why not thrown in an LED?
You can use a dropper resistor and LED to discharge the caps and shorten the 'play-on' time. If you're going + to ground, a 15k 1/2 watt resistor and blue LED look and work great. If you go + to -, you'll need a 1 watt resistor. Mount the resistor in free air.
You'll still have a few seconds of distortion when the power supply voltage drops. As an alternative you could just turn the preamp off first, or do like i do and never turn the amps off
Cheers,
M
You can use a dropper resistor and LED to discharge the caps and shorten the 'play-on' time. If you're going + to ground, a 15k 1/2 watt resistor and blue LED look and work great. If you go + to -, you'll need a 1 watt resistor. Mount the resistor in free air.
You'll still have a few seconds of distortion when the power supply voltage drops. As an alternative you could just turn the preamp off first, or do like i do and never turn the amps off
Cheers,
M
Disconnect the speakers first;
In my amps I always run a seperate transformer winding (or transformer) and run a rectified partially smoothed supply to the a speaker relay (or DC detect cct).
This enures that when the mains is turned off (from anywhere) the first thing that gets disconnected are the speakers.
This is very simple, cheap and it means no thumps, no distortion, no cone movement at all.
Cheers
In my amps I always run a seperate transformer winding (or transformer) and run a rectified partially smoothed supply to the a speaker relay (or DC detect cct).
This enures that when the mains is turned off (from anywhere) the first thing that gets disconnected are the speakers.
This is very simple, cheap and it means no thumps, no distortion, no cone movement at all.
Cheers
In my circuit Active bleeder,any common cheap opto isolator can be used eg:MCT2E.
Almost all high power audio amps employ switch on delay and fast switch off circuit to protect loud speakers from annoying clicks and other noises,this can be combined with DC protection so only a single relay with 2 c/o can be used for protecting both channels.
Almost all high power audio amps employ switch on delay and fast switch off circuit to protect loud speakers from annoying clicks and other noises,this can be combined with DC protection so only a single relay with 2 c/o can be used for protecting both channels.
http://www.diyaudio.com/forums/showthread.php?postid=546052#post546052
See my last para of the above post for a similar, but slightly quicker-acting upon power-off scheme.
See my last para of the above post for a similar, but slightly quicker-acting upon power-off scheme.
Re; disconnect the speakers first.
Hi Terry,
Sorry it's taken a while. All I do is run a seperate supply for a speaker relay.
This is a seperate secondary winding, fully rectified and partially smoothed by a small capacitor (say 10uf). This is connected to the relay coil. The smaller the capacitor the faster the relay will turn off, but too small and the relay may buzz.
When the power is turned off the relay turns off and disconnects the speakers before the amplifier power supply discharges. So any problems associated with this discharge will not include the speakers.
Cheers
Hi Terry,
Sorry it's taken a while. All I do is run a seperate supply for a speaker relay.
This is a seperate secondary winding, fully rectified and partially smoothed by a small capacitor (say 10uf). This is connected to the relay coil. The smaller the capacitor the faster the relay will turn off, but too small and the relay may buzz.
When the power is turned off the relay turns off and disconnects the speakers before the amplifier power supply discharges. So any problems associated with this discharge will not include the speakers.
Cheers
I had this problem...decades ago...was one capacitor connected in parallell with the
In parallel with the main swich....and the capacitor started to conduct current, even when the switch was off, some good energy was passing inside the capacitor...
It was always half voltage...was good, because no "thump" when starting.
I did not read all posts....maybe i am out of your subject.
Just a comment, they use that capacitor to avoid to much noise in the moment you switch on and off...some arc of voltage will be diminished or removed...also, you can find some with a resistor in series.
Regards.
Carlos
In parallel with the main swich....and the capacitor started to conduct current, even when the switch was off, some good energy was passing inside the capacitor...
It was always half voltage...was good, because no "thump" when starting.
I did not read all posts....maybe i am out of your subject.
Just a comment, they use that capacitor to avoid to much noise in the moment you switch on and off...some arc of voltage will be diminished or removed...also, you can find some with a resistor in series.
Regards.
Carlos
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