ESP Project 94A, What am I doing wrong? (Simple Mixer)

audiomodder · 06:27 AM

Need a little help on this one. I am trying to build this simple mixer/preamp only without the tone and balance controls. My test circuit is also omitting the volume pots (I'll be using a digital IC for that once it is working.)

As noted in the schem I'm using an OPA2211 for the opamp in single supply setup for testing. I get +2.2v at B1 but nothing comes out when the amp is connected.

Any ideas?

audiomodder · 10th January 2010, 08:47 PM

ah, nevermind- figured it out. Even though the OPA2211 is supposed to be single supply it seems to need dual supply. Maybe only the OPA211 is single supply.

If anyone knows if I can omit the inverter buffer on the output that would be good to know. It looks like the volume pot I'm using might already have one:
QuickView - MAX5486 Stereo Volume Control with Pushbutton Interface

Great little preamp mixer but IMO ESP could use some work on joining schems better.

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10th January 2010, 08:47 PM	#2
audiomodder diyAudio Member Join Date: Jun 2009	ah, nevermind- figured it out. Even though the OPA2211 is supposed to be single supply it seems to need dual supply. Maybe only the OPA211 is single supply. If anyone knows if I can omit the inverter buffer on the output that would be good to know. It looks like the volume pot I'm using might already have one: QuickView - MAX5486 Stereo Volume Control with Pushbutton Interface Great little preamp mixer but IMO ESP could use some work on joining schems better.