Voltage Drop for an op-amp circuit

[Dellyjoe]

Hello everyone,

I'm working on a home project during these COVID times.

The project is a Distortion effects peddle for a bass guitar.

Here is the output circuit, when I have an 8ohm speaker connected to it.

Does anyone know why the voltage drops? Does it have to do with the output impedance drops to 8ohms when I connect the speaker?

[Dellyjoe]

This shows the circuit without an load on it

[Dellyjoe]

Here is the circuit in full.

Sorry for all the posts wasn't sure how to attach more then one attachment at a time.


Thank you for reading,
Joe

[schmitt trigger]

The amount of bias current in the output buffer is at least 4 orders of magnitude too small to drive an 8 ohm load.
That, and the 2N3904 cannot handle the load even with proper bias.

[Paul Rose]

That final emitter follower isn't enough to drive an 8 ohm load accurately.
(plus it will put DC across your speaker without either a blocking cap or transformer).
You really want a full power amp stage if you want to drive a speaker.
You could just use amplified computer speakers, or use something like an LM386 or TDA7267 for a low power small speaker amp.

[Dellyjoe]

That final emitter follower isn't enough to drive an 8 ohm load accurately.
(plus it will put DC across your speaker without either a blocking cap or transformer).
You really want a full power amp stage if you want to drive a speaker.
You could just use amplified computer speakers, or use something like an LM386 or TDA7267 for a low power small speaker amp.

Hmm ok that makes sense,

Lucky I have a LM386 that I randomly bought two weeks ago.

I will look into how to run this as a buffer and hope it will give me the power I need to drive the speaker.

Now if I can do that I'm going to plug it into a head my dad has down stairs and see if that works b/c atm it doesn't and I think it has to do with the output buffer not being able to handle the load.


Thanks for the help both of you.
Joe