What should an active tilt eq consist of to work

[Transistor-Transistor]

I wanna make a tilt eq. I built it up on the breadboard and it only boosted in one direction and then cut all the volume in the other direction. What might cause this?



I built this one from the tone control library/calculator you guys showed me.
I made this one with a single power supply and put the 4.5 reference voltage into the noninverting input.

I stared at it on the board for like a half hour, went to work, came back and stared some more and I swear all the values are right and that they're in the right spot.

Gentleman I am perplexed

[Rob Strand]

IF Rin isn't low impedance then it could behave weird.   Also I suspect if the pot value is too low compared to the resistors it might work in an odd manner.  Off hand it would be a weak control.   

Then there's human error.   If you get the connections muddled up it won't work.   The way you have drawn it should work but it's not symmetrical (flip C2 & R2 positions).   That could promote wiring errors.   (You need a dual supply, or, for single supply bias the opamp +input to half supply.)

[ElectricDruid]

Then there's human error.   If you get the connections muddled up it won't work.

+1 this. It caught me out *after* I'd already done a PCB design!

Staring at it never works because you finish up seeing what you *think* is there. Go for long walk instead, and then have a look when you come back.

[Rob Strand]

I can at least confirm the part values look correct, including the pot value.

There is only one pot value which results in a symmetric tilt.
Too high a value gives more low side +/- dB than high side, and visa-versa.
The pot also affects the amount of boost/cut.

[PRR]

Explain the build to your brother. Or your dog. Even if they don't want to help, the charade of explaining will sometimes jar a loose or jammed thought.

[ElectricDruid]

Explain the build to your brother. Or your dog. Even if they don't want to help, the charade of explaining will sometimes jar a loose or jammed thought.

+1, this is another excellent technique. My wife stares at me blankly while I explain the problem, and then I go ".....aaaahHHHH!" and run off in the middle. She's used to it by now.

[Transistor-Transistor]

After takin a nap and annoying the living daylights out of my girlfriend and family I finally found it. I was using a resistor with very thin legs that were bent in such a way that it couldn't make electrical contact on the breadboard. I just rebent it and the active eq works perfectly

[amptramp]

After takin a nap and annoying the living daylights out of my girlfriend and family I finally found it. I was using a resistor with very thin legs that were bent in such a way that it couldn't make electrical contact on the breadboard. I just rebent it and the active eq works perfectly

If a breadboard can accommodate electrolytic capacitor leads, it will definitely not hold small component leads and if it holds small component leads, you cannot jam an electrolytic cap in it.  I had the opportunity to get a breadboard unit with ± 15 VDC power built into the unit and I passed on it.  I have had too much trouble with breadboards in the past.  Prototyping boards are better and you can solder a component in faster than you can jam a lead in and prove it is working.

[Transistor-Transistor]

Actually this is only the second time I've had trouble with a breadboard