PA Discrete Class D Amplifier Schematic

[kartino]

This is working schematic. A Discrete Class D with 2 sets of mosfet at 90Vdc supply will give you enough power to drive 18" speaker at pretty loud.

Don't ask layout
Don't commercialize
Try if you like, as it is. Don't try if you doubt it.

Ltspice file is attached.

Regards,
Kartino

 

[kartino]

The amp. All general discrete part can be found everywhere

 

[kartino]

Output ripple, showing well. As well as showing speed at about 300kHz, fine for PA Amplifier.

 

[mbogdan]

Anyone know what schematic values need to be modified for a lower supply voltage. Say 2x40 - 2x50 volts.
I've built one of these, it doesn't work at these voltages.

So far, I've lowered R22 and R23 to about half value, but still i can't get it to work.

 

[odnaizutra]

good work Kartino.

 

[odnaizutra]

This kind of protection ,sometimes kicks in because of big decoupling cap value.

 

[odnaizutra]

Did you had any trouble about this?

 

[Mark Tillotson]

Surprized the 555 wasn't discretized too!

 

[ICG]

Surprized the 555 wasn't discretized too!

Discrete circuits got the advantage that you can repair them even after decades. The feedback after the output choke is a plus too. A more elaborate protection would be quite useful though for PA use.

 

[Reactance]

Surprized the 555 wasn't discretized too!

Are you serious? Have you seen the cost of a low propagation delay, fully differential comparator over a 6 transistor discrete design.?

 

[kartino]

Are you serious? Have you seen the cost of a low propagation delay, fully differential comparator over a 6 transistor discrete design.?

I have it
But consider cost and footprint 555 is better choice
The same reason for prestage op amp.

 

[kartino]

This kind of protection ,sometimes kicks in because of big decoupling cap value.

Never
This is first version ever I have my own UcD pro.
Later version including fullbridge UcD also very stable.

 

[jkuetemann]

Wanted to try this, sim first.

Kartino,


I am trying to simulate your design in post 1, for the purposes of the sim leaving out the protection and font end buffers, and am getting a completely intractable -12 or so offset on the output. I am also using 80V supplies as I have several transformers that would give that voltage after rectification and filtering. I have experimented with different transistor types but that doesn't seem to matter, nor does the offset adjustment seem to do anything.


Would yo mind taking a peek at the schematic and see if I'm just blind to a mistake or if you can offer some suggestions on ridding the sim of the offset?

 

[jkuetemann]

N'er mind. Found my bone-headed mistake.

 

[NMOS]

N'er mind. Found my bone-headed mistake.

does it work stable now ?

 

[jkuetemann]

Seems to, but then I'm a real newb when it comes to Class D. My historical experience is with Class A / AB. Was looking for a (mostly) discrete design and this caught my attention.

 

[NMOS]

Seems to, but then I'm a real newb when it comes to Class D. My historical experience is with Class A / AB. Was looking for a (mostly) discrete design and this caught my attention.

Does Cartino discret working stable same like D4K5 ?

Who does build this discret Class D Amp ?

Feedback ?

 

[mbogdan]

I did buid one based on OP's schematic. I'm however having some problems with it.
At +/- 90V, it seems to distort at about 20-30W output power and when probing with a scope before the output filter, it seems I'm loosing modulation for a fraction of a second - while the amp distorts sound.
Can anyone point me on what to check to fix this behaviour?

 

[kartino]

I did buid one based on OP's schematic. I'm however having some problems with it.
At +/- 90V, it seems to distort at about 20-30W output power and when probing with a scope before the output filter, it seems I'm loosing modulation for a fraction of a second - while the amp distorts sound.
Can anyone point me on what to check to fix this behaviour?

Please post your schematic exactly as real kit

 

[kartino]

Does Cartino discret working stable same like D4K5 ?

Who does build this discret Class D Amp ?

Feedback ?

Mine very stable for live performance