# Distortion via Powered Speakers and not in Headphones - 1 Transistor Amplifier

I'm trying to make this NPN amplifier circuit work for my battery powered computer speakers. This circuit works fine if i connect headphones to it in output, but has distortion when connected to a powered amplifier like computer speakers (which i have connected with a battery).

I tried few values of different R and C, but the distortion doesn't go away, while the sound is clear on headphones.

Is there a way to make this circuit compatible for an amplifier, so that there is no distortion... I understand that the speaker in this amplifier circuit is in series, and maybe that is the reason for the distortion, via the 5v computer speakers.

simulate this circuit – Schematic created using CircuitLab

Here is the Falstad Simulation Code:

\$ 1 0.000005 6.450009306485578 99 5 50 t 256 224 320 224 0 1 -0.9117717732516294 0.5832571155113225 100 c 256 224 160 224 0 0.000009999999999999999 0.6832571155113225 r 256 224 256 128 0 100000 g 320 240 320 304 0 v 432 304 432 128 0 0 40 1.5 0 0 0.5 w 320 240 368 240 0 w 368 240 368 304 0 w 368 304 432 304 0 v 96 224 96 288 0 0 40 0.1 0 0 0.5 w 96 224 160 224 0 w 96 288 96 352 0 w 96 352 368 352 0 w 368 352 368 304 0 r 320 208 320 32 0 8 w 256 128 256 32 0 w 256 32 320 32 0 w 320 32 432 32 0 w 432 32 432 128 0

I am using this in a second stage amplification (for headphones) in a guitar pre amplifier circuit from this website, the circuit of same is as below: http://www.lbguitar.arkku.net/miniamp/miniamp.html

simulate this circuit

So while this works perfectly for the guitar or audio signal, using headphones, there is only distortion when i connect this to the 1st amplifier circuit drawn before.

The full circuit - Guitar headphone amplifier - looks like this...

LAYOUT....

FULL CIRCUIT SCHEMATIC ....

simulate this circuit

While the 1st circuit works as a guitar amplifier in itself, the full circuit sounds good, with a bit of fuzz and distortion with headphones.

My question is how to remove distortion in the circuit, in which speaker is replaced with an amplifier input terminal.

• What's wrong with the LM386 you showed on an earlier question? Is it quiescent power consumption? You can auto disable it when no audio is detected. – Andy aka Mar 21 '19 at 13:01
• Use a low powered op-amp to drive the amplifier's input. Also, how did you connect the amplifier up - show how it interfaced. – Andy aka Mar 21 '19 at 13:04
• You need to show a schematic and not a layout. – Andy aka Mar 21 '19 at 13:37
• You are not showing how you connected the Audio in of the USB speakers. That is crucial to this question. Your question is about reducing distortion when driving an amplifier and I assume by amplifier you mean the usb speakers? Be very clear. – Andy aka Mar 21 '19 at 14:11
• There possibly lies the problem. The 0 volt signal reference on your input is now either connected to battery positive or worse still connected to the collector. There is a very good chance that the input is also decoupled internally preventing DC current flow and that will not work well for the transistor because it needs DC current flowing in the collector for it to work. – Andy aka Mar 21 '19 at 14:20