Hi,
I've in the process of testing my new Tripath Class D amp (TC2001).
Design is based off the 41Hz Amp 4 schematic.
I've gone with GaN output transistors mainly because they don't have any reverse recovery so have much cleaner switching transitions.
Output filter is still a work in progress - currently running at 26uH inductor into C0G ceramics with the posibilty of adding a film if needed. Running at about 30kHz low pass as this will be used for a mid speaker (60-1.2kHz). Currently no Zobel which is why you can see a peak at 30kHz in the FFT. If anyone has any tips on filter implementaiton let me know. Scope is only 8-bit so can't measure accurately below about -60dB.
First test is into a 4R resistive load. I'll try running them into speakers later on this week when I'm happy with the performance.
I've in the process of testing my new Tripath Class D amp (TC2001).
Design is based off the 41Hz Amp 4 schematic.
I've gone with GaN output transistors mainly because they don't have any reverse recovery so have much cleaner switching transitions.
Output filter is still a work in progress - currently running at 26uH inductor into C0G ceramics with the posibilty of adding a film if needed. Running at about 30kHz low pass as this will be used for a mid speaker (60-1.2kHz). Currently no Zobel which is why you can see a peak at 30kHz in the FFT. If anyone has any tips on filter implementaiton let me know. Scope is only 8-bit so can't measure accurately below about -60dB.
First test is into a 4R resistive load. I'll try running them into speakers later on this week when I'm happy with the performance.
Attachments
Finally got around to adding the zobel network (15.7R + 47nF cap) with an amobeads in each capacitor leg.
The idea of using amobeads was to supress the high frequency losses in the zobel resistors (everthing above ~300kHz) although other magnetic materials may be more suitable - it's just what I had on my desk.
The zobel has managed to get rid of the 30kHz filter resonance even with high impedance loads (15R).
I noticed that the output stage gain is a bit high when running from a 24V supply so this could be tweeked to improve SNR by a few dBs.
Next stage is to test with xover and speaker, and then to put it all in a box.
Let me know what you think of my progress or if anyone wants schematic or PCB layouts
The idea of using amobeads was to supress the high frequency losses in the zobel resistors (everthing above ~300kHz) although other magnetic materials may be more suitable - it's just what I had on my desk.
The zobel has managed to get rid of the 30kHz filter resonance even with high impedance loads (15R).
I noticed that the output stage gain is a bit high when running from a 24V supply so this could be tweeked to improve SNR by a few dBs.
Next stage is to test with xover and speaker, and then to put it all in a box.
Let me know what you think of my progress or if anyone wants schematic or PCB layouts
Attachments
Cool project for such an old chip. I think I still have some TC2001, but I don't need another amplifier.
First sweep with REW - no EQs in place apart from the crossover. The subwoofer is a generic car audio 12" sealed speaker and the other speaker is a Tannoy i8. Subwoofer looks low (but sounds good) as the microphone is placed 15" in front of the Tannoys and the subwoofer is in the corner of the room. I might adjust the crossover points to reduce the 70Hz hump (from the Tannoy ported enclosure resonance)
