Op Amps: Op Amp Phase Splitter 

To further confuse the matter, there are consumer and pro line levels. Broadly speaking, "line level" is around a volt for the max level. Pro is a little higher than consumer (think in terms of a little under a volt versus a little over a volt for 0 VU). "Instrument level" depends a lot on the instrument. If it's a modern keyboard, it will likely be at consumer line level (or possibly pro line level if it's a higher end unit). For a passive guitar, that will depend on the pickup. Generally speaking, when feeding a high impedance load, you might get a few hundred millivolts for a loud chord, but I have heard of pickups that will pump out over a volt. Mic level is a couple of orders of magnitude smaller, so think millivolts instead of hundreds of millivolts. If you're converting from consumer line level to pro line level, you'll need about 12 dB of gain (x4). FYI, consumer line level is sometimes called "-10 dBV" and pro "+4 dBu". For reference, 0 dBV is 1 volt, thus -10 dBV is a little over 300 mV. 0 dBu is 0.775 volts, thus +4 dBu is a little over 1.2 volts. More details on dB at the beginning of the Op Amps playlist. Ultimately, your best best is to get out a digital o'scope and measure the signals!

@@ElectronicswithProfessorFiore I have been reading your text on the subject, which had made my understanding of dB better. I think for novice analog folks that voltage is easier to visualize.

I've use the TL07X series many times over the years with success. It's been around since the 1970s. There are newer designs that have lower noise and distortion, so you might want to broaden your choices.

@@ElectronicswithProfessorFiore I am certainly open to suggestions. I have several different ones in my personal stock including the OPA134 and LM741.

@@jimbelcher6877 Off the top of my head, the NE5532 is nice. I believe there is a dual version. Also, the LF411 (again, I think there is a dual version). I suggest you go to ti.com and search on their audio op amps.

That really shouldn't make much difference. The cross-talk on modern op amps is tiny. I'm not saying that there is zero difference, but I suspect that it would be negligible in virtually any practical application. I like the 5532 series. I've used them a few times for audio projects. It's some four decades old and was top-of-the-class back then, but it's still a solid performer, especially for the price.

@@ElectronicswithProfessorFiore Did you see my link to the opamp shootout from Doug Self?

@@simonyoungglostog I missed that. Can you repost it here?

It's TINA-TI, free from ti.com. It's an older version of the TINA simulator.

@@ElectronicswithProfessorFiore Thank you.