounds a bit intricate but overall it saves time because you don't get clumps black stuff that won't solder stuck between the wires. Also, if you don't prepare the wire properly, one or more wires could possibly end up not connected or forming a shorted turn with the result that the current rating of the amp could be reduced.

SPLAY: Before you burn the litz wire, take the time to carefully splay apart all the cores of the litz wire. If you don't splay the threads, the burnt enamel sticks them all together so it's difficult to separate them after burning. Although the following photo shows the wire after the wire has been burnt and sanded, the splaying was done before it was burnt.
 
BURN: Here's the heat gun that I used. You could use something much smaller than this. It only takes a couple of seconds to burn the enamel away. Start from the end of the wire and work inwards until the burnt wire goes most of the way back to the coil. I guess that if you have a gas stove but don't have a gas gun handy, you could actually use the flame from the gas stove itself.
 
SAND: After you burn the wire, you need to sand the wire to remove all the burnt enamel. 100 grit sandpaper works well. You need to individually sand each thread. After sanding the wire should become reasonably copper coloured but it doesn't need to be perfect.

• Brushing with a fine brass wire brush is easier, quicker and does a better job than sandpaper.

TIN: Next you run the soldering iron and solder to tin it over every splayed thread. Soldering flux helps here, or alternatively just add some additional solder for the extra flux it contains.

WIND: Wind the wire so that all the splayed threads wrap neatly back into the wire.

SOLDER: Run the soldering iron and solder over the entire wire. The solder will take to the wire and and a nice shiny lead will result that fits nicely through the PCB hole during mounting.

Set up the SMT Sheet

• Stick the SMT sheet to your workbench:
  • Run a vertical strip of double sided sticky tape on top of the SMT sheet down the "Paste SMT parts here" column. Run a second strip beside the first if necessary to that the full length of  horizontally mounted the SMT strips are stuck to the page. This is important because opening an SMT strip which is not firmly attached will likely flick the parts across the room never to be seen again.
  • Run some double sided tape or glue under the SMT sheet and stick it to the workbench. Be sure that there is tape or glue under the "Paste SMT parts here" column to ensure that the SMT strips are fully secure.
• Take each strip of SMT components and stick it to its allocated place on the SMT sheet using the double sided tape.

Solder the SMT components.

SMT Soldering Video.

This video shows Audiophool's SMT soldering method.

 

 

• Start from the first strip of components. Open the strip (tweezers help here) and using the PCB overlay, transfer each component to it's proper location on the PCB and solder it in place. I find it useful to progressively mark the component locations on the PCB overlay as I place them.

 

• Similarly place and solder all the resistors.
  
• Place all the other SMT components. These are the ESD sensitive components. Take precautions by wrist strap, earth one hand, etc. , but note that there is no known case of any Truepath component being damaged by ESD.
  
  
• Visually inspect these but you don't need to test them. Pay particular attention to those tiny SOT-23 transistors.
  
  
• Your SMT sheet should now be empty.

Fit Through-hole Components

After the SMT components are fitted, solder all the through-hole components to the PCB, in accordance with the PCB Component Overlay.Most through hole soldering is very straight-forward. Here are some notes.

• The over current sense resistors (RS) should be mounted approx. 5mm above the PCB with gently curved leads like the ones in the following picture.
  

 
Picture compliments of tuo 

 

• The power MOSFETs' lead length should be kept to a minimum, but consider how these will be fitted to heatsinks before fitting them.
  
  
• The power MOSFETs have a shoulder that is wider than their PCB pad. Take care to fit the MOSFETs at least 1mm above the PCB.
  
  
• Consider fitting the coils first. It's much easier to fit them before the components around them are in place. Also, it's much easier to solder the coils if you mount them in place with cable ties first.
  
  
• All electrolytic capacitors should face in the same direction.
  
  
• Consider how you will fit the Heatsinks before soldering the C113/C213 CHBR , (the larger electrolytic in the following photo). It may be useful for you to mount these 1mm or so above the PCB as this will enable them to be temporarily tilted back to allow the heatsink mounting screws to be fitted. 

.

.

 

• Be sure to insert C311 in accordance with the red text on the PCB Component Overlay, otherwise the amp may suffer from sticky mute. The following picture shows C311 fitted in the correct direction. You can read more about sticky mute here.

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Learn about Truepath

Watch the video.

