Why my 4558 equivalent does not work?!

[rikk]

Hi everybody,
I'm new in this world and I'm facing a strange problem.
In the past days I used the following schema
https://imgur.com/a/0DGvsV7

My guitar is the input and I'm using a speaker as output. It works using a UA741CP.
Recently, I'm trying to use only the opamp(A) of a MC4558CN (equivalent to the JRC4558) to do the same thing but it seems to not work at all! 
With "not work" I mean that the speaker is not emitting any kind of sound as if it was without power 
The schema I'm using is the following.
https://imgur.com/a/4kxCTp2

Please, could you help me?

[idy]

Welcome to the forum.
Driving with a speaker with an opamp is a dubious proposition. Really? Directly? What kind of speaker?
This is like one of those "how many things are wrong with this picture" puzzles.

Second diagram takes output from -input, not output. Your solution right there?

No bias. Maybe you took your example from a "bipolar" arrangement, +5 to pin 8 and -5 to pin 4. If you are using a "single" supply you have to create a mid voltage bias for the + input.

No blocking caps. Your DC will run up the cable to the guitar, throwing bias off and making scratchy noise when you turn the guitar volume. You are also running DC through your speaker.

this has a gain of 1.22. (1+ r1/r2) It is hard to believe you would hear that. Again, maybe you are using a powered speaker?

A finer point is that when using only one half of a  dual opamp, it is best to hook up output to inverting in (buffer configuaration) and then feed the + input that mid-supply voltage you used to bias the other side...

[idy]

Then there is the lack of series resistors on input and output. This is not really a circuit... Or not a real circuit.

[GGBB]

You may find that your +5V single sided supply is insufficient. Recommended minimum for the RC4558 (according to the TI datasheet) is +/-5V dual which would equate to +10V single sided. They are often run lower in pedals - 8-9V maybe - but 5V might be pushing the limits too much (no direct personal experience).

[GibsonGM]

"It works using a UA741CP."

I didn't see if it was mentioned, but, since you said you made it work with the 741...a 4558 is a dual opamp so the pinout will be different than for a single opamp like the 741. If you haven't accounted for this, compare the pinouts for the 2 chips and see what you have to change to use only 1 side of the 4558...disregard if you've already done this - the other answers are more than correct too.  It might be able to be MADE to work with the appropriate caps and R's as detailed above...

[antonis]

Before facing power issue(supply rails and output current) let's get a working circuit..



P.S.
Also Welcome...

[GibsonGM]

Antonis how do you draw so fast? 

[antonis]

Antonis how do you draw so fast? 

I mod drawing even faster..
(previous draw had an output position flaw..)

[anotherjim]

I'm not going to throw the original idea out. It may be one of those mad schemes that somehow works for the wrong reasons.

[antonis]

I'm not going to throw the original idea out. It may be one of those mad schemes that somehow works for the wrong reasons.

I'm trying to "simulate" it with a Common Base amp but that kinky outpout directly taken from inverting input puzzles me a bit..

[GibsonGM]

I'm sure it's not giving high fidelity results   

[anotherjim]

Not hi-fi no.
The output does come from amp output - via a resistor.  Some BJT opamp inputs may bias from input leakage current developing voltage across the DC coupled guitar?
If the amp circuit is done normally, @5v a BJT opamp, on a good day, maybe gives 150mW into 8R speakers?

[rikk]

First of all, thank you so much for all of your answers. I'm reading in detail all suggestions and it is very useful for me.
The schema that I've uploaded is totally wrong and for now, what I understand is that the most important fails are:
1. A wrong output position
2. The missing of decoupling caps

In each case, yes I'm using a powered speaker and my goal was to make a simple booster for it.
I've reached my goal, and the sound seems to be very clean.
Thank you so much!

[antonis]

Just a terminology comment..

Coupling caps are considered those which are in series with signal path (and block DC)..
Decoupling (bypass) caps  //      //         //    in shunt with any "unwanted" AC signal/ripple/spike..

P.S.
In case you managed to have clean signal without input mid-supply biasing, you have a very small signal togetrher with a very leaky op-amp..