I finished with my surgery and ready to start with this project. I ordered proto PCB, have to decide what to use for low voltage power supply, for high voltage I'll use temporary an old linear power supply. Later I will use switching PS, but not yet decided about type.
Attached linear power amp board.
Damir
Attachments
Hi John,
Thank you for interest. I have now high voltage LLC switching power supply (+- 60V) and missing low voltage power supply (+- 6V) to proceed with this project. I tried to find switching power supply solution for low voltage but with no success and now I will do linear one with transformer. All other necessary parts I have. There even ready other version of this amp, ClassA driven by ClassB (PCB ) so I will try both.
BR Damir
Damir, I just read (part of) this thread after our exchange.
While I worry , as you imagine, with the phases and delay differences you will encounter with the two amp, I had an idea that is may-be stupid. There is always a remaining trace of the class D switching frequency after its filter. My idea is to extract-it and use the feedback of the class A amp to cancel-it further (as much as possible).
Just my two cents.
Using a SMPS for the Class A, in this situation, do not seem anyway a good Idea to me. If its frequency is close enough to the one of the class D, there is a risk of beat in the audio range, A linear will ensure it will be far away in frequency.
The other solution should be to use the same oscillator for the two.
Now, you are in SMPS and Class D stuff .... I believe a lot of stuff to discover and learn. Good luck.
While I worry , as you imagine, with the phases and delay differences you will encounter with the two amp, I had an idea that is may-be stupid. There is always a remaining trace of the class D switching frequency after its filter. My idea is to extract-it and use the feedback of the class A amp to cancel-it further (as much as possible).
Just my two cents.
Using a SMPS for the Class A, in this situation, do not seem anyway a good Idea to me. If its frequency is close enough to the one of the class D, there is a risk of beat in the audio range, A linear will ensure it will be far away in frequency.
The other solution should be to use the same oscillator for the two.
Now, you are in SMPS and Class D stuff .... I believe a lot of stuff to discover and learn. Good luck.
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Tryphone, this is uncharted territory for me and I am excited with what I can find there.
Thanks for interest,
Damir
I need +-6V (or +-7V) 15A and middle will be driven by ClassD amp. What mosfet is doing here, could you explain?
By the way all that low voltage SMPS are for LED, not sure good enough for audio.
Dual +/- low voltage supply is hard to come by but good quality 12V and 15V PSU for medical use are readily available.
The MOSFET is holding a low impedance voltage reference V_COM at ~6V above V_DD to serve as connection point to Class D amplifier. Seems to work fine when tried in LtSpice. Any comments?
The MOSFET is holding a low impedance voltage reference V_COM at ~6V above V_DD to serve as connection point to Class D amplifier. Seems to work fine when tried in LtSpice. Any comments?
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Have you tried this in real life, not only simulation? I'm warried how stable is power supply middle point.
I have ready a PCB where instead of ClassD a ClassB amp is used, similar what you showed here.
No, nothing built yet, that's why I'm asking your opinion in case you have any suggestion or cautions for possible pitfalls and problems. You do not think it could work well enough?
I don't have opinion yet, I have to try it first.
Could you suggest good 12V or 15V 15A SMPS, not those used for LED?
