Help With Op-Amps

[TSMartin]

I am still fairly new to all of this, so bear with me.

Whenever I use an op-amp for anything, I lose a lot of sustain, and my notes fade out quickly, resulting in a gross, distorted, "plucky" sound. I've used TL082, TL074CN, OPA2134PA, RC4558P, LM833N. They all seem to give me the same issues. I connect them to 4.5V Vcc+. In general, I've been using them to boost a signal before an overdrive clipping section, or after a clipping section, like you would see in an OCD style overdrive.

I'm hoping there is a fairly common cause to this that someone can help me with quickly. If it could be a number of problems, a nudge in the right direction would be great. Thanks!

EDIT: Here's one of the schematics I was trying to follow: https://www.google.com/search?q=ocd+schematic&rlz=1C5CHFA_enUS751US751&tbm=isch&source=iu&ictx=1&fir=si_6qbR0kHNtgM%253A%252COUlgUiDhTjY2zM%252C_&vet=1&usg=AI4_-kTKcIxloVF_IxLpAyxB4FUOkHsoFw&sa=X&ved=2ahUKEwikvsaUnfPiAhUF5awKHURJD4EQ9QEwAHoECAYQBA#imgrc=si_6qbR0kHNtgM:

[antonis]

Any schematic (diagram) of your builds should be helpful..

[GibsonGM]

Hi TS, Antonis is correct - a schematic of something you have built and which gives you trouble would help up pin-point what's wrong.   Generally, the error is a build error, or a problem with our design if we made it ourselves.  Happens to all of us! 

The symptoms you describe suggest that maybe some clarification on how opamps work with AC signals could be in order, but we'll know more after we can look at a schematic.


Welcome to the forum! 

[antonis]

Welcome to the forum! 

You could duplicate the above on my behalf, couldn't you Sir.. 

[duck_arse]

ohhh, I've seen the circuit! and I'll add a welcome.

on the left is the "Power section". in that section you'll see a black down-poining triagle and an open down-pointer. all black triagles (ground, earth, common, 0V) to the right of the power section connect together with the one in power. all the open triangles (V/2, bias, Vb, +4V5) connect together with the open triangle in the power. this provides all the grounds and biases around the circuit. [ignore the name "op-amp ground" - think of it as bias instead, worry about relative nomenclature later.]

all except one - the IC supply connections are not shown on that dia, and they are verrrr important! connect pin 4 of your op-amp to ground, the solid black, and pin 8 of the oppie to the 9V line.

and also - two more grounds are missing, one for the input jack sleeve, and one for the output jack sleeve. all your grounds connect together.

[ElectricDruid]

Wot Duck sed. Sounds like you're having trouble with the "bipolar supply" requirement of the op-amps. Once you get that sorted, you'll be fine.

[antonis]

Hmmm...

I'll bet you guys a bottle of cider (especially for Stephen) in case of problem doesn't concern output current limiting resistors.. 

[GibsonGM]

Welcome to the forum! 

You could duplicate the above on my behalf, couldn't you Sir.. 

From Antonis and myself, Welcome!

Like that?

[Rixen]

Welcome, when you say you connect them to +4.5V Vcc, do you mean that is from where you supply power to the op-amp ? The +4.5V is a ground reference point and the op-amp should be powered from the +9 and 0 V rails. Apologies if this is how you have it connected, but I've seen (and done) all manner of incorrect stuff with op-amps

[GibsonGM]

Welcome, when you say you connect them to +4.5V Vcc, do you mean that is from where you supply power to the op-amp ? The +4.5V is a ground reference point and the op-amp should be powered from the +9 and 0 V rails. Apologies if this is how you have it connected, but I've seen (and done) all manner of incorrect stuff with op-amps

I think that is why we need a schematic...

[bluebunny]

Welcome, when you say you connect them to +4.5V Vcc, do you mean that is from where you supply power to the op-amp ? The +4.5V is a ground reference point and the op-amp should be powered from the +9 and 0 V rails. Apologies if this is how you have it connected, but I've seen (and done) all manner of incorrect stuff with op-amps

I think that is why we need a schematic...

The added link in the edited OP is a Google search which eventually leads you to this:

[ElectricDruid]

I'll bet you guys a bottle of cider (especially for Stephen) in case of problem doesn't concern output current limiting resistors.. 

What's your thinking, there, Antonis?

I was thinking that if the OP was having trouble with many different op-amp circuits, then it was probably power related (get that wrong, and nothing works). But it's also true many circuits have a series resistor on the output.

[duck_arse]

I'll bet you guys a bottle of cider (especially for Stephen) in case of problem doesn't concern output current limiting resistors.. 

wot hizz druidness said. how'zit work antonis?

but I'll still have the cider, thanks.

[antonis]

Just a wrong (low) value resistor before clipping section should cause the issue, Tom..

OK Stephen, no cider for you anymore...