@amirm When do you think you will find time to repeat the measurements of the D10 with OPA1612 and the other op amps guys sent you?
Btw, Topping just confirmed that the replaceable Op amp is doing the filtering. That means its impact on signal is not as high as those 2 op amps doing I/V conversion but it is still on the signal path, so it makes sense to measure what will happen if it is replaced with the op amp with better specs.
Here is a nice article where different op aps have been tested acting as I/V converter and LP filtering, OPA134 (single version of OPA 2134) being one of them. According to the author, this I/V and LP circuit was meant to be at the output of the DAC in a CD player:
https://www.by-rutgers.nl/IV-converter.html
Keep in mind that LME 49710/49720 has come to end of life and that OPA1612 has much better specs, which explains why Topping chose it for D50 and DX7s.
Btw, Topping just confirmed that the replaceable Op amp is doing the filtering. That means its impact on signal is not as high as those 2 op amps doing I/V conversion but it is still on the signal path, so it makes sense to measure what will happen if it is replaced with the op amp with better specs.
Here is a nice article where different op aps have been tested acting as I/V converter and LP filtering, OPA134 (single version of OPA 2134) being one of them. According to the author, this I/V and LP circuit was meant to be at the output of the DAC in a CD player:
https://www.by-rutgers.nl/IV-converter.html
Keep in mind that LME 49710/49720 has come to end of life and that OPA1612 has much better specs, which explains why Topping chose it for D50 and DX7s.
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