Hi everyone.... what is the safe dc spike level for speakers? I'm getting 2v dc spike at the output when i turn on the amp.
Is fine as long as it's less than a few hundred ms (small thump with cone settling to rest position immediately, no bounce). I send far more when using AC coupling, and no issues. With DC coupling, it's a little more complicated and probably safer to have a delay turn-on.
In reality it will be more than 2V, if you've observed this with speaker connected. The load current results in a voltage drop at the output. If you have more than 30V supply it's better to charge output caps before connecting the load. If it's a DC coupled amp, better to have delay and protection against sustained DC.
In reality it will be more than 2V, if you've observed this with speaker connected. The load current results in a voltage drop at the output. If you have more than 30V supply it's better to charge output caps before connecting the load. If it's a DC coupled amp, better to have delay and protection against sustained DC.
Hi, it's an ac coupled D 2030A amplifier with a common emitter single transistor pre stage. Amp output DC offset is less than 5mV. The thump is quite loud though. I guess it's normal for such setup.
After checking that your DC offset is acceptable and there aren't other issues I would install a soft start delay circuit, I have done it with many amplifiers, some circuits also offer DC protection.
It's a low cost diy fm radio setup with tight space so i'm kind of hesitant to use relay delay. Dc offset is minimal but i can see momentary bounce on spkr.
A 3-5 second delay with relay is really a no-brainer to add to amps.
If loading is needed at turn-on, a resistor around 500-2000 ohms can be added as well.
No more thumps.
If loading is needed at turn-on, a resistor around 500-2000 ohms can be added as well.
No more thumps.
You mean 500R-2000R 1w resistor in parallel with spkr? This is the pre stage i'm using with that amp.
Edit- omitted 100R resistor in series with the +V & reduced the output cap to 4.7uf. But similar result.
A DPDT relay after a coupling cap, with a resistor on the cap to ground.
It would allow the coupling cap to charge (to the 1/2V level) before the speaker is connected.
You're confusing things.
AC coupled uses a coupling cap.
DC does not.
Either way, a delayed relay is the solution.
I believe it's an AC coupled amplifier & without output cap! Anyway i found that the turn on pop/ noise problem is inherent to that common emitter transistor preamp. I disconnected it & now everything is fine.
That amp schematic clarifies things - it's AC coupled INPUT, but DIRECT (DC) Coupled OUTPUT.
Your previous comments made things confusing.