Which power supply???

[HT Junky]

PurePower guys just sent me a replacement 1050 for the one that was defective. No problems so far. I was in agony while it was gone. Once you have this in your system, you won't want to do without it.

The 1050 powers my whole system, including projector, and still has never exceeded 55% current capability.

What are you guys going to do with a 2000. Going to plug in your refrigerator, in hopes that it will cool better?

[kennyt]

I want the 2000 as I have seen 80% on my 700, I know, the 1050 would likely be enough, but I want to also add my surround amp and maybe even subwoofer to the unit, and I always go with the too much power is almost enough theory!

Glad to hear they took care of your problem HTJ!

[HT Junky]

Hey Ken,

Have you noticed that your amps have a little bit of transformer hum when using the PurePower? Both my Musical Design amp and my Outlaw Audio 755 amp have a little bit of transformer hum. It is loud enough that you would notice it when the system is idle, if the amps were out in the open.

I have the amps in the back of my rack, so it is of no concern to me. They even have this transformer hum when plugged into the same circuit as the 1050, but not into the 1050 itself.

I talked to Musical Design and Outlaw Audio. Both mentioned that there must be a little DC leakage into the line somewhere. It makes sense, given the battery is an integral part of the design of these units. Both manufacturers also said that it, in no way, should be a concern to the amps proper functioning.

I plugged my whole system into outlets on the same circuit, but not into the 1050 (so nothing was plugged into the 1050). If I plug the 1050 into the same circuit, my amps have transformer hum. When I unplug the 1050, it stops. The transormer hum was also there on the first unit (1050) that went bad on me.

Like I said, it is of no concern to me, but if my amps sat out in the room it would annoy me for sure.

[rlpiii]

Originally Posted by HT Junky

Hey Ken,

Have you noticed that your amps have a little bit of transformer hum when using the PurePower? Both my Musical Design amp and my Outlaw Audio 755 amp have a little bit of transformer hum. It is loud enough that you would notice it when the system is idle, if the amps were out in the open.

I have the amps in the back of my rack, so it is of no concern to me. They even have this transformer hum when plugged into the same circuit as the 1050, but not into the 1050 itself.

I talked to Musical Design and Outlaw Audio. Both mentioned that there must be a little DC leakage into the line somewhere. It makes sense, given the battery is an integral part of the design of these units. Both manufacturers also said that it, in no way, should be a concern to the amps proper functioning.

I plugged my whole system into outlets on the same circuit, but not into the 1050 (so nothing was plugged into the 1050). If I plug the 1050 into the same circuit, my amps have transformer hum. When I unplug the 1050, it stops. The transormer hum was also there on the first unit (1050) that went bad on me.

Like I said, it is of no concern to me, but if my amps sat out in the room it would annoy me for sure.

I really dislike hearing hum, and would probably pull out anything making it. My experience has been that hum is usually due to a grounding problem. Maybe something in the 1050 is loose which could eventually cause it to fail, like your first unit. As much as you paid for a 1050, I would think hearing hum would be unacceptable. If there is "DC leakage" I would ask for a unit with a better quality build that is not "leaking."

[wes]

None of these power supply will reduce the hum due to grounding, you have to get rid of the ground loop other wise you will continue to be plagued with it.

I have tried Tripp, Lite, Furman Pro, Monster Cable, APC none of them where able to get rid of hum then I got a cheap plug

Here are some methods to help you get rid of ground loops. Try these first and don't waste money on a power "conditioner" which, in most cases, won't help. (There is no need to "condition" the AC power for your system. Your receiver or amplifier already has a power supply with its own filters and transformers. No further filtering is normally required.)

* If you get your system up and running and hear an audible buzz or hum, the first culprit to look at is either the powered subwoofer or your cable-TV or satellite-box feed at the entry point to your system.

* First, the subwoofer: unplug the coaxial cable that connects to your powered subwoofer to see if the ground-loop hum disappears. If it does, it's likely coming in through your cable/satellite TV feed.

* Reconnect your subwoofer's coaxial cable from the subwoofer input to your receiver's subwoofer output and disconnect the cable-TV feed (or satellite feed) from your outboard set-top cable box or satellite tuner. Be sure and disconnect the cable before any splitters. Now see if the hum/buzz from your subwoofer stops.

If that eliminates the hum, you can install one of these inexpensive in-line ground isolators from Parts Express or Bass Home. Note that these transformer-based ground isolators will work fine with analog cable-TV feeds, but depending on their design they may interfere with or block reception of HDTV signals via a digital cable or satellite dish feed.

Install the ground isolator between the cable-TV feed and the input of your outboard cable-TV box or satellite tuner (or the TV display's antenna or cable input if you have a set with a built-in TV tuner or a cable-card ready set). In many cases, the ground isolator will "break" the loop and remove the annoying hum or buzz by isolating the TV-cable ground.

If a hum remains with the TV cable completely disconnected from your system, or you don't want to risk degrading reception of HD signals from a cable or satellite system, then you may have to add a ground isolator like this Radio Shack Model 270-054 between the line-level coaxial subwoofer cable from your A/V receiver and the line-level input jack on your powered subwoofer.

In all cases, if your subwoofer has a ground-lift screw like some of Axiom's subwoofers, try first removing the screw (or replacing it) to see if it increases or eliminates the hum. It may or may not make a difference.

If you do not have easy access to the aforementioned ground isolators, here are a few more tips:

* Try plugging the subwoofer into a different AC outlet in the room, one that isn't supplying power to your components (A/V receiver, TV, cable box, etc.). That might fix it.

* Try reversing the AC plug for your A/V receiver or the powered subwoofer. If it's a 3-wire plug or a polarized plug, which has one prong wider than the other, you won't be able to reverse the plug. For safety, do not use a "cheater plug" to bypass the 3-wire plug.

* With the power OFF, reverse the AC plugs one by one of any other components that have a standard 2-prong AC plug that isn't polarized. Each time you reverse a plug, turn on the system with the attached component and your subwoofer and see if the hum disappears. In some cases, reversing one or more plugs will eliminate the hum.

If you have a turntable, try connecting a separate ground wire to a chassis screw on your preamp or receiver and see if the hum disappears. If you already have a turntable ground wire, try removing it from the preamp. One or the other may eliminate the hum.

Finally, here is another solution that worked well for a member of our message boards who decided to discard his ground-loop isolator on his subwoofer: "I took off the ground-loop isolator I'd been using and connected a plain 14-gauge wire to chassis screws on the sub and the receiver then powered everything on. Although hum was still there, it was far lower than before. Next I unscrewed the ground-loop screw on the back of the sub and that took care of the hum completely."


http://www.epanorama.net/documents/groundloop/

http://www.gbaudio.co.uk/data/ground.htm

[kennyt]

I have had a really slight transformer hum from my sub and on occasion the surround amp that aren't run through the PP, I'll have to check if it goes away when I unplug the PP.