I want to save my ears from power-up & power-down noise.
Typical hookup -- car receiver's "aux" power lead signals the amplifiers to power up (they are connected to the battery to draw power directly). There is sometimes a "pop" when powering on, and almost always a fuzzy-static on power down.
My thought it is to control the speaker lines, let everything power up, then turn speakers on after 15seconds. Similarly, on receiver power down, cut the speaker lines before power actually drops.
I don't know the actual power being used by the speakers -- but max is about 200 watts peak...
would 1amp reed relays work? or could I use mosfet transistors ? Would I need head sinks?
I have already tried disconnecting the line-levels and powering off... and ground the body down to bare metal & ensured a good ground.
would 1amp reed relays work?
No. 200W into 4-Ohms is 7 amps* (and 28 Volts).
or could I use mosfet transistors ?
No. The audio signal is AC. Maybe you could do it with a pair of MOSFETs on each channel and the right positive & negative power supplies, but I wouldn’t try it.
I tried a similar thing, but I used a relay to break the line-level connection when the stereo was powered-down. The turn-off noise noise was coming from the head-unit, and everything was OK if I turned-off the head unit first. But, otherwise I was getting a thump from the subwoofer when I turned-off the ignition. But, the relay wasn’t fast-enough and it didn’t work. Now, I’m just living with the turn-off thump. I’ve got a tri-amped system and I just didn’t want to use 6 relays on the speakers…
- Power (Watts) = Voltage x Current
Power = V2/R
Power = I2 x R