Class-D build walk me through it. [Archive] - Audio & Video Forums

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BoJonJovi
11-03-2013, 08:39 AM
Could you guys/gals kinda walk me through a class-d build. I completed a basic amplifier kit from class-d audio (board, toroidal, power module) and it works great. I purchased the basic kit then purchased separately inputs, outputs, on/off switch etc. from Parts Express. I could simply order another kit but I really would not add much to my "current" knowledge; pardon the pun.
I would like to do another class-d build using something like Parts Express TAS5630 or IRS2092. Although I built the basic classdaudio kit I really do not have a thorough understanding of how to choose or how the individual parts interact, particularly amplifier board, toroidal transformer and power supply. What does each do and how do you select parts for a particular amplifier board.
I suspect someone might say well research it and you will learn a bunch.
The truth is I have spent hours on the net reading and still do not have a clear understanding or how to select these basic parts and how they interact. Many sites on the web are way too detailed going deep into the builds or not detailed enough for me to select parts on my own. I just need basics. I am not trying to build one from a circuit board up.

I plan to take this class
https://www.coursera.org/course/powerelectronics
to increase my knowledge but I could really use a little help now as I would like to go ahead and start another build. I do not need help with speaker outputs, inputs or the stuff you see on the outside off the chassis. Basically I just need help with the big three power supply, toroidal, and amplifier; how to select and basics on what is happening to the current as it moves from one to the other.

It would be great if someone could walk me through the current flow such as from 115 current power goes to toroidal transformer and is ....then goes to power module and is....then to amplifier and is.....

This is how you choose and match each to the other and briefly why.

I know I could just buy a SMPS and and the board and be done with it but once again I would not learn much beyond plug and play.

Considering the amount of time I have spent trying to find a simple explanation such as this I am sure many would benefit. I for one would be deeply appreciative.

Feanor
11-03-2013, 12:10 PM
I don't know a lot more than you do and I'm sure there are a few around here who do. But I think your understanding is on the right track. Be careful: electronics are unforgiving and if you do something wrong you can destroy components or kill yourself.

I understand that you need at minimum an amp module and a power supply as well power and input and output connectors, fuses, wiring, and a case. AB amps usually also require heat sinks.

The amp module is key because it's what determines the power supply and other requirements. As an untrained hobbyist, stay away from any amp module that lacks documentation you can understand or that seems incomplete.. Some amps require slow-start or muted-delay circuits; (the Class D Audio modules don't need these as whatever is need is built-in).

Sometimes the amp module has its own, complete PS; sometimes it needs a transformer but is otherwise complete; sometimes it needs one or more separate PSs. If more than one PS is required, it's usual that one is high output while the other(s) is/are lower powered with a different output voltages. (Some tube amps require three different output voltage & current supplies).

The power supplies are generally two types: linear and switching mode (SMPS). The linear type, in turn, maybe regulated or unregulated, and will consist at minimum of a transformer and PS module that does AC to DC rectification, and regulation ICs if required. It might or might not provide an input (AC) fuse and/or output (DC) fuses. In an simple, unregulated power supply, the amp module's voltage requirement will determine both the PS module and the transformer specifications; the PS' output will be 1.4x the transformer's output voltage.)

Typically an SMPS are self-contained, including whatever transformer, rectification, and regulation and switch mode circuitry as required. An SMPS might also include a "slow start" and/or muting delay circuit.

Rod Elliott's website includes a great deal of general info about amp and power supply design ... see HERE (http://sound.westhost.com/).

A source for amp and PS modules and related components is Connexelectronic.com (http://connexelectronic.com/). Some, (not all), of their amp modules come with relatively comprehensive descriptions & instructions.

BoJonJovi
11-05-2013, 07:32 PM
I think it is slowly making sense. I am kinda slow after all.
So if I wanted the Parts Express TAS5630 2 x 300W of Class-D power
Great for use as a subwoofer amp and with tactile transducers
Over-engineered protection circuits
Robust heatsink with two-stage fan
Requires 20 to 50 VDC power supply

This is how things come together.
House current 120AC comes into a toroidal transformer and the AC current is either raised or lowered by the transformer. It does not change it from AC to DC it simply changes the voltage. So for the above Parts Express amplifier I need a voltage of 20-50VDC.

A simple Power Supply converts one form of power to another form of power. In my case I want to go from AC to DC. The power Supply will also increase input power from the toroidal transformer by 1.4.
To get the right volts DC, I take 50/1.4=35.7
I also take 20/1.4=14.3

So I need a toroidal transformer that will take my 120v AC house current and step it down to somewhere between 35.7 AC to 14.3 AC.

The Power Supply will then take the stepped down current from the toroidal transform, convert the AC current to DC current and raise it by a factor of 1.4.

So I would like to keep my DC current high for the amplifier to make sure it does not run out of OOmph so I would be looking at a toroidal that changes the 120 AC to around 35 AC.

