A little help for a beginner...?

[scottbarnesbass]

Was hoping for a little of your wisdom....

I'm losing low end and can only calculate a high pass cutoff of 3 or 4 Hz for either the 47nF and 10uF caps...?

Any advice/suggestions?

Thanks

[scottbarnesbass]

Sorry, just to clarify, I was testing this blend pedal idea with the send receive plugged straight into one another...

[R.G.]

Not sure. I calculate a 3-4Hz for the 47nF, and a minimum of under 1Hz for the 10uF/100K if the load on the output terminal is large compared to 100K.

There are other parts which affect your circuit's operation that are not shown.

With a DC connection from the send buffer to the send point, your load could be trying to pull the first opamp's output from +4.5Vdc, where it is held by that bias network, to ground. As long as the 3.3K resistor and the load on the send output can't pull it down, you'll still get signal out, but there will be that big DC level riding on it. I would have put a capacitor between the opamp output and the send point to break that DC level.

But if send and receive are connected together for testing, you're OK, as the input cap on the receive will break the DC, and they're both trying to be at the same DC anyway.

What is the function of the 3.3K?

I would have put a 1M or so from out to ground, just to keep cap leakage from making insert/remove pops in the path.

Loading on the output terminal will affect the total output on the blend. At either extreme, you'll get the 100% of the signal for that extreme, with the one on the other end "outvoted" by the 100K it goes through. In the middle, each opamp output goes through 50K, and is then voltage-divided down by whatever the output load is. If that's too small, you'll get signal level drop compared to each end. May be OK.

I don't see a bass loss offhand, though.

I personally don't like the passive blend setup like that, because the blend output is variable level and loading sensitive. For one more opamp, you can get true panning/blending with constant level and load insensitivity. See http://geofex.com/Article_Folders/panner.pdf