If a picture paints a thousand words then this video paints a whole book. Watch it until you understand what happens when the Truepath's four power supplies are switched and how they interact with each other. An understanding of this will help in recognition and diagnosis of faults when the Truepath is being tested. Firstly, here's a photo to show the demo setup. The yellow labels identify the meters for VN10, V5, VPP and VNN. All four supplies have current meters. VPP and VNN also have voltage meters. VN10 and V5 do not have voltmeters; they are fixed at 10V and 5V respectively.
 
The Truepath, which is not shown, has the four power supplies connected to it, and has nothing connected to its inputs or outputs.You can't see the Truepath's mute LED, however, you can tell when it is unmuted because there is current flowing in VN10. VPP and VNN are set for ~40V with current limit at ~200mA.

Initially all power supplies are off. Next the normal power up sequence is followed: V5, VN10, VNN and VPP.

1. Note the 10mA step in V5 (from ~40 to ~50mA)  a few seconds after it is switched on. The 10mA step happens when the Mute Delay Capacitor (C311) charges up enough and the FET turns on. A long delay before this step indicates sticky mute.
2. When VN10 is switched on, only a tiny pulse of current current flows in VN10 as the onboard caps charge. That's because the amp is muted by the under voltage sense (ie VPP and VNN are switched off).
3. After VNN and VPP are both switched on, the amp unmutes. VN10 jumps to 200mA (this current is what the TA3020 is using to drive the MOSFET gates) and VNN and VPP jump to approx. 120mA.

.

Power Up and Test Procedure

Follow this procedure carefully. It is constructed with several ideals in mind.

• Quick and easy to do without sophisticated equipment.
• Minimise risk of damage caused by assembly faults.

Test Resistors.

The power up and test procedure uses the pair of test resistors in series with VPP and VNN to make testing less likely to damage the amplifier by a short on VPP or VNN but they are not essential. If you are assembling a Base Truepath then you can use a pair of 68 ohm 2.5W resistors.

If you are assembling an Optimised Truepath then you will have been supplied with two test resistors.

If you don't use the resistors then you should either:

1. Use low value (200mA or so) SB fuses in VPP and VNN.
2. Use dual bench supply with variable voltage and current. (In fact a bench supply with current limiting function is preferable using either the test resistors or relying on fuses, but most Truepath builders don't have a bench supply)

The resistors ensure that there is enough VPP/VNN current to unmute the amp (approximately 120mA) but not enough to do any damage if something goes wrong and there is a sort. At this current at the Truepath VPP/VNN input terminals will be reduced to ~38V which is the minimum needed to keep the amp unmuted.

Setup for the Test

The test is much easier if you have several multimeters, in which case, use one for each supply. If you only have one then monitor V5 current for the V5 test and - unless mentioned otherwise - VN10 for the other tests. Do not underestimate the hassle of testing the Truepath with its 4 power supplies. It's really difficult to keep a handle on what is happening with all of these power supplies at the same time. A panel of 8 meters would allow you to see what's going on at all times (similar to the above video on Truepath).

Test V5.

 

Part 1: Before TA3020 is fitted.

1. Put in the mute jumper to UNMUTE the amp.
2. Switch on V5.
3. Mute LED is OFF; I5 = 10mA
4. With a spare wire, temporarily short TA3020 socket HMUTE (pin 15) to V5
5. Mute LED is ON; I5 jumps to 30mA for a few seconds and then drops to 20mA. 
6. Switch off V5 and remove temp wire.
7. Insert the TA3020 chip (or solder it in if you have not provided a socket for the TA3020.)

Part 2: After TA3020 is fitted.

1. Switch on V5.
2. Mute LED is ON;
3. I5 current will go to 40mA for a few seconds and then step up to 50mA.
4. Note that the amp will not unmute unless this step occurs.

If there is no I5 step then

• check the mute circuit, particularly the soldering of the little SOT-23 transistors.
• There is a PCB via in the mute circuit between R307 and R309. It's easy to form a solder bridge between of these resistors and the via.
• Read about "sticky mute" and make sure you have C311 in the right way around.

If I5 steps down to ~30mA instead of up, then

• make sure the mute jumper is in.

Test VN10

If VN10 droops then there will not be enough IN10 to properly switch the MOSFETs and a chirping or hissing sound could result. This is noted later in the section Hisses and Hums

.