I think the Antec 4434 400VA Audio Toroidal Transformers would be a good match providing:
Outputs 4x
Power 400VA
Output Voltage Current
34V 5.9A
34V 5.9A
15V 2A
15V 2A
Antek - AS-4434 (http://www.antekinc.com/details.php?p=705)

I also think the 4430 would be a good match providing:
Outputs 4x
Power 400VA
Output Voltage Current
30V 6.7A
30V 6.7A
15V 2A
15V 2A

I also like the Antec 3434 300VA Audio Toroidal Transformers providing:
Outputs 4x
Power 300VA
Output Voltage Current
34V 4.4A
34V 4.4A
15V 2A
15V 2A

Probably the best amp would be the Antec 6435
Electrical Characteristics
Outputs 2x
Power 600VA
Output Voltage Current
35V 8.6A
12V 2A
18V 2A

I like that these transformers have 4 outlets so I could add another power supply and amplifier on each output or more down the road. This would mean on the ext board I could save a little mula.

From the Antec 6435, a 35 V AC current would go to the Power Supply and be increased by 1.41 and converted to DC current and come out of the PS as 49.35 V DC.


The power supply I would select for this little exercise is the ClassDAudio Power Supply.

From there website,
"This DC Power supply operates up to +/- 75 volts. Huge filter capacitance of 28,200 (14,100 microfarad per side) significantly reduces ripple. Two blue LED power indicators. This power supply is suitable for all of our amplifiers. Comes with 3 watt bleeder resistors, 8 Amp 800V rectifier, large 100V 105 degree capacitors, so with larger bleeder capacitors can handle up to 85 volts. Size: 4.5" D X 4.25" W X 2.25" Tall. You will need a transformer with either center tap or dual seconderies. You can calculate the voltage the power supply will put out by multiplying the transformer secondaries by 1.41... example: if your transformer has 30 volt secondaries, multiply 30 X 1.41 = 42.3 volts. "

This power supply goes up to 75 volts so the 35 volt Antec should not be a problem.

I think I understand what I am doing and why. I still have a question on amperage. How important is it? I do not see the class-d amplifier boards specifying what amperage they operate at. I would hate to burn up the amplifier board from having too much or too little amperage.

I guess the study continues for a bit longer.

Feanor
11-10-2013, 04:07 PM
I think it is slowly making sense. I am kinda slow after all.
So if I wanted the Parts Express TAS5630 2 x 300W of Class-D power
Great for use as a subwoofer amp and with tactile transducers
Over-engineered protection circuits
Robust heatsink with two-stage fan
Requires 20 to 50 VDC power supply

This is how things come together.
House current 120AC comes into a toroidal transformer and the AC current is either raised or lowered by the transformer. It does not change it from AC to DC it simply changes the voltage. So for the above Parts Express amplifier I need a voltage of 20-50VDC.

A simple Power Supply converts one form of power to another form of power. In my case I want to go from AC to DC. The power Supply will also increase input power from the toroidal transformer by 1.4.
To get the right volts DC, I take 50/1.4=35.7
I also take 20/1.4=14.3

So I need a toroidal transformer that will take my 120v AC house current and step it down to somewhere between 35.7 AC to 14.3 AC.

The Power Supply will then take the stepped down current from the toroidal transform, convert the AC current to DC current and raise it by a factor of 1.4.

So I would like to keep my DC current high for the amplifier to make sure it does not run out of OOmph so I would be looking at a toroidal that changes the 120 AC to around 35 AC.

I think the Antec 4434 400VA Audio Toroidal Transformers would be a good match providing:
Outputs 4x
Power 400VA
Output Voltage Current
34V 5.9A
34V 5.9A
15V 2A
15V 2A
Antek - AS-4434 (http://www.antekinc.com/details.php?p=705)
...

I like that these transformers have 4 outlets so I could add another power supply and amplifier on each output or more down the road. This would mean on the ext board I could save a little mula.

From the Antec 6435, a 35 V AC current would go to the Power Supply and be increased by 1.41 and converted to DC current and come out of the PS as 49.35 V DC.


The power supply I would select for this little exercise is the ClassDAudio Power Supply.

From there website,
"This DC Power supply operates up to +/- 75 volts. Huge filter capacitance of 28,200 (14,100 microfarad per side) significantly reduces ripple. Two blue LED power indicators. This power supply is suitable for all of our amplifiers. Comes with 3 watt bleeder resistors, 8 Amp 800V rectifier, large 100V 105 degree capacitors, so with larger bleeder capacitors can handle up to 85 volts. Size: 4.5" D X 4.25" W X 2.25" Tall. You will need a transformer with either center tap or dual seconderies. You can calculate the voltage the power supply will put out by multiplying the transformer secondaries by 1.41... example: if your transformer has 30 volt secondaries, multiply 30 X 1.41 = 42.3 volts. "

This power supply goes up to 75 volts so the 35 volt Antec should not be a problem.

I think I understand what I am doing and why. I still have a question on amperage. How important is it? I do not see the class-d amplifier boards specifying what amperage they operate at. I would hate to burn up the amplifier board from having too much or too little amperage.

I guess the study continues for a bit longer.
Well I'm not tech expert but what you say all sound correct to me but it you can verify this stuff from other source so much the better.

As for the the transformer, you need the correct voltage and a single of dual outputs as required by the PS rectifier module, e.g. 35-0-35 center tap or 35-0 + 35-0 dual secondaries as mentioned for the CDA PS. To the best of my knowledge, if the transformer's rated maximum amperage is higher than the PS module's, there is not danger or problem; the current draw will be limited by the output voltage plus the internal impedance of the PS+amp modules.

With the Parts Xpress to power a subwoofer, I think I'd just go with at SMPS.