Maker Pro
Maker Pro

Getting more gain from 5532 op amp?

Bluesguy

May 19, 2013
3
Joined
May 19, 2013
Messages
3
I am using a 5532 op amp for a small mixer to mix two keyboards for live performance. I know the op amp is desgned/compensated for unity gain.. One of the key boards out put is quite a bit greater than the other so I have been using a feedback resistor 5 to 10 times the the resistors on the inputs for 5 to 10 gain. It works pretty well but I now get distortion fron the hotter keyboard if I turn it up much. I am new to the site and could not get a diagram to upLoad as the buttons were greyed out but I took the design frm Craig Anderton's Electronics Projects for Muscians which a lot of People seen familiar with.


Is there an easy way to get more gain without this distortion? I can work around it but would like to know how to fix this.
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Why don't you use a switch to select the feedback resistor (Rf)? This way you can have two gain positions to handle either keyboard. The other option would be two inputs with a different value of Rin connected to each input jack.

Chris
 

Bluesguy

May 19, 2013
3
Joined
May 19, 2013
Messages
3
That's a great idea! I need them both going at the same time so a switch will not work but if you mean using a lower input resistor for the keyboard with the lower line level signal so I will get a unity for the stronger signal but boost the lower signal that would be cool Here is my understanding of what you are suggesting. I will try it out on my breadboard this week. I attached a GIF. Hope it shows up. And either way thanks a bunch.
 

Attachments

  • Op Amp Mixer Circuit.gif
    Op Amp Mixer Circuit.gif
    6 KB · Views: 171

Bluesguy

May 19, 2013
3
Joined
May 19, 2013
Messages
3
Oh, and I meant to include R1 = 10k = RF for the hotter input and R2 approx = 1-2K for 5 to 10 v gain for the weaker one.
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Yes, that's the general idea.

Chris
 

BobK

Jan 5, 2010
7,682
Joined
Jan 5, 2010
Messages
7,682
I would go with higher resistors all around though. 10K 100K and 100K. The 1K input resistor is probably loading that input more than it should.

Bob
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
May 8, 2012
Messages
4,960
Bob brings up a good point. I'm not a musician but I believe the input impedance of many instrument amps are hi Z, so the drivers that feed them expect same.

Chris
 
Top