[jopagi]

Hi
 My Sig 30 has suddenly developed a noticeable hum (coming from both speakers) when I switch the amp to charging mode and turn off the rest of my equipment.   
Turning the preamp back on reduced the hum substantially, but it didn't go away completely.  I tried unplugging the sub from the RCA outs, and unplugging the inputs, but it didn't appear to matter.  I ended up having to disconnect the speaker wires when charging.
Has anyone experienced this?

The Sig 30 was beat up a bit by the shippers when I purchased it about a month ago.  The pins on the wall-wart charger were severely bent, but I think the main unit survived relatively intact.  The ground pin may have become disconnected, however.  Might that cause the problem?

Thanks,
Jonathan

p.s. I know, it's even more incentive to upgrade to the 30.2...  that will come in time!

[Mariusz]

Hi Jonathan,

I am sure Vinnie can answer your question better then I, but before you send the unit for the repair or upgrade (which makes more sense value wise repair cost v.s upgrade) IMPOV. .....check few things first.

Inspect the wiring for ground problems, damage, battery condition and battery connection. Also , I have noticed that  cables/wires crossing each other at very close distance and or touching one another will create interference in the form of noise - which is then pick up and amplify by the amp itself. One of such a examples happend during my recent experimentation with different sources in the chain.
While swapping things around I have noticed noise coming from both speakers.....At first  I thought that source or one of the tubes went bad.....However quickly discover that one of the interconnects was crossing and in contact with speaker cables.  Lifting the cables up and away from the speaker wire solved that problem. Since you said that you have disconnected everything and noise is still coming through it might be a damage cause by mishandling during shipment or........maybe your power line is in fault, so you might  want  to check that out too.

Cheers

Mariusz

[IronLion]

When I'm using my partially upgraded Signature 30.2 I don't have a hum, but if I switch it off I get a minor hum through my subwoofer.  The speakers though (I'm not using a preamp) do not hum at all and go silent the minute the toggle is switched off.  Its not an issue for me because when I turn the Sig 30.2 on, its not charging and separated from the wall wart so the subwoofer doesn't hum.   

[Vinnie R.]

When I'm using my partially upgraded Signature 30.2 I don't have a hum, but if I switch it off I get a minor hum through my subwoofer.  The speakers though (I'm not using a preamp) do not hum at all and go silent the minute the toggle is switched off.  Its not an issue for me because when I turn the Sig 30.2 on, its not charging and separated from the wall wart so the subwoofer doesn't hum.   

Hi IronLion,

This is probably a minor ground loop between the charger's GND to the outlet and your subwoofer's GND to the output.  Sometimes a "cheater plug" (which converts from a 3-prong to a 2 prong) solves the problem... installed on the subwoofers power cable.


Hi jopagl,

Welcome to the RWA forum and audiocircle!

You also might have a GND loop, as mentioned above.

Just to confirm, was everything fine when you received your used Sig 30, and now there is a problem?

Check the following:

-- Make sure all your interconnects are clean and secure (fully inserted onto the RCA jacks, and clean). 

-- When you turn the amp off, can you verify that the red LED on the front of the amp is OFF, and the led on the charger is glowing red (followed by green when it is finished charging)?  I want to make sure that the ON/Charge switch is properly switching.   This is where I believe the problem might be.

The Sig 30 was beat up a bit by the shippers when I purchased it about a month ago.  The pins on the wall-wart charger were severely bent, but I think the main unit survived relatively intact.  The ground pin may have become disconnected, however.  Might that cause the problem? 

I don't think this is your problem, but I don't want to rule it out.

Mariusz's suggestions are also good so please try them if you can.

As always, you can send me your Sig 30 and I'll take a look to make sure everything is ok on the inside.  If you go this route, please also send the charger so I can verify that is it OK.

Also feel free to email/call me for more help troubleshooting. 

Best regards,

Vinnie

[jopagi]

Thanks for all your suggestions everyone.   They've all been helpful.

Vinnie, I think the main issue is with the on/charger switch as you suspected.   Tonight when I switched it off, I only got about 1 second of speaker hum before the charger kicked in and started glowing red.   There was no sound from the speakers after this point.     This one second of hum happened consistently, except for once when I flipped the switch (with the amp unplugged from the charger) and the amp didn't turn off at all!   It looks like I'll be sending in the unit for repair/upgrade soon.

And yes, the Sig 30 seemed to be working fine for the first three weeks that I had it.   Strange, huh?

I also may have a problem with some of my interconnects.   The left output had clearly diminished treble.  It's not the amp, because I could also hear it from the headphones.  I'll have to experiment with swapping cables around.

 Thanks again for all your help!

[Vinnie R.]

Thanks for all your suggestions everyone.   They've all been helpful.

Vinnie, I think the main issue is with the on/charger switch as you suspected.   Tonight when I switched it off, I only got about 1 second of speaker hum before the charger kicked in and started glowing red.   There was no sound from the speakers after this point.     This one second of hum happened consistently, except for once when I flipped the switch (with the amp unplugged from the charger) and the amp didn't turn off at all!   It looks like I'll be sending in the unit for repair/upgrade soon.

And yes, the Sig 30 seemed to be working fine for the first three weeks that I had it.   Strange, huh?

I also may have a problem with some of my interconnects.   The left output had clearly diminished treble.  It's not the amp, because I could also hear it from the headphones.  I'll have to experiment with swapping cables around.

 Thanks again for all your help!

Hi jopagi,

I'll be happy to take a look for you... should be simple enough to put a new switch in there (which is most likely the culprit).

Send it on over whenever you are ready.

Best regards,

Vinnie