Hello everyone - I have built a little circuit that makes noise, and I want to have the option to either output directly to a built in speaker, or to a 1/4" jack. I am using a “switching” jack, so that the signal will be cut form the speaker when using the jack. I am having some problems with this set up though. The main problem is that, going into the jack the output is fine, volume-wise. plugging in headphones or a little powered computer speaker works great. The headphones are 64Ω. When I plug in the speaker however, the volume is very low. I am using a small 4Ω speaker. I put a lm386 basic amp in line here which helped, but I still cannot get the desired volume from the speaker. Any ideas for how to make this work better?
Sorry if this is a basic question, still learning. Thank you everyone for your help!
It sounds like an impedance issue. I’m no expert, but I think you’ll probably want to get a different speaker/amplifier if the rest of the setup sounds good. It used to be that most headphones were 8ohm but since they sat right next to your ears massive amplification wasn’t necessary. Try a guitar amp or feeding it into a mixer and see if it sounds better.
You need to work on your titles, if not else (your title makes it sound like you think this is caused by the jack and not the amplifier/speaker combination)
Driving a 4 ohm speaker with line out doesn’t really work; you need an amplifier designed for low-impedance output, not a line out buffer designed for high-impedance inputs. The LM386 amplifier is designed for 4-32 ohm speakers, but the volume you get out depends on how it’s configured, supply voltages, and also the speaker efficiency. Have you tested the amplifier with some other source?
You may also want to check the existing output threads, btw; see this topic and the topics linking to it:
I missed this bit and assumed line out (or synth levels), but “a little circuit” can be anything Do you know what levels the circuit produces? Can you point us to the schematics?
The output, before the amp is ~2.5V, but varying as the signal varies. Schematics I might be able to produce. I have it more or less drawn up in easy EDA, but I think it has changed a little since then.
I think I should add that this is a standalone circuit, so I want to build the speaker into it to be used as a complete standalone item. I will have the 1/4" jack there too because the small speak really doesn’t sound great, but I want that functionality either way.
(your title makes it sound like you think this is caused by the jack and not the amplifier/speaker combination)