After getting my Dayton HPSA500 500W plate amp and a 12" Titanic Mk III subwoofer installed in its enclosure, there was some hum not after turning the plate amp power on but after it automatically came on by itself during calibrating sessions to get the output level set properly. I am using a premium quality audio cable to connect the subwoofer output jack of my AV receiver to the LFE input jack of the plate amp. I did tried all the suggestions in the manual to isolate which of the other AV components might be causing the hum, even disconnecting the CATV cable did not stop fix the hum problem.

I don't own the Onkyo 705 which I know causes this problem after reading other threads in the AVS forum. I have a Pioneer.

The simplest fix that actually worked for me is exactly what the manual said never to do: remove a ground pin from any power plug. Well, other than my HT multi-outlet surge protector, the new plate amp is the only plug having a ground pin. I didn't remove the ground pin but instead used a two prong cheater adapter on the plate amp's power plug to one of the outlets on the surge protector. The hum is gone entirely. The plate amp must be the faulty component and/or poorly designed. Is there anything wrong in doing that to fix a hum problem that didn't exist until I hooked up a plate amp other than probably voiding its warranty?

Is the plate amp hooked up to the same wall outlet as the rest of your system? If not, you may have a bad ground at the outlet.

Is the plate amp hooked up to the same wall outlet as the rest of your system? If not, you may have a bad ground at the outlet.

That's what it probably is. Get a power conditioner or PS Audio Power Ports. I've read they work quite well.

Is the plate amp hooked up to the same wall outlet as the rest of your system? If not, you may have a bad ground at the outlet.

Yes, it is connected to the multi-outlet surge protector which is connected to the wall socket. The surge protector however has a green LED ground indicator that is is lit up. This means that it has a good ground connection. Is the surge protector ground detection valid or just a gimmick to get you to buy it?

All the other home theater components are connected to the same surge protector too. Nothing else causes the hum. I have checked other wall outlets around my living room with the surge protector. All of them have good grounds as well.

That's what it probably is. Get a power conditioner or PS Audio Power Ports. I've read they work quite well.

Thank's for the suggestion. The plate amp has to be the culprit. It should have had the isolated ground already built in. I bet my AV power amp that supplies power to the other 7 channels has proper ground isolation. It has monstrous power transformers weighing nearly twice as much as the this plate amp's 15 lb torroidial. Pioneer makes a better product because I don't hear any hum coming from the front tower speakers, center or surrounds. If I knew I would have to spend another 50 bucks to fix the plate amp's design flaw, I should have bought the QSC power amp that was around $50 more. The thing was, I didn't want to fool with XLR connections since my Pioneer AV am doesn't have those. I should have priced how much XLR to RCA plug adaptors cost too. I am betting that the QSC being a profession quality amp wouldn't have this problem like this Dayton piece of crap. Still, my question stands: Why do I need the ground pin anyway if it fixes the hum problem?

That's what it probably is. Get a power conditioner or PS Audio Power Ports. I've read they work quite well.

I went to PS Audio website:

http://www.psaudio.com/products/xstream_power_punch_overview.asp

There it discusses the exact same problem that I am experiencing with my sub plate amp. It answered my question under the section: Removable Ground Pin. Their product, a high end power cord, actually features a removable ground pin. They discuss removing the ground pin if any hum and buzz is experienced after hooking up your audio equipment. They even mention the cheap solution cheater plug that I am using. However, the cheater plug, because of its cheap construction negates the advantages of their high end power cord.

So, the solution that I found that works is what audio and theater enthusiasts have used for years: a simple cheater plug to break the ground loop. Fantasically simple. EUREKA.

Thanks for pointing me in the right direction!

A ground loop problem may also be introduced into your system through the cable TV wire. Unhook your coaxial cable and see if the hum goes away...

A ground loop problem may also be introduced into your system through the cable TV wire. Unhook your coaxial cable and see if the hum goes away...

The plate amp manual has a section called Notes About Hum. It suggested exactly the same thing. So your suggestion is right on. I unhooked the coaxial cable from the surge protector input which supposively has a noise reduction filter for the cable, and also after the surge protector (output was unhooked). I was trying to see if the surge protector was introducing hum.

Unhooking the coaxial cable both ways did not eliminate the hum, though. I am not supprised because when I had my house built 5 years ago, I asked the contractor to install the cable network and satellite dish. Thus, it's all custom installed into my house and grounded with the house electrical grounding. I heard horror stories about satellite dish companies' so called standard installion. I paid the contractor to have mine put in right to begin with. So perhaps improper grounding by the satellite dish companies is a common source of hum that you and my manual were referring to.

It looks like the plate amp is the culprit since nothing else is causing the hum.