Okay yeah i will spring for the OPA134s I cant seem to find any through mount packages or sim models but i will i suppose.I did not say OPA314, instead I said OPA134. Yes, they are expensive like a cup of coffee at a restaurant.
The NE5532 is cheap but its noise level is not spec'd. The more expensive NE5532A has guaranteed low noise.
I thought you wanted modern high fidelity, not cheap old NE5532 opamps then spending a lot of money on huge expensive 10uF film capacitors.
Due to input offset voltages, you do not know which polarity to connect cheap electrolytic capacitors.
Due to a minimum input resistance of only 30k you need low value resistors and high value capacitors.
You can build a circuit with cheap old NE5532 opamps and cheap 10uF electrolytic capacitors then measure the polarity voltage on the capacitors then correct it if needed.
You can also measure the input resistance of hundreds of cheap old NE5532 opamps and pick ones with a input resistance much higher than 30k then use better lower value film capacitors that polarity does not matter.
If you change the circuit to work with a single positive supply then the 10uF electrolytic coupling capacitors will always have the correct polarity and cheap old NE5532 opamps will be fine. The output might make a POP sound when turned on.
The TL072 dual opamp is high fidelity and since it is used in millions of stereos its cost is much less than a single NE5532. The Phase Inversion problem never occurs when playing recordings that never have the signal level too high (unless you turn it up too high). Its input resistance is extremely high so you can use higher resistor values and lower value film capacitors.
The DC offset voltage is DC only, frequency does not change it.
OKay i understand what you mean about the caps and res values, but i've altered what you've said in my sim and there is no difference in the frequency response at all, also having all the coupling caps on the main line in all 5 stages of the parametric as 10uF it causes a hipass at like 160Hz, I understand the maths behind what you are suggesting but i cant seem to make it apply to the simulation?
Sorry this seems to just get worse at every turn here aha.
As always very thankful for the help.