Sunfire True Sub - Help Fixing Auto On

[thuffman03]

Or, some pre-amps have switched rear panel outlets.

You should never plug an amp into the back of a preamp.  Bad things will happen to the preamp power supply.  Magic smoke could be let out.

[OldiesButGoodies]

Sunfire subs do require their own power station,  preferably connected to a separate light pole transformer several streets over,  to minimize hum (that and a prayer to the Gods of hum at least daily).   But Macgeek's idea could be made to work. 

[MacGeek]

A/C power management, including switching, can be a pain.  McIntosh and maybe other companies used to make a power strip (MAC was an R-612).  Six outlets rated at 15 amps that plugged into the wall with a beefy power cord.  On the opposite end of the strip is a second power cord that plugs into a switched outlet on an amp or receiver.  When the amp is turned on, a small a/c signal from the switched outlet passes to the power strip activating it.  Anything plugged into the strip comes on when the switched outlet is on.  Audio Classics has one listed for just over $100.

Belkin makes a power strip with a current sensing outlet.  Plug an amp or preamp into the current sensing outlet and when the amp is turned on, the rest of the strip is activated.  It's about $30 at home centers, K-mart, etc.

Both my analog audio rig and home theater have about a dozen a/c plugs to manage.  I am using both of these devices with excellent results at relatively low cost.  I do have to note, my amplifiers are currently activated via 12v triggers, so the gear plugged into the power strips draws less current than the amps do.  However, before the 12v triggers, I did use these devices to switch the amps

[OldiesButGoodies]

MG:

I recently updated the receiver that drives my home theater rig to an Onkyo TX-NR1009.  This receiver has every bell & whistle currently available except a switched outlet or a 12v signal for zone 1 (strangely, it has zone 2 and zone 3 12v triggers - strange design decision - hoping a firmware update will change it).  I am going to try the Belkin as a solution for that problem - thanks. 

OBG

[MacGeek]

I got my Belkin strip for free.  Log onto your electric suppliers website and check to see if there is an energy audit, or whatever they may call it.  I did the audit on line and in return, a few weeks later, received a box full of stuff, including the Belkin, a couple of LED nightlights and around 10 CFL light bulbs.  I'll guess about $50 worth of useful stuff for free, not even a shipping charge.

[bigdealz]

I am slowly removing imperfections from the Sunfire True Sub Mark IV sub.  The recent output cap replacements were a huge improvement - the hum appears to be gone and it sounds cleaner and tighter.  The next frontier is the auto-on circuit.  It takes a while for this cube to detect there is music playing and kick in.  I have to significantly pump up the volume in the pre or go fiddle with the potentiometer in the plate amp so it wakes up (the latter erases the level setpoint,  so it is a bit of  pain).   Any ideas on how to troubleshoot this? 

Thanks,

OBG

Can you share the details about the hum fix.  I've been doing some research and think I may need to replace my caps.  My sub will frequently start humming at 60 hertz, when it hums I can turn down the sub volume all the way and get no noise and no sound.  I can lower the crossover setting and minimize the hum.  Unplugging the sub from outlet or rca will get rid of the hum and keep it away for a while after I plug it back in.  I've also recently found turning the lights on and off can also get rid of the hum.  I tested with a cheater plug and that didn't help, actually the sub has a bit of noise when not playing, so it was worse that using the grounded plug.  I don't believe this is a ground loop.

After getting the hum fixed I'm also interested in changing the auto power on to something with a remote trigger from my receiver.

I'd like to document the fix if this works so other can use it.  I also like the JL sub swap, I think I may try that in the future if I can fix the amp and if the sub ever needs replacement.