You don't need any gain from the driver stage but you will need U3 as it handles the global feedback from the drivers - the first two opamps and their surrounding resistors can be left out as they wouldn't be needed in your case unless you wanted a balanced input, in which case the R3 change I mentioned would be required.vinylnvalves wrote: ↑Tue Mar 06, 2018 6:10 am I think I may not have expressed to question well. The output stage in the DSP is an Opamp gain stage(in mine I am using OPA627’s), why do I need to add another Opamp stage before the current buffer output stage If I can live with 6V ? The DSP and power amps won’t be in the same box but are close, so was ignoring any cable length effects.
3W amps - options: SS which sounds as good as DHT’s
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#31 Re: 3W amps - options: SS which sounds as good as DHT’s
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#32 Re: 3W amps - options: SS which sounds as good as DHT’s
Maybe I am being thick but I don’t see any feedback to u3 from the paralleled buffer.
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#33 Re: 3W amps - options: SS which sounds as good as DHT’s
Look at R8...vinylnvalves wrote: ↑Tue Mar 06, 2018 8:03 am Maybe I am being thick but I don’t see any feedback to u3 from the paralleled buffer.
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#34 Re: 3W amps - options: SS which sounds as good as DHT’s
More blind than thick. Need to get this schematic with a white background so I can see it.
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#35 Re: 3W amps - options: SS which sounds as good as DHT’s
Not thick at all - all very sensible questions. It's interesting that if you look at the schematic in detail, the part he's used is the AD797 which is pin-compatible, so he changed it later to the LME part or basically he couldn't be bothered to create a new part.vinylnvalves wrote: ↑Tue Mar 06, 2018 8:22 am More blind than thick. Need to get this schematic with a white background so I can see it.
Last edited by jack on Tue Mar 06, 2018 8:27 am, edited 1 time in total.
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#36 Re: 3W amps - options: SS which sounds as good as DHT’s
Answers my question about a deleting the input stage, need it for feedback.
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#37 Re: 3W amps - options: SS which sounds as good as DHT’s
I am not an IC aficionados so would not know if an AD797 is better than the LME49990. I had thought of using the Burson discrete ones as they cost about the same as the discontinued LME49990’s. They are limited to +/-15v. So would have had to drop the voltage to the input stage or reduce it across everything.