Parasound A23 amp output fused??

It sounds like the problem is with the HSU sub not the Parasound!

Been quite awhile since I have been inside an A23. If I recall, the amp does not use output fuses, but instead uses output relays. You should hear these relays, within 3 to 5 seconds, click on when you turn on the amp. If you do not hear them click on, inside the amp, there are rail fuses that are there to further protect the output stage / speakers, in case the relays do not react fast enough. John Curl was very careful, and still is very careful, with all of his " protection " in the amplifier circuits. If the relays are not clicking, you might want to open up the amp to check these rail fuses. Amp needs to be unplugged ( I tell everyone that, as I have heard of mishaps ). These fuses are glass fuses, and if they are blown, you are likely to see it. ONLY replace these fuses with the exact same rated fuses ( brands are either Buss or Littlefuse, likely ). Why did it happen ? Typically a very low impedance was presented to the amplifier ( 6 ohms or below, as an example, when in bridged mode ). I hope this helps. Good Luck, and Enjoy ! MrD.

Yogiboy, the sub works with another amplifier, as the OP indicated. OP, If the amplifier was in bridged mode driving the sub, the HSU might have an impedance that is lower than the bridged amp can handle.

Bingo! Thank you mrdecibel! There was a burned fuse...and it was cracked. It actually looks like someone had been after it with a screwdriver! I have a good friend and electronics nut coming over to check it over so I'm not gonna touch it till he gets here. Thanks again!

oops!!

The reason the fuse burned is because in bridged mono mode the voltage is doubled at each channel. This has the same effect as halving the load on the amplifier so a 4-ohm subwoofer load presents itself as a 2-ohm load in bridged mono.

You basically shorted the amplifier at the output.

Thanks gs5556