Re: sch
Your english is quite alright. 
Are you really usre about the parallel connection?
Don't you need any resistors in series as the rest of the world does?
I haven't seen any signs of this yetbbp said:my english is so so so poor
Your english is quite alright. Are you really usre about the parallel connection?
Don't you need any resistors in series as the rest of the world does?Re: Re: sch
The post#1 shows the real schematic ,and post#3 only shows the theory,not the one I really want to build
😉
On the PCB, I will use 4 * 0.47-1 omega resistors on each board.
bbp said:my english is so so so poor
peranders said:
I haven't seen any signs of this yet
Are you really usre about the parallel connection?
The post#1 shows the real schematic ,and post#3 only shows the theory,not the one I really want to build
😉
On the PCB, I will use 4 * 0.47-1 omega resistors on each board.
Have you really tested to connect the inputs of LM1876 they way you do? 
I really suggest you take a look at AN-1192!
http://www.national.com/an/AN/AN-1192.pdf
I really suggest you take a look at AN-1192!
http://www.national.com/an/AN/AN-1192.pdf
......
Many thanks for your suggestion,actually I have not test it before,I made the schemartic through my experience,but I will test the circuit later,and then make a report .
Many thanks for your suggestion,actually I have not test it before,I made the schemartic through my experience,but I will test the circuit later,and then make a report .
It will most likely not work when you connect the inputs in parallel. Why don't you try it with a couple of normal opamps first?
Hi,
each of the balanced inputs sees a resistance of 22k//680r=660r
Is your pre-amp able to drive 680ohm impedance to about a volt to get maximum output?
Have you considered where the input offset currents flow?
each of the balanced inputs sees a resistance of 22k//680r=660r
Is your pre-amp able to drive 680ohm impedance to about a volt to get maximum output?
Have you considered where the input offset currents flow?
AndrewT said:
Many OP can drive 600ohm impedance easily, for example,LM4562
But I have not considered the input offset before, that's really a problem...
🙁
Thanks
I agree that many opamps can drive 600ohms but NOT easily.bbp said:
I think only a few can achieve good 600ohm capability.
Check how much distortion degrades as load impedance is lowered.
Remember also that the NFB is parallel to the output and both must be driven. Then add a bit of extra current feeding any parallel capacitance (this reduces the HF impedance even further).
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