1. Check that there is no obvious short between VN10 and VNN
2. Next switch on VN10.
3. There will be a little inrush as the cap charges but then the current will quickly drop back to ~0.

Troubleshooting VN10

It is much easier to trace short circuits in VN10 if you follow this schematic excerpt which is centred around VN10; that is, shows where IN10 goes during normal operation. As you read this drawing, remember that the common for VN10 is VNN.

Suggestion - How to Trace a Short on a PCB.

Shorts on PCBs are sometimes difficult to trace, especially if the short is in a power supply rail because in that case there are many possible current paths.

Methods for tracing a short.

1. Carefully inspect tracks on the current path to see if a physical short can be found. Remove any suspicious components which are socketed.

2. Apply a limited current of approx 100mA and take a photo with your camera on infrared mode. The current path of the short will be highlighted in red. (Unfortunately this extremely effective method won't work because cameras don't have infrared mode)

3. Apply a limited current of approx 100mA and trace the current path with a millivolt meter. Consider using an ordinary dressmakers pin as a voltage probe and use it to pierce the solder resist coating.

4. Turn the current up a bit higher and see if anything gets hot.

5. Keep increasing the current until you see smoke. (This can be surprisingly effective. Often it shows you where the short is and clears the short)

6. Trial and error. Cut tracks, component pins, etc.

Test VNN and VPP

1. Mute the amp by removing the unmute jumper.
2. Switch on VNN.
3. There will be an inrush followed by ~1mA. Test resistor should be cold.
4. Switch on VPP.
5. There will be an inrush followed by ~1mA. Test resistor should be cold.

If you touch adjacent MOSFETS simultaneously then you will get a tingle.If current flows here then you have a short or some other fault. Test resistors should protect the amp from damage while the short is being traced, but don't leave the offending rail switched on for more than 30 seconds or so.

1. Unmute the amp.
2. Within a second the mute LED will go off and VN10 current should jump to ~200mA.
3. Touch the MOSFETs.
4. MOSFETs will get warm as IPP and INN are ~80mA for IRFP4321 and IRFP4228 (~120mA for STW34NB20 MOSFETs)
5. Switch off.

Suggestion - Tracing short circuts in the output circuit.

It is much easier to trace short circuits in the output circuit if you follow this schematic excerpt which is centred around the VPP and VNN; that is, one which clearly shows where IPP and INN can go. The thick lines show where most of the current flows during normal operation.

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Some faults in the output circuit are difficult to find. There are many variables which interact with each other and often it's difficult to tell if you are looking at the cause or merely an effect of the fault.

Fault-finding guide.

Symptom	Fault	Solution
When unmuted:INN=IPP and not approx 120mA	BBM jumpers not or wrongly fitted.	Check that they are fitted as indicated on J2 and J3 on the component overlay.
When unmuted: - Mute LED goes off as expected. - IN10 = 0	VBoot circuit not working	-If you are using VPP/VNN test resistors make sure that the resistor is connected as shown in this diagram. If VN10 is connected to the right side of the resistor then the resistor will cause a voltage drop in the VN10 circuit. -Measure VBootn between TA3020 pins VBOOTn and HOnCOM,  where n= 1 and 2. - Both VBoot1 and Vboot2 must be ~10V. - If not, find the fault in the boot circuit.When the TA3020 is unmuted it sends 20 pulses to the gate of each low side MOSFET. In this time, each Vboot should charge. If it doesn't then the TA3020 output stops as if it were muted, but the mute LED does not come on.If the pulses don't happen when the TA3020 is unmuted (you need an oscilloscope to check this) then the amp is comatose. There is no definitive cure for a comatose Truepath, but socketing the TA3020 may help. Please post about your problem here.
When muted or unmuted and load connected: - High IPP or INN. - One heatsink hot.	Defective MOSFET - partial short.	Find the RS that has voltage across it when muted. The associated MOSFET is defective.
When unmuted: - High but equal IPP and INN. - One heatsink too hot.	Defective MOSFET - switching time too slow causes too much shoot-through	Use an oscilloscope to observe the shoot-through by monitoring the voltage across RSs: OR Simply replace one MOSFET on the hot heatsink. There's a 50% chance that this will be the faulty one. If it isn't then replace the other MOSFET.
When unmuted: - High IPP or INN. - One heatsink gets hot.	510k MOSFET gate pull down resistor (R118/218/119/219) is open circuit, eg from dry solder joint	With power off, ensure that there is 510k between the MOSFET gate (or either side of the gate resistor, RG) and GND.

