Hello everyone, I have an amplifier USBLASTER USB3003, I'll use it as a guinea pig to turn this into a full-range Class D.
The amplifier uses the original IRF640 MOSFET on the high side that is on the low side.
Using a driver card very similar to that of hollywood HXA3K.
My idea was to change the low-pass filter output, adapting frequency up to 20khz.
I already did some testing:
- I isolated the preamp section on board.
- I created a preamplifier built apart and I injected her audio signal directly into the amplifier driver board.
- I re-wound the inductor of the filter using the same enameled copper wire, changing the number of turns.
- I replaced the filter capacitors with a polyester specially calculated capacitor.
Everything else, for now remained unchanged.
Currently the amp sounds good in full range, but there is a serious problem:
the low-pass filter inductor becomes very hot after only 5 minutes of use at moderate volumes and more minutes pass more heats, to become really hot.
I noticed that the filter becomes hot even without audio signal.
I've never done such alteration of a Class D subwoofer, for this, I ask you, what else you would you change?
I have attached some pictures.
The amplifier uses the original IRF640 MOSFET on the high side that is on the low side.
Using a driver card very similar to that of hollywood HXA3K.
My idea was to change the low-pass filter output, adapting frequency up to 20khz.
I already did some testing:
- I isolated the preamp section on board.
- I created a preamplifier built apart and I injected her audio signal directly into the amplifier driver board.
- I re-wound the inductor of the filter using the same enameled copper wire, changing the number of turns.
- I replaced the filter capacitors with a polyester specially calculated capacitor.
Everything else, for now remained unchanged.
Currently the amp sounds good in full range, but there is a serious problem:
the low-pass filter inductor becomes very hot after only 5 minutes of use at moderate volumes and more minutes pass more heats, to become really hot.
I noticed that the filter becomes hot even without audio signal.
I've never done such alteration of a Class D subwoofer, for this, I ask you, what else you would you change?
I have attached some pictures.
Attachments
wow!
Unfortunately, the driver board is covered with a black mastic material.
I would not know how to remove the material without the risk of breaking the Driver board.
I admit that I can remove that material, in your experience, you could change the switching frequency by varying some resistor or capacitor?
Unfortunately, the driver board is covered with a black mastic material.
I would not know how to remove the material without the risk of breaking the Driver board.
I admit that I can remove that material, in your experience, you could change the switching frequency by varying some resistor or capacitor?
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