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Hello John,thank you for the detailed reply. So yes, I brought up the topic because of my phono stage. It's a simple one, and I was curious to see if at all possible to improve it. To remove/replace those 2 electrolytic caps in the signal path and, looking at the active EQ section, to replace the resistors with transformers. Is it possible with this type of opamp phono stage? I think it would be interesting to see how good a single opamp based phono can sound... this is why I brought up the topic.-Herman
Pete,>>The circuit could also be reworked somewhat and those bigger caps replaced with 1uF caps. That would take a small change to the feedback network around the op amp, but the cost is only a single additional resistor.How would I do that with a single additional resistor? Then the 470uf and 47uf can be substituted with 1uf film caps? Maybe it's worth it... need to try.Thanks. Herman
Hello Pete,I am glad I found another phono schematic. Before I post my sketched diagram of your described modifications (I'm working on that) I would like to point out that this new schematic is of a famous (and reliable) mixer Xone 62 -- industry standard for sound quality for what it is. It is also a Single opamp but I believe they are doing what you propose, already. I see no coupling caps in the signal path, compared to the previous schematic. It seems this second one is a better phono, no? Better opamp, no caps, is this the best one can do with a single opamp? Can I then eliminate all coupling caps in the previous phono schematic in a similar way? In other words can I use this for ideas to incorporate into my phono? regards,Herman
Dear Pete,Going back 2 posts, I drew up the modified (per your instructions) schematic. Please take a look and verify that I understood correctly. If so I will proceed with both channels, I have the needed parts to do this. Only showing one channel mods for clarification.Also, can I simply omit the (1uf) output cap, as done with no issues in the other, posted above, schematic? Or do you still recommend to keep it?best regards,Herman
Dear Pete,Like this?I updated R121 to 150ohms, but can do any value now that I am changing it. As far as the stock opamp -- it's mc4580. http://www.unisonic.com.tw/datasheet/MC4580.pdfIs there any point of replacing it with NE5532? Just going to be a different sound, not necessarily better? Should I bother with this, in you opinion?Thank you for all the help! I am looking forward to comparing stock with your mods, and plan to clearly post my findings.Best regards,Herman
The OPA1611 or OPA1612 with 1.1-nV/√Hz noise and a THD of 0.000015% might also be a good choice. This same opamps are used to good effect in the Auralic Vega. Scotty
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