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Set Offset Adjust

Next, remove the test resistors, add the heatsinks.

1. No signal on input
2. After 10 minutes' warm-up time the offset on each channel rises by ~6mV. You can either (1) ignore this because it's such a small amount (2) run the amp for 10 minutes before doing the adjustment or (3) set the offset to ~-6mV with the amp cold.
3. Put your most accurate voltmeter across Channel 1 output (ie J101-1 and J101-2)
4. Power up the Truepath.
5. There will be approx 2V on the output.
6. Turn the offset adjust POT (R104) to minimise the offset. <10mV is ideal.
7. Switch the Truepath OFF.

Repeat the above steps for Channel 2, ie J201 and R204.

 

Hisses and Hums

1. Switch off the power, connect speakers and audio source.
2. There may be a pop when the Truepath unmutes. This is annoying but normal unless you have fitted pop suppression circuitry.
3. With the source switched off the speakers should be completely silent. 

If there is a hiss, hum or other strange sound:

1. If the noise disappears at when you disconnect the input wires then ensure that the input wires are kept well away from the speaker wires.
2. If the noise disappears when you unplug the input signal cable from the source equipment then you may have a ground loop. Often this is caused by a short across the heatsink insulator on either the V5 or VN10 regulator.
3. These noises are often caused by soldering problems in the output stages of the amp, particularly the soldering of the coils.
4. Check that VN10 remains at >9V when the amp is unmuted (if not, the MOSFETs will not be switched properly). Manifestations of this "droopy VN10" problem include
   1. After unmute the amp works OK for 1 second before the noise starts. (In this case VN10 is maintained for a second by the VN10 bulk cap)
   2. After a second of the noise, the amp goes silent but doesn't mute. (because VN10 drops below the MOSFET gate threshold.)
5. Did you carefully check connectivity of each SMT component per the section Fit the SMT Components ? Buzzes and hisses can be caused by soldering errors in the output section of the Truepath
6. Jan's document Troubleshooting AMP Kits from 41Hz Audio has a good section on Noise

Load Test.

Listen to music at normal volume for a while.

• Heatsinks, TA3020 chip, and the coils will get warm.
• Check that the Heatsinks are the same temperature
• Check that the coils are the same temperature.

Listen to music at high volume for a while.

• Check heatsinks and coils as with the normal listening test, above.

If the amp mutes and unmutes before it reaches high volume then

• There may be  a problem with the overcurrent sensing. Post on the forum about this.

Final Step: Enjoy the music.

Happy listening.

Building a Complete Amplifier Around Truepath.

To make a complete amplifier from Truepath means provision and connection of heatsinks, enclosure, power supplies, internal wiring and other optional functions including speaker protection, pop suppression, synchronization of multiple Truepaths, balanced amplifier, balanced signal receiver and so on. In fact there are so many options that it is unlikely that any two amplifiers will end up exactly the same. Following are a few examples of different amplifier configurations that have been tried and tested.
Warning: High voltage electricity is dangerous. Working on the primary side of a transformer could kill you and depending on where you live is likely to be illegal. Always consult a qualified person.

41Hz Basic Configuration.

This is called "Basic" because it uses components originally supplied by 41Hz to build the amplifier.The components are PSU1-PS, PSU1-VR, PSU1-SS. This picture was kindly produced by ThomasEliot. ThomasEliot has carefully provided wiring connections between all PCBs. This is a proven configuration which is highly suitable for a first Truepath based amplifier.

Picture compliments of thomaseliot

Tbrick Configuration

The Tbrick is designed for small size whilst maximizing sound quality. It's also designed to be simple to build; notice that only six wires are required apart from the ones that are integral to the transformer. It can also be used in in active speakers. The Tbrick comprises two auxiliary boards that provide additional functionality to the Truepath. These additional functions are V5 and VN10 power supply, and speaker protection.

SMPS Configuration

Acknowledgments

Sincere thanks to Jan for running 41Hz. Thanks to Benn for designing the wonderful Truepath. Thanks to everyone who stood by me and my long-suffering comatose amps. Thanks to all members who contribute to the forum to make it a positive learning and enjoyable place.