If it has always been like that, your power on delay should be powered from a DC line with very low smoothing value. The idea is that the supply to the relay drops off before the amplifier loses power and of course will not affect the on delay timing.
If it is getting worse, check the muting circuit.
If it is getting worse, check the muting circuit.
I bought it used and don't know if it had the thump when it was new. Also I don't know if it has a power on delay at all. I think it does not have one because there is no relay click heard. Will open it and see if it has a relay or not. Anyway the shutoff thump is anoying, would like to find a workaround for this problem.
I agree - delay ON and instant OFF for the speaker relay.Hi, an independently powered speaker protection circuit would probably be the simplest, one that gives on delay and instant off in addition to DC protection of the speaker
The relay can be a mechanical switch, or a Solid State switch.
Simplest thing to try is an X-rated cap across the mains transformer primary. Anything in the range 10nF to 100nF should be fine. You may find there is already one present, in which case it may be faulty. Or one across the switch, which is even more likely to be faulty. X-rated caps often gradually lose their capacitance.
If it's an early REL sub, these had amps made by BK Electronics. I have a plate amp sub with a BK amp and it does this as well. Have a look at this thread. I bought some of these XY boards before this thread started. I must get around to putting one in my sub!
http://www.diyaudio.com/forums/solid-state/308128-speaker-protection-kit-under-5-a.html
http://www.diyaudio.com/forums/solid-state/308128-speaker-protection-kit-under-5-a.html
you also look at the possibility of getting a UPC1237 protection ckt that has a fast AC loss detect. If AC is absent on pin 4 of the chip, it will disconnect the speaker.
http://www.promelec.ru/pdf/upc1237ha.pdf
reg
Prasi
http://www.promelec.ru/pdf/upc1237ha.pdf
reg
Prasi
http://www.diyaudio.com/forums/solid-state/308128-speaker-protection-kit-under-5-a.html
The above might also work if power switch controls the 12v relay.
The above might also work if power switch controls the 12v relay.
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