Descent sub transformer noise

[Reverb2009]

OK guys,
I think I can help with this one. I had the same experiance with my descent sub untill I called ML direct. Try the following-it worked for me...

Go to any hardware store and buy a cheap (less than 1 dollar) ac adapter that will convert the 3 prong plug into a 2 prong plug.

It solved my buzz problem and it is easy/cheap to try. ML assures me that this will not have any adverse affects.

GL...Let us know,
Dominick

You’re referring to a cheater plug to lift the ground. Cheater plugs are used when you have a ground loop. In this situation I don’t think it will help. If he was getting a buzzing wile the sub is on and playing then yes a cheater plug should help, be the buzz he is referring to is when the sub is off. Don’t think a cheater plug will help with that but they are only $1.00 or so, he could try it.

 

[David O]

Zip, you're right. I have already ruled out a ground loop. This is something else. I visited a store that had a Descent on the floor and heard a similar buzz. However, it seemed less pronounced than mine. What is really interesting is that two were on the floor and one was louder than the other. I figure it is normal to some extent and that my line voltage may be higher than average. I checked my line and it fluctuates btw 121 and 124. Again, when on the sub is quiet, even when I place my ear against the enclosure. But when in standby the Descent always draws a current. Therefore, I believe the transistor has to deal with being the only piece of equipment on the circuit pulling a small amt of juice. My concern is that the transformer loosened during shipment and that it will eventually cause a problem. But since I can only hear it by making a conscious effort I should just let it go and enjoy.

 

[Craig]

I was able to identify a ground loop hum by disconnecting the input to the sub. If the hum goes away when the input is not connected then the source of the hum is clearly coming from an upstream component.

I'm not a qualified techie but as I understand it, a humming transformer is usually caused by the AC voltage cycle/hertz. 60hz means the current is alternating 60 times a second. The transformer literally vibrates as a result of this alternating current. If it is loose then it vibrates more. Its common and normal to feel a transformer vibrate on a tube amp. Some vibrate more than others.

 

[David O]

Thx Craig, I have disconnected the input and still hear the transformer inside the unit. By the way, the woofers are quiet during all this. No hum. The noise is centered around the AC line to the wall. Doesn't matter if I disconnect the cable and other equipment on the circuit. I unplugged everything on the circuit and still can hear the transformer buzzing away. It is very slight and I cannot hear it from across the room. You can't even hear it from a foot away. And of course when I turn the main power off on the rear of the Descent everything is quiet.

 

[Reverb2009]

Thx Craig, I have disconnected the input and still hear the transformer inside the unit. By the way, the woofers are quiet during all this. No hum. The noise is centered around the AC line to the wall. Doesn't matter if I disconnect the cable and other equipment on the circuit. I unplugged everything on the circuit and still can hear the transformer buzzing away. It is very slight and I cannot hear it from across the room. You can't even hear it from a foot away. And of course when I turn the main power off on the rear of the Descent everything is quiet.

I should add that I am using a PS Audio Ultimate Xstream power cord with my descent. The Ultimate Xstream is a 6 gauge, quad shielded monster of a power cable with a PS Audio ultimate outlet (40db of noise reduction) power conditioner built in.

It sounds like you may have some DC on your power line. A little direct current can cause a transformer to buzz like that. Ps Audio made a product just for this type of application called the Hub Buster. It’s designed to filter out any DC on the line, to help quite down those noisy transformers. I don’t think PS Audio makes it anymore but they do pop up on Audiogon from time to time. It might be worth it for you to try one if the transformer buzz is bothering you.

 

[edwinr]

If it makes you feel better, I used to own an M&K 150 THX subwoofer. A great sub for movies, but there was a constant low frequency hum from the thing. The hum never affected the performance of the sub, it was just always in background. Nothing I could do would make it go away. Well actually, I tell a lie. There WAS one thing I could do... So now I don't own a sub.